1
|
Ikeda H, Uchikawa T, Kondo Y, Takahashi N, Shishikui T, Watahiki MK, Kubota A, Endo M. Circadian Clock Controls Root Hair Elongation through Long-Distance Communication. Plant Cell Physiol 2023; 64:1289-1300. [PMID: 37552691 DOI: 10.1093/pcp/pcad076] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 07/06/2023] [Accepted: 07/13/2023] [Indexed: 08/10/2023]
Abstract
Plants adapt to periodic environmental changes, such as day and night, by using circadian clocks. Cell division and elongation are primary steps to adjust plant development according to their environments. In Arabidopsis, hypocotyl elongation has been studied as a representative model to understand how the circadian clock regulates cell elongation. However, it remains unknown whether similar phenomena exist in other organs, such as roots, where circadian clocks regulate physiological responses. Here, we show that root hair elongation is controlled by both light and the circadian clock. By developing machine-learning models to automatically analyze the images of root hairs, we found that genes encoding major components of the central oscillator, such as TIMING OF CAB EXPRESSION1 (TOC1) or CIRCADIAN CLOCK ASSOCIATED1 (CCA1), regulate the rhythmicity of root hair length. The partial illumination of light to either shoots or roots suggested that light received in shoots is mainly responsible for the generation of root hair rhythmicity. Furthermore, grafting experiments between wild-type (WT) and toc1 plants demonstrated that TOC1 in shoots is responsible for the generation of root hair rhythmicity. Our results illustrate the combinational effects of long-distance signaling and the circadian clock on the regulation of root hair length.
Collapse
Affiliation(s)
- Hikari Ikeda
- Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, 630-0192 Japan
| | - Taiga Uchikawa
- Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, 630-0192 Japan
| | - Yohei Kondo
- Quantitative Biology Research Group, Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, Okazaki, 444-8787 Japan
| | - Nozomu Takahashi
- Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, 630-0192 Japan
- PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama, 332-0012 Japan
| | - Takuma Shishikui
- Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, 630-0192 Japan
| | - Masaaki K Watahiki
- Graduate School of Life Science, Hokkaido University, Sapporo, 060-0810 Japan
- Faculty of Science, Hokkaido University, Sapporo, 060-0810 Japan
| | - Akane Kubota
- Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, 630-0192 Japan
| | - Motomu Endo
- Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, 630-0192 Japan
| |
Collapse
|
2
|
Balandra A, Doll Y, Hirose S, Kajiwara T, Kashino Z, Inami M, Koshimizu S, Fukaki H, Watahiki MK. P-MIRU, a Polarized Multispectral Imaging System, Reveals Reflection Information on the Biological Surface. Plant Cell Physiol 2023; 64:1311-1322. [PMID: 37217180 DOI: 10.1093/pcp/pcad045] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 04/12/2023] [Accepted: 05/20/2023] [Indexed: 05/24/2023]
Abstract
Reflection light forms the core of our visual perception of the world. We can obtain vast information by examining reflection light from biological surfaces, including pigment composition and distribution, tissue structure and surface microstructure. However, because of the limitations in our visual system, the complete information in reflection light, which we term 'reflectome', cannot be fully exploited. For example, we may miss reflection light information outside our visible wavelengths. In addition, unlike insects, we have virtually no sensitivity to light polarization. We can detect non-chromatic information lurking in reflection light only with appropriate devices. Although previous studies have designed and developed systems for specialized uses supporting our visual systems, we still do not have a versatile, rapid, convenient and affordable system for analyzing broad aspects of reflection from biological surfaces. To overcome this situation, we developed P-MIRU, a novel multispectral and polarization imaging system for reflecting light from biological surfaces. The hardware and software of P-MIRU are open source and customizable and thus can be applied for virtually any research on biological surfaces. Furthermore, P-MIRU is a user-friendly system for biologists with no specialized programming or engineering knowledge. P-MIRU successfully visualized multispectral reflection in visible/non-visible wavelengths and simultaneously detected various surface phenotypes of spectral polarization. The P-MIRU system extends our visual ability and unveils information on biological surfaces.
Collapse
Affiliation(s)
| | - Yuki Doll
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo, 113-0033 Japan
| | - Shogo Hirose
- Faculty of Agriculture, Meijo University, Shiogamaguchi 1-501, Tempaku-ku, Nagoya, 468-0073 Japan
| | - Tomoaki Kajiwara
- Graduate School of Biostudies, Kyoto University, Yoshida-Konoecho, Sakyo-ku, Kyoto, 606-8502 Japan
| | - Zendai Kashino
- Research Center for Advanced Science and Technology, The University of Tokyo, Komaba 4-6-1, Meguro-ku, Tokyo, 153-8904 Japan
| | - Masahiko Inami
- Research Center for Advanced Science and Technology, The University of Tokyo, Komaba 4-6-1, Meguro-ku, Tokyo, 153-8904 Japan
| | - Shizuka Koshimizu
- School of Agriculture, Meiji University, Higashimita 1-1-1, Tama-ku, Kawasaki, 214-8571 Japan
- Research Center for Advanced Science and Technology, The University of Tokyo, Komaba 4-6-1, Meguro-ku, Tokyo, 153-8904 Japan
| | - Hidehiro Fukaki
- Department of Biology, Graduate School of Science, Kobe University, Rokkodaicho 1-1, Nada-ku, Kobe, 657-8501 Japan
| | - Masaaki K Watahiki
- Faculty of Science and Graduate School of Life Science, Hokkaido University, Kita 10 Nishi 8, Kita-ku, Sapporo, 060-0810 Japan
| |
Collapse
|
3
|
Maki Y, Soejima H, Sugiyama T, Sato T, Yamaguchi J, Watahiki MK. Conjugates of 3-phenyllactic acid and tryptophan enhance root-promoting activity without adverse effects in Vigna angularis. Plant Biotechnol (Tokyo) 2022; 39:173-177. [PMID: 35937525 PMCID: PMC9300432 DOI: 10.5511/plantbiotechnology.21.1217a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 12/17/2021] [Indexed: 06/15/2023]
Abstract
3-Phenyllactic acid (PLA) is a common secondary product of Lactobacillus sp. and promotes adventitious-root formation in Azuki beans (Vigna angularis). Root promotion activity of PLA is synergistically enhanced by tryptophan (Trp). In this study, stereoisomers of PLA and Trp amide conjugates and their alkyl esters were synthesized to investigate the structure-activity relationships on root-promotion activity. The rooting activity of D-PLA-L-Trp conjugate shows more than 40 times higher than that of the mixture of D-PLA and L-Trp. Modification of PLA-Trp with ethyl ester showed the highest activity at 3,400 times of a mixture of D-PLA and L-Trp. However, L-or D-PLA-D-Trp conjugate and the isopropyl ester of PLA-Trp conjugates, both lost the root promotion activity and implicated that a requirement for steric structure for PLA related root promotion mechanism. Unlike auxin substances, which are commonly used as rooting agents that displayed high activity in low concentrations, PLA-Trp ethyl ester exhibited far less phytotoxicity at high concentration of 1 mM, despite its high rooting activity. Innovation of PLA-Trp ethyl ester may be expected for agricultural aspects with low environmental impact.
