An overview of genomics assisted improvement of drought tolerance in maize (Zea mays L.): QTL approaches

Abstract

Today drought is the worldwide problem that causes the reduction in the crop yield of plants. Maize (Zea mays L.) is greatly affected by drought and its production is declining day by day. However there are many techniques accessible today to achieve a better understanding of the multifarious network of plant responses to drought and to maneuver these responses. These techniques comprise the association mapping, mapping of quantitative trait loci (QTLs), studies of gene expression and genetic transformation. Selection based on performance in multi-environment trials (MET) has increased grain yield under drought through increased yield potential and kernel set, rapid silk exertion, and reduced barrenness, though at a lower rate than under optimal conditions. Knowledge of the physiology of drought tolerance has been used to dissect the trait into a series of key processes. This has been complemented by genetic dissection through the identification of QTL associated with these same traits. Both have been used to identify suitable organ- and temporal-specific promoters and structural genes. The present paper will overview both conventional breeding and QTL/MAS approaches towards improvement of maize yield in drought-prone environments and will briefly describe a QTL approach. Key Wards: Drought, QTL, Maize, zea mays, multi-environment trials, promoters, marker assisted selection, Pakistan.