高等植物的種子發育可分為胚胎發育期及成熟期。種子成熟後隨即進入休眠，然後於適當的時間萌芽。B3 domain 家族是參與種子發育的重要轉錄因子。以玉米為例，vp1 基因突變後，玉米種子不會經過休眠期，直接在母體的穗上萌發。相似的，阿拉伯芥中玉米VP1的orthology基因，ABI3，在abi3 基因突變後，阿拉伯芥種子也會對離層酸不感知，並產生綠色不成熟的種子。最近，在阿拉伯芥中發現三個VP1/ABI3-Like(VAL)基因，AtVAL1、AtVAL2、及AtVAL3 ，已經知道它們在阿拉伯芥幼苗的生長發育上扮演重要的角色。此外，AtVAL1/HSI2 也是受糖調控Spomin 啟動子的抑制子。 水稻是世界上重要的糧食作物之ㄧ，也是很好的單子葉模式植物。由資料庫的比對，找到在水稻中有兩個和阿拉伯芥AtVALs序列相近OsVALs基因，分別將它們命名為OsVAL1和OsVAL2。本篇論文中，利用建構OsVALs過量表達及基因靜默的轉殖水稻，分析在單子葉植物水稻中，OsVALs 是否參與糖訊息調控的途徑中以及對水稻的生長發育是否具有影響。在初步的實驗中發現，OsVAL1及OsVAL2 在水稻各部位組織皆有表現，並且在水稻種子萌發的過程，第一天就開始表現。此外，在OsVAL1 過量表達轉殖水稻方面，有四個獨立的品系(#19、#41、#59、#61)的葉片上有明顯褐斑的生成；而在OsVALs 基因靜默方面，相較於野生型水稻，則有較早結穗的外表型。除此之外，也發現OsVALs在水稻中是受糖所調控的，在缺糖的情況下比有糖的情況表現量多，並且推測，對於水稻的澱粉水解酶αAmy3 可能是作為一個抑制子的角色。 The VP1/ABI3, which belongs to B3 domain like transcription factor,plays an importment role during plant seed embryogenesis and maturation. Previous studies have shown that when vp1/abi3 mutate, seeds could not sense endogenous abscisic acid and then direct germinate without dormancy. Recently,three VP1/ABI3-LIKE (VAL) genes, AtVAL1, AtVAL2, and AtVAL3, have been identified from Arabidopsis and played essential roles in seedlings growth. Moreover, AtVAL1/HSI2 has been demonstrated as a transcriptional repressor for a sugar-inducible Spomin promoter. Rice is one of the most important crops and also a model plant for monocots. In order to study the function of VAL genes in rice seed development and in sugar signal transduction pathway, we identified two AtVAL homologs, OsVAL1 and OsVAL2, and then gain-of-function and loss-of-function analyses were applied. We find that OsVALs are ubiquitously expressed in rice different tissues, and emerge after rice seeds imbibed in water only one day. Moreover, four independent lines of OsVAL1 overexpression transgenic rice exhibit distinct brownish lesions. On the other hand, OsVAL RNAi transgenic rice plants present earlier heading than wild-type. In addtion,OsVALs are sugar-regulated and may play as a repressor for the rice αAmy3 gene.
