Genome-wide analysis of the auxin response factor (ARF) gene family in maize (<Emphasis Type="Italic">Zea mays</Emphasis>)

Auxin response factors (ARFs) are an important family involved in auxin-mediated response through specific binding to auxin response elements (AuxREs). A few members of the ARF family have been functionally characterized in Arabidopsis, rice (Oryza sativa), Poplar (Populous trichocarpa). However, little is known about ARF genes in maize (Zea mays). We performed a comprehensive bioinformatics analysis of the maize ARF gene family including analysis of the genome sequence, conserved domains, chromosomal locations, phylogenetic relationships, gene duplication, and expression profiles. 35 ZmARF genes were identified and categorized into four groups (Class I, II, III, and IV). In addition, a segmental ZmARF duplication event was shown to play an important role in maize ARF gene expansion. 7 ZmARF genes had no expression in specific tissues we obtained, but presented in mixed tissues according to the NCBI EST database, respectively. These studies have laid the theoretical foundation for further functional verification of these ZmARF genes.     

植物生长素反应因子研究进展

生长素反应因子（ARFs）是植物生长和发育的重要调节因子,在生长素早期反应蛋白（Aux／IAAs）的参与下,通过和生长素反应基因启动子区AuxRE元件的JTGTCTC序列结合,共同调控这些基因的表达。近年来关于生长素反应因子的分子结构和ARF与Aux／IAA的相互作用及其对植物生长和发育的影响、作用的靶基因以及分子机制受到人们的重视,并在这些方面做了大量的研究。     

Genome-wide analysis of primary auxin-responsive Aux/IAA gene family in maize (Zea mays. L.)

The phytohormone auxin is important in various aspects of organism growth and development. Aux/IAA genes encoding short-lived nuclear proteins are responsive primarily to auxin induction. Despite their physiological importance, systematic analysis of Aux/IAA genes in maize have not yet been reported. In this paper, we presented the isolation and characterization of maize Aux/IAA genes in whole-genome scale. A total of 31 maize Aux/IAA genes (ZmIAA1 to ZmIAA31) were identified. ZmIAA genes are distributed in all the maize chromosomes except chromosome 2. Aux/IAA genes expand in the maize genome partly due to tandem and segmental duplication events. Multiple alignment and motif display results revealed major maize Aux/IAA proteins share all the four conserved domains. Phylogenetic analysis indicated Aux/IAA family can be divided into seven subfamilies. Putative cis-acting regulatory DNA elements involved in auxin response, light signaling transduction and abiotic stress adaption were observed in the promoters of ZmIAA genes. Expression data mining suggested maize Aux/IAA genes have temporal and spatial expression pattern. Collectively, these results will provide molecular insights into the auxin metabolism, transport and signaling research.     

Irrepressible,truncated Auxin Response Factors: Natural roles and applications in dissecting auxin gene regulation pathways

The molecularly well-characterized auxin signal transduction pathway involves two evolutionarily conserved families interacting through their C-terminal domains III and IV: the Auxin Response Factors (ARFs) and their repressors the Aux/IAAs, to control auxin-responsive genes, among them genes involved in auxin transport.^1,2 We have developed a new genetic tool to study ARF function. Using MONOPTEROS (MP)/ARF5, we have generated a truncated version of MP (MPΔ),³ which has lost the target domains for repression by Aux/IAA proteins. Besides exploring genetic interactions between MP and Aux/IAAs, we used this construct to trace MP’s role in vascular patterning, a previously characterized auxin dependent process.^4,5 Here we summarize examples of naturally occurring truncated ARFs and summarize potential applications of truncated ARFs as analytical tools.     

生长素响应因子与植物的生长发育

生长素响应因子(Auxin response factor, ARF)作为一类调控生长素响应基因表达的转录因子, 是生长素研究的重要内容。它可与生长素响应基因启动子区域内的生长素响应元件结合, 促进或抑制基因的表达。文章介绍了植物体内ARF家族的分子生物学近年来的研究进展, 同时也讨论了ARF转录因子的结构、ARF基因的表达调控、ARF在植物生长发育及信号转导中的作用以及ARF对靶基因的调控机制等内容。植物ARF成员都有一定的同源性, 大多含有4个结构域, 在多种组织和器官中都有表达, 其表达受到转录及转录后调控, 并且在介导生长素与其它激素之间相互作用方面扮演重要角色。