Molecular mechanism and molecular breeding of phosphate storage during seed maturation in rice.

1L-肌醇-1-磷酸[Ins(3)P_1]合成酶催化肌醇生物合成的第一步，以葡萄糖6-磷酸生成Ins(3)P_1为代表。在与INS(3)P_1不同的各种代谢途径中，一条是植酸(六磷酸肌醇)的生物合成，它是种子中磷酸盐的储存形式。我们从酵母和植物中分离到一个与INS(3)P_1高度同源的水稻基因克隆pRINO_1。对发育中种子的原位杂交和组织学分析表明，RINO1转录本的积累模式与含有菲丁的颗粒的定位很好地吻合。RINO1转录本和颗粒都在盾片和糊粉层中积累到高水平。此外，RINO1转录本的积累被发现先于菲丁颗粒的出现。这些结果表明，Ins(3)P_1合成酶在水稻种子发育过程中对植酸的生物合成起着关键作用。它是很好的…更多的人知道，ABA调节着种子发育中的许多基因。葡萄糖6-磷酸是INS(3)P_1合成酶的底物，是蔗糖从来源组织转运过来的代谢物之一。因此，我们研究了ABA和蔗糖对成熟水稻种子盾片诱导培养细胞INS(3)P_1合成酶基因表达的影响。在蔗糖或ABA处理后，Ins(3)P_1转录本的积累量明显增加，其表达水平取决于蔗糖浓度(10~100 mM)和ABA浓度(10^~(-8)~10~(-4)~(-4)~(-5)M)。蔗糖和葡萄糖对基因诱导均有效，而甘露醇对基因诱导无效。ABA和蔗糖处理均可导致更高水平的转录物积累。ABA和蔗糖的联合处理表明，它们在诱导Ins(3)P_1合成酶基因方面具有协同作用。基因转录水平在治疗后2~4h升高，以后逐渐下降。对RINO1基因的启动子分析表明，RINO1启动子中存在许多负责ABA反应、种子特异性表达和重金属反应的顺式作用元件。较少

1L-myo-inositol-1-phosphate [Ins(3)P_1] synthase catalyzes the first step of myo-inositol biosynthesis, represented by the formation of Ins(3)P_1 from glucose 6-phosphate. Of the various metabolic routes diverging from Ins(3)P_1, one is the biosynthesis of phytin (inositol hexakisphosphate), a storage form of phosphate in seeds. We have isolated a rice cDNA clone, pRINO1, which is highly homologous to Ins(3)P_1 from yeast and plants. In situ hybridization and histological analyses of developing seeds revealed that the accumulation pattern of the RINO1 transcripts coincided well With the localization of phytin-containing particles. Both the RINO1 transcripts and the particles accumulated to high levels within the scutellum and the aleurone layer. In addition, the accumulation of the RINO1 transcripts was found to precede the appearance of the phytin particles. These findings suggested that Ins(3)P_1 synthase plays a key role in phytin biosynthesis in developing seeds in rice.It is well … More known that ABA regulates many genes in developing seeds. Glucose 6-phosphate, the substrate of Ins(3)P_1 synthase, is one of the metabolites of sucrose that is translocated from the source tissues. Therefore, we investigated the effects of ABA and sucrose on the expression of the Ins(3)P_1 synthase gene in cultured cells induced from the scutellum of mature rice seeds. Higher levels of the Ins(3)P_1 transcript accumulation were evident after the treatment of either sugar or ABA.The expression level depended on sucrose concentration (10 to 100mM) and ABA concentration (10^<-8>M to 10^<-4>M). Both sucrose and glucose were effective in the gene induction but mannitol was not. Treatment with both ABA and sucrose resulted in much higher levels of transcript accumulation. A combined treatment of ABA and sucrose revealed that they work synergistically in the induction of the Ins(3)P_1 synthase gene. The level of transcript increased 2 to 4 hours after treatment, when it began to decrease gradually. The promoter analysis of the RINO1 gene revealed that many cis-acting elements responsible for ABA response, seed-specific expression, and heavy metal response existed in the RINO1 promoter. Less