Collapse
Affiliation(s)
- Yuko Maki
- Snow Brand Seed Co. Ltd., Horonai 1066-5, Naganuma, Hokkaido 069-1464, Japan
| | - Hiroshi Soejima
- Snow Brand Seed Co. Ltd., Horonai 1066-5, Naganuma, Hokkaido 069-1464, Japan
| | - Tamizi Sugiyama
- Department of Agricultural Chemistry, Meiji University, Higashimita 1-1-1, Tama-ku, Kawasaki, Kanagawa 214-8571, Japan
| | - Takeo Sato
- Faculty of Science and Graduate School of Life Science, Hokkaido University, Kita-ku N10-W8, Sapporo, Hokkaido 060-0810, Japan
| | - Junji Yamaguchi
- Faculty of Science and Graduate School of Life Science, Hokkaido University, Kita-ku N10-W8, Sapporo, Hokkaido 060-0810, Japan
| | - Masaaki K. Watahiki
- Faculty of Science and Graduate School of Life Science, Hokkaido University, Kita-ku N10-W8, Sapporo, Hokkaido 060-0810, Japan
| |
Collapse
|
4
|
Maki Y, Soejima H, Sugiyama T, Watahiki MK, Sato T, Yamaguchi J. 3-Phenyllactic acid is converted to phenylacetic acid and induces auxin-responsive root growth in Arabidopsis plants. Plant Biotechnol (Tokyo) 2022; 39:111-117. [PMID: 35937539 PMCID: PMC9300423 DOI: 10.5511/plantbiotechnology.21.1216a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2021] [Accepted: 12/16/2021] [Indexed: 06/15/2023]
Abstract
Many microorganisms have been reported to produce compounds that promote plant growth and are thought to be involved in the establishment and maintenance of symbiotic relationships. 3-Phenyllactic acid (PLA) produced by lactic acid bacteria was previously shown to promote root growth in adzuki cuttings. However, the mode of action of PLA as a root-promoting substance had not been clarified. The present study therefore investigated the relationship between PLA and auxin. PLA was found to inhibit primary root elongation and to increase lateral root density in wild-type Arabidopsis, but not in an auxin signaling mutant. In addition, PLA induced IAA19 promoter fused β-glucuronidase gene expression, suggesting that PLA exhibits auxin-like activity. The inability of PLA to promote degradation of Auxin/Indole-3-Acetic Acid protein in a yeast heterologous reconstitution system indicated that PLA may not a ligand of auxin receptor. Using of a synthetic PLA labeled with stable isotope showed that exogenously applied PLA was converted to phenylacetic acid (PAA), an endogenous auxin, in both adzuki and Arabidopsis. Taken together, these results suggest that exogenous PLA promotes auxin signaling by conversion to PAA, thereby regulating root growth in plants.
Collapse
Affiliation(s)
- Yuko Maki
- Snow Brand Seed Co. LTD., Horonai 1066-5, Naganuma, Hokkaido 069-1464, Japan
| | - Hiroshi Soejima
- Snow Brand Seed Co. LTD., Horonai 1066-5, Naganuma, Hokkaido 069-1464, Japan
| | - Tamizi Sugiyama
- Department of Agricultural Chemistry, Meiji University, 1-1-1 Higashimita, Tama-ku, Kawasaki, Kanagawa 214-8571, Japan
| | - Masaaki K. Watahiki
- Faculty of Science and Graduate School of Life Science, Hokkaido University, Kita-ku, N10-W8, Sapporo, Hokkaido 060-0810, Japan
| | - Takeo Sato
- Faculty of Science and Graduate School of Life Science, Hokkaido University, Kita-ku, N10-W8, Sapporo, Hokkaido 060-0810, Japan
| | - Junji Yamaguchi
- Faculty of Science and Graduate School of Life Science, Hokkaido University, Kita-ku, N10-W8, Sapporo, Hokkaido 060-0810, Japan
| |
Collapse
|
5
|
Maki Y, Soejima H, Kitamura T, Sugiyama T, Sato T, Watahiki MK, Yamaguchi J. 3-Phenyllactic acid, a root-promoting substance isolated from Bokashi fertilizer, exhibits synergistic effects with tryptophan. Plant Biotechnol (Tokyo) 2021; 38:9-16. [PMID: 34177319 PMCID: PMC8215458 DOI: 10.5511/plantbiotechnology.20.0727a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 07/27/2020] [Indexed: 06/13/2023]
Abstract
Bokashi fertilizer, an organic fertilizer made of plant residue, has been used in Japan not only to fertilize plants but to regulate their growth. Lactic acid bacteria have been found to play an important role in the fermentation process of Bokashi, but the relationship between these bacteria and plant growth activity has not been clarified. Using the adzuki rooting assay, this study identified 3-phenyllactic acid (PLA) produced by lactic acid bacteria as a root promoting compound in Bokashi. PLA showed synergistic effect with tryptophan, but no stem elongation activity. Lactic acid bacteria produced equal quantities of the L- and D-forms of PLA, which have similar root promoting activity. PLA did not significantly affect the amount of endogenous indole-3-acetic acid (IAA), although the chemical structure of PLA is highly similar to that of L-2-aminooxy-3-phenypropionic acid (L-AOPP), which inhibits IAA biosynthesis. These results indicate that the root promoting activity of PLA is not simply due to its increase in the amount of active auxin.
