1
|
Xu Y, Tian W, Yin M, Cai Z, Zhang L, Yuan D, Yi H, Wu J. The miR159a-DUO1 module regulates pollen development by modulating auxin biosynthesis and starch metabolism in citrus. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2024; 66:1351-1369. [PMID: 38578168 DOI: 10.1111/jipb.13656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2023] [Accepted: 03/15/2024] [Indexed: 04/06/2024]
Abstract
Achieving seedlessness in citrus varieties is one of the important objectives of citrus breeding. Male sterility associated with abnormal pollen development is an important factor in seedlessness. However, our understanding of the regulatory mechanism underlying the seedlessness phenotype in citrus is still limited. Here, we determined that the miR159a-DUO1 module played an important role in regulating pollen development in citrus, which further indirectly modulated seed development and fruit size. Both the overexpression of csi-miR159a and the knocking out of DUO1 in Hong Kong kumquat (Fortunella hindsii) resulted in small and seedless fruit phenotypes. Moreover, pollen was severely aborted in both transgenic lines, with arrested pollen mitotic I and abnormal pollen starch metabolism. Through additional cross-pollination experiments, DUO1 was proven to be the key target gene for miR159a to regulate male sterility in citrus. Based on DNA affinity purification sequencing (DAP-seq), RNA-seq, and verified interaction assays, YUC2/YUC6, SS4 and STP8 were identified as downstream target genes of DUO1, those were all positively regulated by DUO1. In transgenic F. hindsii lines, the miR159a-DUO1 module down-regulated the expression of YUC2/YUC6, which decreased indoleacetic acid (IAA) levels and modulated auxin signaling to repress pollen mitotic I. The miR159a-DUO1 module reduced the expression of the starch synthesis gene SS4 and sugar transport gene STP8 to disrupt starch metabolism in pollen. Overall, this work reveals a new mechanism by which the miR159a-DUO1 module regulates pollen development and elucidates the molecular regulatory network underlying male sterility in citrus.
Collapse
Affiliation(s)
- Yanhui Xu
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan, 430070, China
| | - Wenxiu Tian
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan, 430070, China
| | - Minqiang Yin
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan, 430070, China
| | - Zhenmei Cai
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan, 430070, China
| | - Li Zhang
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan, 430070, China
| | - Deyi Yuan
- Key Laboratory of Cultivation and Protection for Non-Wood Forest Trees of the Ministry of Education and Key Laboratory of Non-Wood Forest Products of the Forestry Ministry, Central South University of Forestry and Technology, Changsha, 410004, China
| | - Hualin Yi
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan, 430070, China
| | - Juxun Wu
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan, 430070, China
| |
Collapse
|
2
|
Yang D, Liu Y, Ali M, Ye L, Pan C, Li M, Zhao X, Yu F, Zhao X, Lu G. Phytochrome interacting factor 3 regulates pollen mitotic division through auxin signalling and sugar metabolism pathways in tomato. THE NEW PHYTOLOGIST 2022; 234:560-577. [PMID: 34812499 PMCID: PMC9299586 DOI: 10.1111/nph.17878] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Accepted: 11/15/2021] [Indexed: 05/27/2023]
Abstract
The development of viable pollen determines male fertility, and is crucial for reproduction in flowering plants. Phytochrome interacting factor 3 (PIF3) acts as a central regulator of plant growth and development, but its relationship with pollen development has not been determined. Through genetic, histological and transcriptomic analyses, we identified an essential role for SlPIF3 in regulating tomato (Solanum lycopersicum) pollen development. Knocking out SlPIF3 using clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 resulted in pollen mitosis I arrest, and a failure to form viable pollen. We further demonstrated that both glutamate synthase 1 (SlGLT1) and cell wall invertase 9 (SlCWIN9), involved in auxin and sugar homeostasis, respectively, colocalised with SlPIF3 in the anthers and were directly regulated by SlPIF3. Knockout of either SlGLT1 or SlCWIN9 phenocopied the pollen phenotype of SlPIF3 knockout (Slpif3) lines. Slpif3 fertility was partially restored by exogenous auxin indole-3-acetic acid in a dose-dependent manner. This study reveals a mechanism by which SlPIF3 regulates pollen development and highlights a new strategy for creating hormone-regulated genic male sterile lines for tomato hybrid seed production.
Collapse
Affiliation(s)
- Dandan Yang
- Department of HorticultureZhejiang UniversityHangzhou310058China
| | - Yue Liu
- Department of HorticultureZhejiang UniversityHangzhou310058China
| | - Muhammad Ali
- Department of HorticultureZhejiang UniversityHangzhou310058China
| | - Lei Ye
- Department of HorticultureZhejiang UniversityHangzhou310058China
| | - Changtian Pan
- Department of HorticultureZhejiang UniversityHangzhou310058China
| | - Mengzhuo Li
- Department of HorticultureZhejiang UniversityHangzhou310058China
| | - Xiaolin Zhao
- Department of HorticultureZhejiang UniversityHangzhou310058China
| | - Fangjie Yu
- Department of HorticultureZhejiang UniversityHangzhou310058China
| | - Xinai Zhao
- Department of Stem Cell BiologyCentre for Organismal StudiesHeidelberg UniversityIm Neuenheimer Feld 230Heidelberg69120Germany
| | - Gang Lu
- Department of HorticultureZhejiang UniversityHangzhou310058China
- Key Laboratory of Horticultural Plant Growth, Development and Quality ImprovementMinistry of AgriculturalZhejiang UniversityHangzhou310058China
| |
Collapse
|
3
|
Meng J, Peng M, Yang J, Zhao Y, Hu J, Zhu Y, He H. Genome-Wide Analysis of the Cyclin Gene Family and Their Expression Profile in Medicago truncatula. Int J Mol Sci 2020; 21:E9430. [PMID: 33322339 PMCID: PMC7763586 DOI: 10.3390/ijms21249430] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 11/23/2020] [Accepted: 12/09/2020] [Indexed: 11/23/2022] Open
Abstract
Cyclins, together with highly conserved cyclin-dependent kinases (CDKs), play an important role in the process of cell cycle in plants, but less is known about the functions of cyclins in legume plants, especially Medicago truncatula. Our genome-wide analysis identified 58, 103, and 51 cyclin members in the M. truncatula, Glycine max, and Phaseolus vulgaris genomes. Phylogenetic analysis suggested that these cyclins could be classified into 10 types, and the CycB-like types (CycBL1-BL8) were the specific subgroups in M. truncatula, which was one reason for the expansion of the B-type in M. truncatula. All putative cyclin genes were mapped onto their own chromosomes of each genome, and 9 segmental duplication gene pairs involving 20 genes were identified in M. truncatula cyclins. Determined by quantitative real-time PCR, the expression profiling suggested that 57 cyclins in M. truncatula were differentially expressed in 9 different tissues, while a few genes were expressed in some specific tissues. Using the publicly available RNAseq data, the expression of Mtcyclins in the wild-type strain A17 and three nodule mutants during rhizobial infection showed that 23 cyclins were highly upregulated in the nodulation (Nod) factor-hypersensitive mutant sickle (skl) mutant after 12 h of rhizobium inoculation. Among these cyclins, six cyclin genes were also specifically expressed in roots and nodules, which might play specific roles in the various phases of Nod factor-mediated cell cycle activation and nodule development. Our results provide information about the cyclin gene family in legume plants, serving as a guide for further functional research on plant cyclins.
