抗茎腐病分子标记在159份玉米自交系中的验证及实用性评价

为了评价抗茎腐病基因分子标记在辅助育种中的实用性,本研究对159份玉米自交系进行了茎腐病田间抗性鉴定,并检测了与4个茎腐病抗性QTL(qRfg1、qRfg2、Rpi QI319-1和Rpi QI319-2)紧密连锁的11个分子标记在上述材料中的扩增情况。结果表明:供试玉米自交系的平均发病率为26.30%,发病率低于30.0%的材料占67.92%,抗病资源丰富。来源于国外、东北、西南和黄淮海地区的材料平均发病率分别为27.67%、17.92%、15.12%和36.80%,与东北和西南地区种质相比,黄淮海地区抗性种质相对缺乏。通过比较分子标记扩增带型与田间茎腐病表型,发现与同一QTL连锁的不同分子标记的检测结果存在较大差异,其中分子标记STS01(qRfg1)、STSZ479(qRfg2)、bnlg1866(Rpi QI319-1)和bnlg1716(Rpi QI319-2)的阳性检测结果与田间表型符合度较高,分别为76.79%、78.95%、91.67%、73.33%,具有上述特异扩增多态性的材料平均发病率分别为22.06%、19.01%、10.65%、19.63%,可作为抗茎腐病分子检测的有效标记。本研究为开展玉米抗茎腐病分子育种提供了重要参考。

Evaluation and Validation of Molecular Markers Associated with Stalk Rot Resistance in 159 Maize Inbred Lines

Stalk rot in maize,a soil-born disease around the world,could cause severe yield and quality loss.In order to evaluate the practicability of molecular markers linked to stalk rot resistance genes in maize assisted breeding,159 maize inbred lines were used to screen resistance to stalk rot in the fields,and the characteristics of amplified bands of eleven molecular markers (STS01,STS378,STS414,STSZ514,STSZ479,bnlg1203,bnlg1866,SSRZ33,SSRZ47,umc2069 and bnlg1716)linked to four resistant QTLs,qRfg1,qRfg2,RpiQI319-1 and RpiQI319-2were analyzed in the above-mentioned inbred lines.The results showed that the disease-resistant germplasms were plentiful in the tested materials.There were 55 inbred lines with a zero incidence rate accounting for 34.59％ of the total,42 inbred lines with an incidence between 0.1％ to 20.0％ accounting for 26.42％,19 between 20.1％ to 40.0％ accounting for 12.58％,13 between 40.1％ to 60.0％ accounting for 8.18％,14 between 60.1％ to 80.0％ accounting for 8.81％,and 15 between 80.1％ to 100％ accounting for 9.43％.The average incidence of the total materials was 26.30％,and the incidence of 108 inbred lines accounting for 67.92％ were less than 30.0％.The resistance of tested materials from different regions showed big difference.The average incidence of the inbred lines from abroad,Northeast,Southwest and Huanghuaihai region were 27.67％,17.92％,15.12％ and 36.80％ with a proportion of the resistant inbred lines of 62.69％,82.36％,88.24％ and 53.66％,respectively.It was obvious that the proportion of resistant germplasms in Huanghuaihai region was lower than that in Northeast or Southwest region.Besides the genetic factor,the stalk rot phonotype of materials was also influenced by locations,years and researchers.The degree of stalk rot disease was obviously associated with the field conditions for plant growth and development,and most of the resistant materials were late-maturing.It was therefore an urgent problem to be solved about how to breed the early-maturing and resistant inbred lines in Huanghuaihai region.There were significant differences among the PCR results of several markers linked to the same QTL.Practicability of molecular markers was evaluated by checking the conformity between genotype tested by molecular markers and phenotype identified in the fields.Four molecular markers,STS01,STSZ479,bnlg1866 and bnlg1716,linked to qRfg1,qRfg2,RpiQI319-1 and RpiQI319-2 respectively,had a high conformity rate of 76.79％,78.95％,91.67％ and 73.33％.The average incidence rates of positive materials detected by the above four markers were 22.06％,19.01％,10.65 ％ and 19.63 ％,respectively.Thus,STS01,STSZ479,bnlg1866 and bnlg1 716 can be used as effective markers for molecular assisted selection on stalk rot resistance in maize breeding.By comparing the conformity between phenotype and genotype tested by molecular markers linked to Pythium stalk rot resistant QTL (RpiQI319-1 and RpiQI319-2)or Fasarium stalk rot resistant QTL(qRfg1 and qRfg2),it was found that the Fasarium resistant QTL (qRfg1 and qRfg2)was useful to the Pythium stalk rot.Some highly resistant inbred lines,such as F19 and SW113,were not found in any tested QTL,which needs to be further studied for new resistant QTLs.This study provided important information for molecular breeding of stalk rot in maize.