Collapse
Affiliation(s)
- Yuko Maki
- Snow Brand Seed Co. Ltd., 1066-5 Horonai, Naganuma, Hokkaido 069-1464, Japan
| | - Hiroshi Soejima
- Snow Brand Seed Co. Ltd., 1066-5 Horonai, Naganuma, Hokkaido 069-1464, Japan
| | - Toru Kitamura
- Snow Brand Seed Co. Ltd., 1066-5 Horonai, Naganuma, Hokkaido 069-1464, Japan
| | - Tamizi Sugiyama
- Department of Agricultural Chemistry, Meiji University, 1-1-1 Higashimita, Tama-ku, Kawasaki, Kanagawa 214-8571, Japan
| | - Takeo Sato
- Faculty of Science and Graduate School of Life Science, Hokkaido University, N10-W8 Kita-ku, Sapporo, Hokkaido 060-0810, Japan
| | - Masaaki K. Watahiki
- Faculty of Science and Graduate School of Life Science, Hokkaido University, N10-W8 Kita-ku, Sapporo, Hokkaido 060-0810, Japan
| | - Junji Yamaguchi
- Faculty of Science and Graduate School of Life Science, Hokkaido University, N10-W8 Kita-ku, Sapporo, Hokkaido 060-0810, Japan
| |
Collapse
|
6
|
Yamamoto KT, Watahiki MK, Matsuzaki J, Satoh S, Shimizu H. Correction to: Space-time analysis of gravitropism in etiolated Arabidopsis hypocotyls using bioluminescence imaging of the IAA19 promoter fusion with a destabilized luciferase reporter. J Plant Res 2018; 131:889. [PMID: 30022268 PMCID: PMC6105213 DOI: 10.1007/s10265-018-1055-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The article Space-time analysis of gravitropism in etiolated Arabidopsis hypocotyls using bioluminescence imaging of the IAA19 promoter fusion with a destabilized luciferase reporter, written by Kotaro T. Yamamoto, Masaaki K. Watahiki, Jun Matsuzaki, Soichirou Satoh and Hisayo Shimizu, was originally published electronically on the publisher's internet portal (currently SpringerLink) on 10 April 2017 without open access.
Collapse
Affiliation(s)
- Kotaro T Yamamoto
- Division of Biological Sciences, Faculty of Science, Hokkaido University, Sapporo, 060-0810, Japan.
- Biosystems Science Course, Graduate School of Life Science, Hokkaido University, Sapporo, 060-0810, Japan.
| | - Masaaki K Watahiki
- Division of Biological Sciences, Faculty of Science, Hokkaido University, Sapporo, 060-0810, Japan
- Biosystems Science Course, Graduate School of Life Science, Hokkaido University, Sapporo, 060-0810, Japan
| | - Jun Matsuzaki
- Division of Biological Sciences, Faculty of Science, Hokkaido University, Sapporo, 060-0810, Japan
- Center for Sustainable Resource Science, RIKEN, Tsurumi-ku, Yokohama, 230-0045, Japan
| | - Soichirou Satoh
- Division of Biological Sciences, Faculty of Science, Hokkaido University, Sapporo, 060-0810, Japan
- Graduate School of Life and Environmental Sciences, Kyoto Prefecture University, Sakyo-ku, Kyoto, 606-8522, Japan
| | - Hisayo Shimizu
- Biosystems Science Course, Graduate School of Life Science, Hokkaido University, Sapporo, 060-0810, Japan
| |
Collapse
|
7
|
Yamamoto KT, Watahiki MK, Matsuzaki J, Satoh S, Shimizu H. Space-time analysis of gravitropism in etiolated Arabidopsis hypocotyls using bioluminescence imaging of the IAA19 promoter fusion with a destabilized luciferase reporter. J Plant Res 2017; 130:765-777. [PMID: 28396964 PMCID: PMC6105228 DOI: 10.1007/s10265-017-0932-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Accepted: 02/14/2017] [Indexed: 05/23/2023]
Abstract
Imaging analysis was carried out during the gravitropic response of etiolated Arabidopsis hypocotyls, using an IAA19 promoter fusion of destabilized luciferase as a probe. From the bright-field images we obtained the local deflection angle to the vertical, A, local curvature, C, and the partial derivative of C with respect to time, [Formula: see text]. These were determined every 19.9 µm along the curvilinear length of the hypocotyl, at ~10 min intervals over a period of ~6 h after turning hypocotyls through 90° to the horizontal. Similarly from the luminescence images we measured the luminescence intensity of the convex and concave flanks of the hypocotyl as well as along the median of the hypocotyl, to determine differential expression of auxin-inducible IAA19. Comparison of these parameters as a function of time and curvilinear length shows that the gravitropic response is composed of three successive elements: the first and second curving responses and a decurving response (autostraightening). The maximum of the first curving response occurs when A is 76° along the entire length of the hypocotyl, suggesting that A is the sole determinant in this response; in contrast, the decurving response is a function of both A and C, as predicted by the newly-proposed graviproprioception model (Bastien et al., Proc Natl Acad Sci USA 110:755-760, 2013). Further, differential expression of IAA19, with higher expression in the convex flank, is observed at A = 44°, and follows the Sachs' sine law. This also suggests that IAA19 is not involved in the first curving response. In summary, the gravitropic response of Arabidopsis hypocotyls consists of multiple elements that are each determined by separate principles.