Collapse
Affiliation(s)
| | | | | | | | | | | | - Hengbin He
- Beijing Key Laboratory of Ornamental Plants Germplasm Innovation and Molecular Breeding, National Engineering Research Center for Floriculture, Beijing Laboratory of Urban and Rural Ecological Environment, School of Landscape Architecture, Beijing Forestry University, Beijing 100083, China; (J.M.); (M.P.); (J.Y.); (Y.Z.); (J.H.); (Y.Z.)
| |
Collapse
|
4
|
Sukawa Y, Okamoto T. Cell cycle in egg cell and its progression during zygotic development in rice. PLANT REPRODUCTION 2018; 31:107-116. [PMID: 29270910 DOI: 10.1007/s00497-017-0318-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Accepted: 12/04/2017] [Indexed: 05/20/2023]
Abstract
Rice egg is arrested at G1 phase probably by OsKRP2. After fusion with sperm, karyogamy, OsWEE1-mediated parental DNA integrity in zygote nucleus, zygote progresses cell cycle to produce two-celled embryo. In angiosperms, female and male gametes exist in gametophytes after the complementation of meiosis and the progression of nuclear/cell division of the haploid cell. Within the embryo sac, the egg cell is specially differentiated for fertilization and subsequent embryogenesis, and cellular programs for embryonic development, such as restarting the cell cycle and de novo gene expression, are halted. There is only limited knowledge about how the cell cycle in egg cells restarts toward zygotic division, although the conversion of the cell cycle from a quiescent and arrested state to an active state is the most evident transition of cell status from egg cell to zygote. This is partly due to the difficulty in direct access and analysis of egg cells, zygotes and early embryos, which are deeply embedded in ovaries. In this study, precise relative DNA amounts in the nuclei of egg cells, developing zygotes and cells of early embryos were measured, and the cell cycle of a rice egg cell was estimated as the G1 phase with a 1C DNA level. In addition, increases in DNA content in zygote nuclei via karyogamy and DNA replication were also detectable according to progression of the cell cycle. In addition, expression profiles for cell cycle-related genes in egg cells and zygotes were also addressed, and it was suggested that OsKRP2 and OsWEE1 function in the inhibition of cell cycle progression in egg cells and in checkpoint of parental DNA integrity in zygote nucleus, respectively.
Collapse
Affiliation(s)
- Yumiko Sukawa
- Department of Biological Sciences, Tokyo Metropolitan University, Minami-osawa 1-1, Hachioji, Tokyo, 192-0397, Japan
| | - Takashi Okamoto
- Department of Biological Sciences, Tokyo Metropolitan University, Minami-osawa 1-1, Hachioji, Tokyo, 192-0397, Japan.
| |
Collapse
|
5
|
Singh BN, Mudgil Y, John R, Achary VMM, Tripathy MK, Sopory SK, Reddy MK, Kaul T. Cell cycle stage-specific differential expression of topoisomerase I in tobacco BY-2 cells and its ectopic overexpression and knockdown unravels its crucial role in plant morphogenesis and development. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2015; 240:182-92. [PMID: 26475198 DOI: 10.1016/j.plantsci.2015.09.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Revised: 09/17/2015] [Accepted: 09/19/2015] [Indexed: 05/24/2023]
Abstract
DNA topoisomerases catalyze the inter-conversion of different topological forms of DNA. Cell cycle coupled differential accumulation of topoisomerase I (Topo I) revealed biphasic expression maximum at S-phase and M/G1-phase of cultured synchronized tobacco BY-2 cells. This suggested its active role in resolving topological constrains during DNA replication (S-phase) and chromosome decondensation (M/G1 phase). Immuno-localization revealed high concentrations of Topo I in nucleolus. Propidium iodide staining and Br-UTP incorporation patterns revealed direct correlation between immunofluorescence intensity and rRNA transcription activity within nucleolus. Immuno-stained chromosomes during metaphase and anaphase suggested possible role of Topo I in resolving topological constrains during mitotic chromosome condensation. Inhibitor studies showed that in comparison to Topo I, Topo II was essential in resolving topological constrains during chromosome condensation. Probably, Topo II substituted Topo I functioning to certain extent during chromosome condensation, but not vice-versa. Transgenic Topo I tobacco lines revealed morphological abnormalities and highlighted its crucial role in plant morphogenesis and development.
Collapse
Affiliation(s)
- Badri Nath Singh
- Plant Molecular Biology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi 110067, Delhi, India
| | - Yashwanti Mudgil
- Plant Molecular Biology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi 110067, Delhi, India
| | - Riffat John
- Department of Botany, University of Kashmir, Hazratbal, Srinagar 190006, Jammu and Kashmir, India
| | - V Mohan Murali Achary
- Plant Molecular Biology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi 110067, Delhi, India
| | - Manas Kumar Tripathy
- Plant Molecular Biology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi 110067, Delhi, India
| | - Sudhir K Sopory
- Plant Molecular Biology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi 110067, Delhi, India
| | - Malireddy K Reddy
- Plant Molecular Biology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi 110067, Delhi, India
| | - Tanushri Kaul
- Plant Molecular Biology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi 110067, Delhi, India.
| |
Collapse
|
6
|
Dynamics of DNA replication during premeiosis and early meiosis in wheat. PLoS One 2014; 9:e107714. [PMID: 25275307 PMCID: PMC4183481 DOI: 10.1371/journal.pone.0107714] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Accepted: 08/21/2014] [Indexed: 11/19/2022] Open
Abstract
Meiosis is a specialised cell division that involves chromosome replication, two rounds of chromosome segregation and results in the formation of the gametes. Meiotic DNA replication generally precedes chromosome pairing, recombination and synapsis in sexually developing eukaryotes. In this work, replication has been studied during premeiosis and early meiosis in wheat using flow cytometry, which has allowed the quantification of the amount of DNA in wheat anther in each phase of the cell cycle during premeiosis and each stage of early meiosis. Flow cytometry has been revealed as a suitable and user-friendly tool to detect and quantify DNA replication during early meiosis in wheat. Chromosome replication was detected in wheat during premeiosis and early meiosis until the stage of pachytene, when chromosomes are associated in pairs to further recombine and correctly segregate in the gametes. In addition, the effect of the Ph1 locus, which controls chromosome pairing and affects replication in wheat, was also studied by flow cytometry. Here we showed that the Ph1 locus plays an important role on the length of meiotic DNA replication in wheat, particularly affecting the rate of replication during early meiosis in wheat.
Collapse
|
7
|
Buendía-Monreal M, Rentería-Canett I, Guerrero-Andrade O, Bravo-Alberto CE, Martínez-Castilla LP, García E, Vázquez-Ramos JM. The family of maize D-type cyclins: genomic organization, phylogeny and expression patterns. PHYSIOLOGIA PLANTARUM 2011; 143:297-308. [PMID: 21707637 DOI: 10.1111/j.1399-3054.2011.01498.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: 05/13/2023]
Abstract
Cyclin proteins, associated to cyclin-dependent kinases (CDKs), play fundamental roles in cell cycle control as they constitute a very important driving force to allow cell cycle progression. D-type cyclins (CycDs) are important both for interpreting external mitogenic signals and in the control of the G1 phase. The maize (Zea mays) genome appears to contain at least 17 different CycD genes, and they fall into the subgroups previously described for other plants. Maize CycDs have been named according to identity percentages of the corresponding orthologs in rice and Arabidopsis. In silico analysis confirmed the presence of characteristic cyclin domains in each maize CycD gene and showed that their genomic organization is similar to their orthologs in rice and Arabidopsis. The expression of maize CycD genes was followed in seeds, during germination in the presence/absence of exogenously added hormones, and also in different plantlet tissues (mesocotyl, root tips and first leaf). Most cyclins were expressed in germinating seeds and at least in one of the plantlet tissues tested; almost all of the detected cyclins show an accumulating pattern of mRNA along germination (0-24 h) and higher levels in root tissue. Interestingly, some cyclins show high levels in non-proliferating tissues as leaf. Addition of auxins or cytokinins does not seem to importantly modify transcript levels; on the other hand, addition of abscisic acid repressed the expression of several cyclins. The role of each CycD during germination and plant growth and its interaction with other cell cycle proteins becomes a topic of the highest interest.
Collapse
Affiliation(s)
- Manuel Buendía-Monreal
- Facultad de Química, Departamento de Bioquímica, Universidad Nacional Autónoma de México, México Distrito Federal, Mexico
| | | | | | | | | | | | | |
Collapse
|
8
|
Jia Y, Anderson JV, Chao WS. Autophosphorylation is crucial for CDK-activating kinase (Ee;CDKF;1) activity and complex formation in leafy spurge. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2011; 180:259-267. [PMID: 21421369 DOI: 10.1016/j.plantsci.2010.08.017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2010] [Revised: 08/25/2010] [Accepted: 08/26/2010] [Indexed: 05/30/2023]
Abstract
Ee;CDKF;1 protein is a leafy spurge (Euphorbia esula) CDK-activating kinase that is involved in a phosphorylation cascade linked to early stages of cell cycle progression. Yeast two-hybrid screening performed using Ee;CDKF;1 as a bait indicated that one of the interacting proteins was Ee;CDKF;1. Protein-protein interaction of Ee;CDKF;1 was further confirmed by yeast two-hybrid interaction and in vitro pull-down assays. Gel exclusion chromatography and/or native PAGE showed that GST-CDKF;1, MBP-CDKF;1, GST-CDKF;1 devoid of GST, and endogenous Ee;CDKF;1 were capable of forming homo protein complexes which are in dimer, trimer, and/or higher molecular-mass complex in its native state. In addition, Ee;CDKF;1 complexes were autophosphorylated and able to phosphorylate CDK. Moreover, mutant forms of Ee;CDKF;1 (106G/A, 166K/A), which lost autophosphorylation capability completely, were unable to form homo protein complexes in their native state. The result thus demonstrated that autophosphorylation of Ee;CDKF;1 is crucial for both kinase activity and complex formation.
