Specific Gibberellin 2-Oxidase 3 (SbGA2ox3) Mutants Promote Yield and Stress Tolerance in Sorghum bicolor

Abstract

Sorghum (Sorghum bicolor (L.) Moench) is a raw material that can be used as food, feed, bioenergy, and wine; it is also a gramineous crop with drought, salt, waterlogging, and high temperature resistance. However, liquor-making sorghum faces the disadvantages of having a narrow genetic basis, poor resources, and few high-quality varieties. Ethyl methane sulfonate (EMS) is a common alkylating agent that can react with one or more bases to alkylate and cause changes in the molecular structure of DNA, thereby causing mutations. It has a minimum effect on organisms and the highest efficiency. The obtained mutant populations are of great significance for cultivating new plant varieties and enriching plant germplasm resources. Therefore, in this study, ‘Hongyingzi’ a liquor-making sorghum variety, was studied using seeds treated with 0.5% EMS and 415 M3 generation plants were obtained. (1) Investigation and statistical analysis of agronomic traits in mutant libraries showed that in the M3 generation, nine important phenotypic mutant lines were obtained, including plant type, leaf blade, spike, glume, growth period, fertility, plant height, and drought resistance. The variation frequency from high to low was as follows: glume color (75.42%) > spike type (54.70%) > spike shape (47.23%) > chaff coating degree (28%) > plant growth period (23.86%) > plant height (23.61%) > absorption degree (16.14%) > branchiness (10.84%) > leaf color (4.58%) > tillering (2.16%). (2) The PCR sequencing of SbGA2ox3 from 415 sorghum M3 plants revealed that the mutation frequency of SbGA2ox3 was 1/99.02 kb. Eight plants underwent mutations, but only one line experienced missense mutations of different amino acid types, changing Ser/Ala/Val/Leu/Gln/Ser/Pro/Ala to Asn/Thr/Gly/Val/Gln/Ala/Ser. The mutant line also had shorter plant height, reduced glume coating degree, and enhanced drought resistance. The constructions of the sorghum mutant library widened the sorghum germplasm library and provided a method for sorghum breeding with a molecular basis for the functional verification of related genes and the analysis of related regulatory networks.