Pleiotropy in the wild: the dormancy gene DOG1 exerts cascading control on life cycles.

In the wild, organismal life cycles occur within seasonal cycles, so shifts in the timing of developmental transitions can alter the seasonal environment experienced subsequently. Effects of genes that control the timing of prior developmental events can therefore be magnified in the wild because they determine seasonal conditions experienced by subsequent life stages, which can influence subsequent phenotypic expression. We examined such environmentally induced pleiotropy of developmental-timing genes in a field experiment with Arabidopsis thaliana.

DOG1 expression is predicted by the seed-maturation environment and contributes to geographical variation in germination in Arabidopsis thaliana.

Seasonal germination timing of Arabidopsis thaliana strongly influences overall life history expression and is the target of intense natural selection. This seasonal germination timing depends strongly on the interaction between genetics and seasonal environments both before and after seed dispersal. DELAY OF GERMINATION 1 (DOG1) is the first gene that has been identified to be associated with natural variation in primary dormancy in A.

Major flowering time gene, flowering locus C, regulates seed germination in Arabidopsis thaliana.

Flowering locus C (FLC) is a major regulator of flowering responses to seasonal environmental factors. Here, we document that FLC also regulates another major life-history transition-seed germination, and that natural variation at the FLC locus and in FLC expression is associated with natural variation in temperature-dependent germination. FLC-mediated germination acts through additional genes in the flowering pathway (FT, SOC1, and AP1) before involving the abscisic acid catabolic pathway (via CYP707A2) and gibberellins biosynthetic pathway (via GA20ox1) in seeds.

Diversification of phytochrome contributions to germination as a function of seed-maturation environment.

Environmental conditions during seed maturation influence germination, but the genetic basis of maternal environmental effects on germination is virtually unknown. Using single and multiple mutants of phytochromes, it is shown here that different phytochromes contributed to germination differently, depending on seed-maturation conditions. Arabidopsis thaliana wild-type seeds that were matured under cool temperatures were intensely dormant compared with seeds matured at warmer temperature, and this dormancy was broken only after warm seed-stratification followed by cold seed-stratification.

Phytochrome mediates germination responses to multiple seasonal cues.

We identified a new role of phytochrome in mediating germination responses to seasonal cues and thereby identified for the first time a gene involved in maternal environmental effects on germination. We examined the germination responses of a mutant, hy2-1, which is deficient in the phytochrome chromophore. The background genotype, Landsberg erecta (Ler), lacked dormancy in most treatments, while hy2-1 required cold stratification for germination in a manner that resembled a more dormant ecotype, Columbia (Col).