Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, College of Biological Sciences and Technology, National Engineering Laboratory of Tree Breeding, Beijing Forestry University, Beijing, China.
College of Forestry, Beijing Forestry University, Beijing, China.
J Exp Bot. 2018 Nov 26;69(22):5519-5530. doi: 10.1093/jxb/ery304.
The hemibiotroph Colletotrichum gloeosporioides and the necrotroph Cytospora chrysosperma cause poplar foliage and stem disease, respectively, resulting in substantial economic losses. In this study, Populus trichocarpa ptc-miR472a was down-regulated in leaves treated with salicylic acid, jasmonic acid (JA) or bacterial flagellin (flg22). Here, ptc-miR472a and a short tandem target mimic (STTM) of miR472a were overexpressed in P. alba × P. glandulosa, and overexpression lines of miR472a and silenced lines of STTM472a were generated. Compared with the STTM472a and wild type lines, lower reactive oxygen species accumulation was detected in miR472a overexpressing plants treated with flg22, C. gloeosporioides or C. chrysosperma. In addition, the miR472a overexpressing lines exhibited the highest susceptibility to the hemibiotroph, C. gloeosporioides, but the highest effective defence response to the necrotroph, C. chrysosperma. The JA/ethylene marker gene ERF1 was rapidly up-regulated in miR472a overexpressing plants. Furthermore, five phased, secondary, small interfering RNAs (phasiRNAs) were confirmed in the miR472a overexpressing and STTM472a lines, triggering phasiRNAs predicted to enhance NBS-LRR silencing. Taken together, our results revealed that ptc-miR472a exerts a key role in plant immunity to C. gloeosporioides and C. chrysosperma by targeting NBS-LRR transcripts. This study provides a new strategy and method in plant breeding to improve plant disease resistance.
半活体营养型炭疽菌（Colletotrichum gloeosporioides）和坏死营养型核盘菌（Cytospora chrysosperma）分别引起杨树叶片和茎部病害，导致重大经济损失。在本研究中，水杨酸、茉莉酸（JA）或细菌鞭毛蛋白（flg22）处理叶片后，胡杨 ptc-miR472a 下调。在此，胡杨 ptc-miR472a 和 miR472a 的短串联靶标模拟物（STTM）在银白杨×腺果杨中过表达，并生成 miR472a 的过表达系和 STTM472a 的沉默系。与 STTM472a 和野生型系相比，flg22、炭疽菌或核盘菌处理过表达 miR472a 的植株中活性氧积累较低。此外，miR472a 过表达系对半活体营养型炭疽菌表现出最高的敏感性，但对坏死营养型核盘菌表现出最高的有效防御反应。JA/乙烯标记基因 ERF1 在 miR472a 过表达植株中迅速上调。此外，在 miR472a 过表达和 STTM472a 系中证实了五个相、二级、小干扰 RNA（phasiRNAs），触发了预测增强 NBS-LRR 沉默的 phasiRNAs。总之，我们的结果表明，ptc-miR472a 通过靶向 NBS-LRR 转录物在杨树对炭疽菌和核盘菌的免疫中发挥关键作用。本研究为提高植物抗病性提供了一种新的策略和方法。