Collapse
Affiliation(s)
- Ying Jia
- Department of Plant Science, North Dakota State University, Fargo, ND 58105, USA
| | | | | |
Collapse
|
9
|
Harrison CJ, Alvey E, Henderson IR. Meiosis in flowering plants and other green organisms. JOURNAL OF EXPERIMENTAL BOTANY 2010; 61:2863-75. [PMID: 20576791 DOI: 10.1093/jxb/erq191] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Sexual eukaryotes generate gametes using a specialized cell division called meiosis that serves both to halve the number of chromosomes and to reshuffle genetic variation present in the parent. The nature and mechanism of the meiotic cell division in plants and its effect on genetic variation are reviewed here. As flowers are the site of meiosis and fertilization in angiosperms, meiotic control will be considered within this developmental context. Finally, we review what is known about the control of meiosis in green algae and non-flowering land plants and discuss evolutionary transitions relating to meiosis that have occurred in the lineages giving rise to the angiosperms.
Collapse
Affiliation(s)
- C Jill Harrison
- Department of Plant Sciences, University of Cambridge, Cambridge, UK.
| | | | | |
Collapse
|
10
|
Hu Y, Wang Z, Wang Y, Bao F, Li N, Peng Z, Li J. Identification of brassinosteroid responsive genes in Arabidopsis by cDNA array. ACTA ACUST UNITED AC 2009; 44:637-43. [PMID: 18763105 DOI: 10.1007/bf02879358] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2001] [Indexed: 10/22/2022]
Abstract
We have systematically monitored brassinosteroid (BR) responsive genes in a BR-deficient mutant det2 suspension culture of Arabidopsis by using a cDNA array approach. Among 13000 cDNA clones arrayed on filters, 53 BR responsive clones were identified and designated BRR1-BRR53. Sequence analysis of 43 clones showed that 19 clones are novel genes, 3 clones are genes involved in the control of cell division, 4 clones are genes related to plant stress responses, 4 clones are transcriptional factor or signal transduction component genes, and 3 clones are genes involved in RNA splicing or structure forming. In addition, we also found that BR regulated the transcription of genes related to many physiological processes, such as photoreaction, ion transportation and some metabolic processes. These findings present molecular evidence that BR plays an essential role in plant growth and development.
Collapse
Affiliation(s)
- Y Hu
- Institute of Genetics, Chinese Academy of Sciences, Beijing, China
| | | | | | | | | | | | | |
Collapse
|
11
|
Verdier J, Thompson RD. Transcriptional regulation of storage protein synthesis during dicotyledon seed filling. PLANT & CELL PHYSIOLOGY 2008; 49:1263-71. [PMID: 18701524 DOI: 10.1093/pcp/pcn116] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Seeds represent a major source of nutrients for human and animal livestock diets. The nutritive value of seeds is largely due to storage products which accumulate during a key phase of seed development, seed filling. In recent years, our understanding of the mechanisms regulating seed filling has advanced significantly due to the diversity of experimental approaches used. This review summarizes recent findings related to transcription factors that regulate seed storage protein accumulation. A framework for the regulation of storage protein synthesis is established which incorporates the events before, during and after seed storage protein synthesis. The transcriptional control of storage protein synthesis is accompanied by physiological and environmental controls, notably through the action of plant hormones and other intermediary metabolites. Finally, recent post-genomics analyses on different model plants have established the existence of a conserved seed filling process involving the master regulators (LEC1, LEC2, ABI3 and FUS3) but also revealed certain differences in fine regulation between plant families.
Collapse
Affiliation(s)
- Jérôme Verdier
- Unité Mixte de Recherche en Génétique et Ecophysiologie des Légumineuses à Graines (UMR-LEG), Institut National de la Recherche Agronomique (INRA), BP 86510, F-21065 Dijon, France
| | | |
Collapse
|
12
|
Liu J, Zhang Y, Qin G, Tsuge T, Sakaguchi N, Luo G, Sun K, Shi D, Aki S, Zheng N, Aoyama T, Oka A, Yang W, Umeda M, Xie Q, Gu H, Qu LJ. Targeted degradation of the cyclin-dependent kinase inhibitor ICK4/KRP6 by RING-type E3 ligases is essential for mitotic cell cycle progression during Arabidopsis gametogenesis. THE PLANT CELL 2008; 20:1538-54. [PMID: 18552199 PMCID: PMC2483368 DOI: 10.1105/tpc.108.059741] [Citation(s) in RCA: 133] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2008] [Revised: 05/01/2008] [Accepted: 05/31/2008] [Indexed: 05/19/2023]
Abstract
Following meiosis, plant gametophytes develop through two or three rounds of mitosis. Although the ontogeny of gametophyte development has been defined in Arabidopsis thaliana, the molecular mechanisms regulating mitotic cell cycle progression are not well understood. Here, we report that RING-H2 group F 1a (RHF1a) and RHF2a, two RING-finger E3 ligases, play an important role in Arabidopsis gametogenesis. The rhf1a rhf2a double mutants are defective in the formation of male and female gametophytes due to interphase arrest of the mitotic cell cycle at the microspore stage of pollen development and at female gametophyte stage 1 of embryo sac development. We demonstrate that RHF1a directly interacts with and targets a cyclin-dependent kinase inhibitor ICK4/KRP6 (for Interactors of Cdc2 Kinase 4/Kip-related protein 6) for proteasome-mediated degradation. Inactivation of the two redundant RHF genes leads to the accumulation of ICK4/KRP6, and reduction of ICK4/KRP6 expression largely rescues the gametophytic defects in rhf1a rhf2a double mutants, indicating that ICK4/KRP6 is a substrate of the RHF E3 ligases. Interestingly, in situ hybridization showed that ICK4/KRP6 was predominantly expressed in sporophytes during meiosis. Our findings indicate that RHF1a/2a-mediated degradation of the meiosis-accumulated ICK4/KRP6 is essential to ensure the progression of subsequent mitoses to form gametophytes in Arabidopsis.
Collapse
Affiliation(s)
- Jingjing Liu
- National Laboratory for Protein Engineering and Plant Genetic Engineering, Peking-Yale Joint Research Center for Plant Molecular Genetics and AgroBiotechnology, College of Life Sciences, Peking University, Beijing 100871, People's Republic of China
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
13
|
Huang YW, Tsay WS, Chen CC, Lin CW, Huang HJ. Increased expression of the rice C-type cyclin-dependent protein kinase gene, Orysa;CDKC;1, in response to salt stress. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2008; 46:71-81. [PMID: 18054244 DOI: 10.1016/j.plaphy.2007.10.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2007] [Indexed: 05/25/2023]
Abstract
Cyclin-dependent protein kinases (CDKs) form a conserved superfamily of eukaryotic serine/threonine protein kinases which require binding to a regulatory cyclin for activity. CDKs are organized in several gene families and are involved in different aspects of cell biology, such as gene transcription, cell proliferation and differentiation. In this study, we present the characteristics of the rice C-type CDK gene, Orysa;CDKC;1. The gene was expressed in all organs of the plant and relatively high amounts of its transcript were detected in mature leaves and panicles. This indicated a putative role during later stages of leaf and panicle development. Using yeast two-hybrid analysis, we identified Orysa;CYCT as an interactor with Orysa;CDKC;1. The expression profiles of the new Orysa;CDKC;1 in response to various factors from rice cells were compared with those of previously described Orysa;CDKA;1, and Orysa;CDKB2;1. The Orysa;CDKC;1 transcript was induced by salt stress and ABA treatments, but was unaffected by mannitol. In addition, the MBP kinase activity associated with Orysa;CDKC;1 immunocomplexes was induced under salt stress. We propose that Orysa;CDKC;1 may be involved in developmental programs, as well as in the salt- and ABA-signaling pathway.
