Ranganatha Hosahally Muddrangappa, Lohithaswa Hirenallur Chandappa, Pandravada Anand
Department of Genetics and Plant Breeding, College of Agriculture - Mandya, University of Agricultural Sciences, Bengaluru, Bengaluru, India.
Corteva Agriscience Pvt. Ltd., Kallinayakanahalli, India.
Front Genet. 2021 Jan 29;11:548407. doi: 10.3389/fgene.2020.548407. eCollection 2020.
Among various foliar diseases affecting maize yields worldwide, northern corn leaf blight (NCLB) is economically important. The genetics of resistance was worked out to be quantitative in nature thereby suggesting the need for the detection of quantitative trait loci (QTL) to initiate effective marker-aided breeding strategies. From the cross CML153 (susceptible) × SKV50 (resistant), 344 F progenies were derived and screened for their reaction to NCLB during the rainy season of 2013 and 2014. The identification of QTL affecting resistance to NCLB was carried out using the genetic linkage map constructed with 194 polymorphic SNPs and the disease data recorded on F progeny families. Three QTL for NCLB resistance were detected on chromosomes 2, 5, and 8 with the QTL explaining the highest phenotypic variation of 16.34% followed by with 10.24%. QTL for resistance to sorghum downy mildew (SDM) and southern corn rust (SCR) were also identified from one season phenotypic data, and the co-location of QTL for resistance to three foliar diseases was investigated. QTL present in chromosome bins 8.03, 5.03, 5.04, and 3.04 for resistance to NCLB, SDM, and SCR were co-localized, indicating their usefulness for the pyramiding of quantitative resistance to multiple foliar pathogens. Marker-assisted selection was practiced in the crosses CM212 × SKV50, HKI162 × SKV50, and CML153 × SKV50 employing markers linked to major QTL on chromosomes 8, 2, and 10 for NCLB, SDM, and SCR resistance, respectively. The populations were advanced to F stage to derive multiple disease-resistant inbred lines. Out of the 125 lines developed, 77 lines were tested for their combining ability and 39 inbred lines exhibited high general combining ability with an acceptable level of resistance to major diseases.
在全球影响玉米产量的各种叶部病害中，玉米大斑病在经济上具有重要意义。抗性遗传研究表明其本质上是数量性状，这意味着需要检测数量性状位点（QTL）以启动有效的分子标记辅助育种策略。以CML153（感病）×SKV50（抗病）杂交组合构建了344个F 代群体，并在2013年和2014年雨季对其进行玉米大斑病抗性筛选。利用由194个多态性单核苷酸多态性（SNP）构建的遗传连锁图谱以及F 代家系的病害数据，对影响玉米大斑病抗性的QTL进行鉴定。在第2、5和8号染色体上检测到3个玉米大斑病抗性QTL，其中一个QTL解释了最高的表型变异率，为16.34%，另一个为10.24%。还从一个季节的表型数据中鉴定出高粱霜霉病（SDM）和玉米南方锈病（SCR）抗性QTL，并研究了三种叶部病害抗性QTL的共定位情况。在第8.03、5.03、5.04和3.04染色体区间检测到的玉米大斑病、高粱霜霉病和玉米南方锈病抗性QTL共定位，表明这些QTL在聚合多个叶部病原菌的数量抗性方面具有应用价值。在CM212×SKV50、HKI162×SKV50和CML153×SKV50杂交组合中分别利用与第8、2和10号染色体上主要QTL连锁的分子标记进行标记辅助选择，这些QTL分别与玉米大斑病、高粱霜霉病和玉米南方锈病抗性相关。将这些群体推进到F 代以培育多病害抗性自交系。在育成的125个自交系中，对77个自交系进行了配合力测试，其中39个自交系表现出较高的一般配合力，并对主要病害具有可接受的抗性水平。
