Litholdo Celso Gaspar, Eamens Andrew Leigh, Waterhouse Peter Michael
School of Life and Environmental Sciences, The University of Sydney, Camperdown, NSW, 2006, Australia.
Citrus Biotechnology Lab, Centro de Citricultura, Instituto Agronômico de Campinas, Cordeirópolis, SP, 13490-000, Brazil.
Mol Genet Genomics. 2018 Apr;293(2):503-523. doi: 10.1007/s00438-017-1399-9. Epub 2017 Dec 1.
In plants, microRNAs (miRNAs) have evolved in parallel to the protein-coding genes that they target for expression regulation, and miRNA-directed gene expression regulation is central to almost every cellular process. MicroRNA, miR163, is unique to the Arabidopsis genus and is processed into a 24-nucleotide (nt) mature small regulatory RNA (sRNA) from a single precursor transcript transcribed from a single locus, the MIR163 gene. The MIR163 locus is a result of a recent inverted duplication event of one of the five closely related S-ADENOSYL-METHYLTRANSFERASE genes that the mature miR163 sRNA targets for expression regulation. Currently, however, little is known about the role of the miR163/S-ADENOSYL-METHYLTRANSFERASE regulatory module in response to biotic stress. Here, we document the expression domains of MIR163 and the S-ADENOSYL-METHYLTRANSFERASE target genes following fusion of their putative promoter sequences to the β-glucuronidase (GUS) reporter gene and subsequent in planta expression. Further, we report on our phenotypic and molecular assessment of Arabidopsis thaliana plants with altered miR163 accumulation, namely the mir163-1 and mir163-2 insertion knockout mutants and the miR163 overexpression line, the MIR163-OE plant. Finally, we reveal miR163 accumulation and S-ADENOSYL-METHYLTRANSFERASE target gene expression post treatment with the defence elicitors, salicylic acid and jasmonic acid, and following Fusarium oxysporum infection, wounding, and herbivory attack. Together, the work presented here provides a comprehensive new biological insight into the role played by the Arabidopsis genus-specific miR163/S-ADENOSYL-METHYLTRANSFERASE regulatory module in normal A. thaliana development and during the exposure of A. thaliana plants to biotic stress.
在植物中，微小RNA（miRNA）与它们靶向进行表达调控的蛋白质编码基因平行进化，并且miRNA介导的基因表达调控几乎对每个细胞过程都至关重要。微小RNA miR163是拟南芥属所特有的，它从单个基因座MIR163基因转录的单个前体转录本加工成一个24个核苷酸（nt）的成熟小调控RNA（sRNA）。MIR163基因座是成熟miR163 sRNA靶向进行表达调控的五个密切相关的S-腺苷甲硫氨酸转移酶基因之一最近发生反向重复事件的结果。然而，目前对于miR163/S-腺苷甲硫氨酸转移酶调控模块在应对生物胁迫中的作用知之甚少。在这里，我们记录了MIR163和S-腺苷甲硫氨酸转移酶靶基因的表达域，方法是将它们的推定启动子序列与β-葡萄糖醛酸酶（GUS）报告基因融合，随后在植物中表达。此外，我们报告了对miR163积累发生改变的拟南芥植株进行的表型和分子评估，即mir163-1和mir163-2插入敲除突变体以及miR163过表达株系MIR163-OE植株。最后，我们揭示了用防御激发子水杨酸和茉莉酸处理后，以及在尖孢镰刀菌感染、创伤和食草动物攻击后，miR163的积累和S-腺苷甲硫氨酸转移酶靶基因的表达情况。总之，本文所展示的工作为拟南芥属特异性miR163/S-腺苷甲硫氨酸转移酶调控模块在正常拟南芥发育过程中以及拟南芥植株暴露于生物胁迫期间所起的作用提供了全面的新生物学见解。
