植物microRNAs在植物发育和非生物胁迫响应中的作用

microRNAs(miRNAs)是一类内源的长度约为22个核苷酸的非编码小分子RNA,其通过对靶基因mRNA进行切割或翻译抑制调节mRNA的表达,在植物中起到重要的作用.主要介绍了植物miRNAs的特征、合成和作用机制,综述了miRNAs在植物生长发育和非生物胁迫响应中的作用.     

Overproduction of the Membrane-bound Receptor-like Protein Kinase 1, RPK1, Enhances Abiotic Stress Tolerance in Arabidopsis

RPK1 (receptor-like protein kinase 1) localizes to the plasma membrane and functions as a regulator of abscisic acid (ABA) signaling in Arabidopsis. In our current study, we investigated the effect of RPK1 disruption and overproduction upon plant responses to drought stress. Transgenic Arabidopsis overexpressing the RPK1 protein showed increased ABA sensitivity in their root growth and stomatal closure and also displayed less transpirational water loss. In contrast, a mutant lacking RPK1 function, rpk1-1, was found to be resistant to ABA during these processes and showed increased water loss. RPK1 overproduction in these transgenic plants thus increased their tolerance to drought stress. We performed microarray analysis of RPK1 transgenic plants and observed enhanced expression of several stress-responsive genes, such as Cor15a, Cor15b, and rd29A, in addition to H₂O₂-responsive genes. Consistently, the expression levels of ABA/stress-responsive genes in rpk1-1 had decreased compared with wild type. The results suggest that the overproduction of RPK1 enhances both the ABA and drought stress signaling pathways. Furthermore, the leaves of the rpk1-1 plants exhibit higher sensitivity to oxidative stress upon ABA-pretreatment, whereas transgenic plants overproducing RPK1 manifest increased tolerance to this stress. Our current data suggest therefore that RPK1 overproduction controls reactive oxygen species homeostasis and enhances both water and oxidative stress tolerance in Arabidopsis.     

microRNA在玉米生长发育及非生物胁迫响应中的调控功能

microRNA（miRNA）是一类广泛存在于真核生物中长度为20~24 nt的内源非编码小RNA，它们通过对靶基因mRNA进行切割或翻译抑制，在转录后水平调控靶基因的表达。近期研究表明，miRNA参与植物生长发育与逆境胁迫响应的多个重要生物学过程，对作物的农艺性状也起到重要的调控作用。玉米作为重要的粮食、饲料和工业原料，提高其产量和品质对于保障世界粮食安全至关重要，然而与模式植物拟南芥和水稻相比，玉米中miRNA的研究仍然相对较少，理解miRNA在玉米中的功能和调控机理有助于通过分子育种对关键农艺性状进行遗传改良。本文综述了玉米中miRNA的发现与鉴定，系统总结了参与玉米miRNA代谢途径的关键蛋白DCL、AGO和HEN1的研究进展，重点阐述了在玉米生长发育和非生物胁迫响应过程中已开展功能研究miRNA的调控作用，并对玉米miRNA研究当前存在的问题和未来的发展趋势进行了讨论。     

拟南芥漆酶基因AtLAC4参与生长及非生物胁迫响应

植物漆酶基因家族在拟南芥(Arabidopsis thaliana)中共有17个成员,目前各基因的具体功能尚不十分清楚.该研究利用过量表达的方法初步分析了拟南芥AtLAC4的功能.GUS染色显示AtLAC4在拟南芥的维管组织中有较强的表达,并在叶片排水器中特异表达.AtLAC4过量表达导致植株木质素含量增多、次生壁加厚、植株变小和莲座叶叶柄变短.ABA对AtLAC4的表达具有明显的诱导作用,AtLAC4过量表达植株对外源ABA敏感;干旱处理后,AtLAC4过量表达植株的耐旱能力比野生型明显增强.以上结果表明,AtLAC4基因在调控植物生长发育及非生物胁迫响应中具有重要作用.     

Plant RABs: Role in Development and in Abiotic and Biotic Stress Responses

Endosomal trafficking plays an integral role in various eukaryotic cellular activities and is vital for higher-order functions in multicellular organisms. RAB GTPases are important proteins that influence various aspects of membrane traffic, which consequently influence many cellular functions and responses. Compared to yeast and mammals, plants have evolved a unique set of plant-specific RABs that play a significant role in their development. RABs form the largest family of small guanosine triphosphate (GTP)-binding proteins, and are divided into eight sub-families named RAB1, RAB2, RAB5, RAB6, RAB7, RAB8, RAB11 and RAB18. Recent studies on different species suggest that RAB proteins play crucial roles in intracellular trafficking and cytokinesis, in autophagy, plant microbe interactions and in biotic and abiotic stress responses. This review recaptures and summarizes the roles of RABs in plant cell functions and in enhancing plant survival under stress conditions.     

异源表达CkLEA1基因增强了拟南芥对非生物胁迫的耐受性

植物在生长过程中会受到各种非生物胁迫的伤害,导致生长发育和产量受到严重影响,胚胎晚期丰富蛋白（late embryogenesis abundant proteins,LEA蛋白）在植物抵抗非生物胁迫过程中起着重要的保护作用。在前期的研究基础上,将受多种胁迫诱导的柠条锦鸡儿CkLEA1（GenBank登录号KC309408）基因转入野生型拟南芥,通过实时荧光定量PCR从7株T₃代纯合体中筛选出3个转基因株系做进一步研究。种子萌发率实验发现,在200 mmol/L NaCl和400 mmol/L甘露醇处理下,转基因株系萌发率均高于野生型拟南芥。干旱处理2周大的幼苗后,转基因株系明显比野生型更抗旱,存活率高于野生型,并且失水率低于野生型。同时,转基因株系积累了较少的丙二醛（MDA）,超氧化物歧化酶（SOD）活性和谷胱甘肽（GSH）含量也高于野生型。这些结果表明,柠条锦鸡儿CkLEA1基因在种子萌发阶段提高了拟南芥对盐和渗透胁迫的耐受性,并且提高了转基因拟南芥幼苗生长阶段对干旱胁迫的抵抗能力。