等位变异Vrn-B1a和Vrn-B1b的春化效应及其在黄淮冬麦区小麦品种中的分布

春化基因Vrn-B1是决定黄淮冬麦区小麦品种冬春性的主要基因之一,研究其不同显性等位变异的低温春化作用效应及分布,对该区小麦品种选育和推广具有重要意义。以等位变异Vrn-B1a品种皖麦33与等位变异Vrn-B1b品种豫麦34为亲本构建杂交组合,对其F2代进行5～35 d的低温春化处理,并在温室(22±3℃,16 h昼/8 h夜)鉴定抽穗期,结合分子标记分析低温春化处理时间对各等位变异型抽穗期的影响。同时对228个黄淮冬麦区小麦品种进行相关位点分子检测,分析该基因等位变异的分布特点。各春化处理均使两种等位变异小麦植株的抽穗期提前,但Vrn-B1a抽穗时间比Vrn-B1b晚约2 d。从春化处理当天至处理后25 d,2种等位变异类型的抽穗时间均随春化时间的延长而缩短;继续延长春化时间,抽穗期不再缩短,表明满足两种等位变异完成春化的低温时间为20～25 d。在228个品种中,Vrn-B1位点有214个(93.9%)隐性和14个(6.1%)显性等位变异。其中,显性等位变异Vrn-B1a有6个,占总品种数的2.6%;Vrn-B1b有8个,占总品种数的3.5%。在黄淮冬麦区小麦品种中,春化基因Vrn-B1位点至少存在Vrn-B1a和Vrn-B1b两种显性等位变异类型,两种等位变异类型纯合小麦植株的抽穗时间不同。

Vernalization Effects of Dominant Alleles Vrn-B1a and Vrn-B1b and Their Distributions in Cultivars from Yellow and Huai River Valleys Facultative Winter Wheat Zone

Vrn-B1 is a key gene controlling vernalization of wheat in the Yellow and Huai River Valleys Facultative Winter Wheat Zone of China. This study aimed to understand the allelic distribution at Vrn-B1 locus and their effects on heading date of wheat cultivars. To compare the vernalization responses of dominant alleles Vrn-B1a with Vrn-B1b on heading date, we planted F₂ plants derived from the cross between Yumai 34 (Vrn-B1b genotype) and Wanmai 33 (Vrn-B1a genotype) in greenhouse (22±3°C and 16 h day/8 h night) with 4°C treatment for different periods (5–35 d). Besides, the Vrn-B1 allelic variation and distribution of 228 historic and current wheat cultivars were evaluated using molecular markers. The results showed that heading date of Vrn-B1a genotype was about two days later than that of Vrn-B1b genotype. Vernalization treatment at 4°C for 5–25 d obviously shortened the period from sowing to heading in genotype Vrn-B1a or Vrn-B1b; however, continuous vernalization had no effect to further accelerate heading. Therefore, 20–25 d is enough for vernalization in both genotypes. In the 228 cultivars, 214 carried the recessive vrn-B1 allele with the frequency of 93.9%, and the remaining 14 cultivars had dominantalleles on Vrn-B1 locus, including6 (2.6%) of Vrn-B1a genotype and 8 (3.5%) of Vrn-B1b genotype. The two dominant alleles on Vrn-B1 locus had different effects to accelerate heading in winter wheat, and can be used in wheat breeding programs to improve adaptability and cold tolerance in wheat.