赤霉素敏感性不同矮秆基因对小麦胚芽鞘长度和株高的效应

 【目的】明确赤霉素敏感性不同的矮秆基因对小麦株高和胚芽鞘长度的效应，促进小麦不同矮秆基因的合理利用。【方法】利用分子标记和系谱分析相结合，对中国小麦主产区部分小麦品种及品系中所含的矮秆基因Rht-B1b、Rht-D1b和Rht8进行分类，结合田间株高和室内胚芽鞘长度调查，比较赤霉素（GA3）敏感性不同的矮秆基因对胚芽鞘长度和株高的效应。【结果】分子标记检测结合系谱分析对129份供试品种进行分类，含有矮秆基因Rht-B1b的小麦品种58份，含有Rht-D1b的24份，含有Rht8的73份。其中35份品种含有2个矮秆基因Rht-B1b和Rht8，16份品种含有Rht-D1b和Rht8。赤霉素敏感性检测发现含有矮秆基因Rht-B1b或Rht-D1b的小麦品种多对赤霉素反应不敏感，含有矮秆基因Rht8的小麦品种多对赤霉素反应敏感，而同时含有2个矮秆基因Rht-B1b+Rht8或Rht-D1b+Rht8的小麦品种绝大多数对赤霉素反应不敏感。赤霉素不敏感的矮秆基因Rht-B1b和Rht-D1b以及同时含有赤霉素不敏感和赤霉素敏感2个矮秆基因的小麦品种（Rht-B1b+Rht8和Rht-D1b+ Rht8）降低株高的效应较大，分别为24.6%、30.4%、28.2%和32.2%，而赤霉素敏感的矮秆基因Rht8降低株高的效应为14.3%。赤霉素不敏感的矮秆基因Rht-B1b、Rht-D1b以及Rht-B1b+Rht8和Rht-D1b+Rht8在降低株高的同时，也缩短了胚芽鞘长度，其效应分别为25.4%、31.3%、28.4%和31.3%，而赤霉素敏感的矮秆基因Rht8缩短胚芽鞘长度的效应较小，仅为6.0%。【结论】以上分析结果表明，赤霉素不敏感的矮秆基因Rht-B1b和Rht-D1b在降低株高的同时也限制了胚芽鞘的伸长，不适于旱地小麦改良利用，而赤霉素敏感的矮秆基因Rht8既降低了株高又不影响胚芽鞘长度，是旱地小麦改良中比较理想的矮秆基因。

Effects of Dwarfing Genes of Rht-B1b, Rht-D1b and Rht8 with Different Response to GA3 on Coleoptile Length and Plant Height of Wheat

Objective] Understanding the effects of wheat dwarfing genes on coleoptile length and plant height is crucial for the proper utilization of dwarfing genes in yield improvement of wheat. Method] Molecular markers analysis combined with pedigree information were used to classify wheat cultivars widely used in the major wheat growing regions of China into different categories based on the dwarfing genes carried, then the effects of dwarfing genes with different response to Gibberellins (GA_3) on coleoptile length and plant height were analyzed based on plant height data from the field and coleoptile length data from the lab. Result] The screening of 129 cultivars with molecular markers revealed that 58 genotypes contained the dwarfing gene Rht-B1b, 24 genotypos had Rht-D1b, and 73 genotypes possessed Rht8, and among them there were 35 genotypes with two dwarfing genes Rht-B1b+RhtS, and 16 genotypes with two dwarfing genes Rht-D1b+RhtS. Test on response to GA_3 of these cultivars revealed that wheat cultivars with the dwarfing genes Rht-B1b or Rht-D1b were insensitive to GA_3, and those with the dwarfing gene Rht8 were responsive to GA_3. Genotypes with Rht-B1b+Rht8 and Rht-D1b+Rht8 were also insensitive to GA_3. The height reducing effects of GA_3 insensitive dwarfing genes Rht-B1b, Rht-D1b, Rht-B1b+Rht8, and Rht-D1b+Rht8 were as 24.6%, 30.4%, 28.2% and 32.2%, respectively, while that of GA_3-responsive dwarfing gene Rht8 was 14.3%. The GA_3 insensitive dwarfing genes Rht-B1b, Rht-D1b, Rht-B1b+Rht8, and Rht-D1b+Rht8 also shortened the coleoptile length by 25.4%, 31.3%, 28.4%, and 31.3%, respectively, whereas the GA_3-responsive dwarfing gene Rht8 only shortened the coleoptile length by 6.2%. Conclusion] To summarize, the GA_3 insensitive dwarfing genes Rht-B1b and Rht-D1b shorten the eoleoptile length largely as well as reducing plant height and are not suitable to wheat improvement for dryland, while the GA_3-respoasive dwarfing gene Rht8 has much less effects on shortening eoleoptile length and also could reduce plant height to some extent, it is the right dwarfing gene for wheat improvement of dry land.