Exploration of genetic selection in rice leaf length and width

Leaf length and width are two of the most important components of rice (Oryza sativa L.) plant architecture and directly contribute to yield. The genetic effects of leaf length and width are controlled by quantitative trait loci (QTLs). In this study, a double haploid (DH) population derived from a cross of O. sativa subsp. japonica cultivar ‘Maybelle’ and subsp. indica cultivar ‘Baiyeqiu’ (‘BYQ’) was used to determine genetic effects on leaf length and width. Analysis of phenotypic effects indicated that all of the detected traits exhibited continuous, transgressive distributions in the DH population. Correlation analysis revealed a strong association between the two adjacent leaves for the same trait. A total of 25 QTLs within 17 genetic intervals distributed on chromosomes 1, 2, 3, 4, 5, 6, 8, and 12 were detected for rice leaf length and width, with likelihood of odds values that ranged from 2.75 to 10.62. Among these loci, two major QTLs, which were located in the intervals RM3262–RM3452 and RM16432–RM7472, played very important roles in regulating leaf length and width, respectively. Diversity analysis of the two major QTLs revealed that the genetic interval RM16432–RM7472 should be an optimal target for rice breeding programs, and may inspire new research efforts.