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United States Department of Agriculture

Agricultural Research Service

Research Project: GENETIC ANALYSES AND TRAIT MAPPING TO EXPLOIT UNTAPPED GENETIC DIVERSITY IN SORGHUM

Location: Crop Germplasm Research

Title: Molecular mapping and candidate gene identification of the Rf2 gene for pollen fertility restoration in sorghum (Sorghum bicolor (L.) Moench)

Authors
item Jordan, David -
item Mace, Emma -
item Henzell, Robert -
item Klein, Patricia -
item Klein, Robert

Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 15, 2009
Publication Date: May 1, 2010
Citation: Jordan, D.R., Mace, E.S., Henzell, R.G., Klein, P.E., Klein, R.R. 2010. Molecular mapping and candidate gene identification of the Rf2 gene for pollen fertility restoration in sorghum (Sorghum bicolor (L.) Moench). Theoretical and Applied Genetics. 120(7):1279-1287.

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. 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 identifies a gene controlling pollen viability, which is critical for producing hybrid seed grown in growers' fields across the globe. This detailed, mapping study will permit more efficient screening of parental lines used in commercial hybrid seed production, and will allow scientists to understand those key features of the genetic blueprint that make sorghum the desired crop for US producers. Information will be primarily used by fellow scientists but the work will ultimately result in better adapted, higher producing crop varieties available to American farmers.

Technical Abstract: The A1 cytoplasmic-nuclear male sterility system in sorghum is used almost exclusively for the production of commercial hybrid seed and thus, the dominant genes that restore male fertility in F1 hybrids are of critical importance to commercial seed production. The genetics of fertility restoration in sorghum is complex and is controlled by at least two major genes with additional modifiers. To elucidate the molecular processes controlling fertility restoration and to develop a marker screening system for this important trait, two sorghum recombinant inbred line populations were created by crossing a restorer and a non-restoring inbred line with fertility restoration evaluated in hybrid combination with three unique female lines. In both populations, a single major gene segregated for restoration which was localized to chromosome SBI-02 at approximately 0.5 cM from microsatellite marker, Xtxp304. In addition, evidence for modifier genes was also observed since a continuum of partial restored fertility was exhibited by select lines in both RIL populations. A fine mapping population was used to resolve the Rf2 locus to a 236,219 bp region of chromosome SBI-02, which spanned 31 predicted open reading frames including a pentatricopeptide repeat gene family member. This gene displayed high homology with rice Rf1. Progress towards the development of a marker-assisted screen for fertility restoration is discussed.

Last Modified: 8/22/2014