Molecular basis of natural variation and environmental control of trichome patterning

Abstract

Trichomes are differentiated epidermal cells on above ground organs of nearly all land plants. They play important protective roles as structural defenses upon biotic attacks such as herbivory, oviposition and fungal infections, and against abiotic stressors such as drought, heat, freezing, excess of light, and UV radiation. The pattern and density of trichomes is highly variable within natural population suggesting tradeoffs between traits positively affecting fitness such as resistance and the costs of trichome production. The spatial distribution of trichomes is regulated through a combination of endogenous developmental programs and external signals. This review summarizes the current understanding on the molecular basis of the natural variation and the role of phytohormones and environmental stimuli on trichome patterning.

Keywords: GWAS; QTL; abiotic; biotic; defense; natural variation; trichome development.

FIGURE 1

Schematic representation of the loci influencing trichome density and number on rosette leaves from QTL analyses with different accessions (green; Mauricio, 2005), (blue; Symonds et al., 2005), (orange; Hilscher et al., 2009), and GWAS (red; Atwell et al., 2010). Indicated are the candidate genes that have been shown to influence trichome pattering and as bars the position of the QTL and GWAS loci. For GWAS only regions are indicated that contain the 200 most significant SNPs. AT3G27920 GL1; AT5G40330 MYB23; AT3G13540 MYB5; At5g41315 GL3; At1g63650 EGL3/MYC-2; At4g00480 MYC-1; At5g24520 TGG1; At2g37260 TTG2; At1g79840 GL2; AT2G30420 ETC2; AT2G30424 TCL2; AT2G30432 TCL1; AT2G46410 CPC; AT5G53200 TRY; AT1G01380 ETC1; AT4G01060 ETC3; AT3G58070 GIS; AT5G06650 GIS2; AT2G41940 ZFP8; AT2G31660 SAD2; AT1G10480 ZFP5; AT4G09820 TT8; AT1G66350 RGL1; AT1G70700 JAZ9; AT1G74950 JAZ2; AT2G39940 COI.