Collapse
Affiliation(s)
- Kotaro T Yamamoto
- Division of Biological Sciences, Faculty of Science, Hokkaido University, Sapporo, 060-0810, Japan.
- Biosystems Science Course, Graduate School of Life Science, Hokkaido University, Sapporo, 060-0810, Japan.
| | - Masaaki K Watahiki
- Division of Biological Sciences, Faculty of Science, Hokkaido University, Sapporo, 060-0810, Japan
- Biosystems Science Course, Graduate School of Life Science, Hokkaido University, Sapporo, 060-0810, Japan
| | - Jun Matsuzaki
- Division of Biological Sciences, Faculty of Science, Hokkaido University, Sapporo, 060-0810, Japan
- Center for Sustainable Resource Science, RIKEN, Tsurumi-ku, Yokohama, 230-0045, Japan
| | - Soichirou Satoh
- Division of Biological Sciences, Faculty of Science, Hokkaido University, Sapporo, 060-0810, Japan
- Graduate School of Life and Environmental Sciences, Kyoto Prefecture University, Sakyo-ku, Kyoto, 606-8522, Japan
| | - Hisayo Shimizu
- Biosystems Science Course, Graduate School of Life Science, Hokkaido University, Sapporo, 060-0810, Japan
| |
Collapse
|
8
|
Li N, Teranishi M, Yamaguchi H, Matsushita T, Watahiki MK, Tsuge T, Li SS, Hidema J. UV-B-Induced CPD Photolyase Gene Expression is Regulated by UVR8-Dependent and -Independent Pathways in Arabidopsis. Plant Cell Physiol 2015; 56:2014-23. [PMID: 26272552 DOI: 10.1093/pcp/pcv121] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Accepted: 08/09/2015] [Indexed: 05/21/2023]
Abstract
Plants have evolved various mechanisms that protect against the harmful effects of UV-B radiation (280-315 nm) on growth and development. Cyclobutane pyrimidine dimer (CPD) photolyase, the repair enzyme for UV-B-induced CPDs, is essential for protecting cells from UV-B radiation. Expression of the CPD photolyase gene (PHR) is controlled by light with various wavelengths including UV-B, but the mechanisms of this regulation remain poorly understood. In this study, we investigated the regulation of PHR expression by light with various wavelengths, in particular low-fluence UV-B radiation (280 nm, 0.2 µmol m(-2) s(-1)), in Arabidopsis thaliana seedlings grown under light-dark cycles for 7 d and then adapted to the dark for 3 d. Low-fluence UV-B radiation induced CPDs but not reactive oxygen species. AtPHR expression was effectively induced by UV-B, UV-A (375 nm) and blue light. Expression induced by UV-A and blue light was predominantly regulated by the cryptochrome-dependent pathway, whereas phytochromes A and B played a minor but noticeable role. Expression induced by UV-B was predominantly regulated by the UVR8-dependent pathway. AtPHR expression was also mediated by a UVR8-independent pathway, which is correlated with CPD accumulation induced by UV-B radiation. These results indicate that Arabidopsis has evolved diverse mechanisms to regulate CPD photolyase expression by multiple photoreceptor signaling pathways, including UVR8-dependent and -independent pathways, as protection against harmful effects of UV-B radiation.
Collapse
Affiliation(s)
- Nan Li
- Graduate School of Life Sciences, Tohoku University, Sendai, 980-8577 Japan
| | - Mika Teranishi
- Graduate School of Life Sciences, Tohoku University, Sendai, 980-8577 Japan
| | - Hiroko Yamaguchi
- Graduate School of Life Sciences, Tohoku University, Sendai, 980-8577 Japan
| | - Tomonao Matsushita
- Faculty of Agriculture, Kyushu University, Fukuoka, 812-8581 Japan PRESTO, JST, Saitama, 332-0012 Japan
| | - Masaaki K Watahiki
- Division of Biological Sciences, Faculty of Science, Hokkaido University, Sapporo, 060-0810 Japan
| | - Tomohiko Tsuge
- Institute for Chemical Research, Kyoto University, Uji, 611-0011 Japan
| | - Shao-Shan Li
- Key Laboratory of Ecology and Environmental Science in Guangdong Higher Education, School of Life Sciences, South China Normal University, Guangzhou 510631, China
| | - Jun Hidema
- Graduate School of Life Sciences, Tohoku University, Sendai, 980-8577 Japan
| |
Collapse
|
9
|
Kami C, Allenbach L, Zourelidou M, Ljung K, Schütz F, Isono E, Watahiki MK, Yamamoto KT, Schwechheimer C, Fankhauser C. Reduced phototropism in pks mutants may be due to altered auxin-regulated gene expression or reduced lateral auxin transport. Plant J 2014; 77:393-403. [PMID: 24286493 DOI: 10.1111/tpj.12395] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Revised: 10/24/2013] [Accepted: 11/20/2013] [Indexed: 05/05/2023]
Abstract
Phototropism allows plants to orient their photosynthetic organs towards the light. In Arabidopsis, phototropins 1 and 2 sense directional blue light such that phot1 triggers phototropism in response to low fluence rates, while both phot1 and phot2 mediate this response under higher light conditions. Phototropism results from asymmetric growth in the hypocotyl elongation zone that depends on an auxin gradient across the embryonic stem. How phototropin activation leads to this growth response is still poorly understood. Members of the phytochrome kinase substrate (PKS) family may act early in this pathway, because PKS1, PKS2 and PKS4 are needed for a normal phototropic response and they associate with phot1 in vivo. Here we show that PKS proteins are needed both for phot1- and phot2-mediated phototropism. The phototropic response is conditioned by the developmental asymmetry of dicotyledonous seedlings, such that there is a faster growth reorientation when cotyledons face away from the light compared with seedlings whose cotyledons face the light. The molecular basis for this developmental effect on phototropism is unknown; here we show that PKS proteins play a role at the interface between development and phototropism. Moreover, we present evidence for a role of PKS genes in hypocotyl gravi-reorientation that is independent of photoreceptors. pks mutants have normal levels of auxin and normal polar auxin transport, however they show altered expression patterns of auxin marker genes. This situation suggests that PKS proteins are involved in auxin signaling and/or lateral auxin redistribution.
