Basnet Rasbin, Zhang Jiarun, Hussain Nazim, Shu Qingyao
National Key Laboratory of Rice Biology, Institute of Crop Sciences, Zhejiang University, Hangzhou, China.
Hubei Collaborative Innovation Center for the Grain Industry, Yangtze University, Jingzhou, China.
Front Plant Sci. 2019 Aug 2;10:992. doi: 10.3389/fpls.2019.00992. eCollection 2019.
Monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG) are the two predominant galactolipids present in the photosynthetic membrane in many photosynthetic organisms, including algae and higher plants. These galactolipids are the main constituents of thylakoid membrane and are essential for chloroplast biogenesis and photoautotrophic growth. analysis revealed that rice ( L.) genome has three genes encoding MGDG synthase (, and ). Although subcellular localization analysis demonstrated that OsMGD2 is localized to chloroplast, its expression was observed mainly in anther and endosperm, suggesting that MGDG might have an important role in the development of flower and grain in rice. Knock-out mutants of were generated employing the CRISPR/Cas9 system and their morphology, yield and grain quality related traits were studied. The leaf of mutants showed reduced MGDG (∼11.6%) and DGDG (∼9.5%) content with chlorophyll content decreased by ∼23%, consequently affecting the photosynthesis. The mutants also exhibited poor agronomic performance with plant height and panicle length decreased by ∼12.2 and ∼7.3%, respectively. Similarly, the number of filled grains per panicle was reduced by 43.8%, while the 1000 grain weight was increased by ∼6.3% in the mutants. The milled rice of mutants also had altered pasting properties and decreased linoleic acid content (∼26.6%). Put together, the present study demonstrated that is the predominantly expressed gene encoding MGDG synthase in anther and grain and plays important roles in plant growth and development, as well as in grain quality.
单半乳糖基二酰基甘油（MGDG）和双半乳糖基二酰基甘油（DGDG）是许多光合生物（包括藻类和高等植物）光合膜中存在的两种主要半乳糖脂。这些半乳糖脂是类囊体膜的主要成分，对叶绿体生物发生和光合自养生长至关重要。分析表明，水稻（L.）基因组有三个编码MGDG合酶的基因（、和）。虽然亚细胞定位分析表明OsMGD2定位于叶绿体，但其表达主要在花药和胚乳中观察到，这表明MGDG可能在水稻花和籽粒发育中起重要作用。利用CRISPR/Cas9系统构建了基因敲除突变体，并对其形态、产量和籽粒品质相关性状进行了研究。突变体的叶片显示MGDG含量降低（约11.6%），DGDG含量降低（约9.5%），叶绿素含量降低约23%，从而影响光合作用。突变体还表现出较差的农艺性能，株高和穗长分别降低了约12.2%和7.3%。同样，突变体每穗实粒数减少了43.8%，而千粒重增加了约6.3%。突变体的糙米糊化特性也发生了改变，亚油酸含量降低（约26.6%）。综上所述，本研究表明是花药和籽粒中主要表达的编码MGDG合酶的基因，在植物生长发育以及籽粒品质方面发挥重要作用。
