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Dabbert T, Okagaki RJ, Cho S, Heinen S, Boddu J, Muehlbauer GJ. The genetics of barley low-tillering mutants: low number of tillers-1 (lnt1). TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2010; 121:705-15. [PMID: 20407739 DOI: 10.1007/s00122-010-1342-5] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2009] [Accepted: 04/03/2010] [Indexed: 05/10/2023]
Abstract
Barley (Hordeum vulgare L.) carrying recessive mutations at the Low number of tillers1 (Lnt1) gene does not develop secondary tillers and only develops one to four tillers by maturity. Double mutant analysis determined that the lnt1 mutant was epistatic to five of the six low and high tillering mutants tested. Double mutants of lnt1 and the low tillering mutant intermedium-b (int-b) resulted in a uniculm plant, indicating a synergistic interaction and that Lnt and Int-b function in separate tillering pathways. RNA profiling identified 70 transcripts with either increased or decreased abundance in the lnt1 mutant compared to wild-type. One gene with reduced transcript levels in the lnt1 mutant was the BELL-like homeodomain transcription factor JuBel2. The JuBel2 allele in the lnt1.a mutant contained a frameshift mutation that eliminated most of the predicted polypeptide, indicating that the Lnt1 gene encodes JuBel2. Previous studies with the low-tillering mutant absent lower laterals (als) showed that the tillering phenotypes and genetic interactions of als and lnt1 with other tillering mutants were very similar. However, the transcriptomes were very different; many transcripts annotated as stress and defense response exhibited increased abundance in the als mutant. This difference suggests a functional separation between Als and Lnt1 in the genetic control of tillering.
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Affiliation(s)
- Timothy Dabbert
- Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, MN 55108, USA
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252
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Crawford S, Shinohara N, Sieberer T, Williamson L, George G, Hepworth J, Müller D, Domagalska MA, Leyser O. Strigolactones enhance competition between shoot branches by dampening auxin transport. Development 2010; 137:2905-13. [PMID: 20667910 DOI: 10.1242/dev.051987] [Citation(s) in RCA: 228] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Strigolactones (SLs), or their derivatives, were recently demonstrated to act as endogenous shoot branching inhibitors, but their biosynthesis and mechanism of action are poorly understood. Here we show that the branching phenotype of mutants in the Arabidopsis P450 family member, MAX1, can be fully rescued by strigolactone addition, suggesting that MAX1 acts in SL synthesis. We demonstrate that SLs modulate polar auxin transport to control branching and that both the synthetic SL GR24 and endogenous SL synthesis significantly reduce the basipetal transport of a second branch-regulating hormone, auxin. Importantly, GR24 inhibits branching only in the presence of auxin in the main stem, and enhances competition between two branches on a common stem. Together, these results support two current hypotheses: that auxin moving down the main stem inhibits branch activity by preventing the establishment of auxin transport out of axillary branches; and that SLs act by dampening auxin transport, thus enhancing competition between branches.
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253
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Unconditional and conditional QTL mapping for the developmental behavior of tiller number in rice (Oryza sativa L.). Genetica 2010; 138:885-93. [PMID: 20623365 DOI: 10.1007/s10709-010-9471-y] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2009] [Accepted: 06/28/2010] [Indexed: 10/19/2022]
Abstract
A single segment substitution population of 26 lines and their recipient parent Hua-jing-xian 74 (HJX74) were selected as experimental materials for analyzing the developmental behavior of tiller number in rice. By the unconditional QTL (quantitative trait locus) mapping method, a total number of 14 SSSLs were detected with QTLs controlling rice tiller number. The number of QTLs significantly affecting tiller number and their effect values estimated differed across measuring stages. More QTLs could be detected based on time-dependent measures of different stages. By the conditional QTL mapping method, it is possible to reveal net expression of gene in a time interval. 14 QTLs on tiller number expressed their effects in dynamic patterns of themselves during whole ontogeny. They exhibited mainly negative effects within 7 days after transplanting. During 7-21 days, QTLs were in active status and expressed larger positive effects. In the mid-period of 21-35 days, they had opposite genetic effects to wither tillers. Since then these QTLs expressed positive effects again to cause the appearance of noneffective tillers. The dynamics of QTL effects was in agreement with the actual change of tillers. Mapping QTL combining unconditional with conditional analysis for time-dependent measures is helpful to understand roundly the genetic bases for the development of quantitative traits.
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254
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Akiyama K, Ogasawara S, Ito S, Hayashi H. Structural requirements of strigolactones for hyphal branching in AM fungi. PLANT & CELL PHYSIOLOGY 2010; 51:1104-17. [PMID: 20418334 PMCID: PMC2900820 DOI: 10.1093/pcp/pcq058] [Citation(s) in RCA: 214] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2010] [Accepted: 04/19/2010] [Indexed: 05/18/2023]
Abstract
Strigolactones are a group of terpenoid lactones that act as a host-derived signal in the rhizosphere communication of plants with arbuscular mycorrhizal (AM) fungi and root parasitic weeds as well as an endogenous plant hormone regulating shoot branching in plants. Strigolactones induce hyphal branching in AM fungi at very low concentrations, suggesting a highly sensitive perception system for strigolactones present in AM fungi. However, little is known about the structural requirements of strigolactones for hyphal branching in AM fungi. Here, we tested a series of natural and synthetically modified strigolactones as well as non-strigolactone-type germination stimulants for hyphal branching-inducing activity in germinating spores of the AM fungus Gigaspora margarita. All tested compounds with a tricyclic lactone coupled to a methylbutenolide via an enol ether bond showed activity, but differed in the active concentration and in the branching pattern of hyphae. Truncation of the A- and AB-rings in the tricyclic ABC lactone of strigolactones resulted in a drastic reduction in hyphal branching activity. Although the connection of the C-ring in the tricyclic lactone to the methylbutenolide D-ring was shown to be essential for hyphal branching, the bridge structure in the C-D part was found not necessarily to be enol ether, being replaceable with either alkoxy or imino ethers. These structural requirements in AM fungi are very similar but not identical to those observed in root parasitic weeds, especially with respect to the enol ether bridge in the C-D part.
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Affiliation(s)
- Kohki Akiyama
- Graduate School of Life and Environmental Sciences, Osaka Prefecture University, 1-1 Gakuen-cho, Nakaku, Sakai, Osaka, 599-8531 Japan.
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255
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Minakuchi K, Kameoka H, Yasuno N, Umehara M, Luo L, Kobayashi K, Hanada A, Ueno K, Asami T, Yamaguchi S, Kyozuka J. FINE CULM1 (FC1) works downstream of strigolactones to inhibit the outgrowth of axillary buds in rice. PLANT & CELL PHYSIOLOGY 2010; 51:1127-35. [PMID: 20547591 PMCID: PMC2900823 DOI: 10.1093/pcp/pcq083] [Citation(s) in RCA: 197] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2010] [Accepted: 06/03/2010] [Indexed: 05/18/2023]
Abstract
Recent studies of highly branched mutants of pea, Arabidopsis and rice have demonstrated that strigolactones (SLs) act as hormones that inhibit shoot branching. The identification of genes that work downstream of SLs is required for a better understanding of how SLs control the growth of axillary buds. We found that the increased tillering phenotype of fine culm1 (fc1) mutants of rice is not rescued by the application of 1 microM GR24, a synthetic SL analog. Treatment with a high concentration of GR24 (10 microM) causes suppression of tiller growth in wild-type plants, but is not effective on fc1 mutants, implying that proper FC1 functioning is required for SLs to inhibit bud growth. Overexpression of FC1 partially rescued d3-2 defects in the tiller growth and plant height. An in situ hybridization analysis showed that FC1 mRNA accumulates in axillary buds, the shoot apical meristem, young leaves, vascular tissues and the tips of crown roots. FC1 mRNA expression was not significantly affected by GR24, suggesting that transcriptional induction may not be the mechanism by which SLs affect FC1 functioning. On the other hand, the expression level of FC1 is negatively regulated by cytokinin treatment. We propose that FC1 acts as an integrator of multiple signaling pathways and is essential to the fine-tuning of shoot branching in rice.
