The influence of a spring habit gene, Vrn‐D1, on heading time in wheat

The adaptability of wheat cultivars to environmental conditions is known to be associated with a vernalization requirement, that is, spring/winter habit. To clarify the genetic effect of the spring habit gene, Vrn-D1, on heading time in the field, recombinant inbred lines (RILs) with or without the Vrn-D1 gene were produced from F2 plants of the cross between ‘Nanbukomugi’ and ‘Nishikazekomugi’, non-carrier and carrier cultivars of this gene, respectively. Using growth chambers with a controlled temperature and photoperiod, three components of heading time, i.e. vernalization requirement, photoperiodic sensitivity and narrow-sense earliness (earliness per se), were evaluated in each RIL. RILs with the Vrn-D1 gene (E lines) showed greatly reduced vernalization requirements and slightly shorter narrow-sense earliness than RILs without Vrn-D1 (L lines), although no difference in photoperiodic sensitivity was observed between the two groups. RILs were planted at four different sites in Japan and examined for their heading time in the field. E lines headed significantly earlier than L lines at all locations, indicating that the earliness of E lines is stable in various environmental conditions. These results indicated that spring habit caused by Vrn-D1 gene, as well as narrow-sense earliness, was responsible for heading time in the field.