Genetic variation in Arabidopsis thaliana for night-time leaf conductance

Abstract

Night-time leaf conductance (gnight) and transpiration may have several adaptive benefits related to plant water, nutrient and carbon relations. Little is known, however, about genetic variation in gnight and whether this variation correlates with other gas exchange traits related to water use and/or native habitat climate. We investigated gnight in 12 natural accessions and three near isogenic lines (NILs) of Arabidopsis thaliana. Genetic variation in gnight was found for the natural accessions, and gnight was negatively correlated with native habitat atmospheric vapour pressure deficit (VPDair), suggesting lower g night may be favoured by natural selection in drier habitats. However, there were also significant genetic correlations of gnight with daytime gas exchange traits expected to affect plant fitness [i.e. daytime leaf conductance, photosynthesis and intrinsic water-use efficiency (WUE i)], indicating that selection on daytime gas exchange traits may result in indirect selection on gnight. The comparison of three NILs to their parental genotypes identified one quantitative trait locus (QTL) contributing to variation in gnight. Further characterization of genetic variation in gnight within and among populations and species, and of associations with other traits and native habitats will be needed to understand gnight as a putatively adaptive trait. © 2008 The Authors.