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Affiliation(s)
- Kosuke Minakuchi
- Graduate School of Agriculture and Life Sciences, University of Tokyo, Yayoi, Bunkyo, Tokyo, 113-8657 Japan
| | - Hiromu Kameoka
- Graduate School of Agriculture and Life Sciences, University of Tokyo, Yayoi, Bunkyo, Tokyo, 113-8657 Japan
| | - Naoko Yasuno
- Graduate School of Agriculture and Life Sciences, University of Tokyo, Yayoi, Bunkyo, Tokyo, 113-8657 Japan
| | | | - Le Luo
- Graduate School of Agriculture and Life Sciences, University of Tokyo, Yayoi, Bunkyo, Tokyo, 113-8657 Japan
| | - Kaoru Kobayashi
- Graduate School of Agriculture and Life Sciences, University of Tokyo, Yayoi, Bunkyo, Tokyo, 113-8657 Japan
| | - Atsushi Hanada
- RIKEN Plant Science Center, Tsurumi, Yokohama, 230-0045 Japan
| | - Kotomi Ueno
- Graduate School of Agriculture and Life Sciences, University of Tokyo, Yayoi, Bunkyo, Tokyo, 113-8657 Japan
| | - Tadao Asami
- Graduate School of Agriculture and Life Sciences, University of Tokyo, Yayoi, Bunkyo, Tokyo, 113-8657 Japan
| | | | - Junko Kyozuka
- Graduate School of Agriculture and Life Sciences, University of Tokyo, Yayoi, Bunkyo, Tokyo, 113-8657 Japan
- *Corresponding author: E-mail; ; Fax, +81-3-5841-5087
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256
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Umehara M, Hanada A, Magome H, Takeda-Kamiya N, Yamaguchi S. Contribution of strigolactones to the inhibition of tiller bud outgrowth under phosphate deficiency in rice. PLANT & CELL PHYSIOLOGY 2010; 51:1118-26. [PMID: 20542891 PMCID: PMC2900824 DOI: 10.1093/pcp/pcq084] [Citation(s) in RCA: 213] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2010] [Accepted: 06/07/2010] [Indexed: 05/18/2023]
Abstract
Strigolactones (SLs) or SL-derived metabolite(s) have recently been shown to act as endogenous inhibitors of axillary bud outgrowth. SLs released from roots induce hyphal branching of arbuscular mycorrhizal (AM) fungi that facilitate the uptake of inorganic nutrients, such as phosphate (Pi) and nitrate, by the host plants. Previous studies have shown that SL levels in root exudates are highly elevated by Pi starvation, which might contribute to successful symbiosis with AM fungi in the rhizosphere. However, how endogenous SL levels elevated by Pi starvation contribute to its hormonal action has been unknown. Here, we show that tiller bud outgrowth in wild-type rice seedlings is inhibited, while root 2'-epi-5-deoxystrigol (epi-5DS) levels are elevated, in response to decreasing Pi concentrations in the media. However, the suppression of tiller bud outgrowth under Pi deficiency does not occur in the SL-deficient and -insensitive mutants. We also show that the responsiveness to exogenous SL is slightly increased by Pi deficiency. When Pi-starved seedlings are transferred to Pi-sufficient media, tiller bud outgrowth is induced following a decrease in root epi-5DS levels. Taken together, these results suggest that elevated SL levels by Pi starvation contribute to the inhibition of tiller bud outgrowth in rice seedlings. We speculate that SL plays a dual role in the adaptation to Pi deficiency; one as a rhizosphere signal to maximize AM fungi symbiosis for improved Pi acquisition and the other as an endogenous hormone or its biosynthetic precursor to optimize shoot branching for efficient Pi utilization.
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257
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Ito S, Kitahata N, Umehara M, Hanada A, Kato A, Ueno K, Mashiguchi K, Kyozuka J, Yoneyama K, Yamaguchi S, Asami T. A new lead chemical for strigolactone biosynthesis inhibitors. PLANT & CELL PHYSIOLOGY 2010; 51:1143-50. [PMID: 20522488 PMCID: PMC2900822 DOI: 10.1093/pcp/pcq077] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Several triazole-containing chemicals have previously been shown to act as efficient inhibitors of cytochrome P450 monooxygenases. To discover a strigolactone biosynthesis inhibitor, we screened a chemical library of triazole derivatives to find chemicals that induce tiller bud outgrowth of rice seedlings. We discovered a triazole-type chemical, TIS13 [2,2-dimethyl-7-phenoxy-4-(1H-1,2,4-triazol-1-yl)heptan-3-ol], which induced outgrowth of second tiller buds of wild-type seedlings, as observed for non-treated strigolactone-deficient d10 mutant seedlings. TIS13 treatment reduced strigolactone levels in both roots and root exudates in a concentration-dependent manner. Co-application of GR24, a synthetic strigolactone, with TIS13 canceled the TIS13-induced tiller bud outgrowth. Taken together, these results indicate that TIS13 inhibits strigolactone biosynthesis in rice seedlings. We propose that TIS13 is a new lead compound for the development of specific strigolactone biosynthesis inhibitors.
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Affiliation(s)
- Shinsaku Ito
- Department of Applied Biological Chemistry, The University of Tokyo, 1-1-1 Yayoi, Bunkyo, Tokyo, 113-8657 Japan
- These authors contributed equally to this work
| | - Nobutaka Kitahata
- Department of Applied Biological Chemistry, The University of Tokyo, 1-1-1 Yayoi, Bunkyo, Tokyo, 113-8657 Japan
- These authors contributed equally to this work
| | | | | | - Atsutaka Kato
- Department of Applied Biological Chemistry, The University of Tokyo, 1-1-1 Yayoi, Bunkyo, Tokyo, 113-8657 Japan
| | - Kotomi Ueno
- Department of Applied Biological Chemistry, The University of Tokyo, 1-1-1 Yayoi, Bunkyo, Tokyo, 113-8657 Japan
| | | | - Junko Kyozuka
- Department of Agricultural and Environmental Biology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo, Tokyo, 113-8657 Japan
| | - Koichi Yoneyama
- Weed Science Center, Utsunomiya University, 350 Mine-machi, Utsunomiya, 321-8505 Japan
| | | | - Tadao Asami
- Department of Applied Biological Chemistry, The University of Tokyo, 1-1-1 Yayoi, Bunkyo, Tokyo, 113-8657 Japan
- *Corresponding author: E-mail, ; Fax, +81-3-5841-5157
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258
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Zhang S, Li G, Fang J, Chen W, Jiang H, Zou J, Liu X, Zhao X, Li X, Chu C, Xie Q, Jiang X, Zhu L. The interactions among DWARF10, auxin and cytokinin underlie lateral bud outgrowth in rice. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2010; 52:626-38. [PMID: 20590993 DOI: 10.1111/j.1744-7909.2010.00960.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Previous studies have shown that DWARF10 (D10) is a rice ortholog of MAX4/RMS1/DAD1, encoding a carotenoid cleavage dioxygenase and functioning in strigolactones/strigolactone-derivatives (SL) biosynthesis. Here we use D10- RNA interference (RNAi) transgenic plants similar to d10 mutant in phenotypes to investigate the interactions among D10, auxin and cytokinin in regulating rice shoot branching. Auxin levels in node 1 of both decapitated D10-RNAi and wild type plants decreased significantly, showing that decapitation does reduce endogenous auxin concentration, but decapitation has no clear effects on auxin levels in node 2 of the same plants. This implies that node 1 may be the location where a possible interaction between auxin and D10 gene would be detected. D10 expression in node 1 is inhibited by decapitation, and this inhibition can be restored by exogenous auxin application, indicating that D10 may play an important role in auxin regulation of SL. The decreased expression of most OsPINs in shoot nodes of D10-RNAi plants may cause a reduced auxin transport capacity. Furthermore, effects of auxin treatment of decapitated plants on the expression of cytokinin biosynthetic genes suggest that D10 promotes cytokinin biosynthesis by reducing auxin levels. Besides, in D10-RNAi plants, decreased storage cytokinin levels in the shoot node may partly account for the increased active cytokinin contents, resulting in more tillering phenotypes.
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Affiliation(s)
- Shuying Zhang
- The State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
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259
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Yamaguchi S, Kyozuka J. Branching hormone is busy both underground and overground. PLANT & CELL PHYSIOLOGY 2010; 51:1091-1094. [PMID: 20621958 DOI: 10.1093/pcp/pcq088] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
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260
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Hu Z, Yan H, Yang J, Yamaguchi S, Maekawa M, Takamure I, Tsutsumi N, Kyozuka J, Nakazono M. Strigolactones negatively regulate mesocotyl elongation in rice during germination and growth in darkness. PLANT & CELL PHYSIOLOGY 2010; 51:1136-42. [PMID: 20498118 PMCID: PMC2900821 DOI: 10.1093/pcp/pcq075] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2010] [Accepted: 05/17/2010] [Indexed: 05/18/2023]
Abstract
Strigolactones (SLs) are newly discovered plant hormones that regulate plant growth and development including shoot branching. They also stimulate symbiosis with arbuscular mycorrhizal fungi. Rice has at least three genes that are involved in SL synthesis (D10, D17/HTD1 and D27) and at least two genes that are involved in SL signaling (D3) and SL signaling or downstream metabolism (D14/D88/HTD2). We observed that mesocotyl elongation in darkness was greater in rice mutants defective in these genes than in the wild type. Exogenous application of a synthetic SL analog, GR24, rescued the phenotype of mesocotyl elongation in the SL-deficient mutants, d10-1, d17-1 and d27-1, in a dose-dependent manner, but did not affect mesocotyl lengths of the SL-insensitive mutants, d3-1 and d14-1. No significant differences in cell length were found between the d mutants and the wild type, except for some cells on the lower half of the d3-1 mesocotyl that were shortened. On the other hand, the number of cells in the mesocotyls was 3- to 6-fold greater in the d mutants than in the wild type. Treatment with GR24 reduced the number of cells in the d10-1 mesocotyl to the wild-type level, but did not affect the number of cells in the d3-1 and d14-1 mesocotyls. These findings indicate that SLs negatively regulate cell division, but not cell elongation, in the mesocotyl during germination and growth of rice in darkness.
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Affiliation(s)
- Zhongyuan Hu
- Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo, Tokyo, 113-8657 Japan
| | - Haifang Yan
- Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo, Tokyo, 113-8657 Japan
- College of Life Science, Northeast Forestry University, Harbin, 150040 PR China
| | - Jinghua Yang
- Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo, Tokyo, 113-8657 Japan
- Department of Horticulture, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, 310029 PR China
| | | | - Masahiko Maekawa
- Research Institute for Bioresources, Okayama University, 2-20-1 Chuo, Kurashiki, Okayama, 710-0046 Japan
| | - Itsuro Takamure
- Faculty of Agriculture, Hokkaido University, Sapporo, 060-8589 Japan
| | - Nobuhiro Tsutsumi
- Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo, Tokyo, 113-8657 Japan
| | - Junko Kyozuka
- Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo, Tokyo, 113-8657 Japan
| | - Mikio Nakazono
- Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo, Tokyo, 113-8657 Japan
- Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa, Nagoya, 464-8601 Japan
- *Corresponding author: E-mail, ; Fax: +81-52-789-4018
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261
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Abstract
Axillary meristems form in the axils of leaves. After an initial phase of meristematic activity during which a small axillary bud is produced, they often enter a state of suspended growth from which they may be released to form a shoot branch. This post-embryonic growth plasticity is typical of plants and allows them to adapt to changing environmental conditions. The shoot architecture of genotypically identical plants may display completely contrasting phenotypes when grown in distinct environmental niches, with one having only a primary inflorescence and many arrested axillary meristems and the other displaying higher orders of branches. In order to cease and resume growth as required, the plant must co-ordinate its intrinsic developmental programme with the responses to environmental cues. It is thought that information from the environment is integrated throughout the plant using plant hormones as long-distance signals. In the present review, we focus primarily on how two of these hormones, auxin and strigolactones, may be acting to regulate shoot branching.
