A maize introgression library reveals ample genetic variability for root architecture, water use efficiency and grain yield under different water regimes
Résumé
The genetic dissection of root system architecture (RSA) provides valuable opportunities towards a better understanding of its role in determining yield under different water regimes. To this end, a maize introgression library comprised of 75 BC5 lines derived from the cross between Gaspé Flint (an early line; donor parent) and B73 (an elite line; recurrent parent) were evaluated in two experiments conducted under well-watered and water-deficit conditions (WW and WD, respectively) in order to identify QTLs for RSA, biomass accumulation (BA), water use efficiency (WUE), flowering time (FT), grain yield (GY) and yield components (YC). RSA features (shovelomics), FT, GY and YC were investigated in the field while BA and WUE were measured in plants grown in the high-throughput phenotyping platform PhenoArch (INRA, Montpellier). QTLs were identified for all investigated traits. Several QTLs for FT affected also RSA, BA, WUE, GY and/or GY, thus underlying the pivotal role of phenology in controlling morpho-physiological traits and yield. For several QTLs, a sizeable QTL x water regime interaction was evidenced in both experiments. A particularly interesting QTL for WUE in both WW and WD conditions was mapped on bin 9.01, with Gaspé Flint contributing the positive allele. Strong concurrent QTL effects on RSA and YC were identified on bin 1.03, 2.04 and 3.03. The most interesting QTLs are being considered for fine mapping and cloning.