Collapse
Affiliation(s)
- Chitose Kami
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Genopode Building, 1015, Lausanne, Switzerland
| | | | | | | | | | | | | | | | | | | |
Collapse
|
10
|
Sako K, Maki Y, Kanai T, Kato E, Maekawa S, Yasuda S, Sato T, Watahiki MK, Yamaguchi J. Arabidopsis RPT2a, 19S proteasome subunit, regulates gene silencing via DNA methylation. PLoS One 2012; 7:e37086. [PMID: 22615900 PMCID: PMC3353898 DOI: 10.1371/journal.pone.0037086] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2011] [Accepted: 04/18/2012] [Indexed: 01/03/2023] Open
Abstract
The ubiquitin/proteasome pathway plays a crucial role in many biological processes. Here we report a novel role for the Arabidopsis 19S proteasome subunit RPT2a in regulating gene activity at the transcriptional level via DNA methylation. Knockout mutation of the RPT2a gene did not alter global protein levels; however, the transcriptional activities of reporter transgenes were severely reduced compared to those in the wild type. This transcriptional gene silencing (TGS) was observed for transgenes under control of either the constitutive CaMV 35S promoter or the cold-inducible RD29A promoter. Bisulfite sequencing analysis revealed that both the transgene and endogenous RD29A promoter regions were hypermethylated at CG and non-CG contexts in the rpt2a mutant. Moreover, the TGS of transgenes driven by the CaMV 35S promoters was released by treatment with the DNA methylation inhibitor 5-aza-2'-deoxycytidine, but not by application of the inhibitor of histone deacetylase Trichostatin A. Genetic crosses with the DNA methyltransferase met1 single or drm1drm2cmt3 triple mutants also resulted in a release of CaMV 35S transgene TGS in the rpt2a mutant background. Increased methylation was also found at transposon sequences, suggesting that the 19S proteasome containing AtRPT2a negatively regulates TGS at transgenes and at specific endogenous genes through DNA methylation.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | | | - Junji Yamaguchi
- Faculty of Science and Graduate School of Life Science, Hokkaido University, Sapporo, Japan
- * E-mail:
| |
Collapse
|
11
|
Tashiro S, Tian CE, Watahiki MK, Yamamoto KT. Changes in growth kinetics of stamen filaments cause inefficient pollination in massugu2, an auxin insensitive, dominant mutant of Arabidopsis thaliana. Physiol Plant 2009; 137:175-187. [PMID: 19719484 DOI: 10.1111/j.1399-3054.2009.01271.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We investigated the physiological and molecular basis of lower fecundity of massugu2 (msg2), which is a dominant mutant of an auxin primary response gene, IAA19, in Arabidopsis thaliana. By measuring the length of all stamens and pistils in inflorescences and the reference growth rate of pistils, we constructed growth curves of pistils and stamens between stages 12 and 15 of flower development. Pistil growth was found to consist of a single exponential growth, while stamen growth consisted of three exponential phases. During the second exponential phase, the growth rate of stamen filaments was approximately 10 times greater than the growth rates in the other two phases. Consequently, stamens whose growth was initially retarded grew longer than the pistil, putting pollen grains on the stigma. msg2-1 stamens, on the other hand, exhibited a less obvious growth increase, resulting in less frequent contact between anthers and stigma. MSG2 was expressed in the stamen filaments and its expression almost coincided with the second growth phase. Stamen filaments appeared to elongate by cell elongation rather than cell division in the epidermal cell file. Considering that MSG2 is likely to be a direct target of the auxin F-box receptors, MSG2 may be one of the master genes that control the transient growth increase of stamen filaments.
Collapse
Affiliation(s)
- Satoko Tashiro
- Biosystems Science Course, Graduate School of Life Science, Hokkaido University, Sapporo, Japan
| | | | | | | |
Collapse
|
12
|
Muto H, Watahiki MK, Yamamoto KT. What Makes each Aux/IAA Gene Unique in its Gene Family, Expression Pattern or Properties of the Gene Product? Plant Signal Behav 2007; 2:390-392. [PMID: 19704610 PMCID: PMC2634223 DOI: 10.4161/psb.2.5.4264] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2007] [Accepted: 04/12/2007] [Indexed: 05/28/2023]
Abstract
In the auxin signal transduction, two protein families, Aux/IAAs and auxin response factors, play a crucial role just downstream of auxin F-box receptors. Distinct and overlapping phenotypes of the dominant Aux/IAA mutants suggest some functional differentiation of the Aux/IAA genes in auxin signaling. Taking advantage of unique phenotypes of the msg2/iaa19 mutants, we carried out promoter-exchange experiments, where cDNA of the msg2, axr2/iaa7 or slr/iaa14 gene was driven by the MSG2 or AXR2 promoter. The cDNAs were translationally fused to the green fluorescent protein gene to measure levels of expressed protein. Results showed that many abnormal phenotypes of the dominant Aux/IAA mutants were governed by their promoter activity, but some were dependent on their gene products. The latter result highlights the possible importance of Aux/IAA protein level controled by auxin F-box receptors.