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262
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Liang J, Zhao L, Challis R, Leyser O. Strigolactone regulation of shoot branching in chrysanthemum (Dendranthema grandiflorum). JOURNAL OF EXPERIMENTAL BOTANY 2010; 61:3069-78. [PMID: 20478970 PMCID: PMC2892150 DOI: 10.1093/jxb/erq133] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2010] [Revised: 03/29/2010] [Accepted: 04/23/2010] [Indexed: 05/18/2023]
Abstract
Previous studies of highly branched mutants in pea (rms1-rms5), Arabidopsis thaliana (max1-max4), petunia (dad1-dad3), and rice (d3, d10, htd1/d17, d14, d27) identified strigolactones or their derivates (SLs), as shoot branching inhibitors. This recent discovery offers the possibility of using SLs to regulate branching commercially, for example, in chrysanthemum, an important cut flower crop. To investigate this option, SL physiology and molecular biology were studied in chrysanthemum (Dendranthema grandiflorum), focusing on the CCD8/MAX4/DAD1/RMS1/D10 gene. Our results suggest that, as has been proposed for Arabidopsis, the ability of SLs to inhibit bud activity depends on the presence of a competing auxin source. The chrysanthemum SL biosynthesis gene, CCD8 was cloned, and found to be regulated in a similar, but not identical way to known CCD8s. Expression analyses revealed that DgCCD8 is predominantly expressed in roots and stems, and is up-regulated by exogenous auxin. Exogenous SL can down-regulate DgCCD8 expression, but this effect can be overridden by apical auxin application. This study provides evidence that SLs are promising candidates to alter the shoot branching habit of chrysanthemum.
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Affiliation(s)
- Jianli Liang
- Department of Ornamental Horticulture and Landscape Architecture, China Agricultural University, Beijing 100193, China
- Department of Biology, University of York, York YO10 5YW, UK
| | - Liangjun Zhao
- Department of Ornamental Horticulture and Landscape Architecture, China Agricultural University, Beijing 100193, China
- To whom correspondence should be addressed: E-mail: ;
| | - Richard Challis
- Department of Biology, University of York, York YO10 5YW, UK
| | - Ottoline Leyser
- Department of Biology, University of York, York YO10 5YW, UK
- To whom correspondence should be addressed: E-mail: ;
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263
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Walter MH, Floss DS, Strack D. Apocarotenoids: hormones, mycorrhizal metabolites and aroma volatiles. PLANTA 2010; 232:1-17. [PMID: 20396903 DOI: 10.1007/s00425-010-1156-3] [Citation(s) in RCA: 141] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2010] [Accepted: 03/12/2010] [Indexed: 05/18/2023]
Abstract
Apocarotenoids are tailored from carotenoids by oxidative enzymes [carotenoid cleavage oxygenases (CCOs)], cleaving specific double bonds of the polyene chain. The cleavage products can act as hormones, signaling compounds, chromophores and scent/aroma constituents. Recent advances were the identification of strigolactones as apocarotenoids and the description of their novel role as shoot branching inhibitor hormones. Strigolactones are also involved in plant signaling to both harmful (parasitic weeds) and beneficial [arbuscular mycorrhizal (AM) fungi] rhizosphere residents. This review describes the progress in the characterization of CCOs, termed CCDs and NCEDs, in plants. It highlights the importance of sequential cleavage reactions of C(40) carotenoid precursors, the apocarotenoid cleavage oxygenase (ACO) nature of several CCOs and the topic of compartmentation. Work on the biosynthesis of abundant C(13) cyclohexenone and C(14) mycorradicin apocarotenoids in mycorrhizal roots has revealed a new role of CCD1 as an ACO of C(27) apocarotenoid intermediates, following their predicted export from plastid to cytosol. Manipulation of the AM-induced apocarotenoid pathway further suggests novel roles of C(13) apocarotenoids in controlling arbuscule turnover in the AM symbiosis. CCD7 has been established as a biosynthetic crosspoint, controlling both strigolactone and AM-induced C(13) apocarotenoid biosynthesis. Interdependence of the two apocarotenoid pathways may thus play a role in AM-mediated reduction of parasitic weed infestations. Potential scenarios of C(13) scent/aroma volatile biogenesis are discussed, including the novel mechanism revealed from mycorrhizal roots. The recent progress in apocarotenoid research opens up new perspectives for fundamental work, but has also great application potential for the horticulture, food and fragrance industries.
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Affiliation(s)
- Michael H Walter
- Abteilung Sekundärstoffwechsel, Leibniz-Institut für Pflanzenbiochemie, Halle (Saale), Germany.
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264
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Waldie T, Hayward A, Beveridge CA. Axillary bud outgrowth in herbaceous shoots: how do strigolactones fit into the picture? PLANT MOLECULAR BIOLOGY 2010; 73:27-36. [PMID: 20112050 DOI: 10.1007/s11103-010-9599-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2009] [Accepted: 01/07/2010] [Indexed: 05/11/2023]
Abstract
Strigolactones have recently been identified as the long sought-after signal required to inhibit shoot branching (Gomez-Roldan et al. 2008; Umehara et al. 2008; reviewed in Dun et al. 2009). Here we briefly describe the evidence for strigolactone inhibition of shoot branching and, more extensively, the broader context of this action. We address the central question of why strigolactone mutants exhibit a varied branching phenotype across a wide range of experimental conditions. Where knowledge is available, we highlight the role of other hormones in dictating these phenotypes and describe those instances where our knowledge of known plant hormones and their interactions falls considerably short of explaining the phenotypes. This review will focus on bud outgrowth in herbaceous species because knowledge on the role of strigolactones in shoot branching to date barely extends beyond this group of plants.
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Affiliation(s)
- Tanya Waldie
- School of Biological Sciences and Australian Research Council Centre of Excellence in Integrative Legume Research, The University of Queensland, Brisbane, QLD 4072, Australia
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265
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Cui X, Ge C, Wang R, Wang H, Chen W, Fu Z, Jiang X, Li J, Wang Y. The BUD2 mutation affects plant architecture through altering cytokinin and auxin responses in Arabidopsis. Cell Res 2010; 20:576-86. [DOI: 10.1038/cr.2010.51] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
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266
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Fujita D, Ebron LA, Araki E, Kato H, Khush GS, Sheehy JE, Lafarge T, Fukuta Y, Kobayashi N. Fine mapping of a gene for low-tiller number, Ltn, in japonica rice (Oryza sativa L.) variety Aikawa 1. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2010; 120:1233-40. [PMID: 20062964 DOI: 10.1007/s00122-009-1251-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2009] [Accepted: 12/19/2009] [Indexed: 05/09/2023]
Abstract
Tillering is one of the most important agronomic traits related to grain production in rice (Oryza sativa L.). A japonica-type variety, Aikawa 1, is known to have low-tiller number. The detailed location of a low-tillering gene, Ltn, which has been localized on chromosome 8 in Aikawa 1, was confirmed by molecular mapping. Using BC5F2 individuals derived from a cross between IR64 and Aikawa 1, the low-tillering gene was mapped to an interval defined by SSR markers ssr5816-3 and A4765. This was designated as Ltn because there was no reported gene for tillering in the region of chromosome 8. Through high-resolution linkage analysis, the candidate region of Ltn was located between DNA markers ssr6049-23 and ind6049-1 corresponding to 38.6 kbp on the Nipponbare genome sequence. These DNA markers, which were tightly linked to Ltn, are useful for marker-assisted selection in breeding studies.
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Affiliation(s)
- Daisuke Fujita
- International Rice Research Institute, DAPO Box 7777, Metro Manila, Philippines
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267
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Abstract
For several decades, auxin and cytokinin were the only two hormones known to be involved in the control of shoot branching through apical dominance, a process where the shoot apex producing auxin inhibits the outgrowth of axillary buds located below. Grafting studies with high branching mutants and cloning of the mutated genes demonstrated the existence of a novel long distance carotenoid derived signal which acted as a branching inhibitor. Recently, this branching inhibitor has been shown to belong to the strigolactones, a group of small molecules already known to be produced by roots, exuded in the rhizosphere and as having a role in both parasitic and symbiotic interactions.
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Affiliation(s)
- Catherine Rameau
- Institut National de la Recherche Agronomique, institut Jean-Pierre Bourgin, UMR 1318 INRA-AgroParisTech, INRA Centre de Versailles-Grignon, Versailles cedex, France.
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268
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Kebrom TH, Brutnell TP, Finlayson SA. Suppression of sorghum axillary bud outgrowth by shade, phyB and defoliation signalling pathways. PLANT, CELL & ENVIRONMENT 2010; 33:48-58. [PMID: 19843258 DOI: 10.1111/j.1365-3040.2009.02050.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
In recent years, several genetic components of vegetative axillary bud development have been defined in both monocots and eudicots, but our understanding of environmental inputs on branching remains limited. Recent work in sorghum (Sorghum bicolor) has revealed a role for phytochrome B (phyB) in the control of axillary bud outgrowth through the regulation of Teosinte Branched1 (TB1) gene. In maize (Zea mays), TB1 is a dosage-dependent inhibitor of axillary meristem progression, and the expression level of TB1 is a sensitive measure of axillary branch development. To further explore the mechanistic basis of branching, the expression of branching and cell cycle-related genes were examined in phyB-1 and wild-type sorghum axillary buds following treatment with low-red : far-red light and defoliation. Although defoliation inhibited bud outgrowth, it did not influence the expression of sorghum TB1 (SbTB1), whereas changes in SbMAX2 expression, a homolog of the Arabidopsis (Arabidopsis thaliana) branching inhibitor MAX2, were associated with the regulation of bud outgrowth by both light and defoliation. The expression of several cell cycle-related genes was also decreased dramatically in buds repressed by defoliation, but not by phyB deficiency. The data suggest that there are at least two distinct molecular pathways that respond to light and endogenous signals to regulate axillary bud outgrowth.
