【原】Plant Journal|扬州大学陈忱教授团队发现 OsNF-YB9 调控水稻籽粒发育机制

PaperRSS 2021-04-06

展开全文

LEAFY COTYLEDON1(LEAFY COTYLEDON1，LEC1)是核因子-Y(NF-Y)家族成员，在拟南芥胚胎发生和种子发育过程中发挥重要作用。先前的研究表明，水稻OsNF-YB9和OsNF-YB7与拟南芥LEC1同源。然而，水稻中类LEC1基因的功能仍不清楚。

在此，我们报道了OsNF-YB9和OsNF-YB7在水稻中显示亚功能化。

结果表明，OsNF-YB7主要在胚中表达，而OsNF-YB9在发育中的胚乳中优先表达。在拟南芥lec1-1中异源表达OsNF-YB9或OsNF-YB7可以弥补lec1-1缺陷。由于OsNF-YB7缺陷的致死性，我们未能产生osnf-bo7纯合子突变体。OsNF-YB9功能缺失导致种子发育异常：种子长、窄、细，垩白率高。此外，在osnf-Mo9中，与淀粉合成相关的基因的表达被解除了调控。OsNF-YB9能与水稻胚乳中主要表达的蔗糖合成酶蛋白激酶SPK相互作用。SPK基因敲除导致了与在osnf-Mo9突变体中观察到的相似的白垩色种子。

OsNF-YB9在水稻和拟南芥中的异位表达导致了种子小而不健康的植株。综上所述，这些结果表明OsNF-YB9在水稻种子发育中起着关键作用。

LEAFY COTYLEDON1 (LEC1), a NUCLEAR FACTOR‐Y (NF‐Y) family member, plays a critical role in embryogenesis and seed development in Arabidopsis. Previous studies have shown that rice OsNF‐YB9 and OsNF‐YB7 are homologous to Arabidopsis LEC1. However, the functions of LEC1‐like genes in rice remain unclear. Here we report that OsNF‐YB9 and OsNF‐YB7 display sub‐functionalization in rice. We demonstrate that OsNF‐YB7 is expressed mainly in the embryo, whereas OsNF‐YB9 is preferentially expressed in the developing endosperm. Heterologous expression of either OsNF‐YB9 or OsNF‐YB7 in Arabidopsis lec1‐1 was able to complement the lec1‐1 defects. We failed to generate osnf‐yb7 homozygous mutants due to lethality caused by OsNF‐YB7 defects. Loss of OsNF‐YB9 function caused abnormal seed development: seeds were longer, narrower and thinner and exhibited a higher chalkiness ratio. Furthermore, the expression of genes related to starch synthesis was deregulated in osnf‐yb9. OsNF‐YB9 could interact with SPK, a sucrose synthase protein kinase that is predominantly expressed in rice endosperm. Knockout of SPK resulted in chalky seeds similar to those observed in the osnf‐yb9 mutants. Ectopic expression of OsNF‐YB9 in both rice and Arabidopsis resulted in unhealthy plants with small seeds. Taken together, these results suggest a critical role for OsNF‐YB9 in rice seed development.