Collapse
Affiliation(s)
- Hideki Muto
- Department of Biological Sciences; Faculty of Science; Hokkaido University; Sapporo Japan
| | | | | |
Collapse
|
13
|
Muto H, Watahiki MK, Nakamoto D, Kinjo M, Yamamoto KT. Specificity and similarity of functions of the Aux/IAA genes in auxin signaling of Arabidopsis revealed by promoter-exchange experiments among MSG2/IAA19, AXR2/IAA7, and SLR/IAA14. Plant Physiol 2007; 144:187-96. [PMID: 17369427 PMCID: PMC1913803 DOI: 10.1104/pp.107.096628] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
As indicated by various and some overlapped phenotypes of the dominant mutants, the Aux/IAA genes of Arabidopsis (Arabidopsis thaliana) concomitantly exhibit a functional similarity and differentiation. To evaluate the contributions of their expression patterns determined by promoter activity and molecular properties of their gene products to Aux/IAA function, we examined phenotypes of transgenic plants expressing the green fluorescent protein (GFP)-tagged msg2-1/iaa19, axr2-1/iaa7, or slr-1/iaa14 cDNA by the MSG2 or AXR2 promoter. When driven by the MSG2 promoter (pMSG2), each GFP-tagged cDNA caused the msg2-1 phenotype, that is, the wild-type stature in the mature-plant stage, long and straight hypocotyls in the dark, reduced lateral root formation, relatively mild agravitropic traits in hypocotyls, and a normal gravitropic response in roots. However, development of one or two cotyledonary primordia was often arrested in embryogenesis of the pMSG2::axr2-1::GFP and pMSG2::slr-1::GFP plants, resulting in monocotyledonary or no cotyledonary seedlings. Such defects in embryogenesis were never seen in pMSG2::msg2-1::GFP or the msg2-1, axr2-1, or slr-1 mutant. The MSG2 promoter-GUS staining showed that expression of MSG2 started specifically in cotyledonary primordia of the triangular-stage embryos. When driven by the AXR2 promoter (pAXR2), each GFP-tagged mutant cDNA caused, in principle, aberrant aboveground phenotypes of the corresponding dominant mutant. However, either the axr2-1::GFP or slr-1::GFP cDNA brought about dwarf, agravitropic stems almost identical to those of axr2-1, and the pAXR2::msg2-1::GFP and pAXR2::slr-1::GFP hypocotyls exhibited complete loss of gravitropism as did axr2-1. These results showed functional differences among the msg2-1, axr2-1, and slr-1 proteins, though some phenotypes were determined by the promoter activity.
Collapse
Affiliation(s)
- Hideki Muto
- Department of Biological Sciences, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan.
| | | | | | | | | |
Collapse
|
14
|
Fujibe T, Saji H, Watahiki MK, Yamamoto KT. Overexpression of the RADICAL-INDUCED CELL DEATH1 (RCD1) gene of Arabidopsis causes weak rcd1 phenotype with compromised oxidative-stress responses. Biosci Biotechnol Biochem 2006; 70:1827-31. [PMID: 16926493 DOI: 10.1271/bbb.50673] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
rcd1 is a mutant of Arabidopsis thaliana that is more resistant to methyl viologen, but more sensitive to ozone than the wild type. rcd1-2 is caused by a single nucleotide substitution that results in a premature stop codon at Trp-332. The rcd1-2 mRNA level does not change significantly with the mutation. Since overexpression of rcd1-1 cDNA has been shown to bring about an rcd1-like phenotype, we created and examined the overexpression lines of RCD1 by the use of the cauliflower mosaic virus 35S promoter. The transgenic lines exhibited a weak rcd1-like phenotype, although no resistance to methyl viologen was observed. Further, they fully complemented the aberrant rcd1-2 phenotype. Subcellular localization of RCD1 was examined by transiently expressing green fluorescent protein (GFP) fused with RCD1 in onion epidermal cells. GFP signals are observed as aggregated foci in the inner nuclear matrix-like region.
Collapse
Affiliation(s)
- Takahiro Fujibe
- Division of Biological Sciences, Graduate School of Science, Hokkaido University, Sapporo, Japan
| | | | | | | |
Collapse
|
15
|
Tatematsu K, Kumagai S, Muto H, Sato A, Watahiki MK, Harper RM, Liscum E, Yamamoto KT. MASSUGU2 encodes Aux/IAA19, an auxin-regulated protein that functions together with the transcriptional activator NPH4/ARF7 to regulate differential growth responses of hypocotyl and formation of lateral roots in Arabidopsis thaliana. Plant Cell 2004; 16:379-93. [PMID: 14729917 PMCID: PMC341911 DOI: 10.1105/tpc.018630] [Citation(s) in RCA: 306] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2003] [Accepted: 12/08/2003] [Indexed: 05/18/2023]
Abstract
We have isolated a dominant, auxin-insensitive mutant of Arabidopsis thaliana, massugu2 (msg2), that displays neither hypocotyl gravitropism nor phototropism, fails to maintain an apical hook as an etiolated seedling, and is defective in lateral root formation. Yet other aspects of growth and development of msg2 plants are almost normal. These characteristics of msg2 are similar to those of another auxin-insensitive mutant, non-phototropic hypocotyl4 (nph4), which is a loss-of-function mutant of AUXIN RESPONSE FACTOR7 (ARF7) (Harper et al., 2000). Map-based cloning of the MSG2 locus reveals that all four mutant alleles result in amino acid substitutions in the conserved domain II of an Auxin/Indole-3-Acetic Acid protein, IAA19. Interestingly, auxin inducibility of MSG2/IAA19 gene expression is reduced by 65% in nph4/arf7. Moreover, MSG2/IAA19 protein binds to the C-terminal domain of NPH4/ARF7 in a Saccharomyces cerevisiae (yeast) two-hybrid assay and to the whole latter protein in vitro by pull-down assay. These results suggest that MSG2/IAA19 and NPH4/ARF7 may constitute a negative feedback loop to regulate differential growth responses of hypocotyls and lateral root formation.