Collapse
Affiliation(s)
- Ya-Wen Huang
- Department of Life Sciences, National Cheng Kung University, No. 1 University Road, Tainan, Taiwan, ROC
| | | | | | | | | |
Collapse
|
14
|
Menges M, Pavesi G, Morandini P, Bögre L, Murray JAH. Genomic organization and evolutionary conservation of plant D-type cyclins. PLANT PHYSIOLOGY 2007; 145:1558-76. [PMID: 17951462 PMCID: PMC2151690 DOI: 10.1104/pp.107.104901] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2007] [Accepted: 10/06/2007] [Indexed: 05/21/2023]
Abstract
Plants contain more genes encoding core cell cycle regulators than other organisms but it is unclear whether these represent distinct functions. D-type cyclins (CYCD) play key roles in the G1-to-S-phase transition, and Arabidopsis (Arabidopsis thaliana) contains 10 CYCD genes in seven defined subgroups, six of which are conserved in rice (Oryza sativa). Here, we identify 22 CYCD genes in the poplar (Populus trichocarpa) genome and confirm that these six CYCD subgroups are conserved across higher plants, suggesting subgroup-specific functions. Different subgroups show gene number increases, with CYCD3 having three members in Arabidopsis, six in poplar, and a single representative in rice. All three species contain a single CYCD7 gene. Despite low overall sequence homology, we find remarkable conservation of intron/exon boundaries, because in most CYCD genes of plants and mammals, the first exon ends in the conserved cyclin signature. Only CYCD3 genes contain the complete cyclin box in a single exon, and this structure is conserved across angiosperms, again suggesting an early origin for the subgroup. The single CYCD gene of moss has a gene structure closely related to those of higher plants, sharing an identical exon/intron structure with several higher plant subgroups. However, green algae have CYCD genes structurally unrelated to higher plants. Conservation is also observed in the location of potential cyclin-dependent kinase phosphorylation sites within CYCD proteins. Subgroup structure is supported by conserved regulatory elements, particularly in the eudicot species, including conserved E2F regulatory sites within CYCD3 promoters. Global expression correlation analysis further supports distinct expression patterns for CYCD subgroups.
Collapse
Affiliation(s)
- Margit Menges
- Institute of Biotechnology, University of Cambridge, Cambridge CB2 1QT, United Kingdom
| | | | | | | | | |
Collapse
|
15
|
Chao WS, Serpe MD, Jia Y, Shelver WL, Anderson JV, Umeda M. Potential roles for autophosphorylation, kinase activity, and abundance of a CDK-activating kinase (Ee;CDKF;1) during growth in leafy spurge. PLANT MOLECULAR BIOLOGY 2007; 63:365-79. [PMID: 17063377 DOI: 10.1007/s11103-006-9094-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2006] [Accepted: 09/24/2006] [Indexed: 05/12/2023]
Abstract
Leafy spurge (Euphorbia esula L.) is a deep-rooted perennial weed that propagates both by seeds and underground adventitious buds located on the crown and roots. To enhance our understanding of growth and development during seed germination and vegetative propagation, a leafy spurge gene (Accession No. AF230740) encoding a CDK-activating kinase (Ee;CDKF;1) involved in cell-cycle progression was identified, and its function was confirmed based on its ability to rescue a yeast temperature-sensitive CAK mutant (GF2351) and through in vitro kinase assays. Site-directed mutagenesis of Ee;CDKF;1 indicated that two threonine residues (Thr291 and Thr296) were mutually responsible for intra-molecular autophosphorylation and for phosphorylating its substrate protein, cyclin-dependent kinase (CDK). Polyclonal antibodies generated against the Ee;CDKF;1 protein or against a phosphorylated Ee;CDKF;1 peptide [NERYGSL(pT)SC] were used to examine abundance and phosphorylation of CDKF;1 during seed germination and bud growth. The levels of CDKF;1 were lower in dry or imbibed seeds than in germinating seeds or seedlings. Differences in CDKF;1 were also observed during adventitious bud development; small buds appeared to have greater levels of CDKF;1 than large buds. Similar patterns of CDKF;1 expression were detected with either the polyclonal antibody developed using the CDKF;1 protein or the phosphorylated peptide. These results indicated that Thr291 is constitutively phosphorylated in vivo and associated with Ee;CDKF;1 activity. Our results further suggest that a certain level of CDKF;1 activity is maintained in most tissues and may be an important phenomenon for enzymes that regulate early steps in cell-cycle signaling pathways.
Collapse
Affiliation(s)
- Wun S Chao
- USDA-Agricultural Research Service, Biosciences Research Laboratory, 1605 Albrecht Blvd., Fargo, ND 58105-5674, USA.
| | | | | | | | | | | |
Collapse
|
16
|
Aguilar-Martínez JA, Poza-Carrión C, Cubas P. Arabidopsis BRANCHED1 acts as an integrator of branching signals within axillary buds. THE PLANT CELL 2007; 19:458-72. [PMID: 17307924 PMCID: PMC1867329 DOI: 10.1105/tpc.106.048934] [Citation(s) in RCA: 543] [Impact Index Per Article: 31.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Shoot branching patterns depend on a key developmental decision: whether axillary buds grow out to give a branch or whether they remain dormant in the axils of leaves. This decision is controlled by endogenous and environmental stimuli mediated by hormonal signals. Although genes involved in the long-distance signaling of this process have been identified, the genes responding inside the buds to cause growth arrest remained unknown in Arabidopsis thaliana. Here, we describe an Arabidopsis gene encoding a TCP transcription factor closely related to teosinte branched1 (tb1) from maize (Zea mays), BRANCHED1 (BRC1), which represents a key point at which signals controlling branching are integrated within axillary buds. BRC1 is expressed in developing buds, where it arrests bud development. BRC1 downregulation leads to branch outgrowth. BRC1 responds to developmental and environmental stimuli controlling branching and mediates the response to these stimuli. Mutant and expression analyses suggest that BRC1 is downstream of the MORE AXILLARY GROWTH pathway and that it is required for auxin-induced apical dominance. Therefore, BRC1 acts inside the buds as an integrator of signals controlling bud outgrowth and translates them into a response of cell growth arrest. The conservation of BRC1/tb1 function among distantly related angiosperm species suggests that a single ancestral mechanism of branching control integration evolved before the radiation of flowering plants.
Collapse
Affiliation(s)
- José Antonio Aguilar-Martínez
- Departamento de Genética Molecular de Plantas, Centro Nacional de Biotecnología/Consejo Superior de Investigaciones Cientificas, Campus Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | | | | |
Collapse
|
17
|
Stiller JW. Emerging genomic and proteomic evidence on relationships among the animal, plant and fungal kingdoms. GENOMICS PROTEOMICS & BIOINFORMATICS 2005; 2:70-6. [PMID: 15629046 PMCID: PMC5172449 DOI: 10.1016/s1672-0229(04)02012-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Sequence-based molecular phylogenies have provided new models of early eukaryotic evolution. This includes the widely accepted hypothesis that animals are related most closely to fungi, and that the two should be grouped together as the Opisthokonta. Although most published phylogenies have supported an opisthokont relationship, a number of genes contain a tree-building signal that clusters animal and green plant sequences, to the exclusion of fungi. The alternative tree-building signal is especially intriguing in light of emerging data from genomic and proteomic studies that indicate striking and potentially synapomorphic similarities between plants and animals. This paper reviews these new lines of evidence, which have yet to be incorporated into models of broad scale eukaryotic evolution.
