QTL Identification in Presence of QTL×Environment Interaction

Quantitative traits are the traits controlled by many genes and each of the genes has a small effect on the trait. The loci controlling quantitative traits are referred to as QTLs (Quantitative Trait Loci) and the procedure of finding and locating the QTLs are called QTL mapping. The available literature on use of molecular markers for detecting loci influencing the performance of Maize in drought stress is very scanty in India, so the data considered belongs to Maize crop in drought stress, for the present investigation. Mapping population with 236 RILs (Recombinant Inbred Lines), using Ac7643S5 (drought tolerant) and Ac7729 (drought susceptible) as male parent, at CIMMYT and evaluated in India under AMBIONET (Asian Maize Biotechnology Network), Maize Genetic Unit, IARI is considered for the present investigation. Phenotypic data on different plant characters have been utilized for the present study. Genotypic data on RILs obtained through 138 RFLP markers and a linkage map of a total length of 2250 cM with an average density of 17 cM are used for QTL detection. Genotypic data is obtained through molecular marker assay whereas phenotypic data is derived from evaluation of mapping population of the target traits of interest. The analysis is done using software QTLMapper (version 1) and it is found that marker MK28 has main-effect on four traits, marker MK28, MK101 and MK34 has main-effect on two traits. Interaction effect has also been found in different marker pairs. The results are obtained considering the main and interaction effect of markers and it is seen that for the trait Anthesis-Silking Interval one QTL is present on chromosome 1 located on marker MK13. For the trait Ear Height, three QTLs are present, first QTL on chromosome 1 located on 4cM to right from MK8, second QTL on chromosome 2 located on MK34 and third QTL on chromosome 8 located on MK101. For the trait Grain Yield two QTLs are present, first is on chromosome 2 located on 2cM to the right from MK28 and second QTL on chromosome 4 located on MK51. For the trait Ear Diameter one QTL is present on chromosome 3 located on MK35. For the trait 100 Kernel Weight one QTL is present on chromosome 2 located on 14cM to the right of MK27. For the trait Plant Height one QTL is present on chromosome 8 located on marker MK101.