Key message

Extensive regulatory divergence during development, abiotic stress and ABA regime observed amongst promoter homologs and homeologs of MIR319 from Brassica juncea.

Abstract

Gene duplication followed by sub-functionalization, neo-functionalization, and pseudogenization are routes to functional and adaptive diversification. The influence of polyploidy on protein-coding genes is well investigated but little is known about their impact on transcriptional regulation of MIRNA gene family. The present study was therefore performed with an aim to uncover regulatory diversification of MIR319 homologs and homeologs in Brassica juncea. We employed comparative genomics to identify and isolate six promoter homologs of MIR319 from B. juncea. Regulatory diversification was studied using analysis of reporter activity driven by BjMIR319 promoters in a heterologous system employing promoter–reporter fusion constructs. MIR319 is known to play important roles in leaf and flower development, and multiple stress responses. Reporter activity was therefore monitored during development, hormonal and stress regimes. In-silico analyses revealed differential distribution of cis-regulatory motifs and functional analysis revealed distinct spatiotemporal expression patterns. The significance of presence of selected cis-regulatory motifs corresponding to heat, cold, salt and ABA stress were further functionally validated. It was observed that promoter of Bj -MIR319a-A01 was upregulated in response to cold and salt stress, while promoter of Bj -MIR319c-A04 (D1) and Bj -MIR319c-A05 (FL) were downregulated in response to high temperature. In summary, comparative analysis of homologous promoters from Brassica juncea, an allopolyploid revealed extensive sequence and functional diversity. Spatiotemporal activity of reporter gene driven by BjMIR319 promoter was distinct, and partially overlapping with from those reported previously for A. thaliana. The present study clearly demonstrates regulatory divergence amongst promoter homologs of MIR319 in Brassica juncea during development and stress response, and underlines the urgent need for dissection of promoter function and detailed characterization including identification of interacting trans-factors.

Genbank accession numbers: MT379853-MT379858.

中文翻译：

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芥菜的MIR319启动子同源物的序列和功能分析揭示了应激下的调节多样性和表达改变

关键信息

在开发过程中强大的监管分歧，非生物胁迫和ABA政权之间启动的同系物和homeologs观察MIR319从芥菜。

抽象的

基因复制后继亚功能化，新功能化和假基因化是实现功能性和适应性多样化的途径。多倍体对蛋白质编码基因的影响已得到充分研究，但对它们对MIRNA基因家族转录调控的影响知之甚少。因此，进行本研究的目的是揭示芥菜中MIR319同源物和同源物的调控多样性。我们采用比较基因组学来识别和分离株，6子同源MIR319从芥菜。通过分析由BjMIR319驱动的报告子活性研究了监管的多样化使用启动子-报告子融合构建体的异源系统中的启动子。众所周知，MIR319在叶片和花朵的发育以及多种胁迫反应中起着重要作用。因此，在发育，荷尔蒙和压力状态下监测记者的活动。计算机模拟分析揭示了顺式调控基序的差异分布，功能分析揭示了独特的时空表达模式。进一步在功能上验证了对应于热，冷，盐和ABA胁迫的所选顺式调控基序存在的重要性。观察到Bj -MIR319a-A01的启动子响应寒冷和盐胁迫而被上调，而Bj的启动子-MIR319c-A04（D1）和Bj -MIR319c-A05（FL）响应于高温而下调。总之，对来自芥菜油菜（同种多倍体）的同源启动子的比较分析显示了广泛的序列和功能多样性。由BjMIR319启动子驱动的报告基因的时空活性是独特的，并且与先前报道的拟南芥的报道基因有部分重叠。本研究清楚地证明了芥菜中MIR319的启动子同源物之间的调控差异在发育和应激反应期间，并强调了迫切需要解剖启动子功能和详细表征，包括鉴定相互作用的反式因子。

Genbank登录号：MT379853-MT379858。