Collapse
Affiliation(s)
- Kiyoshi Tatematsu
- Division of Biological Sciences, Graduate School of Environmental Earth Science, Hokkaido University, Sapporo 060-0810, Japan
| | | | | | | | | | | | | | | |
Collapse
|
16
|
Parton RM, Fischer-Parton S, Trewavas AJ, Watahiki MK. Pollen tubes exhibit regular periodic membrane trafficking events in the absence of apical extension. J Cell Sci 2003; 116:2707-19. [PMID: 12746485 DOI: 10.1242/jcs.00468] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The growing pollen tube provides an excellent single cell model system in which to study the mechanisms determining growth regulation, polarity and periodic behaviour. Previously, using FM4-64, we identified periodic movements within the apical vesicle accumulation that were related to the period of oscillatory growth. This suggested a more complex interdependence between membrane traffic, apical extension and periodicity than previously thought. To investigate this a comparison was made between normally growing and Brefeldin-A-treated, non-growing, tubes. Brefeldin-A treatment established an intriguing, stable yet dynamic system of membrane aggregations in the pollen tube tip that exhibited regular movements of material with a 5-7 second period compared with the normal approximately 30 second periodicity observed in growing tubes. Heat treatment was found to reduce period length in both cases. After BFA treatment membrane was demonstrated to flow from the extreme pollen tube apex back through a distinct subapical Brefeldin-A-induced membrane accumulation. The effects of Brefeldin-A on the distribution of ER- and Golgi-targeted fluorescent proteins revealed that ER did not contribute directly to the system of membrane aggregations while only certain compartments of the Golgi might be involved. The involvement of membrane derived from the apical vesicle accumulation was strongly implicated. Calcium measurements revealed that Brefeldin-A abolished the typical tip-focused calcium gradient associated with growth and there were no obvious periodic fluctuations in apical calcium associated with the continued periodic Brefeldin-A membrane aggregation associated movements. Our experiments reveal an underlying periodicity in the pollen tube that is independent of secretion, apical extension and the oscillating tip-focused calcium gradient normally associated with growth, but requires an active actin cytoskeleton.
Collapse
Affiliation(s)
- Richard M Parton
- Institute of Cell and Molecular Biology, University of Edinburgh, Mayfield Road, Edinburgh EH9 3JU, UK.
| | | | | | | |
Collapse
|
17
|
Parton RM, Fischer-Parton S, Watahiki MK, Trewavas AJ. Dynamics of the apical vesicle accumulation and the rate of growth are related in individual pollen tubes. J Cell Sci 2001; 114:2685-95. [PMID: 11683395 DOI: 10.1242/jcs.114.14.2685] [Citation(s) in RCA: 179] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Regulated secretory vesicle delivery, vesicle fusion and rapid membrane recycling are all contentious issues with respect to tip growth in plant, fungal and animal cells. To examine the organisation and dynamics of membrane movements at the growing pollen tube apex and address the question of their relationship to growth, we have used the membrane stain FM4-64 both as a structural marker and as a quantitative assay. Labelling of living Lilium Longiflorum pollen tubes by FM4-64 resulted in a distinct staining pattern in the tube apex, which corresponds spatially to the previously identified cone-shaped `apical clear zone' containing secretory vesicles. Dye uptake could be inhibited by sodium azide and followed a strict temporal sequence from the plasma membrane to a population of small (1-2 μm diameter) discrete internal structures, with subsequent appearance of dye in the apical region and ultimately in vacuolar membranes. Washout of the dye rapidly removed the plasma membrane staining, which was followed by a gradual decline in the apical fluorescence over more than an hour. Injected aqueous FM4-64 solution showed a relatively even distribution within the pollen tube. Association of FM4-64 with apical secretory vesicles was supported by the effects of the inhibitors Brefeldin-A and Cytochalasin-D, which are known to affect the localisation and number of such vesicles, on the FM4-64 staining pattern. Examination of the dynamics of FM4-64 labelling in the pollen tube tip by time-lapse observation, supported by fluorescence-recovery-after-photobleaching (FRAP) analysis, suggested the possibility of distinct pathways of bulk membrane movement both towards and, significantly, away from the apex. Quantitative analysis of FM4-64 distribution in the apex revealed that fluctuations in fluorescence 5 to 10 μm subapically, and to a lesser extent the apical 3 μm, could be related to the periodic oscillation in pollen tube growth rate. This data reveals a quantitative relationship between FM4-64 staining and growth rate within an individual tube.
Collapse
Affiliation(s)
- R M Parton
- Institute of Cell and Molecular Biology, University of Edinburgh, UK.
| | | | | | | |
Collapse
|
18
|
Fujihira K, Kurata T, Watahiki MK, Karahara I, Yamamoto KT. An agravitropic mutant of Arabidopsis, endodermal-amyloplast less 1, that lacks amyloplasts in hypocotyl endodermal cell layer. Plant Cell Physiol 2000; 41:1193-1199. [PMID: 11092903 DOI: 10.1093/pcp/pcd046] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
We have isolated a new recessive mutant of Arabidopsis thaliana for gravitropism, endodermal-amyloplast less 1 (eal1). eal1 shows reduced gravitropism in hypocotyl, and completely lacks gravitropism in inflorescence stems; root gravitropism is not affected. Starch staining with I-KI solution reveals almost no amyloplasts in eal1 hypocotyls when grown on a sucrose-free medium, though the root columella cells contain as many amyloplasts as wild type. On a medium containing 1% sucrose, eal1 hypocotyls contain as many starch granules as those of wild type, suggesting that starch synthesis is not affected in eal1. The endodermal cell layer which is thought to function as statocytes in hypocotyls is present in eal1. These results suggest that differentiation or development of gravity-responsive amyloplasts are affected in eal1 hypocotyls.
