Award details

Establish the link between Jasmonate Signalling and Cell Cycle

Reference	BB/E003486/1
Principal Investigator / Supervisor	Professor Alessandra Devoto
Co-Investigators / Co-Supervisors
Institution	Royal Holloway, Univ of London
Department	Biological Sciences
Funding type	Research
Value (£)	344,169
Status	Completed
Type	Research Grant
Start date	01/03/2007
End date	31/07/2010
Duration	41 months

Abstract

REVISED TECHNICAL SUMMARY FOLLOWING COMMITTEE RECOMMENDATIONS Jasmonates mediate responses to stress and act like growth inhibitors. Interestingly, several mutants in JA signalling are stunted. We are excited by the likelihood that jasmonate is a distress signal, a physiological role of which is to block cell cycle, slowing vegetative growth during defense responses. The SCFCOI1 complex binds to the histone deacetylase (HDAC) AtRPD3B which is degraded by JA. Novel results indicate a role for COI1 in repressing endoreduplication and in altering the gradient of cell proliferation. Therefore COI1 could have a role in regulating cell cycle and might play a role in organ developmental processes by linking cell cycle control to cell differentiation. This is the first demonstration that a component of JA signal transduction commonly associated with plant stress is likely used for the control of developmental patterning. In this project, a targeted approach will be used to establish the role of JA signaling components in cell cycle. The role of COI1 and/or jasmonate in regulating the switch from proliferative growth to differentiation will be evaluated. SCFCOI1 might targets cell cycle regulators for degradation and affect cell cycle dependent gene expression. RPD3B might also contribute to cell cycle regulation. In this project we will establish, in a functional genomics approach, the role of histone deacetylases in JA-mediated stress and development. We will identify by microarray and database mining, JA-dependent RPD3- repressed genes. To identify downstream binding factors, we will identify in silico subsets of promoters where JA-responsive elements are present together with cell cycle regulatory elements binding sites. The suggested approach will lead to the identification of transcriptional activators with the potential to engineer JA signalling pathway in plant cells.

Summary

Because plants cannot move, they can only survive by adjusting their growth to prevailing environmental conditions. Any change in the environment represents a stress for a plant. Some stresses such as temperature, water availability and pests limit plant growth (development), and often result in reduced yield of crops 'a poor harvest'. An understanding of growth regulation, how plants grow and what internal (hormonal) and external (environmental) factors influence growth is therefore very important. Surprisingly, there is still no consensus on how basic growth processes, cell division and cell expansion are co-ordinated in a growing plant constantly adapting to its environment. Plants respond to stresses such as wounding or pathogen and pest attack by the production of molecular deterrents - chemicals toxic to the attacking pest, but also by changing the internal metabolism of the plant to eg. redirect resources to seeds or storage tissues. One of the hormones shown to regulate plant responses to stress was originally identified in jasmine and it is called jasmonate. This molecule has also an inhibitory effect on plant growth and development. Jasmonate production can be considered as a 'switch' that when triggered acts to reprogramme plant metabolism, growth and development (plant shape and form). Generally, stress tends to stop cells from getting bigger, and stressed plants can be severely dwarfed. In my laboratory we are interested in discovering the cellular components linking plant stress responses to growth processes with the aim to improve seed production, yield and adaptation of plants to their environment. We intend to investigate the role of jasmonate and of genes encoding proteins that allow plants to respond to jasmonate when produced in response to stress. The genes are called COI1 and RPD3 and we believe they are important in controlling cell division, and differentiation (when, where and how division takes place to produce different tissues / leaf versus flower). To investigate this, we are going to analyse DNA content, which is directly correlated to cell size as well as the morphology, (the shape or form / tall, short, bushy), of a series of plants that are modified in the way they respond to jasmonate. We will use a combination of molecular biology and biochemical approaches to analyse when, where and how genes are switched on and off during growth in plants treated with and without jasmonate. Because RPD3 is a protein predicted to bind DNA and to contribute to its packaging inside the cell during the cell cycle, we shall also identify the gene targets of this protein and determine whether their expression is affected by its levels and levels of jasmonate. In this project we also propose to evaluate in more general terms the contribution of proteins like RPD3 to plant responses to stress. This will be achieved by mining public databases to look for genes that co-regulate with RPD3 like proteins.

Committee	Closed Committee - Plant & Microbial Sciences (PMS)
Research Topics	Plant Science
Research Priority	X – Research Priority information not available
Research Initiative	X - not in an Initiative
Funding Scheme	X – not Funded via a specific Funding Scheme

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