Monogalactosyl diacylglycerol (MGDG), the main component of the plastid membrane, is essential for chloroplast photosynthesis; however, little information is available about the function of MGDG synthases gene (TaMGD) in wheat grain. In this manuscript, three homologous genes were identified in wheat grain, and their functions were investigated by gene silencing and overexpression techniques. Three TaMGD homologous genes, TaMGD-6A, -6B, and -6D, located on chromosome 6A, 6B, and 6D, respectively, were isolated from common wheat. The transcription of TaMGD was detected in stems, roots, leaves and grains, and high levels of gene transcripts were detected in stems and leaves. Silencing of TaMGD in common wheat spikes resulted in a decrease in grain weight and starch content, and proteomic analysis showed that the differentially expressed proteins mainly included carbohydrate metabolism- and nucleic acid-related proteins. In comparison with wild-type, transgenic rice plants overexpressing TaMGD-6A and -6D showed an increase in thousand kernel weight, as well as an increase in the expression level of genes related to starch biosynthesis, whereas transgenic rice plants overexpressing TaMGD-6B showed increased grain yield and grain number per spike. The results of gene silencing and overexpression indicated that TaMGD plays an important role in wheat grain weight, which might be associated with carbohydrate metabolism. Hence, this study provides new insights regarding the role of TaMGD in wheat grain characteristics.

单半乳糖基二酰基甘油（MGDG）是质体膜的主要成分，对叶绿体的光合作用至关重要。但是，关于MGDG合酶基因（TaMGD）在小麦籽粒中的功能的信息很少。在该手稿中，鉴定了小麦籽粒中的三个同源基因，并通过基因沉默和过表达技术研究了它们的功能。从普通小麦中分离出分别位于6A，6B和6D染色体上的三个TaMGD同源基因TaMGD-6A，-6B和-6D。TaMGD的转录在茎，根，叶和谷粒中检测到基因，并且在茎和叶中检测到高水平的基因转录物。普通小麦穗中TaMGD的沉默导致籽粒重量和淀粉含量的降低，蛋白质组学分析表明差异表达的蛋白质主要包括碳水化合物代谢相关蛋白质和核酸相关蛋白质。与野生型相比，过量表达TaMGD-6A和-6D的转基因水稻植株增加了千粒重，并且与淀粉生物合成相关的基因的表达水平也有所提高，而过量表达TaMGD-6B的转基因水稻植株表现出增加的籽粒产量和单穗粒数。基因沉默和过表达的结果表明，TaMGD在小麦粒重中起重要作用，这可能与碳水化合物的代谢有关。因此，这项研究提供了有关TaMGD在小麦籽粒特性中的作用的新见解。