Effect of the Vrn1‐Fr1 Interval on Cold Hardiness Levels in Near‐Isogenic Wheat Lines

Abstract

We investigated the feasibility of cold hardiness manipulation in wheat, Triticum aestivum L., with the Vrn1-Fr1 interval on chromosome 5AL. The interval contains a gene(s) that has influenced vernalization requirements and cold hardiness levels. We conducted LT 50 tests (lethal temperature of 50% of plants) on wheat NILs (near-isogenic lines) that differed for alleles at the Vrn1-Fr1 interval, to determine the effects of the interval on cold hardiness levels between hardy and nonhardy wheat. The NILs were derived from five backcrosses between a spring wheat recurrent parent, 'Marfed', and two winter wheat donor parents, 'Suweon 185' and 'Chugoku 81', hardy and nonhardy, respectively. The developed populations were Suweon 185/6*Marfed and Chugoku 81/6*Marfed spring and winter NILs. Results showed that the winter NILs could tolerate a 4.3 °C colder LT 50 score than the spring NILs, and that the Suweon 185/6*Marfed winter NILs could tolerate a 0.5 °C colder LT 50 than Chugoku 81/ 6*Marfed winter NILs. Results indicate that the Vrn1-Fr1 interval explained between 71 and 91% of the variation for LT 50 scores between these genotypes. The NILs were analyzed with the probe Xwg644 to confirm linkage with the Vrn1-Fr1 interval and to determine its utility as a marker for vernalization requirement and cold hardiness. EcoRI-digested DNA of the winter and spring NIL wheat, probed with Xwg644, showed that a 9.7-kb band co-segregated with the winter growth habit. Results indicate that differences in cold hardiness levels between winter wheat cultivars may be explained by this interval and that the interval may be manipulated through plant breeding to improve the cold hardiness of cultivars.