Collapse
Affiliation(s)
- John W Stiller
- Department of Biology, East Carolina University, Greenville, NC 27858, USA.
| |
Collapse
|
18
|
Han W, Rhee HI, Cho JW, Ku MSB, Song PS, Wang MH. Overexpression of Arabidopsis ACK1 alters leaf morphology and retards growth and development. Biochem Biophys Res Commun 2005; 330:887-90. [PMID: 15809079 DOI: 10.1016/j.bbrc.2005.03.056] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2005] [Indexed: 10/25/2022]
Abstract
Cyclin dependent kinases (CDKs) play important roles in the plant cell cycle, a highly coordinated process in plant growth and development. To understand the regulatory network involving the CDKs, we have examined the role of ACK1, a gene that has significant homology to known ICKs (inhibitors of CDKs), but occupies a distinct branch of the ICK phylogenetic tree. Overexpression of ACK1 in transgenic Arabidopsis significantly inhibited growth, leading to effects such as serration of leaves, as a result of strong inhibition of cell division in the leaf meristem. ACK1 transgenic plants also differed morphologically from control Arabidopsis plants, and the cells of ACK1 transgenics were more irregular than the corresponding cells of control plants. These results suggest that ACK1 acts as a CDK inhibitor in Arabidopsis, and that the alterations in leaf shape may be the result of restricted cell division.
Collapse
Affiliation(s)
- Woong Han
- Division of Biotechnology, Kangwon National University, Chuncheon, Kangwon-do 200-701, Republic of Korea
| | | | | | | | | | | |
Collapse
|
19
|
Planchais S, Samland AK, Murray JAH. Differential stability of Arabidopsis D-type cyclins: CYCD3;1 is a highly unstable protein degraded by a proteasome-dependent mechanism. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2004; 38:616-625. [PMID: 15125768 DOI: 10.1111/j.0960-7412.2004.02071.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
In Arabidopsis, the D-type cyclin CYCD3 is rate-limiting for transition of the G(1)/S boundary, and is transcriptionally upregulated at this point in cells re-entering the cell cycle in response to plant hormones and sucrose. However, little is known about the regulation of plant cell-cycle regulators at the protein level. We show here that CYCD3;1 is a phosphoprotein highly regulated at the level of protein abundance, whereas another D-type cyclin CYCD2;1 is not. The level of CYCD3;1 protein falls rapidly on sucrose depletion, correlated with the arrest of cells in G(1) phase, suggesting a rapid turnover of CYCD3;1. Treatment of exponentially growing cells with the protein synthesis inhibitor cycloheximide (CHX) confirms that CYCD3;1 is normally a highly unstable protein, with a half-life of approximately 7 min on CHX treatment. In both sucrose-starved and exponentially growing cells, CYCD3;1 protein abundance increases in response to treatment with MG132 (carbobenzoxyl-leucinyl-leucinyl-leucinal), a reversible proteasome inhibitor, but not in response to the cysteine protease inhibitor E-64 or the calpain inhibitor ALLN (N-acetyl-leucyl-leucyl-norleucinal). The increase on MG132 treatment is because of de novo protein synthesis coupled with the blocking of CYCD3;1 degradation. Longer MG132 treatment leads to C-terminal cleavage of CYCD3;1, accumulation of a hyperphosphorylated form and its subsequent disappearance. We conclude that CYCD3;1 is a highly unstable protein whose proteolysis is mediated by a proteasome-dependent pathway, and whose levels are highly dependent on the rate of CYCD3;1 protein synthesis.
Collapse
Affiliation(s)
- Séverine Planchais
- Institute of Biotechnology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QT, UK
| | | | | |
Collapse
|
20
|
Oldenhof H, Bisová K, van den Ende H, Zachleder V. Effect of red and blue light on the timing of cyclin-dependent kinase activity and the timing of cell division in Chlamydomonas reinhardtii. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2004; 42:341-348. [PMID: 15120120 DOI: 10.1016/j.plaphy.2004.02.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2003] [Accepted: 02/10/2004] [Indexed: 05/24/2023]
Abstract
In this study, we describe the effect of red and blue light on the timing of cell division, DNA synthesis, and activity and presence of cyclin-dependent kinases (CDKs), in synchronous cultures of the unicellular green alga Chlamydomonas reinhardtii. Cell division and DNA synthesis were found to occur later in cells grown in blue or white light, than in red light. CDK-like activity, measured using a histone H1 kinase assay, correspondingly occurred later in cultures that were grown in blue light compared to cultures grown in red light. The amount of CDK-like proteins, as detected using an antibody against the PSTAIRE motif, showed a maximum during the division phase. We conclude that the mechanism that causes the delay in the timing of cell division in blue light has its action before DNA replication takes place and also precedes the increase in CDK-like activity.
Collapse
Affiliation(s)
- Harriëtte Oldenhof
- Laboratory of Plant Physiology, Swammerdam Institute for Life Sciences, University of Amsterdam, Kruislaan 318, 1098 SM Amsterdam, The Netherlands.
| | | | | | | |
Collapse
|
21
|
Gómez Roig E, Vázquez-Ramos JM. Maize DNA polymerase alpha is phosphorylated by a PCNA-associated cyclin/Cdk complex: effect of benzyladenine. JOURNAL OF PLANT PHYSIOLOGY 2003; 160:983-990. [PMID: 14593798 DOI: 10.1078/0176-1617-01088] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The activity of maize DNA polymerases 1 and 2 (delta and alpha-type enzymes, respectively) is stimulated during germination if embryo axes are imbibed in the presence of benzyladenine. In vivo, DNA pol 2 is a phosphorotein that appears to be maximally phosphorylated previous to the S phase start time (by 12 h of germination, Coello and Vázquez-Ramos 1995a). We find that, in vitro, a PCNA-associated cyclin/kinase activity isolated from maize axes acquires an increasing capacity to phosphorylate DNA pol 2 as germination advances; moreover, the PCNA-associated kinase isolated from BA-treated maize axes germinated at 3 h phosphorylates DNA pol 2 at the same level observed in samples of axes germinated for 13 h in the absence of exogenous BA. PCNA-associated kinase activity from BA-treated axes germinated at 13 h maximal using DNA pol 2 as substrate. However, there is no modification in DNA polymerase activity as a consequence of protein phosphorylation. Results are discussed in terms of their significance for cell cycle regulation during seed germination.
Collapse
Affiliation(s)
- Edurne Gómez Roig
- Departamento de Bioquímica, Facultad de Química, UNAM, Avenida Universidad y Copilco, México 04510, D.F.
| | | |
Collapse
|
22
|
Zhou Y, Li G, Brandizzi F, Fowke LC, Wang H. The plant cyclin-dependent kinase inhibitor ICK1 has distinct functional domains for in vivo kinase inhibition, protein instability and nuclear localization. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2003; 35:476-489. [PMID: 12904210 DOI: 10.1046/j.1365-313x.2003.01821.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Interactor/inhibitor 1 of Cdc2 kinase (ICK1) from Arabidopsis thaliana is the first plant cyclin-dependent kinase (CDK) inhibitor, and overexpression of ICK1 inhibits CDK activity, cell division and plant growth in transgenic plants. In this study, ICK1 and deletion mutants were expressed either alone or as green fluorescent protein (GFP) fusion proteins in transgenic Arabidopsis plants. Deletion of the C-terminal 15 or 29 amino acids greatly reduced or completely abolished the effects of ICK1 on the transgenic plants, and recombinant proteins lacking the C-terminal residues lost the ability to bind to CDK complex and the kinase inhibition activity, demonstrating the role of the conserved C-terminal domain in in vivo kinase inhibition. In contrast, the mutant ICK1DeltaN108 with the N-terminal 108 residues deleted had much stronger effects on plants than the full-length ICK1. Analyses demonstrated that this effect was not because of an enhanced ability of ICK1DeltaN108 protein to inhibit CDK activity, but a result of a much higher level of ICK1DeltaN108 protein in the plants, indicating that the N-terminal domain contains a sequence or element increasing protein instability in vivo. Furthermore, GFP-ICK1 protein was restricted to the nuclei in roots of transgenic plants, even with the C-terminal or the N-terminal domain deleted, suggesting that a sequence in the central domain of ICK1 is responsible for nuclear localization. These results provide mechanistic understanding about the function and regulation of this cell cycle regulator in plants.
Collapse
Affiliation(s)
- Yongming Zhou
- Department of Biology, University of Saskatchewan, Saskatoon, SK, Canada S7N 5E2
| | | | | | | | | |
Collapse
|
23
|
Abstract
Cell division in plants is controlled by the activity of cyclin-dependent kinase (CDK) complexes. Although this basic mechanism is conserved with all other eukaryotes, plants show novel features of cell-cycle control in the molecules involved and their regulation, including novel CDKs showing strong transcriptional regulation in mitosis. Plant development is characterized by indeterminate growth and reiteration of organogenesis and is therefore intimately associated with cell division. This may explain why plants have a large number of cell-cycle regulators that appear to have overlapping and distinct functions. Here we review the recent considerable progress in understanding how core cell-cycle regulators are involved in integrating and coordinating cell division at the molecular level.
