title: Morphological Characterization of a New and Easily Recognizable Nuclear Male Sterile Mutant of Sorghum (Sorghum bicolor).
abstract: Sorghum (Sorghum bicolor L. Moench) is one of the most important grain crops in the world. The nuclear male sterility (NMS) trait, which is caused by mutations on the nuclear gene, is valuable for hybrid breeding and genetic studies. Several NMS mutants have been reported previously, but none of them were well characterized. Here, we present our detailed morphological characterization of a new and easily recognizable NMS sorghum mutant male sterile 8 (ms8) isolated from an elite inbred BTx623 mutagenized by ethyl methane sulfonate (EMS). Our results show that the ms8 mutant phenotype was caused by a mutation on a single recessive nuclear gene that is different from all available NMS loci reported in sorghum. In fertile sorghum plants, yellow anthers appeared first during anthesis, while in the ms8 mutant, white hairy stigma emerged first and only small white anthers were observed, making ms8 plants easily recognizable when flowering. The ovary development and seed production after manual pollination are normal in the ms8 mutant, indicating it is female fertile and male sterile only. We found that ms8 anthers did not produce pollen grains. Further analysis revealed that ms8 anthers were defective in tapetum development, which led to the arrest of pollen formation. As a stable male sterile mutant across different environments, greenhouses, and fields in different locations, the ms8 mutant could be a useful breeding tool. Moreover, ms8 might be an important for elucidating male gametophyte development in sorghum and other plants.
authors.affiliation: Plant Stress and Germplasm Development Unit, USDA-ARS, Lubbock, Texas, United States of America.
authors.forename: Zhanguo
authors.initials: Z
authors.lastname: Xin
authors.affiliation: Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, United States of America.
authors.forename: Jian
authors.initials: J
authors.lastname: Huang
authors.affiliation: Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, United States of America.
authors.forename: Ashley R
authors.initials: AR
authors.lastname: Smith
authors.affiliation: Plant Stress and Germplasm Development Unit, USDA-ARS, Lubbock, Texas, United States of America.
authors.forename: Junping
authors.initials: J
authors.lastname: Chen
authors.affiliation: Plant Stress and Germplasm Development Unit, USDA-ARS, Lubbock, Texas, United States of America.
authors.forename: John
authors.initials: J
authors.lastname: Burke
authors.affiliation: USDA-ARS-PA-Grain, Forage, & Bioenergy Res. Unit, 251 Filley Hall/Food Ind. Complex, Lincoln, Nebraska, United States of America.
authors.forename: Scott E
authors.initials: SE
authors.lastname: Sattler
authors.affiliation: Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, United States of America.
authors.forename: Dazhong
authors.identifier: 0000-0001-9167-1421
authors.initials: D
authors.lastname: Zhao
mesh_terms: D002467:Cell Nucleus / Q000235:genetics*; D005298:Fertility / Q000235:genetics; D056426:Genetic Loci; D009154:Mutation / Q000235:genetics*; D051479:Plant Infertility; D011058:Pollen / Q000254:growth & development; D045868:Sorghum / Q000033:anatomy & histology* / Q000235:genetics*