小麦矮秆基因Rht13分子标记开发及新品系选育

Using of dwarfing genes to reduce plant height、enhance lodging resistance、improve harvest index and yield potential has been one of the major strategies for breeding high yield and super high yield wheat varieties. The green-revolution Rht-B1b and Rht-D1b dwarfing alleles are usually associated with increased wheat yields worldwide but are linked to reduced early growth and poor emergence if sowing conditions are unfavorable. It indicates considerable potential for use of gibberellic acid-sensitive Rht13 dwarfing allele for improving wheat performance compared with Rht-B1b and Rht-D1b dwarfing alleles, based on the unique height-reducing phenotype（-34%）, increased grain number and yield as well as harvest index without compromising seedling vigor associated with Rht13. Molecular markers will be developed for Rht13 based on cross and backcross F2～F5 progenies generated by excellent native spring wheat variety Ningchun 4 and bread wheat Magnif M1( providing Rht13 allele). Comparative genomics approach with candidate gene analysis among wheat rice and Brachypodium distachyon will be implemented for detecting corresponding syntenic region and mining polymorphic markers in the population. In addition, F4～F6 population will be generated from Magnif M1×Ningchun45 for analyzing new markers. Effects of Rht13 gene transferred into Ningchun 4 and Rht13﹢Rht2 interactive effects will be analyzed by detecting cross and backcross population plant height, grain number, yield, grain quality and leaf photosynthetic characteristics etc.. Rht13 wheat lines will be selected with above progenies. We expect developing new molecular markers for marker-assisted selection of Rht13 and breeding new Rht13 wheat lines.

应用矮秆基因降低株高，提高抗倒伏性、收获指数和产量潜力是培育高产和超高产小麦品种的主要策略之一。小麦矮秆基因Rht13与绿色革命矮秆基因Rht-B1b和Rht-D1b相比，即能降低株高（-34%）又不影响幼苗的生活力，同时又与提高籽粒数，产量和收获指数相关，被认为是改良小麦性状潜在的矮秆基因。本研究以当地优良品种宁春4号、面包小麦Magnif M1（Rht13供体）、宁春45及其杂交后代为研究对象，利用比较基因组学及候选基因法发掘Rht13基因的分子标记。分析宁春4号，Magnif M1正反交杂种F2～F5代Rht13基因型植株的农艺性状、生理生化指标及品质性状，探索该基因在宁春4号背景下的遗传效应及Rht13﹢Rht2的互作效应，利用Magnif M1×宁春45 杂交F4～F6代验证新开发的标记，并选育Rht13基因型小麦品系，为选育Rht13基因型小麦品种和Rht13基因克隆奠定基础。

摘要：项目以研究矮秆基因互作对株高及产量相关性状的影响为出发点，检测本地育种材料中主要矮秆基因的分布情况，构建宁春4号、宁春40号、宁春44号（均含有Rht-D1b）与Magnif M1（携带Rht13基因）杂交的后代群体，分析各杂交组合F2群体中Rht13和Rht-D1b互作对农艺性状、产量性状、旗叶相对叶绿素含量的影响，利用本地Blast开发Rht13的分子标记，同时选择适合当地生产种植的株系。.（1）212个现有春小麦育种亲本材料主要矮秆基因分布检测表明：目前，宁夏春小麦育种材料中普遍含有矮秆基因Rht8，其次是Rht-B1b（Rht1），主栽品种和主推品种以及育种骨干亲本材料均含有Rht-D1b（Rht2），即现有育种亲本材料中Rht8+Rht-B1b所占比例较Rht8+Rht-D1b多，但新近培育的品种主要含有Rht8+Rht-D1b。.（2）各杂交组合F2代植株农艺性状、产量性状的分析结果表明，矮秆基因Rht13对降低小麦株高的效应比Rht-D1b强，Rht-D1b和Rht13互作降低株高的能力比两个单矮秆基因更强。各杂交组合F2代高秆系（rht13+Rht-D1a）的各性状值均为最大，双矮秆系（Rht-D1b+Rht13）的各性状值均为最小，双矮秆系株高较高秆系分别降低了24.04%、23.94%和18.46%，且均达到显著水平，其他农艺性状的差异也达到了显著水平。双矮秆系的各产量性状值均显著低于高秆系。双矮秆基因（Rht-D1b+Rht13）和单矮秆基因（Rht13）能显著降低旗叶相对叶绿素含量。.研究结果显示Rht-D1b和Rht13的互作对株高等农艺性状和产量性状具有不利影响。.（3）现有标记筛选以及Rht13基因区段与水稻、二穗短柄草、大麦及谷子的矮秆基因和赤霉素基因进行比对分析得出：60对已注释标记中有21对分子标记在双亲（宁春4号和Magnif M1）中存在多态性，占总标记的35%，现有禾谷类作物的矮秆基因和赤霉素基因聚类分析发现，各基因间均具有一定的同源性。发掘的新标记被命名为7BLSSR1和7BLSSR2，分别来源于水稻第11号染色体多蘖矮秆基因d27和小麦7DL的赤霉素基因Traes_7DL_F51807989。构建小麦7B染色体Rht13基因区段的连锁遗传图谱，长度为64cM，标记间的平均遗传距离为3.6cM。