Collapse
Affiliation(s)
- Walter Dewitte
- Institute of Biotechnology, University of Cambridge, Cambridge CB2 1QT, United Kingdom.
| | | |
Collapse
|
24
|
Jasinski S, Perennes C, Bergounioux C, Glab N. Comparative molecular and functional analyses of the tobacco cyclin-dependent kinase inhibitor NtKIS1a and its spliced variant NtKIS1b. PLANT PHYSIOLOGY 2002; 130:1871-82. [PMID: 12481070 PMCID: PMC166698 DOI: 10.1104/pp.008573] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2002] [Revised: 07/08/2002] [Accepted: 08/27/2002] [Indexed: 05/21/2023]
Abstract
In all eukaryotes, cell cycle progression is controlled by cyclin-dependent kinases (CDKs) whose activity is regulated at several levels including inhibition by CDK inhibitors. Here, we report a comparative molecular and functional analysis of the tobacco (Nicotiana tomentosiformis) CDK inhibitor, NtKIS1a, and its spliced variant, NtKIS1b. The C-terminal end of NtKIS1a shares strong sequence similarity with mammalian CIP/KIP inhibitors, which is not the case for NtKIS1b. Consistent with this, NtKIS1a but not NtKIS1b inhibits in vitro the kinase activity of CDK/cyclin complexes, and tobacco (Nicotiana tabacum) D-type cyclins and an A-type CDK are NtKIS1a, but not NtKIS1b, interacting partners. Although both NtKIS1a and NtKIS1b transcripts are mainly found in flowers and more precisely in stamens, NtKIS1b transcript levels are cell cycle regulated, whereas those of NtKIS1a remain constant during the cell cycle. NtKIS1a and NtKIS1b fused to fluorescent proteins are localized in the nucleus when transiently expressed in onion epidermal cells. Furthermore, there is no competition for their nuclear localization when they are simultaneously overexpressed. In vitro competition toward CDK kinase activity suggests that NtKIS1b is a strong competitor of NtKIS1a. Arabidopsis plants overexpressing NtKIS1a-green fluorescent protein (GFP) or NtKIS1b-GFP fusion proteins were obtained. In these plants, the fusion proteins are still localized in the nucleus. Interestingly, NtKIS1a-GFP-overexpressing plants display strong morphological modifications and a reduced CDK kinase activity, whereas NtKIS1b-GFP-overexpressing plants display a wild-type phenotype including a wild-type CDK kinase activity. Our results strongly suggest that the inhibition of the kinase activity is responsible for the phenotypic modifications.
Collapse
Affiliation(s)
- Sophie Jasinski
- Laboratoire Cycle Cellulaire, Institut de Biotechnologie des Plantes, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 8618, Université Paris-Sud, 91405 Orsay cedex, France
| | | | | | | |
Collapse
|
25
|
Menges M, Hennig L, Gruissem W, Murray JAH. Cell cycle-regulated gene expression in Arabidopsis. J Biol Chem 2002; 277:41987-2002. [PMID: 12169696 DOI: 10.1074/jbc.m207570200] [Citation(s) in RCA: 157] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Regulated gene expression is an important mechanism for controlling cell cycle progression in yeast and mammals, and genes involved in cell division-related processes often show transcriptional regulation dependent on cell cycle position. Analysis of cell cycle processes in plants has been hampered by the lack of synchronizable cell suspensions for Arabidopsis, and few cell cycle-regulated genes are known. Using a recently described synchrony system, we have analyzed RNA from sequential samples of Arabidopsis cells progressing through the cell cycle using Affymetrix Genearrays. We identify nearly 500 genes that robustly display significant fluctuation in expression, representing the first genomic analysis of cell cycle-regulated gene expression in any plant. In addition to the limited number of genes previously identified as cell cycle-regulated in plants, we also find specific patterns of regulation for genes known or suspected to be involved in signal transduction, transcriptional regulation, and hormonal regulation, including key genes of cytokinin response. Genes identified represent pathways that are cell cycle-regulated in other organisms and those involved in plant-specific processes. The range and number of cell cycle-regulated genes show the close integration of the plant cell cycle into a variety of cellular control and response pathways.
Collapse
Affiliation(s)
- Margit Menges
- Institute of Biotechnology, University of Cambridge, United Kingdom
| | | | | | | |
Collapse
|
26
|
Oakenfull EA, Riou-Khamlichi C, Murray JAH. Plant D-type cyclins and the control of G1 progression. Philos Trans R Soc Lond B Biol Sci 2002; 357:749-60. [PMID: 12079670 PMCID: PMC1692988 DOI: 10.1098/rstb.2002.1085] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The basic pattern of controls that operate during the G1 phase of the plant cell cycle shows much closer similarity to animals than to the yeasts and other fungi. The activity of D-type cyclin (CycD) kinases is induced in response to stimulatory signals, and these phosphorylate the plant homologue of the retinoblastoma tumour susceptibility (Rb) protein. It is likely that Rb phosphorylation results in the activation of genes under the control of E2F transcription factors, including those required for S phase entry. As the initial triggers of the cascade, attention has focused on the CycDs, and a family of 10 genes is present in Arabidopsis, divided into three major and three minor groups. Analysis to date suggests that these groups are functionally distinct.
Collapse
Affiliation(s)
- E Ann Oakenfull
- Institute of Biotechnology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QT, UK
| | | | | |
Collapse
|
27
|
Menges M, Murray JAH. Synchronous Arabidopsis suspension cultures for analysis of cell-cycle gene activity. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2002; 30:203-12. [PMID: 12000456 DOI: 10.1046/j.1365-313x.2002.01274.x] [Citation(s) in RCA: 210] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Synchronized suspension cultures are powerful tools in plant cell-cycle studies. However, few Arabidopsis cell cultures are available, and synchrony extending over several sequential phases of the cell cycle has not been reported. Here we describe the first useful synchrony in Arabidopsis, achieved by selecting the rapidly dividing Arabidopsis cell suspensions MM1 and MM2d. Synchrony may be achieved either by removing and re-supplying sucrose to the growth media or by applying an aphidicolin block/release. Synchronization with aphidicolin produced up to 80% S-phase cells and up to 92% G2 cells, together with clear separation of different cell-cycle phases. These synchronization procedures can be used for analysis of gene expression and protein activity. We show that representatives of three CDK gene classes of Arabidopsis (CDKA, CDKB1 and CDKB2) show differential expression timing, and that three CDK inhibitor genes show strikingly different expression patterns during cell-cycle re-entry. We propose that ICK2 (KRP2) may have a specific role in this process.
Collapse
Affiliation(s)
- Margit Menges
- Institute of Biotechnology, University of Cambridge, Cambridge CB2 1QT, UK
| | | |
Collapse
|
28
|
García E, Laquel P, Castroviejo M, Plasencia J, Vázquez-Ramos JM. Maize replicative alpha-type DNA polymerase: separation of polymerase and primase activities and recognition of primase subunits. PHYSIOLOGIA PLANTARUM 2002; 114:533-539. [PMID: 11975726 DOI: 10.1034/j.1399-3054.2002.1140405.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
DNA polymerase and DNA primase activities in the maize alpha-type DNA polymerase 2 were dissociated and DNA polymerase-free DNA primase was studied. DNA primase synthesized primers that were 8-34 nucleotides long, with more intense bands at 15-17 nucleotides in length. DNA polymerase 1 (a putative delta-type enzyme) or DNA polymerase 2 were assayed after template-priming with purified DNA primase and showed a differential use of templates: whereas DNA polymerase 2 used a polydT template more efficiently than a natural template, DNA polymerase 1 used both of them poorly. The molecular size of DNA primase was estimated to be 68 kDa by gel filtration, western blotting and by a DNA primase 'trapping' assay.
