糖与激素的关系的.pptVIP

糖与激素的关系; 糖作为信号分子在微生物中已经被广泛了解,最近又 在动物和植物中被发现。糖在植物中的功能不仅是营养物 质还是影响许多与最重要的过程有关的各种基因表达的信 号化合物。这些基因包括编码与种子萌发、生根发芽、抽 叶开花和老化等相关的蛋白的基因。葡萄糖以及其它糖类 调控的基因表达表明这些营养分子还起着激素的作用。 ;;Sugar-signalling mutants reveal the hormone connections;对拟南芥糖信号突变体的遗传学和分子学分析发现糖和激素之间存在紧密的联系。这些突变体除了能改变糖响应，它们的表型还和ABA、乙烯生物合成突变体以及ABA、乙烯信号突变体的表型相似幻灯片 7。例如，小叶，叶色暗绿的gin1突变体与组成型乙烯突变体（野生型植株用葡萄糖处理再用乙烯前体ACC处理）。 令人惊讶的是ctr1突变株在没有外源葡萄糖加入时叶子比野生型致密得多，这是由于ctr1突变株植物的细胞较小，因而其叶子、花序和根系统比野生型致密幻灯片 8。还发现糖不敏感突变体gin1、gin5能诱导种子休眠，它的野生型表型正是ABA缺陷性突变体的特征。这些发现说明糖和ABA,糖和乙烯信号途径之间存在遗传学的联系。;Fig. 1. Arabidopsis glucose-insensitive (gin) mutants. Seedlings were grown on 6% glucose–Murashige and Skoog (MS) medium for 4–5 days under constant light. (a) Wild type (WT). (b) The glucose insensitive phenotype can be mimicked by treatment with the ethylene precursor 1-aminocyclopropane-1-carboxylate(ACC). (c) Abscisic acid-deficient gin1 (aba2) and (d) constitutive ethylene-signalling gin4(ctr1) mutants display a similar glucose-insensitive phenotype except for root elongation. (e) Endogenous abscisic acid is required for the glucose-oversensitive phenotype of the ethylene-insensitive mutant ein2 because (f) the gin1 ein2 double mutant exhibits the glucose-insensitive phenotype.;Abbreviations: ABA, abscisic acid; bZIP, basic leucine zipper domain; CPR5, constitutive expresser of PR; HXK1, hexokinase 1; MCSU, moco sulfurase; SDR, short-chain dehydrogenase/reductase; SnRK, SNF1-related protein kinase; ZEP1, zeaxanthin epoxidase. Mutant names: aba, ABA deficient; abi, ABA insensitive; ein, ethylene insensitive; insensitive; sun, sucrose uncoupled. Gene names and alternative protein names are listed.;Fig. 2. Growth retardation of gin mutants. (a) Wild type (WT), (b) abscisic acid-deficient gin1 (aba2), (c) constitutive ethylene-signalling gin4 (ctr1), (d) ethyleneinsensitive ein2, (e) gin1 ein2 double mutant. In the absence of exogenous glucose,different gin mutants exhibit growth retardation. There might be a signalling network connecting endog