Effect of low light intensity on the VRN-H1 and VRN-H2 vernalization response loci in barley ( Hordeum vulgare L.)

Abstract

The flowering characteristics of a facultative × winter barley mapping population were evaluated in a series of controlled environmental tests in order to study the effect of low light intensity in association with various photoperiod regimes. Functional QTL analysis was used to determine the effect of low light intensity on the functioning of the VRN-H1 and VRN-H2 vernalization response genes and on the allele interactions. Low light intensity exerted the strongest modifying effect on these genes under a 12-hour photoperiod regime, which was intermediate between short and long daylengths. With this photoperiod more than 50% of the phenotypic variance in flowering was explained by the VRN-H2 gene when high light intensity (340 μmol m −2 s −1 ) was applied, but at low light intensity (170 μmol m −2 s −1 ) the VRN-H1 gene became the most important source of variation. There were also significant changes in the interaction between the alleles of the two VRN-H genes, implying that in addition to their role in vernalization-driven regulation, they may also participate in and be subjected to circadian-driven developmental regulation.