玉米水孔蛋白基因ZmPIP4c作为C_(4)特征性基因的确定  

Identification of Maize Aquaporin Gene ZmPIP4c as a Signature of C_(4) Traits

作　　者：李享 梁玉玲[2] 刘征 马峙英[1] Li Xiang;Liang Yuling;Liu Zheng;Ma Zhiying(State Key Laboratory of Crop Improvement and Regulation in North China,College of Agriculture,Hebei Agricultural University,Baoding,071001;College of Life Science,Hebei University,Baoding,071002)

机构地区：[1]河北农业大学农学院,华北作物改良与调控国家重点实验室,保定071001 [2]河北大学生命科学学院,保定071002

出　　处：《分子植物育种》2021年第9期2819-2825,共7页Molecular Plant Breeding

基　　金：河北农业大学引进人才科研专项(YJ2020003)资助。

摘　　要：水孔蛋白作为跨膜运输的一种通道蛋白,不仅可以对植物体内的水分进行运输,同时也对CO2、H2O2等小分子进行运输,影响光合作用等生理代谢过程。尽管光合作用对植物的生长发育至关重要,C_(3)植物与C_(4)植物的光合作用机制却不尽相同,原因之一是C_(3)植物与C_(4)植物在叶片解剖结构上的差异,C_(4)植物拥有更膨大、更发达的维管束鞘细胞,有利于水分的储存。因此,我们对C_(4)模式植物玉米的水孔蛋白进行了一系列生物信息学分析,其中一个命名为ZmPIP4c的基因,该基因呈现叶片维管束鞘细胞特异性高表达,有利于水分通过该蛋白进入鞘细胞储存,并平衡叶肉细胞的水分供应。而且该基因从叶基部到叶尖的表达趋势不但与用来筛选C_(4)光合作用有关转录本的标志基因——NAD-苹果酸酶基因(NAD-ME)表达趋势一致,并与C_(4)循环其他关键基因磷酸烯醇式丙酮酸羧化酶(PEPC)以及碳酸酐酶(CA)表达趋势一致,均为从叶基部到叶尖表达逐渐上调,表明ZmPIP4c基因参与C_(4)叶片的细胞特异性特征的构成,为C_(4)特征的组成部分。此外,ZmPIP4c基因与C_(4)光合作用关键基因PEPC、CA、NAD-ME在时间节律中的表达趋势一致,表明在光照情况下,该基因为束鞘细胞中所进行的C_(4)光合作用提供了充足的水环境,并避免束鞘细胞在黑暗条件下积累过多的水分,而造成水分和能量的浪费。另外,在盐胁迫下束鞘细胞特异性表达基因ZmPIP4c和叶肉细胞特异性表达的PEPC以及CA均呈现下调趋势。由于叶片束鞘细胞和叶肉细胞间存在水力传导信号,该水孔蛋白基因表达下调,可能改变了叶肉细胞内的水溶液环境,进而对PEPC和CA的表达产生影响。总之,对玉米水孔蛋白ZmPIP4c基因的研究,为我们深入研究C_(4)植物中尚未确定的C_(4)新特征提供了候选基因,并有助于我们深入了解细胞特异性水孔蛋白基因介入C_(4)循环过程As a water trans membrane transporter,aquaporin can not only transport water in plants,but also transport small molecules such as CO2 and H2O2,thus affecting physiological processes such as photosynthesis and so on.Although photosynthesis is critical to plant growth,the photosynthetic mechanisms of C_(3)plants are different from that of C_(4)plants as compared with C_(3)leaves,C_(4)leaves have typical Kranz structure and possess larger and well-developed bundle sheath cells which is favorable for water storage.We therefore performed bioinformatic and gene expression analyses on C_(4)maize aquaporin,and identified a gene called ZmPIP4c which shows high specific expression in bundle sheath cells in leaves.Thus is conducive to water transport into sheath cells and to balance the water supply in mesophyll cells.Further expression analysis on the ZmPIP4c along leaf gradient revealed that the expression trend of this gene was not only consistent with that of C_(4)marker gene-NAD-malic enzyme gene(NAD-ME),a gene usually used to screen C_(4)photosynthesis related transcripts,but also consistent with other C_(4)genes such as phosphoenolpyruvate carboxylase gene(PEPC)and carbonic anhydrase gene(CA).The expressions of these genes all showed gradual increase from leaf base to leaf tip,suggesting that ZmPIP4c is a signature of C_(4)traits.In addition,ZmPIP4c,NAD-ME,PEPC and CA also showed similar expression trends under the regulation of circadian rhythm,indicating that ZmPIP4c can provide optimal water environment for the efficient operation of C_(4)cycle in bundle sheath cells under light,and avoid energy and water waste under dark.Moreover,the expressions of ZmPIP4c gene and of mesophyll-specifically-expressed genes,PEPC and CA,were all down-regulated under salt stress.As there exists water conduction signal between bundle sheath cells and mesophyll cells,down-regulation of ZmPIP4c gene may change the inner water solution environment within mesophyll cells,thereafter affecting the expresions of PEPC and CA genes.In brief,o

关 键 词：玉米 C_(4)光合作用 水孔蛋白 生物信息 基因表达 

分 类 号：S513[农业科学—作物学]