玉米抗腐霉茎腐病种质标记基因型鉴定与遗传多样性分析

Marker-Assisted Identification and Genetic Diversity Analysis of Maize Germplasm Resources with Resistance to Pythium Stalk Rot

腐霉茎腐病(Pythium stalk rot)是玉米生产上的重要病害。本研究利用14个与8个抗玉米茎腐病基因连锁的分子标记对196份抗腐霉茎腐病玉米种质进行抗病标记基因型鉴定,并采用42对多态性SSR标记对54份抗病自交系进行遗传多样性分析,以期阐明玉米抗腐霉茎腐病种质的标记基因型和遗传背景,并为资源的有效利用、新基因的挖掘和杂种优势模式确定提供参考信息。14个与抗病基因连锁的分子标记将196份抗性种质鉴定为128种标记基因型,表明存在多样的抗性基因组合方式。191份种质获得与齐319、X178或1145中一个或多个的相同的扩增,表明97.45%种质可能含有与3个抗玉米茎腐病材料相同的抗病基因;粤61、郑653、赤L136、白53和18--14共5份种质均未扩增出与齐319、X178和1145相同的标记基因型,可能携带其他抗茎腐病基因;遗传背景相近的抗性种质分属不同的标记基因型,表明抗病种质携带的抗病基因可能在育种选择中发生了分离。42对多态性SSR引物在54份抗病材料中共检测出119个等位基因(Na),多态位点百分率(PPB)为99.17%,平均有效等位基因数(Ne)为1.7070,平均Nei's基因多样性(H)为0.3999,平均Shannon's信息指数(I)为0.5844,平均多态信息含量(PIC)为0.5527,变幅为0.2061~0.7844;通过UPGMA聚类分析,54份抗病材料被划分为2个类群,共6个亚群中,分别是旅大红骨亚群、BSSS亚群、塘四平头亚群、PA亚群、PB亚群、Lan亚群,表现出较高的遗传多样性。结果表明,我国6个杂种优势群中均含有较为丰富的抗腐霉茎腐病种质资源,其中PA亚群包含的抗病种质最多。

Pythium stalk rot is a serious disease that threats the maize production.Exploration of the resistance maize germplasm resources to this disease will benefit for noval genes mining and the determination of heterosis patterns.Within this study,fourteen molecular markers linked to eight stalk rot resistance genes were used for genotyping 196 resistant maize germplasm accessions.Moreover,42 polymorphic SSR makers were adopted in genetic diversity analysis of 54 selected resistant maize lines.A total of 128 resistance marker genotypes were identified with the eight functional markers.Out of 196 accessions,191 exhibited one or more of fragments being identical with these of Qi319,X178 or 1145.No fragments were detected in five germplasm accessions(Yue61,Zheng653,Chi L136,Bai53,and 18--14),suggsting that these five germplasm might harbor other maize stalk rot resistance gene(s).By deployment of 42 SSR primers,119 alleles were amplified in 54 selected lines,with polymorphic site percentage(PPB)of 99.17%.The average number of alleles(Na),effective number of alleles(Ne),Nei’s gene diversity(H),and Shannon's information index(I)were 2.86,1.7070,0.3999,and 0.5884,respectively.The value of polymorphism information content(PIC)for each marker varied from 0.2061 to 0.7844,with an average of 0.5527.The UPGMA analysis classified 54 inbred lines into 2 groups and 6 subgroups with relatively high genetic diversity,including Lüda red cob(LRC),BSSS,Tang si ping tou(TSPT),PA,PB and Lancaster.Taken together,the results revealed variable resources with resistance to stalk rot in six heterosis groups,among which the most resistance germplasms were found in PA subgroup.