QTL mapping for sorghum downy mildew disease resistance in maize (Zea mays L.) in recombinant inbred line population of UMI79 X UMI936 (w)

Abstract Sorghum downy mildew (SDM) caused by the Oomycete, Peronosclerospora sorghi ((Weston and Uppal) C. G. Shaw) is a major impediment to maize production and productivity. Identifying genomic regions (QTLs), contributing to SDM resistance will aid in a marker-assisted resistant breeding program. In the present study, QTLs have been mapped for SDM resistance using 158 recombinant inbred lines (RILs) derived from the cross between SDM-susceptible (UMI79) and resistant (UMI936 (w)) inbred lines. Phenotyping for SDM reaction was conducted in three environments under artificial epiphytotic conditions. Inclusive composite interval mapping with simple sequence repeat (SSR) markers resulted in the identification of three putative QTLs, one with major-effect (PVE = 17.1 %) on chromosome three and other two with minor effects on chromosome six (PVE = 2.3) and seven (PVE = 3.4). Inclusive composite interval mapping detected one QTL for the all the three environments, all co-localizing near the same marker, bnlg420 on chromosome 3.