高粱丝黑穗病菌4号生理小种抗性基因的定位

【目的】对高粱的丝黑穗病菌4号生理小种抗性基因进行定位分析，筛选与抗病基因连锁的分子标记，为抗丝黑穗病育种奠定基础。【方法】以对高粱丝黑穗病菌1、2、3、4号生理小种均表现免疫的材料961541为母本，以对1、2、3号生理小种免疫、对4号生理小种感病的材料V4B及高感材料PI550607为父本，进行杂交，构建F₂群体。采用菌土法在播种时进行田间接种，抽穗后对抗/感亲本、F₁及F₂群体材料进行发病率调查。利用微卫星分子标记技术（SSR）和分离群体分组分析法(BSA)对961541/V4B的F₂群体进行抗病基因的定位分析。【结果】961541/V4B组合中，抗病亲本961541发病率为0，感病亲本V4B发病率为21.5%，F₁发病率为0，F₂群体发病率为7.25%；961541/PI550607组合中，高感亲本PI550607的发病率为64.81%，F₁及F₂群体发病率分别为0和5%。适合性检验表明，2个组合的F₂群体的抗、感病株比率均符合15﹕1（χ²=0.201、0.322，P>0.05），4号生理小种的抗病性受2对非等位基因控制。所试274对SSR引物中共有53对引物在抗、感亲本间存在差异。利用筛选出的53对引物进一步对抗、感池进行特异引物筛选，仅位于高粱第1染色体上的SSR引物Xtxp325在抗、感池间表现差异。其中，抗池与免疫材料961541的带型一致，感池与鉴别寄主V4B的带型一致；选取5对引物（Xtxp325、Xtxp302、Xtxp32、Xtxp340和Xtxp248）进行连锁图谱构建，构建的连锁图谱全长355.3 cM，4号生理小种抗性基因Shs1与Xtxp325之间的遗传距离为27.7 cM。【结论】高粱丝黑穗病菌4号生理小种的抗病性受2对非等位基因控制。构建的连锁图谱全长355.3 cM，与发表的连锁图谱有较好的对应关系，高粱丝黑穗病菌4号生理小种抗病基因位于第1染色体上，Shs1与Xtxp325的遗传距离为27.7 cM。

Genetic Mapping of the Resistance Gene for the Race 4 of Sphacelotheca reiliana in Sorghum

【Objective】The objective of this study is to conduct mapping genes conferring resistance to physiological race 4 of head smut disease in sorghum and screen the molecular markers linked to the resistance genes, in order to lay a foundation for sorghum resistance breeding against the head smut in future.【Method】To build F2 populations, the material 961541 as a female, which is immune to physiological races 1, 2, 3, and 4, was crossed with V4B which is immune to physiological races 1, 2, and 3 and sensitive to race 4 and PI550607 which is sensitive to physiological races 1, 2, 3, and 4. The seeds were inoculated with soil containing suitable chlamydospores at sowing time, and the disease incidence of the parents, F₁ progenies and F₂ population was investigated at heading stage. The localization of resistance gene was studied by SSR technology and bulked segregation analysis (BSA) method using the 961541/V4B population.【Result】The results of field investigation showed that, for the cross combination 961541/V4B, the morbidities of 961541 and the F₁ progeny both were 0, and that of V4B and F₂ population were 21.5% and 7.25%, respectively. For another cross combination 961541/PI550607, the morbidities of PI550607 was 64.81%, and that of the F₁ progeny, F₂ population were 0 and 5%, respectively. The fitness test indicated that, for the two F₂ populations, the ratio of resistance quantities to sensitive quantities both were conformed to 15:1(χ²=0.201, 0.322, P>0.05), which implied that the resistance genes to head smut race 4 should be controlled by 2 non-allelic genes. The linkage analysis showed that, among the total 274 pairs of SSR primers, 53 pairs showed different amplification between the parents. Then screening of the specificity primers among the 53 pairs were conducted between the resistance pool and the sensitive pool, while only Xtxp325 on chromosome 1 was specific. The banding pattern of resistance pool was the same as 961541, and the sensitive pool was as the material V4B. Linkage mapping with the 5 pairs primers (Xtxp325, Xtxp302, Xtxp32, Xtxp340, Xtxp248) showed that the overall length of linkage map was 355.3 cM, the genetic distance between Xtxp325 and the resistance gene (Shs1) was 27.7 cM.【Conclusion】The resistances to physiological race 4 of sorghum head smut might be controlled by two mutual independent non-allelic genes. The linkage map was good correspondence with the public maps, and which the overall length was 355.3 cM. The resistance gene Shs1 of head smut race 4 is located on No. 1 chromosome of sorghum, and the genetic distance is 27.7 cM from the primer Xtxp325.