The study of shade avoidance has great agricultural importance as the response involves the relocation of reserves into elonga

Introduction

The research is to find shade avoidance genes based on the mutants we got and the whole sequenced gene in Arabidopsis.

1. Light in shade

Light reflected from neighbouring plants is depleted of red light resulting in a low red: far red ratio. Plants have developed a strategy that initiates elongation growth and early flowering to avoid the shade after perceiving this change in red light through the photoreceptor, phytochrome. All of the five phytochromes in Arabidopsis, phyA-phyE, act in the shade avoidance responses which are also gated by the circadian clock. Microarray analysis found that there are 301 shade responsive genes including the PHYB gene itself. PhyB is the major phytochrome acting in shade avoidance but the molecular mechanism of shade avoidance is largely unknown.

Figure 1 shade environment, low R: FR ratio

2. shade avoidance

Shade avoidance , escaping from shade, is the result of environmental and endogenous interactions. Plants have to “decide” whether to stay in shade or to get out of shade when they are under shade. For most plants they will readjust their morphological development and reposition to avoid shade. Plants reposition their leaves to get out of the shade of the neighbours in order to compete for maximum light. The syndrome of shade responses is well characterised by previous research. The typical shade responses are elongation growth and early flowering. The syndrome reported is elongation growth, including elongated hypocotyls and/or petioles, increased length of internodes at the rosette level, increased apical dominance, reduced leaf development, reduction in branching, quick transition to reproductive growth and production of fewer seeds.

The study of shade avoidance has great agricultural importance as the response involves the relocation of reserves into elongation growth at high planting density, reducing the yield.

white light shade

Figure 2 Model plant Arabidopsis

3. Research strategy

Create shade mutants which the shade avoidance is dissected and then clone the shade genes following by the analysis of these genes.

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Update on 2006-2-23