Kumar Kamal, Srivastava Vikas, Purayannur Savithri, Kaladhar V Chandra, Cheruvu Purnima Jaiswal, Verma Praveen Kumar
Plant Immunity Laboratory, National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi 110067, India.
School of Life Sciences, Central University of Gujarat, Gandhinagar 382030, Gujarat, India.
DNA Res. 2016 Jun;23(3):225-39. doi: 10.1093/dnares/dsw010. Epub 2016 Apr 8.
The WRKY genes have been identified as important transcriptional modulators predominantly during the environmental stresses, but they also play critical role at various stages of plant life cycle. We report the identification of WRKY domain (WD)-encoding genes from galegoid clade legumes chickpea (Cicer arietinum L.) and barrel medic (Medicago truncatula). In total, 78 and 98 WD-encoding genes were found in chickpea and barrel medic, respectively. Comparative analysis suggests the presence of both conserved and unique WRKYs, and expansion of WRKY family in M. truncatula primarily by tandem duplication. Exclusively found in galegoid legumes, CaWRKY16 and its orthologues encode for a novel protein having a transmembrane and partial Exo70 domains flanking a group-III WD. Genomic region of galegoids, having CaWRKY16, is more dynamic when compared with millettioids. In onion cells, fused CaWRKY16-EYFP showed punctate fluorescent signals in cytoplasm. The chickpea WRKY group-III genes were further characterized for their transcript level modulation during pathogenic stress and treatments of abscisic acid, jasmonic acid, and salicylic acid (SA) by real-time PCR. Differential regulation of genes was observed during Ascochyta rabiei infection and SA treatment. Characterization of A. rabiei and SA inducible gene CaWRKY50 showed that it localizes to plant nucleus, binds to W-box, and have a C-terminal transactivation domain. Overexpression of CaWRKY50 in tobacco plants resulted in early flowering and senescence. The in-depth comparative account presented here for two legume WRKY genes will be of great utility in hastening functional characterization of crop legume WRKYs and will also help in characterization of Exo70Js.
WRKY基因已被确定为主要在环境胁迫期间发挥重要作用的转录调节因子，但它们在植物生命周期的各个阶段也起着关键作用。我们报告了从鹰嘴豆科豆类鹰嘴豆（Cicer arietinum L.）和桶状苜蓿（Medicago truncatula）中鉴定出WRKY结构域（WD）编码基因。在鹰嘴豆和桶状苜蓿中分别总共发现了78个和98个WD编码基因。比较分析表明，存在保守和独特的WRKY基因，并且WRKY家族在桶状苜蓿中主要通过串联重复而扩张。CaWRKY16及其直系同源基因仅在鹰嘴豆科豆类中发现，它们编码一种新型蛋白质，该蛋白质在III类WD两侧具有跨膜和部分Exo70结构域。与崖豆藤类相比，具有CaWRKY16的鹰嘴豆科植物的基因组区域更具动态性。在洋葱细胞中，融合的CaWRKY16-EYFP在细胞质中显示点状荧光信号。通过实时PCR进一步表征了鹰嘴豆WRKY III类基因在致病胁迫以及脱落酸、茉莉酸和水杨酸（SA）处理期间的转录水平调节。在感染菜豆壳二孢菌和SA处理期间观察到基因的差异调节。对菜豆壳二孢菌和SA诱导基因CaWRKY50的表征表明，它定位于植物细胞核，与W-box结合，并具有C端反式激活结构域。CaWRKY50在烟草植物中的过表达导致早花和衰老。本文对两个豆科植物WRKY基因进行的深入比较分析，将对加速作物豆科植物WRKYs的功能表征非常有用，也将有助于表征Exo70Js。