Collapse
Affiliation(s)
- Elpidio García
- aDepartamento de Bioquímica, Facultad de Química, UNAM, Ave. Universidad y Copilco, México DF, 04510, México bREGER, UMR 50 97 Université Bordeaux-CNRS, bat 3a-3eme étage, 146 rue Leo-Saignat, F-33076, Bordeaux Cedex, France
| | | | | | | | | |
Collapse
|
29
|
Wyrzykowska J, Pien S, Shen WH, Fleming AJ. Manipulation of leaf shape by modulation of cell division. Development 2002; 129:957-64. [PMID: 11861478 DOI: 10.1242/dev.129.4.957] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The role of cell division as a causal element in plant morphogenesis is debatable, with accumulating evidence supporting the action of cell division-independent mechanisms. To directly test the morphogenic function of cell division, we have utilised a microinduction technique to locally and transiently manipulate the expression in transgenic plants of two genes encoding putative effectors of the cell cycle, a tobacco A-type cyclin and a yeast cdc25. The results show that local expression of these genes leads to modulation of cell division patterns. Moreover, whereas altered cell division in the apical meristem had no influence on organogenesis, local induction of cell proliferation on the flanks of young leaf primordia led to a dramatic change in lamina development and, thus, leaf shape. These data indicate that the role of cell division in plant morphogenesis is context dependent and identify cell division in the leaf primordium as a potential target for factors regulating leaf shape.
Collapse
Affiliation(s)
- Joanna Wyrzykowska
- Institute of Plant Sciences, Swiss Federal Institute of Technology (ETH), Universitätstrasse 2, 8092 Zurich, Switzerland
| | | | | | | |
Collapse
|
30
|
Sorrell DA, Menges M, Healy JM, Deveaux Y, Amano C, Su Y, Nakagami H, Shinmyo A, Doonan JH, Sekine M, Murray JA. Cell cycle regulation of cyclin-dependent kinases in tobacco cultivar Bright Yellow-2 cells. PLANT PHYSIOLOGY 2001; 126:1214-23. [PMID: 11457971 PMCID: PMC116477 DOI: 10.1104/pp.126.3.1214] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2000] [Revised: 01/08/2001] [Accepted: 03/15/2001] [Indexed: 05/20/2023]
Abstract
Plants possess two major classes of cyclin-dependent kinases (CDK) with cyclin-binding motifs PSTAIRE (CDK-a) and PPTA/TLRE (CDK-b). Tobacco (Nicotiana tabacum L. cv Bright Yellow-2) cells are the most highly synchronizable plant culture, but no detailed analysis of CDK activities has been reported in this system. Here we describe isolation of new PPTALRE CDKs (Nicta;CdkB1) from Bright Yellow-2 cells and present detailed analysis of the mRNA, protein and kinase activity levels of CdkB1, and the PSTAIRE CDKA during the growth and cell cycles. CdkA and CdkB1 transcripts are more abundant in exponential than in stationary phase cells, but the two genes show strikingly different regulation during the cell cycle. CdkA mRNA and protein accumulate during G1 in cells re-entering the cell cycle, and immunoprecipitated histone H1 kinase activity increases at the G1/S boundary. Aphidicolin synchronized cells show the highest CDKA-associated histone H1 kinase activity during S-G2 phases, although CdkA mRNA and protein levels are not significantly regulated. In contrast, CdkB1 transcripts are present at very low levels until S phase and CDKB1 protein and kinase activity is almost undetectable in G1. CdkB1 mRNA accumulates through S until M phase and its associated kinase activity peaks at the G2/M boundary, confirming that transcription of PPTALRE CDKs is cell cycle regulated. We suggest that CDKA kinase activity likely plays roles at the G1/S phase boundary, during S phase, and at the G2/M phase transition, and that CDKB1 kinase activity is present only at G2/M.
Collapse
Affiliation(s)
- D A Sorrell
- Institute of Biotechnology, University of Cambridge, Cambridge CB2 1QT, United Kingdom
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
31
|
Healy JM, Menges M, Doonan JH, Murray JA. The Arabidopsis D-type cyclins CycD2 and CycD3 both interact in vivo with the PSTAIRE cyclin-dependent kinase Cdc2a but are differentially controlled. J Biol Chem 2001; 276:7041-7. [PMID: 11096103 DOI: 10.1074/jbc.m009074200] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
D-type cyclins (CycD) play key roles in linking the Arabidopsis cell cycle to extracellular and developmental signals, but little is known of their regulation at the post-transcriptional level or of their cyclin-dependent kinase (CDK) partners. Using new antisera to CycD2 and CycD3, we demonstrate that the CDK partner of these Arabidopsis cyclins is the PSTAIRE-containing CDK Cdc2a. Previous analysis has shown that transcript levels of CycD2 and CycD3 are regulated in response to sucrose levels and that both their mRNA levels and kinase activity are induced with different kinetics during the G(1) phase of cells reentering the division cycle from quiescence. Here we analyze the protein levels and kinase activity of CycD2 and CycD3. We show that CycD3 protein and kinase activity parallel the abundance of its mRNA and that CycD3 protein is rapidly lost from cells in stationary phase or following sucrose removal. In contrast to both CycD3 and the regulation of its own mRNA levels, CycD2 protein is present at constant levels. CycD2 kinase activity is regulated by sequestration of CycD2 protein in a form inaccessible to immunoprecipitation and probably not complexed to Cdc2a.
Collapse
Affiliation(s)
- J M Healy
- Institute of Biotechnology, University of Cambridge, United Kingdom
| | | | | | | |
Collapse
|
32
|
Meijer M, Murray JA. Cell cycle controls and the development of plant form. CURRENT OPINION IN PLANT BIOLOGY 2001; 4:44-49. [PMID: 11163167 DOI: 10.1016/s1369-5266(00)00134-5] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The relationship between cell division and plant form has long been a battleground for the debate between those proclaiming and disclaiming an important role for cell division in morphogenetic and developmental processes. Recent evidence suggests that cell division and morphogenesis are intimately interconnected, and whereas overall architecture is determined by patterning genes, the elaboration and execution of developmental programmes require proper control of the cell-division cycle.
Collapse
Affiliation(s)
- M Meijer
- Institute of Biotechnology, University of Cambridge, Tennis Court Road, CB2 1QT, Cambridge, UK.
| | | |
Collapse
|
33
|
John PC, Mews M, Moore R. Cyclin/Cdk complexes: their involvement in cell cycle progression and mitotic division. PROTOPLASMA 2001; 216:119-142. [PMID: 11732181 DOI: 10.1007/bf02673865] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
DNA replication and mitosis are dependent on the activity of cyclin-dependent protein kinase (CDK) enzymes, which are heterodimers of a catalytic subunit with a cyclin subunit. Cyclin binding to specific individual proteins is thought to provide potential substrates to Cdk. Protein binding by cyclins is assessed in terms of its mechanisms and biological significance, using evidence from diverse organisms including substrate specificity in animal Cdk enzymes containing D-, A-, and B-type cyclins and extensive cyclin gene manipulations in yeasts. Assembly of protein complexes with cyclin/Cdk is noted and the capacity of the cyclin-dependent kinase subunit Cks, in such complex, to extend the range of Cdk substrates is documented and discussed in terms of cell cycle regulation. Cell cycle progression involves changing abundance of individual cyclins, due to changing rates of their transcription or proteolysis, with consequent changes in the substrates of CDK through the cell cycle. Some overlap of the functions of individual cyclins in vivo has been identified by cyclin deletions and is suggested to follow a pattern in which cyclins can commonly complete functions initiated by the preceding cyclins well enough to preserve viability as groups of cyclins are removed by proteolysis. Cyclin accumulation is particularly important in terminating the G1 phase, when it raises CDK activity and starts events leading to DNA replication. It is suggested that plants share this mechanism. The distribution of cyclins and Cdk in maize root tip cells during mitosis and cytokinesis indicates the presence of Cdk1 (Cdc2a) and cyclin CycB1zm;2 at the mature and disassembling preprophase band and the presence of CycB1zm;2 at condensing and condensed chromosomes. Both observations correlate with the earlier-reported capacity of injected metaphase cyclin/CDK to accelerate preprophase band disassembly and chromosome condensation and with observations of the location of Cdk and cyclins in other laboratories. Additionally CycB1zm;2 is seen at the nuclear envelope during its breakdown, which correlates with an acceleration of the process by injected metaphase cyclin B/CDK. A phenomenon possibly unique to the plant kingdom is the persistence of mitotic cyclins after anaphase. Participation of cyclins in cytokinesis is indicated by the concentration of the mitotic cyclin CycA1;zm;1 at the phragmoplast. It is suggested that cyclins have a general function of spatially focusing Cdk activity and that in the plant cell the concentrations of cyclins are important mediators of CDK activity at the cytoskeleton, chromosomes, spindle, nuclear envelope, and phragmoplast.
