Genetic control of leaf angle in sorghum and its effect on light interception

Abstract

Developing sorghum genotypes adapted to different light environments requires understanding of a plant’s ability to capture light, determined through leaf angle specifically. This study dissected the genetic basis of leaf angle in three-year field trials at two sites, using a sorghum diversity panel (729 accessions). A wide range of variation in leaf angle with medium heritability was observed. Leaf angle explained 36% variation in canopy light extinction coefficient, highlighting the extent to which variation in leaf angle influences light interception at whole canopy level. This study also found the sorghum races of Guinea and Durra consistently having the largest and smallest leaf angle, respectively, highlighting the potential role of leaf angle in adaptation to distinct environments. The genome-wide association study detected 33 QTL associated with leaf angle. Strong synteny was observed with previously detected leaf angle QTL in maize (70%) and rice (40%) within 10 cM, among which the overlap was significantly enriched according to Chi-square tests, suggesting a highly consistent genetic control in grasses. A priori leaf angle candidate genes identified in maize and rice were found to be enriched within a 1-cM window around the sorghum leaf angle QTL. Additionally, protein domain analysis identified the WD40 protein domain as being enriched within a 1-cM window around the QTL. These outcomes show that there is sufficient heritability and natural variation in the angle of upper leaves in sorghum which may be exploited to change light interception and optimise crop canopies for different contexts.