State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing 210095, China.
National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
Plant Sci. 2021 Apr;305:110831. doi: 10.1016/j.plantsci.2021.110831. Epub 2021 Jan 28.
Cereal crops accumulate large amounts of starch which is synthesized and stored in amyloplasts in the form of starch grains (SGs). Despite significant progress in deciphering starch biosynthesis, our understanding of amyloplast development in rice (Oryza sativa) endosperm remains largely unknown. Here, we report a novel rice floury mutant named enlarged starch grain1 (esg1). The mutant has decreased starch content, altered starch physicochemical properties, slower grain-filling rate and reduced 1000-grain weight. A distinctive feature in esg1 endosperm is that SGs are much larger, mainly due to an increased number of starch granules per SG. Spherical and loosely assembled granules, together with those weakly stained SGs may account for decreased starch content in esg1. Map-based cloning revealed that ESG1 encodes a putative permease subunit of a bacterial-type ABC (ATP-binding cassette) lipid transporter. ESG1 is constitutively expressed in various tissues. It encodes a protein localized to the chloroplast and amyloplast membranes. Mutation of ESG1 causes defective galactolipid synthesis. The overall study indicates that ESG1 is a newly identified protein affecting SG development and subsequent starch biosynthesis, which provides novel insights into amyloplast development in rice.
谷物作物积累大量的淀粉，这些淀粉以淀粉粒（SGs）的形式在淀粉体中合成和储存。尽管在破译淀粉生物合成方面取得了重大进展，但我们对水稻（Oryza sativa）胚乳中淀粉体发育的理解仍知之甚少。在这里，我们报道了一个名为 enlarged starch grain1（esg1）的新型水稻粉质突变体。该突变体的淀粉含量降低，淀粉理化性质发生改变，灌浆速度较慢，千粒重降低。esg1 胚乳的一个显著特征是 SG 大得多，主要是由于每个 SG 中的淀粉颗粒数量增加。球形且松散组装的颗粒，以及那些弱染色的 SG，可能是 esg1 中淀粉含量降低的原因。基于图谱的克隆表明，ESG1 编码细菌型 ABC（ATP 结合盒）脂质转运蛋白的假定渗透酶亚基。ESG1 在各种组织中组成型表达。它编码一种定位于叶绿体和淀粉体膜的蛋白质。ESG1 突变导致半乳糖脂合成缺陷。总的来说，这项研究表明 ESG1 是一种新发现的影响 SG 发育和随后淀粉生物合成的蛋白质，为水稻淀粉体发育提供了新的见解。