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269
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Abstract
Grain yield in rice is a complex trait multiplicatively determined by its three component traits: number of panicles, number of grains per panicle, and grain weight; all of which are typical quantitative traits. The developments in genome mapping, sequencing, and functional genomic research have provided powerful tools for investigating the genetic and molecular bases of these quantitative traits. Dissection of the genetic bases of the yield traits based on molecular marker linkage maps resolved hundreds of quantitative trait loci (QTLs) for these traits. Mutant analyses and map-based cloning of QTLs have identified a large number of genes required for the basic processes underlying the initiation and development of tillers and panicles, as well as genes controlling numbers and sizes of grains and panicles. Molecular characterization of these genes has greatly advanced the mechanistic understanding of the regulation of these rice yield traits. These findings have significant implications in crop genetic improvement.
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Affiliation(s)
- Yongzhong Xing
- National Key Laboratory of Crop Genetic Improvement, National Center of Plant Gene Research (Wuhan), Huazhong Agricultural University, Wuhan, China
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270
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Sunohara H, Kawai T, Shimizu-Sato S, Sato Y, Sato K, Kitano H. A dominant mutation of TWISTED DWARF 1 encoding an alpha-tubulin protein causes severe dwarfism and right helical growth in rice. Genes Genet Syst 2009; 84:209-18. [PMID: 19745569 DOI: 10.1266/ggs.84.209] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Dwarfism is a common type of mutation in many plant species. The pathways and factors regulating biosynthesis and signaling of several plant growth regulators have been clarified through analyses of dwarf mutants in rice, Arabidopsis, pea, and maize. However, the genetic mechanisms controlling dwarfism are not well characterized, and the causal genes underlying most dwarf mutants are still uncovered. Here, we report a dominant mutant, Twisted dwarf 1-1 (Tid1-1), showing dwarfism and twisted growth in rice. Tid1-1 exhibit right helical growth of the leaves and stem and shortening of the roots. They also show an increased number of cells in the shoot apical meristem. Cells in the leaves of Tid1-1 are often ill-shapen, possibly owing to irregular cell division. Cell elongation in roots is suppressed in the elongation zone, and cells in the root apical meristem are enlarged. Map-based cloning of TID1 revealed that it encodes an alpha-tubulin protein comprising microtubules and is an ortholog of Arabidopsis LEFTY genes. Our analysis of the Tid1-1 mutant revealed that the dynamics of microtubules affects not only anisotropic growth in both dicots and monocots, but also meristematic activity and gross plant morphology.
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Affiliation(s)
- Hidehiko Sunohara
- Bioscience and Biotechnology Center, Nagoya University, Furo-cho, Chikusa, Nagoya, Japan
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271
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Liu Y, Feng X, Xu Y, Yu J, Ao G, Peng Z, Zhao Q. Overexpression of millet ZIP-like gene (SiPf40) affects lateral bud outgrowth in tobacco and millet. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2009; 47:1051-60. [PMID: 19766013 DOI: 10.1016/j.plaphy.2009.08.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2008] [Revised: 08/24/2009] [Accepted: 08/28/2009] [Indexed: 05/28/2023]
Abstract
A SiPf40 gene was identified from an immature seed cDNA library of foxtail millet (Setaria italica). This gene encodes for a 29.4 KDa protein containing eight potential transmembrane domains and a highly conserved ZIP signature motif typical of ZIPs (zinc or iron transporter proteins) family. Other SiPf40 potential homologous genes have also been identified in rice, maize, wheat and Arabidopsis by Southern analysis. Expression data showed that this gene is preferentially expressed in millet hypocotyl and bud; however, a minimal level of constitutive expression could be detected in other foxtail millet tissues. Overexpression of SiPf40 gene causes extra branches in tobacco and extra tillering in millet associated with vessel enlarging and xylary fibers increasing, whereas the tiller number decreases in SiPf40 gene silenced plants. Moreover, IAA content decreased significantly in shoot apex of the transgenic tobacco overexpressing SiPf40 gene. All together, these morphological alterations indicate that SiPf40 gene is essential for lateral shoots growth.
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Affiliation(s)
- Yinghui Liu
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing 100193, China
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272
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Dun EA, Hanan J, Beveridge CA. Computational modeling and molecular physiology experiments reveal new insights into shoot branching in pea. THE PLANT CELL 2009; 21:3459-72. [PMID: 19948786 PMCID: PMC2798318 DOI: 10.1105/tpc.109.069013] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2009] [Revised: 09/17/2009] [Accepted: 11/02/2009] [Indexed: 05/20/2023]
Abstract
Bud outgrowth is regulated by the interplay of multiple hormones, including auxin, cytokinin, strigolactones, and an unidentified long-distance feedback signal that moves from shoot to root. The model of bud outgrowth regulation in pea (Pisum sativum) includes these signals and a network of five RAMOSUS (RMS) genes that operate in a shoot-root-shoot loop to regulate the synthesis of, and response to, strigolactones. The number of components in this network renders the integration of new and existing hypotheses both complex and cumbersome. A hypothesis-driven computational model was therefore developed to help understand regulation of shoot branching. The model evolved in parallel with stepwise laboratory research, helping to define and test key hypotheses. The computational model was used to verify new mechanisms involved in the regulation of shoot branching by confirming that the new hypotheses captured all relevant biological data sets. Based on cytokinin and RMS1 expression analyses, this model is extended to include subtle but important differences in the function of RMS3 and RMS4 genes in the shoot and rootstock. Additionally, this research indicates that a branch-derived signal upregulates RMS1 expression independent of the other feedback signal. Furthermore, we propose xylem-sap cytokinin promotes sustained bud outgrowth, rather than acting at the earlier stage of bud release.
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Affiliation(s)
- Elizabeth A. Dun
- The University of Queensland, Australian Research Council Centre of Excellence for Integrative Legume Research and School of Biological Sciences, St. Lucia, 4072 Australia
| | - Jim Hanan
- The University of Queensland, Centre for Biological Information Technology, St. Lucia, 4072 Australia
| | - Christine A. Beveridge
- The University of Queensland, Australian Research Council Centre of Excellence for Integrative Legume Research and School of Biological Sciences, St. Lucia, 4072 Australia
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273
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Gao Z, Qian Q, Liu X, Yan M, Feng Q, Dong G, Liu J, Han B. Dwarf 88, a novel putative esterase gene affecting architecture of rice plant. PLANT MOLECULAR BIOLOGY 2009; 71:265-76. [PMID: 19603144 DOI: 10.1007/s11103-009-9522-x] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2009] [Accepted: 06/30/2009] [Indexed: 05/07/2023]
Abstract
Rice architecture is an important agronomic trait that affects grain yield. We characterized a tillering dwarf mutant d88 derived from Oryza sativa ssp. japonica cultivar Lansheng treated with EMS. The mutant had excessive shorter tillers and smaller panicles and seeds compared to the wild-type. A reduction in number and size of parenchyma cells around stem marrow cavity as well as a delay in the elongation of parenchyma cells caused slender tillers and dwarfism in the d88 mutant. The D88 gene was isolated via map-based cloning and identified to encode a putative esterase. The gene was expressed in most rice organs, with especially high levels in the vascular tissues. The mutant carried a nucleotide substitution in the first exon of the gene that led to the substitution of arginine for glycine, which presumably disrupted the functionally conserved N-myristoylation domain of the protein. The function of the gene was confirmed by complementation test and antisense analysis. D88, thus, represents a new category of genes that regulates cell growth and organ development and consequently plant architecture. The potential relationship between the tiller formation associated genes and D88 is discussed and future identification of the substrate for D88 may lead to the characterization of new pathways regulating plant development.
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Affiliation(s)
- Zhenyu Gao
- National Center for Gene Research/Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 200233 Shanghai, China
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274
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Kant S, Bi YM, Zhu T, Rothstein SJ. SAUR39, a small auxin-up RNA gene, acts as a negative regulator of auxin synthesis and transport in rice. PLANT PHYSIOLOGY 2009; 151:691-701. [PMID: 19700562 PMCID: PMC2754634 DOI: 10.1104/pp.109.143875] [Citation(s) in RCA: 176] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2009] [Accepted: 08/18/2009] [Indexed: 05/18/2023]
Abstract
The phytohormone auxin plays a critical role for plant growth by regulating the expression of a set of genes. One large auxin-responsive gene family of this type is the small auxin-up RNA (SAUR) genes, although their function is largely unknown. The expression of the rice (Oryza sativa) SAUR39 gene showed rapid induction by transient change in different environmental factors, including auxin, nitrogen, salinity, cytokinin, and anoxia. Transgenic rice plants overexpressing the SAUR39 gene resulted in lower shoot and root growth, altered shoot morphology, smaller vascular tissue, and lower yield compared with wild-type plants. The SAUR39 gene was expressed at higher levels in older leaves, unlike auxin biosynthesis, which occurs largely in the meristematic region. The transgenic plants had a lower auxin level and a reduced polar auxin transport as well as the down-regulation of some putative auxin biosynthesis and transporter genes. Biochemical analysis also revealed that transgenic plants had lower chlorophyll content, higher levels of anthocyanin, abscisic acid, sugar, and starch, and faster leaf senescence compared with wild-type plants at the vegetative stage. Most of these phenomena have been shown to be negatively correlated with auxin level and transport. Transcript profiling revealed that metabolic perturbations in overexpresser plants were largely due to transcriptional changes of genes involved in photosynthesis, senescence, chlorophyll production, anthocyanin accumulation, sugar synthesis, and transport. The lower growth and yield of overexpresser plants was largely recovered by exogenous auxin application. Taken together, the results suggest that SAUR39 acts as a negative regulator for auxin synthesis and transport.
