The role of phospholipid lipids signal in rice defense reaction and seeds maturation

1水稻防御反应中的磷脂代谢过氧化氢（H_2O_2）（0.01- 0.1mM）诱导悬浮培养水稻细胞中磷脂酸（PA）的快速瞬时积累。用H_2O_2处理水稻细胞提取液，在0.1%正丁醇存在下测定磷脂酶的活性，发现有迅速而短暂的磷脂酰丁醇（PtdBut）生成。因此，H_2O_2激活的磷脂酶为磷脂酶D（PLD）。此外，H_2O_2在体外直接诱导胞浆部分的PLD活化，而无需H_2O_2处理。在体外和体内激活的PLD完全抑制的存在下，laveustin A（0.05 mM），一种有效的抑制剂蛋白酪氨酸激酶（PTK）。H_2O_2（0.01-0.1 mM）能促进N-乙酰壳寡糖诱导子诱导的植物抗毒素生物合成，而Tiron（一种有效的O_（2^-）清除剂）、正丁醇（0.1%）和laviustin A（0.05 mM）则抑制该诱导子诱导的植物抗毒素生物合成。这些结果表明，H_2O_2诱导的PLD激活增强了水稻细胞中导致植物抗毒素生物合成的信号转导。2水稻种子形成过程中的磷脂代谢当在1-丁醇（0.1%）存在下测定从开花后0-30天的水稻种子制备的细胞提取物组分中的PLD活性时，观察到至少两种PLD活性。通过RT-PCR分析水稻种子在0-20 ℃的RNA中PLD基因的表达模式，表明有4种PLD基因表达。将这4个基因的RNA干扰载体构建到载体PZH 2Bik中，用根癌农杆菌EHA 105转化水稻幼胚。然后种植转基因水稻植株，现在正在进行植株的表型分析。

1 Phospholipid metabolism in rice defense reactionHydrogen peroxide (H_2O_2)(0.01-0.1 mM) induced rapid and transient accumulation of phosphatidic acid (PA) in suspension-cultured rice cells. When phospholipase activity in the cellular extract fraction prepared from rice cells treated with H_2O_2 was assayed in the presence of 1-butanol (0.1 %), rapid and transient phosphatidylbutanol (PtdBut) formation was observed. Thus, the H_2O_2-activated phospholipase was concluded to be phospholipase D (PLD). Furthermore, H_2O_2 directly induced in vitro PLD activation in the cytosolic fraction without H_2O_2 treatment. In vitro and in vivo activation of PLD were completely suppressed in the presence of lavendustin A (0.05 mM), a potent inhibitor of protein tyrosine kinase (PTK). Phytoalexin biosynthesis induced by N-acetylchitooligosaccharide elicitor was enhanced in the presence of H_2O_2 (0.01-0.1 mM), whereas it was suppressed in the presence of tiron, a potent scavenger of O_<2^->, 1-butanol (0.1 %), and lavendustin A (0.05 mM). These results indicate that H_2O_2-inducible PLD activation enhances in signal transduction leading to phytoalexin biosynthesis in rice cells.2 Phospholipid metabolism in rice seed formation.When PLD activity in the cellular extract fraction prepared from rice seeds at 0-30 day after flowering (DAF) was assayed in the presence of 1-butanol (0.1 %), at least two kinds of PLD activities was observed. Expression pattern analysis of PLD genes by RT-PCR analysis in RNA prepared from rice seed at 0-20 DAF indicated the expressions of four kinds of PLD genes. The RNA interference vectors of the four genes were constructed into vector PZH2Bik and transformed into immature rice embryos used with Agrobacterium tumefacience strain EHA105. Then the transgenic rice plants were grown and the phenotype analysis of the plants is now underway.