Genetic control of source-sink relationships in grain sorghum

Authors: CHILUWAL, ANUJ - Kansas State University; PERUMAL, RAMASAMY - Kansas State University; POUDEL, HARI - Agriculture And Agri-Food Canada; MULETA, KEBEDE - Kansas State University; OSTMEYER, TROY - Kansas State University; FEDENIA, LAUREN - Texas A&M University; POKHAREL, MEGHNATH - Kansas State University; Bean, Scott; SEBELA, DAVID - Kansas State University; BHEEMANAHALLI, RAJU - Kansas State University; OUMAROU, HALILOU - Kansas State University; KLEIN, PATRICIA - Texas A&M University; ROONEY, WILLIAM - Texas A&M University; JAGADISH, KRISHNA - Kansas State University

Submitted to: Planta
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/4/2022
Publication Date: 1/17/2022
Citation: Chiluwal, A., Perumal, R., Poudel, H., Muleta, K., Ostmeyer, T., Fedenia, L., Pokharel, M., Bean, S.R., Sebela, D., Bheemanahalli, R., Oumarou, H., Klein, P., Rooney, W., Jagadish, K. 2022. Genetic control of source-sink relationships in grain sorghum. Planta. https://doi.org/10.1007/s00425-022-03822-5.
DOI: https://doi.org/10.1007/s00425-022-03822-5

Interpretive Summary: Sorghum is considered to be one of the hardiest crops to heat and drought stress conditions. However, sorghum often shows low grain yield compared with other grain crops. This low productivity is typically attributed to harsh growing environments and minimal farm inputs which results in exposure to many types of stress. However, previous studies have demonstrated sorghum’s high production potential when grown under non-stress conditions. Therefore this research investigated relationships between photosynthesis ability and panicle growth that relate to the ability of sorghum to adapt to different growing conditions and contribute to grain yield. Results found that the relationship between panicle neck diameter and grain yield were related and genetic regions controlling these traits were identified. These data can be used as genetic markers to select sorghum for improved productivity.

Technical Abstract: A sorghum bi-parental mapping population along with the parents were evaluated under six different environments with considerable range in temperature and soil moisture conditions at Hays and Manhattan, Kansas, USA in 2016 and 2017. The population consisted of 210 recombinant inbred lines developed from US elite post-flowering drought susceptible cultivar (RTx430) and a known post-flowering drought tolerant cultivar (SC35). Physiological traits related to source (effective quantum yield of photosystem II and chlorophyll index), sink (grain yield) and panicle neck diameter were recorded at different growth stages. The results showed strong phenotypic and genotypic association between panicle neck diameter and grain yield during mid-grain filling and at maturity. Multiple QTL model revealed 5 to 12 QTL including 2 to 5 major QTL for each trait. Among them 3, 7 and 8 QTL for quantum yield, panicle neck diameter and chlorophyll index, respectively, have not been identified previously in sorghum. Phenotypic variation explained by different QTL identified across target traits ranged between 5.5 and 25.4%. Panicle neck diameter and grain yield were highly positively associated, indicating the possibility of targeting common co-localized QTL to improve both traits simultaneously through marker assisted selection. Three major QTL hotspots were identified one each on chromosome 1 (52.23 to 61.18 Mb), 2 (2.52 to 11.43 Mb) and 3 (1.32 Mb to 3.95 Mb). The identified genomic regions and underlying candidate genes can be utilized in pyramiding favorable alleles for improving source and sink dynamics in sorghum under diverse and less stressful environments.