紫花苜蓿抗根腐病高密度遗传图谱的构建及QTL遗传分析

Root rot is one of important disease of alfalfa (Medicago sativa L.) and resistant variety is thought as the efficient solution to it. Most of resistances are QDR traits (quantitative disease resistance) which cannot be increased efficiently by standard breeding with some problems such as long period, unachievable breeding goal and trait separation owing to crossing of alfalfa. In order to construct our molecular assistant selection technique to resistance to root rot disease, we will draw up the high density genetic linkage map with parents, F1 and back cross group based on a large number of SNPs of model M. truncatula, identify the genetic marker for autotetraploid M. sativa and study the genetic character and evolution through QTL(quantitative trait loci ) during breeding. This work will help to the utilization from basic research of model plant to practice in economic crop and enrich the molecular assistant selection theory on the resistance to root rot disease of alfalfa.

根腐病是紫花苜蓿（Medicago sativa L.)最主要的病害之一，选育抗病品种被认为是最有效的解决办法。绝大多数抗病性是QDR(quantitative disease resistance)，常规育种手段对多基因控制的数量性状则效率不高，且存在周期长，抗病靶标不容易控制，且紫花苜蓿异花授粉性状易分离等问题。为了建立我国抗病育种分子辅助选择技术体系，本项目基于豆科模式植物-蒺藜状苜蓿开发出来的大量SNP信息，构建紫花苜蓿抗病和感病亲本及F1和回交材料，筛选出可以用于同源四倍体紫花苜蓿抗病分子育种的基因标记，并对与苜蓿抗根腐病相关的QTL（quantitative trait loci）遗传规律以及在育种过程中抗根腐病基因的进化特点进行研究。本项目的实施加快模式植物基础研究到经济植物的应用实践，同时丰富苜蓿抗病分子育种的遗传理论。

项目针对我国苜蓿根腐病抗病性及其遗传机制尚不清楚这一科学与生产问题，构建了抗病、感病及对照苜蓿品种的自交系及F1代群体材料，获得具有抗病苜蓿材料23份、强致病力镰刀菌和烟草花叶病毒6份，完成了多个品种抗病性评价，建立了苜蓿的无性繁殖体系，完成抗根腐病的形态指标测定和遗传分析，获得遗传图谱的分子数据，构建了苜蓿抗病的遗传调控网络，发现了与抗病相关的多个RNA位点以及 AMV外壳蛋白基因组呈现明显的地区分化，以上结果对于抗病育种工作提供了可靠的亲本和病原材料，从某个角度揭示抗病的分子遗传机制，有助于加快多年生豆科牧草的育种进程，对于生产中抗病品种的选择和丰产栽培也具有重要的应用价值。