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Affiliation(s)
- Surya Kant
- Department of Molecular and Cellular Biology, College of Biological Science, University of Guelph, Guelph, Ontario, Canada N1G 2W1
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275
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Jiang HP, Zhang SY, Bao JS, Wang BL, Wang S. [Genetic analysis and mapping of high-tillering and dwarf mutant htd1-2 in rice]. YI CHUAN = HEREDITAS 2009; 31:531-9. [PMID: 19586849 DOI: 10.3724/sp.j.1005.2009.00531] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Tillering is one of the most important agronomic traits of rice. In order to explore the molecular mechanism of rice tillering, a high-tillering dwarf 1-2 (htd1-2) mutant was isolated from the offspring of the indica rice (Oryza sativa L. ssp. indica) variety 9311 treated with 350Gy 60Co gamma-radiation. Genetic analysis showed that both high tillering and dwarf phenotypes of htd1-2 were controlled by a single recessive nuclear gene. By means of molecular marker technique, the HIGH-TILLERING DWARF1-2(HTD1-2) gene was mapped between two CAPS markers A6 and E2 on chromosome 4 within 116 kilobases. Within this region, there is a cloned gene HIGH-TILLERING DWARF1(HTD1), which controls rice tillering. By comparing sequences of HTD1 between htd1-2 and 9311, in combination with the results from dCAPS analysis, we believed that HTD1 is an orthologue of the gene HTD1-2. Because of different genetic backgrounds, htd1 and htd1-2 have different phenotypes although they are the allelic mutants. Furthermore, removal of axillary buds proved that dwarfism of htd1-2 mutant is partly attributed to its excessive tillers.
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Affiliation(s)
- Hai-Pai Jiang
- College of Agronomy, Shenyang Agricultural University, Shenyang 110161, China.
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276
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Shan JX, Zhu MZ, Shi M, Gao JP, Lin HX. Fine mapping and candidate gene analysis of spd6, responsible for small panicle and dwarfness in wild rice (Oryza rufipogon Griff.). TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2009; 119:827-36. [PMID: 19588119 DOI: 10.1007/s00122-009-1092-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2009] [Accepted: 06/08/2009] [Indexed: 05/20/2023]
Abstract
Identification of genes in rice that affect production and quality is necessary for improving the critical global food source. CSSL58, a chromosome segment substitution line (CSSL) containing a chromosome segment of Oryza rufipogon in the genetic background of the indica cultivar Teqing showed significantly smaller panicles, fewer grains per panicle, smaller grains and dwarfness compared with the recurrent parent Teqing. Genetic analysis of the BC(4)F(1) and BC(4)F(2) generations, derived from a cross between CSSL58 and Teqing, showed that these traits are controlled by the recessive gene spd6, which mapped to the short arm of chromosome 6. Fine mapping and high-resolution linkage analysis using 24,120 BC(4)F(3) plants and markers flanking spd6 were carried out, and the gene was localized to a 22.4 kb region that contains four annotated genes according to the genome sequence of japonica Nipponbare. Phenotypic evaluation of the nearly isogenic line NIL(spd6) revealed that spd6 from wild rice has pleiotropic effects on panicle number per plant, grain size, grain weight, grain number per panicle and plant height, suggesting that this gene might play an important role in the domestication of rice. The discovery of spd6 may ultimately be useful for the design and breeding of crops with high grain yield and quality.
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Affiliation(s)
- Jun-Xiang Shan
- National Key Laboratory of Plant Molecular Genetics, Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Graduate School of the Chinese Academy of Science, 200032 Shanghai, China
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277
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Liu W, Wu C, Fu Y, Hu G, Si H, Zhu L, Luan W, He Z, Sun Z. Identification and characterization of HTD2: a novel gene negatively regulating tiller bud outgrowth in rice. PLANTA 2009; 230:649-58. [PMID: 19579033 DOI: 10.1007/s00425-009-0975-6] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2009] [Accepted: 06/19/2009] [Indexed: 05/20/2023]
Abstract
Tiller number is highly regulated by controlling the formation of tiller bud and its subsequent outgrowth in response to endogenous and environmental signals. Here, we identified a rice mutant htd2 from one of the 15,000 transgenic rice lines, which is characterized by a high tillering and dwarf phenotype. Phenotypic analysis of the mutant showed that the mutation did not affect formation of tiller bud, but promoted the subsequent outgrowth of tiller bud. To isolate the htd2 gene, a map-based cloning strategy was employed and 17 new insertions-deletions (InDels) markers were developed. A high-resolution physical map of the chromosomal region around the htd2 gene was made using the F(2) and F(3) population. Finally, the gene was mapped in 12.8 kb region between marker HT41 and marker HT52 within the BAC clone OSJNBa0009J13. Cloning and sequencing of the target region from the mutant showed that the T-DNA insertion caused a 463 bp deletion between the promoter and first exon of an esterase/lipase/thioesterase family gene in the 12.8 kb region. Furthermore, transgenic rice with reduced expression level of the gene exhibited an enhanced tillering and dwarf phenotype. Accordingly, the esterase/lipase/thioesterase family gene (TIGR locus Os03g10620) was identified as the HTD2 gene. HTD2 transcripts were expressed mainly in leaf. Loss of function of HTD2 resulted in a significantly increased expression of HTD1, D10 and D3, which were involved in the strigolactone biosynthetic pathway. The results suggest that the HTD2 gene could negatively regulate tiller bud outgrowth by the strigolactone pathway.
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Affiliation(s)
- Wenzhen Liu
- State Key Laboratory of Rice Biology, China National Rice Research Institute, 310006 Hangzhou, Zhejiang, China.
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278
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Chen C, Zou J, Zhang S, Zaitlin D, Zhu L. Strigolactones are a new-defined class of plant hormones which inhibit shoot branching and mediate the interaction of plant-AM fungi and plant-parasitic weeds. ACTA ACUST UNITED AC 2009; 52:693-700. [DOI: 10.1007/s11427-009-0104-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2009] [Accepted: 04/30/2009] [Indexed: 01/02/2023]
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279
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Arite T, Umehara M, Ishikawa S, Hanada A, Maekawa M, Yamaguchi S, Kyozuka J. d14, a strigolactone-insensitive mutant of rice, shows an accelerated outgrowth of tillers. PLANT & CELL PHYSIOLOGY 2009; 50:1416-24. [PMID: 19542179 DOI: 10.1093/pcp/pcp091] [Citation(s) in RCA: 405] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Recent studies using highly branched mutants of pea, Arabidopsis and rice have demonstrated that strigolactones, a group of terpenoid lactones, act as a new hormone class, or its biosynthetic precursors, in inhibiting shoot branching. Here, we provide evidence that DWARF14 (D14) inhibits rice tillering and may act as a new compo-nent of the strigolactone-dependent branching inhibition pathway. The d14 mutant exhibits increased shoot branch-ing with reduced plant height like the previously characterized strigolactone-deficient and -insensitive mutants d10 and d3, respectively. The d10-1 d14-1 double mutant is phenotypically indistinguishable from the d10-1 and d14-1 single mutants, consistent with the idea that D10 and D14 function in the same pathway. However, unlike with d10, the d14 branching phenotype could not be rescued by exogenous strigolactones. In addition, the d14 mutant contained a higher level of 2'-epi-5-deoxystrigol than the wild type. Positional cloning revealed that D14 encodes a protein of the alpha/beta-fold hydrolase superfamily, some members of which play a role in metabolism or signaling of plant hormones. We propose that D14 functions downstream of strigolactone synthesis, as a component of hormone signaling or as an enzyme that participates in the conversion of strigolactones to the bioactive form.
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Affiliation(s)
- Tomotsugu Arite
- Ishikawa Prefectural University, Nonoichi, Ishikawa 921-8836, Japan
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280
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Dun EA, Brewer PB, Beveridge CA. Strigolactones: discovery of the elusive shoot branching hormone. TRENDS IN PLANT SCIENCE 2009; 14:364-72. [PMID: 19540149 DOI: 10.1016/j.tplants.2009.04.003] [Citation(s) in RCA: 142] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2009] [Revised: 04/09/2009] [Accepted: 04/09/2009] [Indexed: 05/21/2023]
Abstract
The control of axillary bud outgrowth involves a network of hormonal signals and feedback regulation. A repressor of bud outgrowth that is central to the story has been missing since it was first postulated more than 70 years ago. This hormone moves upward in plant stems and can act as a long-distance messenger for auxin. Strigolactones, previously known as carotenoid-derived signals exuded from roots, fit the role of this elusive hormone. The discovery of branching inhibition by strigolactones will help solve many confusing aspects of branch control, including interactions with other signals, and is a great step forward toward uncovering the links between environment, genetics and plant form.
