Zhao Yan, Zhang Yongzhong, Wang Lijing, Wang Xueran, Xu Wei, Gao Xianyu, Liu Baoshen
State Key Laboratory of Crop Biology, College of Agronomy, Shandong Agricultural University, Tai'an, China.
Agricultural Technology Promotion Center of Yanzhou, Jining, China.
Front Plant Sci. 2018 Aug 21;9:1227. doi: 10.3389/fpls.2018.01227. eCollection 2018.
The maize () stigma, which is commonly known as silk, is indispensable for reproduction and thus for grain yield. Here, we isolated a spontaneous mutant , which completely lacks silk; scanning electron microscopy showed that the pistils degenerated during late floret differentiation. Genetic analysis confirmed that this trait was controlled by a recessive nuclear gene and was mapped to a 74.13-kb region on chromosome 2 between the simple sequence repeat markers and . Sequence analysis of candidate genes in this interval identified a single-nucleotide insertion at position 569 downstream of the transcriptional start site in , which encodes a UDP-glycosyltransferase; this insertion produces a frameshift and premature translational termination. RNA-sequencing analysis of young ears identified 258 differentially expressed genes (DEGs) between and the wild type (WT), including 119 up- and 139 down-regulated genes. Interestingly, most DEGs related to jasmonic acid (JA) synthesis were up-regulated in the mutant compared to WT. Consistent with this, the JA and JA-Isoleucine (JA-Ile) contents were significantly higher in ears than in WT. At the same time, RNA-sequencing analysis of tassels showed that could reduce the number of tassel branches in maize by down-regulating the expression of and genes. Our identification of the mutant and the responsible gene will facilitate further studies on female infertility research or maize breeding.
玉米（）的柱头，通常被称为花丝，对于繁殖以及谷物产量而言不可或缺。在此，我们分离出了一个自发突变体，其完全没有花丝；扫描电子显微镜显示该突变体的雌蕊在小花分化后期退化。遗传分析证实该性状由一个隐性核基因控制，并将其定位到2号染色体上位于简单序列重复标记和之间的一个74.13 kb区域。对该区间候选基因的序列分析确定，在编码一个UDP - 糖基转移酶的基因转录起始位点下游569位有一个单核苷酸插入；此插入导致移码并提前终止翻译。对幼穗的RNA测序分析确定了突变体和野生型（WT）之间有258个差异表达基因（DEG），包括119个上调基因和139个下调基因。有趣的是，与茉莉酸（JA）合成相关的大多数DEG在突变体中相对于WT上调。与此一致的是，突变体穗中的JA和茉莉酸异亮氨酸（JA - Ile）含量显著高于WT。同时，对雄穗的RNA测序分析表明，突变体可通过下调和基因的表达减少玉米雄穗分支的数量。我们对突变体及其相关基因的鉴定将有助于进一步开展关于雌性不育研究或玉米育种的研究。
