Study of Genetics and Tagging of Gene Linked to Spotted Stem Borer (Chilo partellus) Resistance in Maize

Abstract

The maize spotted stem borer, Chilo partellus (Swinhoe), is a serious pest that causes yield losses of 24.3-36.3% Knowledge of the genetics of resistance is a prerequisite for the development of resistant cultivars. The present investigation was carried out to study the genetics of resistance to the spotted stem borer and to identify linked SSR markers using BSA. Twenty- eight inbreds, along with 2 checks, were screened for C. partellus resistance by considering damage parameters namely, LIR, exit hole, dead heart, and percent stem tunnelling in a field trial at ICAR-IIMR, New Delhi. Maize genotypes WNZPBTL 2 and HKI 1352 were selected as resistant and susceptible parents, respectively. Individuals of the F2 mapping population developed from WNZPBTL 2 and HKI 1352 were phenotyped for the LIR and classified into 1 to 9 scales. F2 distribution of LIR indicates monogenic control of spotted stem borer resistance in maize with dominance of resistance. Screening of parents with 200 simple sequence repeat (SSR) markers identified 37 polymorphic markers across the genome. Chromosomes 1, 5, and 6 were revealed to carry the most distinct genomes, whereas chromosome 8 was more similar between parents. Only one marker (bnlg1057) at map location bin1.06 showed polymorphism between parents as well as bulks with distinct frequency of resistant and susceptible alleles. Strength of linkage between marker and trait in F2 was assessed by binary logistic regression, which was significant with a value of regression coefficient 1.453. An additional twelve markers from identified bin1.06 flanking bnlg1057 were selected to identify a closer marker to the gene, but the absence of polymorphism between parents for these markers suggests the use of a different population to find more closely linked markers.