Drought-adaptive mechanisms involved in the escape/tolerance strategies of Arabidopsis Landsberg erecta and Columbia ecotypes and their F1 reciprocal progeny

Arabidopsis ecotypes Landsberg erecta (Ler) and Columbia (Col) display differential drought-adaptive strategies when subjected to a progressive drought stress, a procedure designed to address specific, genetically determined, adaptive potentialities: Ler exhibits an escape strategy (early flowering and bolting, high sensitivity of the rosette leaves to water deficit leading to leaf senescence), whereas Col withstands water stress by drought tolerance (higher biomass allocation to vegetative organs, root to shoot ratio, drought rhizogenesis intensity, RWC, and WUE). The traits characterising the escape strategy in Ler, like the traits associated with Col drought tolerance, were inherited as phenotypically dominant in one or both of their F1 progeny. Reciprocal effects, often paternal, were observed in the F1s. The hybrids thus displayed both types of parental strategies which could have conferred enhanced drought adaptability upon them. The pattern of inheritance of the drought-adaptive traits in the F1s demonstrated that the differential strategies, escape/tolerance, of the parental lines cannot be attributed to their differential programme of development. Our results highlight a wide phenotypic plasticity of Col.