Genetic control of sorghum [Sorghum bicolor (L.) Moench] grain quality under variable environments

Authors: AYALEW, HABTAMU - Kansas State University; Peiris, Kamaranga; CHILUWAL, ANUJ - Kansas State University; KUMAR, RITESH - Kansas State University; TIWARI, MANISH - Kansas State University; OSTMEYER, TROY - Kansas State University; Bean, Scott

Submitted to: The Plant Genome
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/18/2022
Publication Date: 9/16/2022
Citation: Ayalew, H., Peiris, K.H., Chiluwal, A., Kumar, R., Tiwari, M., Ostmeyer, T., Bean, S.R. 2022. Genetic control of sorghum [Sorghum bicolor (L.) Moench] grain quality under variable environments. The Plant Genome. 15. Article e20227. https://doi.org/10.1002/tpg2.20227.
DOI: https://doi.org/10.1002/tpg2.20227

Interpretive Summary: Sorghum grain provides nutrition to more than half a billion people in regions of Africa and Asia and is used as a livestock feed and as raw material for biofuel production in the United States. Sorghum is highly adapted to heat and drought prone environments and an important crop for sustainability and risk management. However, little is known about the interactions between genetics, crop management and environment on sorghum grain quality. This study analyzed sorghum grain composition of a mapping population grown across six environments that varied in water availability and crop management to identify quantitative trait loci (QTL) controlling protein, starch and amylose content and to identify potential genes within the QTL's. A total of seven protein, 10 starch and 10 amylose content QTLs were identified. Candidate gene analysis indicated that these QTL hotspots were conditioned by several transcription factors that regulate starch and protein accumulation in the grain. The identified genomic regions and underlying candidate genes provide a starting point for further validation and marker assisted gene pyramiding to improve sorghum grain quality.

Technical Abstract: Understanding the genetic control and inheritance of grain quality traits is instrumental in facilitating end-use quality improvement. This study was conducted to identify and map quantitative trait loci (QTL) controlling protein, starch, and amylose content in grain sorghum grown under variable environmental conditions. A recombinant inbred line (RIL) population derived from a cross between RTx430 (post-flowering drought susceptible cultivar) and SC35 (post-flowering drought tolerant cultivar) was evaluated in six environments across Hays and Manhattan, Kansas, US. Significant variation was observed in genotype, environment, and genotype by environment interaction for all three quality traits. Unlike the RILs, the two parental lines did not show significant differences for these traits. However, significant transgressive segregation was observed for all traits resulting in phenotypic performance extending beyond the two parents. A total of seven protein, 10 starch and 10 amylose content QTLs were identified, distributed in all linkage groups except chromosome 6. Chromosomal regions and level of phenotypic variation (PVE) of QTLs were variable across the growing conditions, however one major protein content QTL, explaining up to 13.6% PVE was detected on chromosome 2 (120.3 – 123.2 cM) under five of the six environments. Similarly, a major amylose content QTL on chromosome 1 (134 - 136 cM), explaining up to 22% PVE, was consistently detected under fully-irrigated environments. QTL hotspots for all three traits were detected on chromosomes 1 (115.2 – 119.2 cM) and 2 (118.2 - 127.4 cM). Candidate gene analysis indicated that these QTL hotspots were conditioned by several transcription factors that regulate starch and protein accumulation in the grain. The identified genomic regions and underlying candidate genes provide a starting point for further validation and marker assisted gene pyramiding to improve sorghum grain quality.