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Genetic control of source–sink relationships in grain sorghum


Main conclusion

QTL hotspots identified for selected source–sink-related traits provide the opportunity for pyramiding favorable alleles for improving sorghum productivity under diverse environments.


A sorghum bi-parental mapping population was evaluated under six different environments at Hays and Manhattan, Kansas, USA, in 2016 and 2017, to identify genomic regions controlling source-sink relationships. The population consisted of 210 recombinant inbred lines developed from US elite post-flowering drought susceptible (RTx430) and a known post-flowering drought tolerant cultivar (SC35). Selected physiological traits related to source (effective quantum yield of photosystem II and chlorophyll index), sink (grain yield per panicle) and panicle neck diameter were recorded during grain filling. The results showed strong phenotypic and genotypic association between panicle neck diameter and grain yield per panicle during mid-grain filling and at maturity. Multiple QTL model revealed 5–12 including 2–5 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 QTL identified across target traits ranged between 5.5 and 25.4%. Panicle neck diameter and grain yield per panicle were positively associated, indicating the possibility of targeting common co-localized QTL to improve both traits simultaneously through marker-assisted selection. Three major QTL hotspots, controlling multiple traits were identified on chromosome 1 (52.23–61.18 Mb), 2 (2.52–11.43 Mb) and 3 (1.32–3.95 Mb). The identified genomic regions and underlying candidate genes can be utilized in pyramiding favorable alleles for improving source–sink relationships in sorghum under diverse environments.

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Data availability statement

The datasets generated during and/or analyzed during the current study are not publicly available but are available from the corresponding author on reasonable request.


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Contribution number 21-055-J from Kansas Agricultural Research Station. Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture. The USDA is an equal opportunity provider and employer. This work was supported in part by the U.S. Department of Agriculture, Agricultural Research Service.

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Correspondence to S. V. Krishna Jagadish.

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Communicated by Anastasios Melis.

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Chiluwal, A., Perumal, R., Poudel, H.P. et al. Genetic control of source–sink relationships in grain sorghum. Planta 255, 40 (2022).

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  • Multi-environment
  • Panicle neck diameter
  • Quantitative trait loci
  • Sorghum
  • Source–sink dynamics