Collapse
Affiliation(s)
- K Fujihira
- Division of Biological Science, Graduate School of Environmental Earth Science, Hokkaido University, Sapporo, 060-0810 Japan
| | | | | | | | | |
Collapse
|
19
|
Harper RM, Stowe-Evans EL, Luesse DR, Muto H, Tatematsu K, Watahiki MK, Yamamoto K, Liscum E. The NPH4 locus encodes the auxin response factor ARF7, a conditional regulator of differential growth in aerial Arabidopsis tissue. Plant Cell 2000; 12:757-70. [PMID: 10810148 PMCID: PMC139925 DOI: 10.1105/tpc.12.5.757] [Citation(s) in RCA: 184] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/1999] [Accepted: 03/02/2000] [Indexed: 05/18/2023]
Abstract
Organ bending through differential growth represents a major mechanism by which plants are able to adaptively alter their morphology in response to local changes in the environment. Two plant hormones, auxin and ethylene, have been implicated as regulators of differential growth responses; however, the mechanisms by which they elicit their effects remain largely unknown. Here, we describe isolation of the NPH4 gene of Arabidopsis, which is conditionally required for differential growth responses of aerial tissues, and we report that NPH4 encodes the auxin-regulated transcriptional activator ARF7. The phenotypes of nph4 mutants, which include multiple differential growth defects associated with reduced auxin responsiveness, including impaired auxin-induced gene expression, are consistent with the predicted loss of function of a transcriptional activator, and these phenotypes indicate that auxin-dependent changes in gene transcription are prerequisite for proper organ bending responses. Although NPH4/ARF7 appears to be a major regulator of differential growth, it is not the sole regulator because phenotypes of nph4 null mutants were suppressed by application of ethylene. This latter finding illustrates the intimate connection between auxin and ethylene in the control of growth in higher plants.
Collapse
Affiliation(s)
- R M Harper
- Division of Biological Sciences, University of Missouri, Columbia 65211, USA
| | | | | | | | | | | | | | | |
Collapse
|
20
|
Watahiki MK, Tatematsu K, Fujihira K, Yamamoto M, Yamamoto KT. The MSG1 and AXR1 genes of Arabidopsis are likely to act independently in growth-curvature responses of hypocotyls. Planta 1999; 207:362-369. [PMID: 9951732 DOI: 10.1007/s004250050493] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Growth-curvature responses of hypocotyls of Arabidopsis thaliana (L.) Heynh. were measured in double mutants between msg1 and axr1, both of which are auxin-resistant and defective in hypocotyl growth curvature induced upon unilateral application of auxin. The msg1 axr1 double mutants showed no auxin-induced growth curvature, that is, they exhibited the msg1 phenotype, though the axr1 defects were partial. Hypocotyls of both the msg1 and axr1 mutants were partially defective in second-positive phototropism, whereas the double mutants lost the response completely. When grown on vertically held agar plates, the axr1 mutant showed normal hypocotyl gravitropism and the mutation did not affect the reduced hypocotyl gravitropism of msg1. Hypocotyls of msg1 and axr1 mutants grew upward like wild-type ones when grown along an agar surface, while they grew more randomly when grown without an agar support, suggesting that axr1 hypocotyls are not completely normal in gravitropism. The extent of defects in growth orientation increased in the order: msg1 axr1 double mutants > msg1 > axr1 > wild type. The hypocotyls of these mutants showed auxin resistance in the order: msg1 axr1 > axr1 > msg1 > wild type. The msg1 mutant had epinastic leaves and axr1 had wrinkled leaves; leaves of the msg1 axr1 double mutants were epinastic and wrinkled. These results suggest that MSG1 and AXR1 act independently in separate pathways of the reactions tested in the present study. In contrast, the phenotype of the msg1 aux1 double mutants shows that AUX1 is not significantly involved in these phenomena.
Collapse
Affiliation(s)
- M K Watahiki
- Division of Biological Science, Graduate School of Environmental Earth Science, Hokkaido University, Sapporo, Japan
| | | | | | | | | |
Collapse
|
21
|
Watahiki MK, Yamamoto KT. The massugu1 mutation of Arabidopsis identified with failure of auxin-induced growth curvature of hypocotyl confers auxin insensitivity to hypocotyl and leaf. Plant Physiol 1997; 115:419-26. [PMID: 9342863 PMCID: PMC158499 DOI: 10.1104/pp.115.2.419] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Unilateral application of indole-3-acetic acid (IAA) in a lanolin base to hypocotyls of partially etiolated seedlings of wild-type Arabidopsis thaliana induced growth curvature in a dose-dependent manner. The effects of IAA in concentrations from 1 to 1000 microM were studied, with maximum IAA-induced curvature at 100 microM. Three IAA-insensitive mutants were isolated and are all in the same locus, massugu1 (msg1). They did not undergo hypocotyl growth curvature at any of the IAA concentrations tested. msg1 is recessive and is located on chromosome 5. msg 1 hypocotyl growth is resistant to 2,4-dichlorophenoxyacetic acid (2,4-D), but the roots are as sensitive to 2,4-D as the wild type. Growth of the hypocotyl was inhibited to essentially the same extent as the wild type by 6-benzylaminopurine, abscisic acid, and 1-aminocyclopropane-1-carboxylate, an ethylene precursor. The msg1 leaves were also resistant to 2,4-D-induced chlorosis. The gravitropic response of the msg1 hypocotyl takes much more time to initiate and achieve the wild-type degree of curvature, whereas the msg1 roots responded normally to gravity. The mature plants and the etiolated seedlings of msg1 were generally wild type in appearance, except that their rosette leaves were either epinastic or hyponastic. msg1 is the first auxin-insensitive mutant in which it effects are mostly restricted to the hypocotyl and leaf, and msg1 also appears to be auxin specific.
Collapse
Affiliation(s)
- M K Watahiki
- Division of Biological Science, Graduate School of Environmental Earth Science, Hokkaido University, Sapporo, Japan
| | | |
Collapse
|
22
|
Affiliation(s)
- M K Watahiki
- Department of Biological Science, Graduate School of Science, University, Sapporo, Japan
| | | |
Collapse
|