The Genetic Analysis Of Nitrate Induced Elongation And Initiation Of Lateral Roots In Rice (Oryza Sativa L.)

To investigate the genetic background of nitrate induced elongation and initiation of lateral roots in rice, a doubled haploid (DH) population, derived from a cross between IR64 and Azucena, which showed different responses to local supplied NO3- in lateral root elongation and initiation, were used in agar culture experiments with three separated layers. The second agar layer was supplied with SmMNO3- or without NO3- as two treatments. Average lateral root length (ALRL), lateral root number (LRN) and surface area of lateral roots (SALR) in the second agar layers with and without nitrate, respectively, were measured. Six putative QTLs and twenty-two pairs of epistatic loci for five lateral root traits in nitrate deficient and nitrate supplied layers were detected. These QTLs individually explained about 9% to 16% of the phenotypic variations in the traits. These twenty-two pairs of epistatic loci accounted for about 16%-51% of the total variations in the parameters, respectively. All of the QTLs detected in this case share, at least, one same or closely linked molecular markers linked to other QTLs for different root traits, which suggests that the genetic factors responsive to local supplied NO3- be involved in root growth and development, and that elongation and initiation of adventitious roots and lateral roots may, at least partially, be controlled by the related genetic mechanisms.