COMPARING MOLECULAR PLASTICITY RESPONSES OF ARABIDOPSIS THALIANA RILS TO COLD STRATIFICATION

Abstract

Phenotypic plasticity is the ability of genetically identical organisms to produce differing phenotypes in response to environmental heterogeneity. While there are two central models for the genetic basis of phenotypic plasticity few studies have identified the genetic and molecular basis of plasticity. I used three recombinant inbred lines (RILs), of Arabidopsis thaliana generated by crossing two natural genotypes, and obtaining progeny after recombination, for a global gene expression study. Of the three RILs, one bolted (transition to reproductive tissue) later if the seeds experienced a coldstratification period relative to the seeds that did not experience this cold-treatment (sensitive-positive), one bolted earlier if the seeds experienced the cold-stratification relative to the non-cold treated seeds (sensitive-negative), and one did not change when it bolted regardless of the cold stratification of seeds (homeostatic). I found different sets of genes differentially expressed in the three RILs suggesting that the response to the same regime of cold-stratification is via different pathways. The homeostatic genotype increased transcription of protein metabolism genes in response to cold stratification; whereas the plastic genotypes differentially expressed genes involved in stress response. This cold-stratification which is a common dormancy breaking cue for these plants may also be perceived as a stress, as the plants differentially expressed stress genes. Thus both gene expression and perception of environment may be involved in plastic responses to environmental heterogeneity.