The genetic architecture of temperature-induced partial fertility restoration in A1 cytoplasm in sorghum (Sorghum bicolor (L.) Moench)

Authors: JORDAN, DAVID - University Of Queensland; Klein, Robert; MELONEK, JOANNA - University Of Western Australia; SMALL, IAN - University Of Western Australia; CRUISHANK, ALAN - Department Of Agriculture And Fisheries; BRADBURN, LEISA - Department Of Agriculture And Fisheries; MALORY, SYLVIA - University Of Queensland; TAO, YU - University Of Queensland; HUNT, CHARLES - Department Of Agriculture And Fisheries; AMENU, LEALEM - University Of Queensland; MACE, EMMA - University Of Queensland

Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/7/2024
Publication Date: 7/2/2025
Citation: Jordan, D., Klein, R.R., Melonek, J., Small, I., Cruishank, A., Bradburn, L., Malory, S., Tao, Y., Hunt, C., Amenu, L., Mace, E. 2025. The genetic architecture of temperature-induced partial fertility restoration in A1 cytoplasm in sorghum (Sorghum bicolor (L.) Moench). Theoretical and Applied Genetics. 138. Article 170. https://doi.org/10.1007/s00122-025-04946-4.
DOI: https://doi.org/10.1007/s00122-025-04946-4

Interpretive Summary: Major advancements in science hinge on the identification of genes controlling plant and animal traits that are critically important to agriculture. Our work focuses on improving major grain crops and, with gene sequences, the genetic blueprint will be visible and this information can make improving the plants more efficient. This study details the identification of genes that control pollen viability in sorghum, and also directly compares the chromosome location of these genes between sorghum and rice. The identification of the location and identiy of genes controlling pollen viability will allow scientists to understand those key features of the genetic blueprint that make sorghum’s physical appearance differ from that of other cereals. Information will be primarily used by fellow scientists but the work should ultimately result in better adapted, higher producing crop varieties available to American farmers.

Technical Abstract: Cytoplasmic-nuclear male sterility, CMS, is used for commercial production of hybrid seed in sorghum. CMS-based hybrid breeding systems require female parental lines to remain male sterile to prevent self-pollination and thereby insure cross-pollination to generate hybrid seed. However, genetic and environmental factors can lead to the loss of male sterility in the female parent, resulting in the production of contaminating self-pollinated seeds with large economic consequences. It is known that high temperatures around flowering time induce sterility breakdown, or partial fertility; however, the genetic control of this phenomenon is poorly understood. To investigate the molecular processes controlling sterility breakdown in A1 CMS, a large association mapping population of elite female parental lines was used to map the genomic regions controlling partial fertility. In this study, we used genome-wide association studies on a panel of sorghum lines grown in six field trials at Emerald Queensland representing six different environments. The seed planting was set up in such a way that flowering corresponded with the hottest part of the year. In total 43 significant SNPs were identified, indicating that the trait is controlled by multiple genes, however the majority of previously identified major genes for fertility restoration were not found to co-locate in the genome. Diversity and linkage disequilibrium decay patterns in separate elite male and CMS pools also indicated the constraints on genetic diversity within the female parents due to partial fertility, rather than the frequency of the previously identified major fertility restoration genes. The understanding of the control of sterility breakdown provides new avenues for trait introgression in elite female pools.