Laboratorio de Biologia Molecular de Plantas, Instituto de Bioquímica Médica, Bl.B-33A, Universidade Federal do Rio de Janeiro, Rua Rodolpho Paulo Rocco s/n, Rio de Janeiro, Brazil.
Plant Cell Environ. 2012 Mar;35(3):502-12. doi: 10.1111/j.1365-3040.2011.02430.x. Epub 2011 Oct 24.
MicroRNAs (miRNAs) are part of a novel mechanism of gene regulation that is active in plants under abiotic stress conditions. In the present study, 12 miRNAs were analysed to identify miRNAs differentially expressed in sugarcane subjected to cold stress (4 °C). The expression of miRNAs assayed by stem-loop RT-PCR showed that miR319 is up-regulated in sugarcane plantlets exposed to 4 °C for 24 h. The induction of miR319 expression during cold stress was observed in both roots and shoots. Sugarcane miR319 was also regulated by treatment with abscisic acid. Putative targets of this miRNA were identified and their expression levels were decreased in sugarcane plantlets exposed to cold. The cleavage sites of two targets were mapped using a 5' RACE PCR assay confirming the regulation of these genes by miR319. When sugarcane cultivars contrasting in cold tolerance were subjected to 4 °C, we observed up-regulation of miR319 and down-regulation of the targets in both varieties; however, the changes in expression were delayed in the cold-tolerant cultivar. These results suggest that differences in timing and levels of the expression of miR319 and its targets could be tested as markers for selection of cold-tolerant sugarcane cultivars.
MicroRNAs (miRNAs) 是一种新的基因调控机制的一部分，该机制在植物应对非生物胁迫条件时活跃。在本研究中，分析了 12 个 miRNA，以鉴定在甘蔗受到冷胁迫（4°C）时差异表达的 miRNA。通过茎环 RT-PCR 分析的 miRNA 表达显示，miR319 在暴露于 4°C 24 小时的甘蔗苗中上调。在根和茎中都观察到冷胁迫过程中 miR319 表达的诱导。ABA 处理也调节了这种 miRNA。鉴定了该 miRNA 的假定靶标，并且在暴露于冷的甘蔗苗中其表达水平降低。使用 5' RACE PCR 分析对两个靶标的切割位点进行了作图，证实了这些基因受 miR319 的调节。当耐冷性不同的甘蔗品种受到 4°C 处理时，我们观察到 miR319 的上调和靶标的下调在两个品种中；然而，在耐冷品种中，表达的变化延迟。这些结果表明，miR319 及其靶标的表达的时间和水平的差异可以作为选择耐冷性甘蔗品种的标记进行测试。