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Affiliation(s)
- Elizabeth A Dun
- The University of Queensland, Australian Research Council Centre of Excellence for Integrative Legume Research, St Lucia, QLD 4072, Australia
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281
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Gao Z, Liu X, Guo L, Liu J, Dong G, Hu J, Han B, Qian Q. Identification of a novel tillering dwarf mutant and fine mapping of the TDDL(T) gene in rice (Oryza sativa L.). Sci Bull (Beijing) 2009. [DOI: 10.1007/s11434-009-0292-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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282
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Tong H, Jin Y, Liu W, Li F, Fang J, Yin Y, Qian Q, Zhu L, Chu C. DWARF AND LOW-TILLERING, a new member of the GRAS family, plays positive roles in brassinosteroid signaling in rice. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2009; 58:803-16. [PMID: 19220793 DOI: 10.1111/j.1365-313x.2009.03825.x] [Citation(s) in RCA: 233] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Rapid progress has been made regarding the understanding of brassinosteroid (BR) signaling in Arabidopsis. However, little is known about BR signaling in monotyledons. Here, we characterized a rice dwarf and low-tillering (dlt) mutant and cloned the corresponding gene via map-based cloning. DLT encodes a new member of the plant-specific GRAS family. The dwarf phenotype of dlt is similar to BR-deficient or signaling mutants in rice. In addition, both lamina bending and coleoptile elongation assays show that dlt is insensitive or much less responsive to brassinolide (BL), the most active BR, suggesting that DLT is involved in BR signaling. Consistent with this conclusion, the accumulation of transcripts of BR biosynthesis genes in the dlt mutant indicated that DLT is involved in feedback inhibition of BR biosynthesis genes. In addition, transcription of several other BR-regulated genes is altered in the dlt mutant. Finally, consistent with the fact that DLT is also negatively feedback-regulated by BR treatment, a gel mobility shift assay showed that OsBZR1 can bind to the DLT promoter through the BR-response element. Taken together, these studies have enabled us to identify a new signaling component that is involved in several specific BR responses in rice.
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Affiliation(s)
- Hongning Tong
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
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283
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Leyser O. The control of shoot branching: an example of plant information processing. PLANT, CELL & ENVIRONMENT 2009; 32:694-703. [PMID: 19143993 DOI: 10.1111/j.1365-3040.2009.01930.x] [Citation(s) in RCA: 138] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Throughout their life cycle, plants adjust their body plan to suit the environmental conditions in which they are growing. A good example of this is in the regulation of shoot branching. Axillary meristems laid down in each leaf formed from the primary shoot apical meristem can remain dormant, or activate to produce a branch. The decision whether to activate an axillary meristem involves the assessment of a wide range of external environmental, internal physiological and developmental factors. Much of this information is conveyed to the axillary meristem via a network of interacting hormonal signals that can integrate inputs from diverse sources, combining multiple local signals to generate a rich source of systemically transmitted information. Local interpretation of the information provides another layer of control, ensuring that appropriate decisions are made. Rapid progress in molecular biology is uncovering the component parts of this signalling network, and combining this with physiological studies and mathematical modelling will allow the operation of the system to be better understood.
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Affiliation(s)
- Ottoline Leyser
- Department of Biology, Area 11, University of York, York YO105YW, UK.
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284
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Brewer PB, Dun EA, Ferguson BJ, Rameau C, Beveridge CA. Strigolactone acts downstream of auxin to regulate bud outgrowth in pea and Arabidopsis. PLANT PHYSIOLOGY 2009; 150:482-93. [PMID: 19321710 PMCID: PMC2675716 DOI: 10.1104/pp.108.134783] [Citation(s) in RCA: 245] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2008] [Accepted: 03/23/2009] [Indexed: 05/18/2023]
Abstract
During the last century, two key hypotheses have been proposed to explain apical dominance in plants: auxin promotes the production of a second messenger that moves up into buds to repress their outgrowth, and auxin saturation in the stem inhibits auxin transport from buds, thereby inhibiting bud outgrowth. The recent discovery of strigolactone as the novel shoot-branching inhibitor allowed us to test its mode of action in relation to these hypotheses. We found that exogenously applied strigolactone inhibited bud outgrowth in pea (Pisum sativum) even when auxin was depleted after decapitation. We also found that strigolactone application reduced branching in Arabidopsis (Arabidopsis thaliana) auxin response mutants, suggesting that auxin may act through strigolactones to facilitate apical dominance. Moreover, strigolactone application to tiny buds of mutant or decapitated pea plants rapidly stopped outgrowth, in contrast to applying N-1-naphthylphthalamic acid (NPA), an auxin transport inhibitor, which significantly slowed growth only after several days. Whereas strigolactone or NPA applied to growing buds reduced bud length, only NPA blocked auxin transport in the bud. Wild-type and strigolactone biosynthesis mutant pea and Arabidopsis shoots were capable of instantly transporting additional amounts of auxin in excess of endogenous levels, contrary to predictions of auxin transport models. These data suggest that strigolactone does not act primarily by affecting auxin transport from buds. Rather, the primary repressor of bud outgrowth appears to be the auxin-dependent production of strigolactones.
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Affiliation(s)
- Philip B Brewer
- University of Queensland, Australian Research Council Centre of Excellence for Integrative Legume Research and School of Biological Sciences, St. Lucia, Queensland 4072, Australia
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285
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Lin H, Wang R, Qian Q, Yan M, Meng X, Fu Z, Yan C, Jiang B, Su Z, Li J, Wang Y. DWARF27, an iron-containing protein required for the biosynthesis of strigolactones, regulates rice tiller bud outgrowth. THE PLANT CELL 2009; 21:1512-25. [PMID: 19470589 PMCID: PMC2700539 DOI: 10.1105/tpc.109.065987] [Citation(s) in RCA: 413] [Impact Index Per Article: 27.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2009] [Revised: 04/30/2009] [Accepted: 05/07/2009] [Indexed: 05/17/2023]
Abstract
Tillering in rice (Oryza sativa) is one of the most important agronomic traits that determine grain yields. Previous studies on rice tillering mutants have shown that the outgrowth of tiller buds in rice is regulated by a carotenoid-derived MAX/RMS/D (more axillary branching) pathway, which may be conserved in higher plants. Strigolactones, a group of terpenoid lactones, have been recently identified as products of the MAX/RMS/D pathway that inhibits axillary bud outgrowth. We report here the molecular genetic characterization of d27, a classic rice mutant exhibiting increased tillers and reduced plant height. D27 encodes a novel iron-containing protein that localizes in chloroplasts and is expressed mainly in vascular cells of shoots and roots. The phenotype of d27 is correlated with enhanced polar auxin transport. The phenotypes of the d27 d10 double mutant are similar to those of d10, a mutant defective in the ortholog of MAX4/RMS1 in rice. In addition, 2'-epi-5-deoxystrigol, an identified strigolactone in root exudates of rice seedlings, was undetectable in d27, and the phenotypes of d27 could be rescued by supplementation with GR24, a synthetic strigolactone analog. Our results demonstrate that D27 is involved in the MAX/RMS/D pathway, in which D27 acts as a new member participating in the biosynthesis of strigolactones.
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Affiliation(s)
- Hao Lin
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
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286
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Dabbert T, Okagaki RJ, Cho S, Boddu J, Muehlbauer GJ. The genetics of barley low-tillering mutants: absent lower laterals (als). TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2009; 118:1351-1360. [PMID: 19241055 DOI: 10.1007/s00122-009-0985-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2008] [Accepted: 01/30/2009] [Indexed: 05/27/2023]
Abstract
Barley (Hordeum vulgare L.) carrying the recessive mutation absent lower laterals (als) exhibits few tillers and irregular inflorescence development. To gain an increased understanding of the genetic control of tillering in barley, we conducted morphological, genetic, and transcriptome analysis of the als mutant. Axillary buds for primary tillers, but not for secondary tillers, developed in als plants. Double mutant combinations of als with one low-tillering and four high-tillering mutants resulted in a tillering phenotype similar to als, indicating that als was epistatic to these tillering genes. However, double mutant combinations of als with another low-tillering mutant, intermedium-b, reduced tiller numbers, indicating there were at least two genetic pathways regulating tillering in barley. Next, we used simple sequence repeat markers to map the Als gene on the long arm of barley chromosome 3H, Bin 11. Finally, the Affymetrix Barley1 GeneChip was used to identify differentially accumulated transcripts in als compared to wild-type. Forty percent of the transcripts with twofold or greater accumulation in als tissues corresponded to stress and defense response genes. This finding suggested that a tillering pathway may modulate the stress response.
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Affiliation(s)
- Timothy Dabbert
- Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, 55108, USA
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287
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Ferguson BJ, Beveridge CA. Roles for auxin, cytokinin, and strigolactone in regulating shoot branching. PLANT PHYSIOLOGY 2009; 149:1929-44. [PMID: 19218361 PMCID: PMC2663762 DOI: 10.1104/pp.109.135475] [Citation(s) in RCA: 186] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2009] [Accepted: 02/03/2009] [Indexed: 05/18/2023]
Abstract
Many processes have been described in the control of shoot branching. Apical dominance is defined as the control exerted by the shoot tip on the outgrowth of axillary buds, whereas correlative inhibition includes the suppression of growth by other growing buds or shoots. The level, signaling, and/or flow of the plant hormone auxin in stems and buds is thought to be involved in these processes. In addition, RAMOSUS (RMS) branching genes in pea (Pisum sativum) control the synthesis and perception of a long-distance inhibitory branching signal produced in the stem and roots, a strigolactone or product. Auxin treatment affects the expression of RMS genes, but it is unclear whether the RMS network can regulate branching independently of auxin. Here, we explore whether apical dominance and correlative inhibition show independent or additive effects in rms mutant plants. Bud outgrowth and branch lengths are enhanced in decapitated and stem-girdled rms mutants compared with intact control plants. This may relate to an RMS-independent induction of axillary bud outgrowth by these treatments. Correlative inhibition was also apparent in rms mutant plants, again indicating an RMS-independent component. Treatments giving reductions in RMS1 and RMS5 gene expression, auxin transport, and auxin level in the main stem were not always sufficient to promote bud outgrowth. We suggest that this may relate to a failure to induce the expression of cytokinin biosynthesis genes, which always correlated with bud outgrowth in our treatments. We present a new model that accounts for apical dominance, correlative inhibition, RMS gene action, and auxin and cytokinin and their interactions in controlling the progression of buds through different control points from dormancy to sustained growth.
