记者从西北农林科技大学获悉，生命科学学院赵惠贤教授团队在小麦控制籽粒大小基因克隆及功能研究方面中取得新进展：克隆得到位于小麦第7同源群染色体短臂上CYP78A家族的新基因TaCYP78A3；利用BSMV-VIGS技术沉默TaCYP78A3基因在小麦籽粒中的表达，导致小麦种子大小降低11%（P<0.01）；通过转基因拟南芥过表达TaCYP78A3基因，导致拟南芥种子增大11%~47%（P<0.01）。进一步的细胞学观察和分子水平检测，揭示了小麦TaCYP78A3基因通过促进胚珠和种子表皮细胞增殖来影响种子大小的分子机制。

该成果于7月6日在线发表于The Plant Journal。本研究工作在国家自然科学基金项目“病毒诱导的基因沉默在小麦穗部的实施及应用（30871578）和“3个小麦种子特异表达的全新microRNA的功能研究（31471482）”等资助下完成。（来源：中国科学报 胡璇子）

Expression of TaCYP78A3, a gene encoding cytochrome P450 CYP78A3 protein in wheat (Triticum aestivum L.), affects seed size

Abstract  Several studies have described quantitative trait loci (QTL) for seed size in wheat, but the relevant genes and molecular mechanisms remain largely unknown. Here we report the functional characterization of the wheat TaCYP78A3 gene and its effect on seed size. TaCYP78A3 encoded wheat cytochrome P450 CYP78A3, and was specifically expressed in wheat reproductive organs. TaCYP78A3 activity was positively correlated with the final seed size. Its silencing caused a reduction of cell number in the seed coat, resulting in an 11% decrease in wheat seed size, whereas TaCYP78A3 over-expression induced production of more cells in the seed coat, leading to an 11–48% increase in Arabidopsis seed size. In addition, the cell number in the final seed coat was determined by the TaCYP78A3 expression level, which affected the extent of integument cell proliferation in the developing ovule and seed. Unfortunately, TaCYP78A3 over-expression in Arabidopsis caused a reduced seed set due to an ovule developmental defect. Moreover, TaCYP78A3 over-expression affected embryo development by promoting embryo integument cell proliferation during seed development, which also ultimately affected the final seed size in Arabidopsis. In summary, our results indicated that TaCYP78A3 plays critical roles in influencing seed size by affecting the extent of integument cell proliferation. The present study provides direct evidence that TaCYP78A3 affects seed size in wheat, and contributes to an understanding of the cellular basis of the gene influencing seed development.

原文链接：http://onlinelibrary.wiley.com/doi/10.1111/tpj.12896/pdf