The outermost surfaces of plants are covered with an epicuticular wax layer that provides a primary waterproof barrier and protection against different environmental stresses. Glossy 1 (GL1) is one of the reported genes controlling wax synthesis. This study analyzed GL1-homologous genes in Oryza sativa and characterized the key members of this family involved in wax synthesis and stress resistance. Sequence analysis revealed 11 homologous genes of GL1 in rice, designated OsGL1-1 to OsGL1-11. OsGL1-1, -2 and -3 are closely related to GL1. OsGL1-4, -5, -6, and -7 are closely related to Arabidopsis CER1 that is involved in cuticular wax biosynthesis. OsGL1-8, -9, -10 and -11 are closely related to SUR2 encoding a putative sterol desaturase also involved in epicuticular wax biosynthesis. These genes showed variable expression levels in different tissues and organs of rice, and most of them were induced by abiotic stresses. Compared to the wild type, the OsGL1-2-over-expression rice exhibited more wax crystallization and a thicker epicuticular layer; while the mutant of this gene showed less wax crystallization and a thinner cuticular layer. Chlorophyll leaching experiment suggested that the cuticular permeability was decreased and increased in the over-expression lines and the mutant, respectively. Quantification analysis of wax composition by GC–MS revealed a significant reduction of total cuticular wax in the mutant and increase of total cuticular wax in the over-expression plants. Compared to the over-expression and wild type plants, the osgl1-2 mutant was more sensitive to drought stress at reproductive stage, suggesting an important role of this gene in drought resistance.
植物最外表面被一層上皮蠟質(zhì)層所覆蓋，是防止水分喪失的主要屏障和保護(hù)植物免受不同環(huán)境脅迫傷害的壁壘。Glossy1(GL1)是已報(bào)道的控制蠟質(zhì)合成的基因之一。本研究中我們分離了水稻GL1同源基因并研究了該家族中的關(guān)鍵成員在蠟質(zhì)合成和脅迫耐受中的作用。序列分析表明水稻中含有11個(gè)GL1的同源基因，分別命名為OsGL1-1至OsGL1-11。OsGL1-1,-2和-3與GL1的同源性最高。OsGL1-4,-5,-6,和-7與擬南芥中參與角質(zhì)層蠟質(zhì)生物合成的CER1同源性最高。OsGL1-8,-9,-10和-11與參與上皮蠟質(zhì)生物合成的甾醇去飽和酶SUR2同源性最高。這些基因在水稻不同組織器官具有不同的表達(dá)水平，大部分受非生物脅迫誘導(dǎo)表達(dá)。與野生型相比，過量表達(dá)OsGL1-2的水稻植株蠟質(zhì)結(jié)晶增加，上表皮層增厚，而該基因的突變體蠟質(zhì)晶體減少，角質(zhì)層變薄。葉綠素浸取實(shí)驗(yàn)表明角質(zhì)層通透性在過量表達(dá)植株中降低而在突變體中升高。利用氣相色譜質(zhì)譜聯(lián)用儀對(duì)蠟質(zhì)成分進(jìn)行定量分析表明總角質(zhì)層蠟質(zhì)在過量表達(dá)植株中顯著升高而在突變體中降低。與過量表達(dá)植株和野生型相比，osgl1-2突變體在生殖生長(zhǎng)期對(duì)干旱脅迫更敏感，表明該基因在抗旱中發(fā)揮重要作用。
結(jié)果：水稻GL1同源基因的鑒定。 GL1類基因家族的聚類分析。 OsGL1類家族基因在水稻不同組織和器官的表達(dá)水平。 OsGL1基因?qū)Ψ巧锩{迫的響應(yīng)。 過量表達(dá)OsGL1-2的植株及突變體的抗旱性及角質(zhì)層通透性的改變。 過量表達(dá)OsGL1-2的植株及突變體中蠟質(zhì)積累發(fā)生變化。