Prospecting quantitative trait loci for maydis leaf blight (MLB) resistance using a population of teosinte‐introgressed maize (Zea mays ssp. mays) and in silico identification of candidate MLB resistance genes

Abstract

Maydis leaf blight (MLB) is an important fungal disease of maize causing yield losses of the magnitude of 38 to 46% worldwide. Present investigation aimed to identify stable and reliable MLB‐resistant QTLs and introgression maize lines to facilitate their utilization in future MLB resistance breeding programmes. For this purpose, 169 backcross inbred lines (BILs), derived using teosinte (Zea mays ssp. parviglumis) as one parent, were grown in randomized block design with two replications in two environments. The lines were phenotyped and genotyped to identify the resistant QTLs by single marker analysis (SMA) method. Also, twenty‐five most resistant and twenty‐five most susceptible lines were selected in order to mimic bidirectional selective genotyping to identify MLB‐resistant QTLs by trait‐based (SGTB) and marker‐based (SGMB) approach. Six and five MLB resistance QTLs were identified in S1 and S2, respectively, by SMA method, while twelve and eight MLB‐resistant QTLs were detected by SGTB and SGMB approach, respectively. A total of fifteen MLB resistance QTLs identified by either SMA, SGTB or SGMB co‐localized with forty‐two QTLs affecting eleven morphological traits in maize. Out of the MLB resistance QTLs detected in both S1 and S2 by SMA, two QTLs linked to marker umc2392 and umc1393 were stable. Four QTLs linked to marker umc1869, umc1720, umc1428 and umc1393 were detected by all three methods and were reliable. A total of 23 genes exhibiting response to fungal pathogens were identified by means of in silico analysis, and these may be validated further so as to be used in future maize improvement programmes.