Collapse
Affiliation(s)
- P C John
- Plant Cell Biology Group, Research School of Biological Sciences, Australian National University, Canberra, ACT 2601, Australia
| | | | | |
Collapse
|
34
|
Ramirez-Parra E, Gutierrez C. Characterization of wheat DP, a heterodimerization partner of the plant E2F transcription factor which stimulates E2F-DNA binding. FEBS Lett 2000; 486:73-8. [PMID: 11108846 DOI: 10.1016/s0014-5793(00)02239-0] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Recent studies suggest that the G1/S transition in plants depends on the activity of E2F transcription factors. In animal cells, E2Fs interact with DP proteins, whose identification in plants has been elusive, so far. Here we show that although an E2F-containing DNA-binding activity can be detected in plant cell extracts, purified E2F protein binds poorly to DNA. In a yeast two-hybrid screening, using wheat E2F as a bait, we have isolated a cDNA clone encoding a wheat DP (TmDP) protein. TmDP is expressed ubiquitously and exhibits a domain organization similar to animal DPs. Contrary to the specificity observed for the plant RBR/E2F interaction, human and plant E2F and DP proteins can interact in a heterologous manner. Purified TmDP protein stimulates E2F-DNA complex formation.
Collapse
Affiliation(s)
- E Ramirez-Parra
- Centro de Biología Molecular 'Severo Ochoa', Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Cantoblanco, 28049, Madrid, Spain
| | | |
Collapse
|
35
|
Hu Y, Bao F, Li J. Promotive effect of brassinosteroids on cell division involves a distinct CycD3-induction pathway in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2000; 24:693-701. [PMID: 11123807 DOI: 10.1046/j.1365-313x.2000.00915.x] [Citation(s) in RCA: 173] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Brassinosteroids (BRs) are steroid hormones that play an essential role in plant growth and development. However, the contradictory results of previous studies make their role in cell division unclear. Using a cDNA array, we identified genes that respond to BR in the det2 suspension culture of Arabidopsis, and found that epi-brassinolide upregulated transcription of the CycD3, a D-type plant cyclin gene through which cytokinin activates cell division. RNA gel-blot analysis and cell culturing showed that epi-brassinolide may promote cell division through CycD3, and can substitute cytokinin in culturing of Arabidopsis callus and suspension cells. The CycD3 induction by epi-brassinolide was further shown to involve de novo protein synthesis, but no protein phosphorylation or dephosphorylation. Induction was also found to occur in cells of a BR-insensitive mutant, bri1, suggesting that BR induces CycD3 transcription through a previously unknown signal pathway in plants.
Collapse
Affiliation(s)
- Y Hu
- Institute of Genetics, Chinese Academy of Sciences, Beijing 100101, China
| | | | | |
Collapse
|
36
|
Abstract
Plant cell division occurs mainly in developing tissues and appears to be highly regulated in both space and time. Recently, genetic and molecular analyses have been able to dissect the function of cell proliferation in the processes of growth and development. Mutant studies have shown that plants have a compensatory mechanism whereby increased cell expansion can partially cover for defects in proliferation. Ectopic expression of developmental and cell-cycle regulators has indicated how growth rate is controlled at the molecular level in meristems and lateral organs.
Collapse
Affiliation(s)
- J Doonan
- John Innes Centre, Colney, NR4 7UH, Norwich, UK.
| |
Collapse
|
37
|
Canaday J, Stoppin-Mellet V, Mutterer J, Lambert AM, Schmit AC. Higher plant cells: gamma-tubulin and microtubule nucleation in the absence of centrosomes. Microsc Res Tech 2000; 49:487-95. [PMID: 10842376 DOI: 10.1002/(sici)1097-0029(20000601)49:5<487::aid-jemt11>3.0.co;2-i] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The assembly of the higher plant cytoskeleton poses several fundamental questions. Since different microtubule arrays are successively assembled during the cell cycle in the absence of centrosomes, we can ask how these arrays are assembled and spatially organized. Two hypotheses are under debate. Either multiple nucleation sites are responsible for the assembly and organization of microtubule arrays or microtubule nucleation takes place at one site, the nuclear surface. In the latter case, microtubule nucleation and organization would be two distinct but coregulated processes. During recent years, novel approaches have provided entirely new insights to understand the assembly and dynamics of the plant cytoskeleton. In the present review, we summarize advances made in microscopy and in molecular biology which lead to novel hypotheses and open up new fields of investigation. From the results obtained, it is clear that the higher plant cell is a powerful model system to investigate cytoskeletal organization in acentrosomal eukaryotic cells.
Collapse
Affiliation(s)
- J Canaday
- Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique, Université Louis Pasteur, Strasbourg, France
| | | | | | | | | |
Collapse
|
38
|
Abstract
In essence, the mitotic cell cycle in eukaryotes involves the duplication and separation of chromosomes, coupled to the process of dividing one cell into two. Cytokinesis is therefore the culmination of a series of events that were triggered during G1 phase, and brings the daughter cells back to the starting position in G1 for another possible round of division. In all eukaryotes, progression through the cell cycle is controlled by cyclin-dependent kinases that bind to positive regulators called cyclins. This review explores some of the pathways that trigger the plant cell cycle, with emphasis on the G1 phase. Examples include signalling pathways involving glutathione and cellular redox potential, the possible existence of a G1 DNA-damage checkpoint, and the plant hormones auxin and cytokinin. Progress in understanding the link between cell proliferation, cell differentiation and the cell-cycle machinery in a developmental context is discussed.
Collapse
Affiliation(s)
- B G den Boer
- Aventis CropScience N.V., Jozef Plateaustraat 22, B-9000, Gent, Belgium
| | | |
Collapse
|
39
|
den Boer BG, Murray JA. Control of plant growth and development through manipulation of cell-cycle genes. Curr Opin Biotechnol 2000; 11:138-45. [PMID: 10753767 DOI: 10.1016/s0958-1669(00)00072-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The plant embryo is a relatively simple structure consisting of a primordial shoot and root, whose development is frozen in the form of a seed. Most development of the mature plant takes place post-embryonically, and is the consequence of cell division and organogenesis in small regions known as meristems, which originate in the embryonic shoot and root apices. Significant recent progress has been made in understanding the mechanisms that control the plant cell cycle at a molecular level, and the first attempts have been made to control plant growth through modulation of cell-cycle genes. These results suggest that there is significant potential to control plant growth and architecture through manipulation of cell division rates. However, a full realisation of the promise of such strategies will probably require a much greater understanding of cell division control and how its upstream regulation is co-ordinated by spatial relationships between cells and by environmental signals.
Collapse
Affiliation(s)
- B G den Boer
- Aventis CropScience NV, Gent, B-9000, Belgium. bart.denboer@aventis. com
| | | |
Collapse
|
40
|
Abstract
Plant cell growth and development depend on continuous cell proliferation which is restricted to small regions of the plant called meristems. Infection by geminiviruses, small DNA viruses whose replicative cycle relies on host cell factors, is excluded from those proliferating areas. Since most of the replicative factors are present, almost exclusively, in proliferating cells, geminivirus infection is believed to induce a cellular state permissive for viral DNA replication, e.g. S-phase or, at least, some specific S-phase functions. The molecular basis for this effect seems to be the interference that certain geminivirus proteins exert on the retinoblastoma-related (RBR) pathway, which analogously to that of animal cells, regulates plant cell cycle activation and G(1)-S transition. In some cases, geminiviruses induce cell proliferation and abnormal growth. Mechanisms other than sequestering plant RBR probably contribute to the multiple effects of geminivirus proteins on cellular gene expression, cell growth control and cellular DNA replication. Current efforts to understand the coupling of geminivirus DNA replication to cell cycle and growth control as well as the directions in which future research is aiming are reviewed.
Collapse
Affiliation(s)
- C Gutierrez
- Centro de Biología Molecular 'Severo Ochoa', Consejo Superior de Investigaciones Cientificas (CSIC)-Universidad Autónoma de Madrid (UAM), Cantoblanco, 28049 Madrid, Spain.
| |
Collapse
|