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Affiliation(s)
- Brett J Ferguson
- School of Integrative Biology and Australian Research Council Centre of Excellence for Integrative Legume Research, University of Queensland, St. Lucia, Queensland 4072, Australia
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288
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Shimizu-Sato S, Tanaka M, Mori H. Auxin-cytokinin interactions in the control of shoot branching. PLANT MOLECULAR BIOLOGY 2009; 69:429-35. [PMID: 18974937 DOI: 10.1007/s11103-008-9416-3] [Citation(s) in RCA: 182] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2008] [Accepted: 10/12/2008] [Indexed: 05/18/2023]
Abstract
In many plant species, the intact main shoot apex grows predominantly and axillary bud outgrowth is inhibited. This phenomenon is called apical dominance, and has been analyzed for over 70 years. Decapitation of the shoot apex releases the axillary buds from their dormancy and they begin to grow out. Auxin derived from an intact shoot apex suppresses axillary bud outgrowth, whereas cytokinin induced by decapitation of the shoot apex stimulates axillary bud outgrowth. Here we describe the molecular mechanisms of the interactions between auxin and cytokinin in the control of shoot branching.
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Affiliation(s)
- Sae Shimizu-Sato
- Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya 464-8601, Japan
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289
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Liu G, Zeng R, Zhu H, Zhang Z, Ding X, Zhao F, Li W, Zhang G. Dynamic expression of nine QTLs for tiller number detected with single segment substitution lines in rice. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2009; 118:443-53. [PMID: 18949451 DOI: 10.1007/s00122-008-0911-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2008] [Accepted: 10/02/2008] [Indexed: 05/05/2023]
Abstract
Nine single segment substitution lines (SSSLs) in rice, which contain quantitative trait loci (QTLs) for tiller number on substituted segments detected in previous studies, were selected as materials to analyse dynamic expression of the QTLs in this study. These SSSLs and their recipient parent, Hua-jing-xian 74 (HJX74), were grown in four different environments and were measured for tiller number at nine different growth stages. An indirect methodology was applied in QTL mapping through analyzing multi-environment phenotypic data. Dynamics of three types of effects (including total effect, main effect, and QE interaction effect) of QTLs was released. It was shown that nine QTLs exhibited statistically significant effects only at certain stages. Effects of a QTL, although insignificant at certain stages, displayed dynamic change with the growth of rice plants. Two common features of nine QTLs were detected, one is no expression within 7 days after transplanting, and the other is opposite expression existed during the whole growth period. Nine QTLs largely focused on expression in certain stages, and accordingly were suggested to partition into three types, expression in prophase, both in prophase and in anaphase, and evenly during the whole stage. It may be reasonable explanation that dynamics of main effects of QTLs are likely due to gene expression selectly at certain times, while dynamics of QE interaction effects of QTLs might attribute to the subrogation of environmental factors. Examination of the association between QE interaction effect and specified environmental factors across stages may provide useful information on how an environmental factor regulates QTL expression.
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Affiliation(s)
- Guifu Liu
- Guangdong Key Lab of Plant Molecular Breeding, South China Agricultural University, 510642, Guangzhou, People's Republic of China
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290
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Affiliation(s)
- Paula McSteen
- Department of Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
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291
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Yasuno N, Takamure I, Kidou SI, Tokuji Y, Ureshi AN, Funabiki A, Ashikaga K, Yamanouchi U, Yano M, Kato K. Rice shoot branching requires an ATP-binding cassette subfamily G protein. THE NEW PHYTOLOGIST 2008; 182:91-101. [PMID: 19140940 DOI: 10.1111/j.1469-8137.2008.02724.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
* Shoot branching is important for the establishment of plant architecture and productivity. * Here, characterization of rice (Oryza sativa) reduced culm number 1 (rcn1) mutants revealed that Rcn1 positively controls shoot branching by promoting the outgrowth of lateral shoots. Molecular studies revealed that Rcn1 encodes a novel member of ATP-binding cassette protein subfamily G (ABCG subfamily), also known as the white-brown complex (WBC) subfamily, and is designated OsABCG5. * Rcn1 is expressed in leaf primordia of main and axillary shoots, and in the vascular cells and leaf epidermis of older leaves. In addition, Rcn1 is expressed in the crown root primordia, endodermis, pericycle and stele in the root. No effect on Rcn1 expression in shoots or roots was seen when the roots were treated with auxins. Phenotypic analyses of rcn1 and tillering dwarf 3 (d3) double mutants at the seedling stage clarified that Rcn1 works independently of D3 in the branching inhibitor pathway. * Rcn1 is the first functionally defined plant ABCG protein gene that controls shoot branching and could thus be significant in future breeding for high-yielding rice.
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Affiliation(s)
- Naoko Yasuno
- Department of Crop Science, Obihiro University of Agriculture and Veterinary Medicine, Nishi 2-11 Inada, Obihiro, Hokkaido 080-8555, Japan
- United Graduate School of Agricultural Sciences, Iwate University, Ueda 3-chome, Morioka, Iwate 020-8550, Japan
| | - Itsuro Takamure
- Graduate School of Agriculture, Hokkaido University, Kita 9 Nishi 9, Kita-ku, Sapporo, Hokkaido 060-8589, Japan
| | - Shin-Ichiro Kidou
- Cryobiosystem Research Center, Faculty of Agriculture, Iwate University, Ueda 3-chome, Morioka, Iwate 020-8550, Japan
| | - Yoshihiko Tokuji
- Department of Crop Science, Obihiro University of Agriculture and Veterinary Medicine, Nishi 2-11 Inada, Obihiro, Hokkaido 080-8555, Japan
| | - An-Na Ureshi
- Department of Crop Science, Obihiro University of Agriculture and Veterinary Medicine, Nishi 2-11 Inada, Obihiro, Hokkaido 080-8555, Japan
| | - Atsushi Funabiki
- Department of Crop Science, Obihiro University of Agriculture and Veterinary Medicine, Nishi 2-11 Inada, Obihiro, Hokkaido 080-8555, Japan
| | - Kazunori Ashikaga
- Department of Crop Science, Obihiro University of Agriculture and Veterinary Medicine, Nishi 2-11 Inada, Obihiro, Hokkaido 080-8555, Japan
| | - Utako Yamanouchi
- National Institute of Agrobiological Sciences, 2-1-2 Kannondai, Tsukuba, Ibaraki 305-8602, Japan
| | - Masahiro Yano
- National Institute of Agrobiological Sciences, 2-1-2 Kannondai, Tsukuba, Ibaraki 305-8602, Japan
| | - Kiyoaki Kato
- Department of Crop Science, Obihiro University of Agriculture and Veterinary Medicine, Nishi 2-11 Inada, Obihiro, Hokkaido 080-8555, Japan
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292
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Umehara M, Hanada A, Yoshida S, Akiyama K, Arite T, Takeda-Kamiya N, Magome H, Kamiya Y, Shirasu K, Yoneyama K, Kyozuka J, Yamaguchi S. Inhibition of shoot branching by new terpenoid plant hormones. Nature 2008; 455:195-200. [PMID: 18690207 DOI: 10.1038/nature07272] [Citation(s) in RCA: 1218] [Impact Index Per Article: 76.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2008] [Accepted: 07/21/2008] [Indexed: 12/18/2022]
Abstract
Shoot branching is a major determinant of plant architecture and is highly regulated by endogenous and environmental cues. Two classes of hormones, auxin and cytokinin, have long been known to have an important involvement in controlling shoot branching. Previous studies using a series of mutants with enhanced shoot branching suggested the existence of a third class of hormone(s) that is derived from carotenoids, but its chemical identity has been unknown. Here we show that levels of strigolactones, a group of terpenoid lactones, are significantly reduced in some of the branching mutants. Furthermore, application of strigolactones inhibits shoot branching in these mutants. Strigolactones were previously found in root exudates acting as communication chemicals with parasitic weeds and symbiotic arbuscular mycorrhizal fungi. Thus, we propose that strigolactones act as a new hormone class-or their biosynthetic precursors-in regulating above-ground plant architecture, and also have a function in underground communication with other neighbouring organisms.
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293
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Lo SF, Yang SY, Chen KT, Hsing YI, Zeevaart JAD, Chen LJ, Yu SM. A novel class of gibberellin 2-oxidases control semidwarfism, tillering, and root development in rice. THE PLANT CELL 2008; 20:2603-18. [PMID: 18952778 PMCID: PMC2590730 DOI: 10.1105/tpc.108.060913] [Citation(s) in RCA: 298] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2008] [Revised: 09/19/2008] [Accepted: 09/30/2008] [Indexed: 05/18/2023]
Abstract
Gibberellin 2-oxidases (GA2oxs) regulate plant growth by inactivating endogenous bioactive gibberellins (GAs). Two classes of GA2oxs inactivate GAs through 2beta-hydroxylation: a larger class of C(19) GA2oxs and a smaller class of C(20) GA2oxs. In this study, we show that members of the rice (Oryza sativa) GA2ox family are differentially regulated and act in concert or individually to control GA levels during flowering, tillering, and seed germination. Using mutant and transgenic analysis, C(20) GA2oxs were shown to play pleiotropic roles regulating rice growth and architecture. In particular, rice overexpressing these GA2oxs exhibited early and increased tillering and adventitious root growth. GA negatively regulated expression of two transcription factors, O. sativa homeobox 1 and TEOSINTE BRANCHED1, which control meristem initiation and axillary bud outgrowth, respectively, and that in turn inhibited tillering. One of three conserved motifs unique to the C(20) GA2oxs (motif III) was found to be important for activity of these GA2oxs. Moreover, C(20) GA2oxs were found to cause less severe GA-defective phenotypes than C(19) GA2oxs. Our studies demonstrate that improvements in plant architecture, such as semidwarfism, increased root systems and higher tiller numbers, could be induced by overexpression of wild-type or modified C(20) GA2oxs.
