摘要：

为将雄性不育基因应用于甜玉米杂交制种中,达到降低劳动成本且保证种子纯度的目的。以来源于甜玉米自交系K78的雄性不育自发突变体male sterility 2020 (ms2020)为材料,构建ms2020与甜玉米自交系M08的F₁及相应的F₂遗传群体,通过表型鉴定、遗传分析和基因定位研究ms2020甜玉米雄性不育突变体。表型鉴定结果表明:F₁群体均表现为雄性可育,F₂群体出现了育性分离。不育植株能够正常抽雄,但花药不开裂、散粉异常,花药变小且颜色淡黄;1% I₂-KI染色发现不育植株的花药内包含不能正常着色的败育花粉粒。遗传分析结果表明:育性正常植株与不育植株的比例符合3∶1,表明ms2020雄性不育突变体是由单基因控制的隐性突变体。利用BSA技术,初步将目的基因定位在7号染色体短臂上;随后利用初定位区间内的20对SSR标记对不育基因进行定位,将不育基因精细定位在标记S1和W10之间,物理距离为11.30 kb。该区间内包含Zm00001d018802和Zm00001d018803 2个注释基因;通过候选基因功能分析,推测已报道为玉米雄性不育基因的编码谷氧还蛋白的Zm00001d018802 (ZmMs22/ZmMSCA1)基因可能是导致ms2020雄性不育的关键候选基因。本研究鉴定了ms2020甜玉米雄性不育突变体的败育特征和遗传特性,为甜玉米雄性不育化杂交制种提供了材料;同时,本研究定位到突变体的关键候选基因,为进一步解析其雄性不育的分子机制奠定了基础。

关键词: 玉米, 雄性不育, 基因定位, 杂交制种

Abstract:

In order to reduce the labor costs and guarantee the seed purity, male sterility gene was applied to sweet corn hybrid seed production. We used male sterility 2020 (ms2020), a spontaneous male sterility mutant derived from sweet corn inbred line K78, as the experimental material to construct F₁ and corresponding F₂ populations of ms2020 and sweet corn inbred line M08. We performed phenotypic identification, genetic analysis, and gene mapping for ms2020 mutant. Phenotypic identification showed that the F₁ population was fertile, and the F₂ population was partially sterile. The sterile plants could be tasseled normally, but the anthers were not exposed, no pollen shed, anthers small, and pale yellow. Employing 1% I₂-KI staining showed that the anthers of sterile plants contained abortive pollen grains that could not stain normally. The results of genetic analysis showed that the ratio of fertile normal plants to sterile plants was 3∶1, indicating that ms2020 male sterile mutant was a recessive mutant controlled by a single gene. The target gene was initially located on the short arm of chromosome 7 by the BSA method. Subsequently, 20 pairs of SSR markers in the initial interval were used to locate the sterile gene, and gene was finely located between markers S1 and W10, with a physical distance of 11.30 kb. Two genes, Zm00001d018802 and Zm00001d018803 were included in this region. Based on the functional analysis of candidate genes, it is speculated that Zm00001d018802 (ZmMs22/ZmMSCA1) encoding gludodoxin, which has been reported as a male sterility gene in maize, may be the key candidate gene for ms2020.The abortion characteristics and genetic regularity of ms2020 male sterility mutant were identified, which provided the material for male sterility hybridization seed production of sweet corn. The key candidate gene of the mutant were located, which laid a foundation for further analysis of its molecular mechanism.

Key words: Maize, Male sterility, Gene mapping, Hybrid seed production