Kashem M A, Hori H, Itoh K, Hayakawa T, Todoroki Y, Hirai N, Ohigashi H, Mitsui T
Laboratory of Molecular Life Sciences, Graduate School of Science and Technology, Niigata University, Japan.
Planta. 1998 Jul;205(3):319-26. doi: 10.1007/s004250050326.
The effects of (+)-8',8',8'-trifluoroabscisic acid (trifluoro-ABA) on alpha-amylase expression were studied in rice embryoless half-seeds, scutella, and suspension-cultured cells derived from the embryo, and the effects of the analog on sugar accumulation were also studied in scutella and suspension-cultured cells. Treatment with (+)-trifluoro-ABA strongly inhibited the gibberellic acid-inducible expression of alpha-amylase I-1 encoded by RAmy1A in the aleurone layers of embryoless half-seeds at the levels of transcription, protein synthesis, and enzyme activity. It was also found that (+)-trifluoro-ABA stimulated (i) the uptake of glucose from the incubation medium and (ii) the synthesis of sucrose in scutellar tissues and suspension-cultured cells of rice. The biological activity of (+)-trifluoro-ABA was found to be more potent and persistent than that of natural ABA. We further examined the effects of trifluoro-ABA on the expression of alpha-amylase I-1 in scutellar tissues and suspension-cultured cells. It was found that (+)-trifluoro-ABA did not inhibit the formation of alpha-amylase I-1 in the absence of external glucose. However, glucose and (+)-trifluoro-ABA cooperatively suppressed the formation of alpha-amylase I-1. Judging from these results, we conclude that the regulatory mechanism for the expression of alpha-amylase I-1 in the scutellar epithelium is distinguishable from that operating in the aleurone layer.
研究了（+）-8',8',8'-三氟脱落酸（三氟脱落酸）对水稻无胚半种子、盾片以及来源于胚的悬浮培养细胞中α-淀粉酶表达的影响，同时也研究了该类似物对盾片和悬浮培养细胞中糖分积累的影响。用（+）-三氟脱落酸处理在转录、蛋白质合成和酶活性水平上强烈抑制了无胚半种子糊粉层中由RAmy1A编码的赤霉素诱导型α-淀粉酶I-1的表达。还发现（+）-三氟脱落酸刺激了（i）水稻盾片组织和悬浮培养细胞从培养液中摄取葡萄糖以及（ii）蔗糖的合成。发现（+）-三氟脱落酸的生物活性比天然脱落酸更强且更持久。我们进一步研究了三氟脱落酸对盾片组织和悬浮培养细胞中α-淀粉酶I-1表达的影响。发现在没有外源葡萄糖的情况下，（+）-三氟脱落酸不抑制α-淀粉酶I-1的形成。然而，葡萄糖和（+）-三氟脱落酸协同抑制α-淀粉酶I-1的形成。根据这些结果，我们得出结论，盾片上皮细胞中α-淀粉酶I-1表达的调控机制与糊粉层中的调控机制不同。