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Affiliation(s)
- Shuen-Fang Lo
- Institute of Molecular Biology, National Chung-Hsing University, Taichung 402, Taiwan, Republic of China
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294
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Gomez-Roldan V, Fermas S, Brewer PB, Puech-Pagès V, Dun EA, Pillot JP, Letisse F, Matusova R, Danoun S, Portais JC, Bouwmeester H, Bécard G, Beveridge CA, Rameau C, Rochange SF. Strigolactone inhibition of shoot branching. Nature 2008; 455:189-94. [PMID: 18690209 DOI: 10.1038/nature07271] [Citation(s) in RCA: 1297] [Impact Index Per Article: 81.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2008] [Accepted: 07/18/2008] [Indexed: 11/09/2022]
Abstract
A carotenoid-derived hormonal signal that inhibits shoot branching in plants has long escaped identification. Strigolactones are compounds thought to be derived from carotenoids and are known to trigger the germination of parasitic plant seeds and stimulate symbiotic fungi. Here we present evidence that carotenoid cleavage dioxygenase 8 shoot branching mutants of pea are strigolactone deficient and that strigolactone application restores the wild-type branching phenotype to ccd8 mutants. Moreover, we show that other branching mutants previously characterized as lacking a response to the branching inhibition signal also lack strigolactone response, and are not deficient in strigolactones. These responses are conserved in Arabidopsis. In agreement with the expected properties of the hormonal signal, exogenous strigolactone can be transported in shoots and act at low concentrations. We suggest that endogenous strigolactones or related compounds inhibit shoot branching in plants. Furthermore, ccd8 mutants demonstrate the diverse effects of strigolactones in shoot branching, mycorrhizal symbiosis and parasitic weed interaction.
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Affiliation(s)
- Victoria Gomez-Roldan
- Université de Toulouse, UPS, CNRS, Surface Cellulaire et Signalisation chez les Végétaux, 24 chemin de Borde Rouge, F-31326 Castanet-Tolosan, France
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295
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Genetic modification of plant architecture and variety improvement in rice. Heredity (Edinb) 2008; 101:396-404. [PMID: 18716608 DOI: 10.1038/hdy.2008.90] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The structure of the aerial part of a plant, referred to as plant architecture, is subject to strict genetic control, and grain production in cereal crops is governed by an array of agronomic traits. Rice is one of the most important cereal crops and is also a model plant for molecular biological research. Recently, significant progress has been made in isolating and collecting rice mutants that exhibit altered plant architecture. In this article we summarize the recent progress in understanding the basic patterning mechanisms involved in the regulation of tillering (branching) pattern, stem structure and leaf arrangement in rice plants. We discuss the relationship between the genetic modification of plant architecture and the improvement of pivotal agronomic traits in rice.
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296
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Lewis JM, Mackintosh CA, Shin S, Gilding E, Kravchenko S, Baldridge G, Zeyen R, Muehlbauer GJ. Overexpression of the maize Teosinte Branched1 gene in wheat suppresses tiller development. PLANT CELL REPORTS 2008; 27:1217-1225. [PMID: 18392625 DOI: 10.1007/s00299-008-0543-8] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2008] [Revised: 03/13/2008] [Accepted: 03/24/2008] [Indexed: 05/26/2023]
Abstract
The number of viable shoots influences the overall architecture and productivity of wheat (Triticum aestivum L.). The development of lateral branches, or tillers, largely determines the resultant canopy. Tillers develop from the outgrowth of axillary buds, which form in leaf axils at the crown of the plant. Tiller number can be reduced if axillary buds are not formed or if the outgrowth of these buds is restricted. The teosinte branched1 (tb1) gene in maize, and homologs in rice and Arabidopsis, genetically regulate vegetative branching. In maize, increased expression of the tb1 gene restricts the outgrowth of axillary buds into lateral branches. In this study, the maize tb1 gene was introduced through transformation into the wheat cultivar "Bobwhite" to determine the effect of tb1 overexpression on wheat shoot architecture. Examination of multiple generations of plants reveals that tb1 overexpression in wheat results in reduced tiller and spike number. In addition, the number of spikelets on the spike and leaf number were significantly greater in tb1-expressing plants, and the height of these plants was also reduced. These data reveal that the function of the tb1 gene and genetic regulation of lateral branching via the tb1 mode of action is conserved between wheat, rice, maize and Arabidopsis. Thus, the tb1 gene can be used to alter plant architecture in agriculturally important crops like wheat.
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Affiliation(s)
- Janet M Lewis
- Department of Agronomy and Plant Genetics, University of Minnesota, 411 Borlaug Hall, 1991 Upper Buford Circle, St Paul, MN 55108, USA
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297
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Sakamoto T, Matsuoka M. Identifying and exploiting grain yield genes in rice. CURRENT OPINION IN PLANT BIOLOGY 2008; 11:209-14. [PMID: 18343712 DOI: 10.1016/j.pbi.2008.01.009] [Citation(s) in RCA: 132] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2007] [Revised: 01/04/2008] [Accepted: 01/29/2008] [Indexed: 05/18/2023]
Abstract
Improved grain yield has been a major focus of crop breeding programs around the world. With the accomplishments of the Rice Genome Project, genes regulating several agronomically important traits related to grain yield, such as tiller number, grain number, grain size, and plant height, have recently been identified. Although these findings have not been enough to fully characterize the mechanisms that regulate each trait, these genes and knowledge of the molecular mechanisms involved provide a set of tools that can be combined to achieve tailor-made breeding suitable for various programs aimed at higher grain yield.
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Affiliation(s)
- Tomoaki Sakamoto
- Institute for Advanced Research, Nagoya University, Chikusa, Nagoya, Aichi 464-8601, Japan
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298
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Madoka Y, Kashiwagi T, Hirotsu N, Ishimaru K. Indian rice "Kasalath" contains genes that improve traits of Japanese premium rice "Koshihikari". TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2008; 116:603-12. [PMID: 18097643 DOI: 10.1007/s00122-007-0693-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2007] [Accepted: 11/28/2007] [Indexed: 05/04/2023]
Abstract
Rice (Oryza sativa L.) chromosome segment substitution lines (CSSLs), in which chromosomal segments of the Indian landrace "Kasalath" replace the corresponding endogenous segments in the genome of the Japanese premium rice "Koshihikari", are available and together cover the entire genome. Chromosome regions affecting a trait (CRATs) can be identified by comparison of phenotypes with genotypes of CSSLs. We detected 99 CRATs for 15 agronomic or morphological traits. "Kasalath" had positively acting alleles in 53 CRATs. Its CRATs increased panicle number per plant by up to 23.3%, grain number per panicle by up to 30.8%, and total grain number by up to 15.1%, relative to "Koshihikari". CRATs were identified for grain size (grain thickness and width), with positive effects of about 5.0%. A CRAT on chromosome 8 almost doubled the weight of roots in uppermost soil layers compared to "Koshihikari". Additionally, "Kasalath" possessed CRATs for higher lodging resistance (reduction in plant height and increase in stem diameter). In some cases, multiple CRATs were detected in the same chromosome regions. Therefore, CSSLs with these chromosome segments might be useful breeding materials for the simultaneous improvement of multiple traits. Five CRATs, one for plant height on chromosome 1, one for stem diameter on chromosome 8, and three for heading date on chromosomes 6, 7, and 8 overlapped with the corresponding QTLs that already had been mapped with back-crossed inbred lines of "Nipponbare" and "Kasalath". In both "Koshihikari" CRATs and "Nipponbare" QTLs, "Kasalath" had similar effects.
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Affiliation(s)
- Y Madoka
- National Institute of Agrobiological Sciences, Kannondai 2-1-2, Tsukuba, Ibaraki, 305-8602, Japan
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299
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Abstract
Higher plants display a variety of architectures that are defined by the degree of branching, internodal elongation, and shoot determinancy. Studies on the model plants of Arabidopsis thaliana and tomato and on crop plants such as rice and maize have greatly strengthened our understanding on the molecular genetic bases of plant architecture, one of the hottest areas in plant developmental biology. The identification of mutants that are defective in plant architecture and characterization of the corresponding and related genes will eventually enable us to elucidate the molecular mechanisms underlying plant architecture. The achievements made so far in studying plant architecture have already allowed us to pave a way for optimizing the plant architecture of crops by molecular design and improving grain productivity.
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Affiliation(s)
- Yonghong Wang
- Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
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300
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Abstract
Here we summarize progress in identification of three classes of genes useful for control of plant architecture: those affecting hormone metabolism and signaling; transcription and other regulatory factors; and the cell cycle. We focus on strong modifiers of stature and form that may be useful for directed modification of plant architecture, rather than the detailed mechanisms of gene action. Gibberellin (GA) metabolic and response genes are particularly attractive targets for manipulation because many act in a dose-dependent manner; similar phenotypic effects can be readily achieved in heterologous species; and induced pleiotropic effects--such as on nitrogen assimilation, photosynthesis, and lateral root production--are usually positive with respect to crop performance. Genes encoding transcription factors represent strong candidates for manipulation of plant architecture. For example, AINTEGUMENTA, ARGOS (auxin-regulated gene controlling organ size), and growth-regulating factors (GRFs) are strong modifiers of leaf and/or flower size. Plants overexpressing these genes had increased organ size and did not display negative pleiotropic effects in glasshouse environments. TCP-domain genes such as CINCINNATA, and the associated regulatory miRNAs such as miRJAW, may provide useful means to modulate leaf curvature and other foliage properties. There are considerable opportunities for comparative and translational genomics in nonmodel plant systems.
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Affiliation(s)
- Victor B Busov
- Michigan Technological University, School of Forest Research and Environmental Science, 101 Noblet Hall, 1400 Townsend Drive, Houghton, MI 49931, USA
| | - Amy M Brunner
- Virginia Polytechnic Institute and State University, Department of Forestry, 304 Cheatham Hall (0324), Blacksburg, VA 24061, USA
| | - Steven H Strauss
- Oregon State University, Department of Forest Science, Corvallis, OR 97331-5752, USA
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