Mapping of yield contributing drought tolerance QTLs in maize and its utilization in marker-assisted breeding

Abstract Drought is considered as one of the major limiting factors in sustainable maize production all over the world as it causes yield reduction by an average of 60% (FAOSTAT 2022). Maize is generally grown in Kharif season but spring maize is now coming up in India. A total of 135 F 8 recombinant inbred lines (RILs) along with parental lines were evaluated under control and drought stress conditions for two consecutive seasons. About 12 QTLs on chromosome 1, 3, 4, 6, 7 and 9 were found to be associated with drought tolerance. The QTL for number of kernel per ear ( qKPE ) present on chromosome 9 ( bnlg1401-umc1634 ) was fine mapped by designing 50 new SSR markers between the bracketed QTL ( qKPE ). The QTL analysis narrowed down the genetic distance to 3.8 cM from 11.5 cM and physical distance to 691 Kb from earlier distance of 15 Mb flanked by two new SSR markers viz. PAU_1137 and PAU_1143. The qKPE is also introgressed through marker assisted backcross breeding (MABB) into two spring maize inbreds LM23 and LM24 of hybrid PMH10 for water use efficiency. The foreground selection has been carried out in three generations i.e., BC 1 F 1, BC 2 F 1 . and BC 3 F 1 . The BC 3 F 1 plants have been raised during Kharif 2019 and screened with new flanking markers. The selected plants were selfed to raise BC 3 F 2 population. The development of drought tolerant PMH10 hybrid will lead to overcome frequent irrigations during spring season and will help to conserve ground water depletion.