Mapping QTLs associated with drought avoidance in upland rice

The identification of molecular markers linked to genes controlling drought resistance factors in rice is a necessary step to improve breeding efficie ncy for this complex trait. QTLs controlling drought avoidance mechanisms w ere analyzed in a doubled-haploid population of rice. Three trials with dif ferent drought stress intensities were carried out in two sites. Leaf rolli ng, leaf drying, relative water content of leaves and relative growth rate under water stress were measured on 105 doubled haploid lines in two trials and on a sub-sample of 85 lines in the third one. Using composite interval mapping with a LOD threshold of 2.5, the total number of QTLs detected in all trials combined was 11 for leaf rolling, 10 for leaf drying, 11 for rel ative water content and 10 for relative growth rate under stress. Some of t hese QTLs were common across traits. Among the eleven possible QTLs for lea f rolling, three QTLs (on chromosomes 1, 5 and 9) were common across the th ree trials and four additional QTLs (on chromosomes 3, 4 and 9) were common across two trials. One QTL on chromosome 4 for leaf drying and one QTL on chromosome 1 for relative water content were common across two trials while no common QTL was identified for relative growth rate under stress. Some o f the QTLs detected for leaf rolling, leaf drying and relative water conten t mapped in the same places as QTLs controlling root morphology, which were identified in a previous study involving the same population. Some QTL ide ntified here were also located similarly with other QTLs for leaf rolling a s reported from other populations. This study may help to chose the best se gments for introgression into rice varieties and improvement of their droug ht resistance.