Background

Digalactosyldiacylglycerol (DGDG) is one of the major lipids found predominantly in the photosynthetic membrane of cyanobacteria, eukaryotic algae and higher plants. DGDG, along with MGDG (Monogalactosyldiacylglycerol), forms the matrix in thylakoid membrane of chloroplast, providing the site for photochemical and electron transport reactions of oxygenic photosynthesis.

Results

In silico analysis reveals that rice (Oryza sativa L.) genome has 5 genes encoding DGDG synthase, which are differentially expressed in different tissues, and OsDGD2β was identified to be the sole DGDG synthase gene expressed in anther. We then developed osdgd2β mutants by using the CRISPR/Cas9 system and elucidate its role, especially in the development of anther and pollen. The loss of function of OsDGD2β resulted in male sterility in rice characterized by pale yellow and shrunken anther, devoid of starch granules in pollen, and delayed degeneration of tapetal cells. The total fatty acid and DGDG content in the anther was reduced by 18.66% and 22.72% in osdgd2β, affirming the importance of DGDG in the development of anther. The mutants had no notable differences in the vegetative phenotype, as corroborated by relative gene expression of DGDG synthase genes in leaves, chlorophyll measurements, and analysis of photosynthetic parameters, implying the specificity of OsDGD2β in anther.

Conclusion

Overall, we showed the importance of DGDG in pollen development and loss of function of OsDGD2β results in male sterility. Here, we have also proposed the use of OsDGD2β in hybrid rice breeding using the nuclear male sterility system.

中文翻译：

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OsDGD2β是花药中唯一高表达的二半乳糖基二酰基甘油合酶基因，其突变赋予水稻雄性不育性。

背景

二半乳糖二酰基甘油（DGDG）是主要存在于蓝细菌、真核藻类和高等植物的光合膜中的主要脂质之一。DGDG 与 MGDG（单半乳糖基二酰基甘油）一起形成叶绿体类囊体膜中的基质，为含氧光合作用的光化学和电子传递反应提供场所。

结果

计算机分析表明，水稻（Oryza sativa L.）基因组中有5个编码DGDG合酶的基因，这些基因在不同组织中差异表达，并且OsDGD2β被确定为唯一在花药中表达的DGDG合酶基因。然后，我们利用 CRISPR/Cas9 系统开发了osdgd2β突变体，并阐明了其作用，特别是在花药和花粉的发育中。OsDGD2β功能丧失导致水稻雄性不育，其特征是花药呈淡黄色且皱缩，花粉中缺乏淀粉颗粒，绒毡层细胞退化延迟。osdgd2β中花药中总脂肪酸和DGDG含量分别降低了18.66%和22.72% ，证实了DGDG在花药发育中的重要性。突变体在营养表型上没有显着差异，叶子中 DGDG 合酶基因的相对基因表达、叶绿素测量和光合参数分析证实了这一点，这暗示了 OsDGD2β 在花药中的特异性。

结论

总体而言，我们证明了 DGDG 在花粉发育中的重要性以及 OsDGD2β 功能丧失导致雄性不育。在这里，我们还提出将OsDGD2β用于利用核雄性不育系统的杂交水稻育种。