GENETIC ANALYSES AND TRAIT MAPPING TO EXPLOIT UNTAPPED GENETIC DIVERSITY IN SORGHUM
Location: Crop Germplasm Research
Title: Mapping and characterization of Rf5: A new gene conditioning pollen fertility restoration in A1 and A2 cytoplasm in sorghum (Sorghum bicolor (L.) Moench)
| Jordan, David - |
| Halloran, Kirsten - |
| Henzell, Robert - |
| Klein, Patricia - |
| Mace, Emma - |
Submitted to: Journal of Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 31, 2011
Publication Date: August 1, 2011
Citation: Jordan, D.R., Halloran, K., Henzell, R.G., Klein, R.R., Klein, P.E., Mace, E.S. 2011. Mapping and characterization of Rf5: A new gene conditioning pollen fertility restoration in A1 and A2 cytoplasm in sorghum (Sorghum bicolor (L.) Moench). Journal of Theoretical and Applied Genetics. 123(3):383-396.
Interpretive Summary: Major advancements in science hinge on the identification of genes controlling plant and animal traits that are critically important to agriculture. Genes are tiny packets of genetic blueprint material that are found inside the cells of all plants and animals and control all of the physical characteristics of these organisms. With gene sequences, the genetic blueprint will be visible, and this information can make improving the plants more efficient. This study details the isolation of a major plant gene, named Rf5, that controls pollen viability in sorghum, and also directly compares the map location of this gene in sorghum and rice. The direct comparison of the Rf5 gene and the genes surrounding it will permit more efficient identification and understanding of the function of this gene, and 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 used primarily by fellow scientists but the work should ultimately result in better adapted, higher producing crop varieties available to American farmers.
With an aim to further characterize the cytoplasmic male sterility-fertility restoration system in sorghum, a major fertility restoration gene was mapped, along with a second locus capable of partial restoration of pollen fertility. The major fertility restoration gene, Rf5, was located on sorghum chromosome SBI-05, and was capable of restoring pollen fertility in both A1 and A2 male sterile cytoplasms. Depending on the restorer parent, mapping populations exhibited fertility restoration phenotypes that ranged from nearly bimodal distribution due to the action of Rf5, to a more normalized distribution reflecting the action of Rf5 and additional modifier/partial restoration genes. A second fertility restoration locus capable of partially restoring pollen fertility in A1 cytoplasm was localized to chromosome SBI-04. Unlike Rf5, pRf1 was not capable of restoring fertility restoration in both A1 and A2 cytoplasms, and only modified the extent of restoration conditioned by the major restorer Rf5 in A1 cytoplasm. In examining the genomic regions spanning the Rf5 locus, a cluster of pentatricopeptide gene family members with high homology to rice Rf1 and sorghum Rf2 were identified, and the role of addition pentatricopeptide genes conditioning fertility restoration in sorghum is discussed.