Kang Tao, Yu Chun-Yan, Liu Yue, Song Wei-Meng, Bao Yan, Guo Xiao-Tong, Li Bei, Zhang Hong-Xia
College of Agriculture, Ludong University, Yantai, China.
Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.
Front Plant Sci. 2020 Jan 10;10:1664. doi: 10.3389/fpls.2019.01664. eCollection 2019.
Plants in the juvenile state are more tolerant to adverse conditions. Constitutive expression of MicroRNA156 (miR156) prolonged the juvenile phase and increased resistance to abiotic stress, but also affected the architecture of transgenic plants. In this study, we investigated the possibility of subtle manipulation of miR156 expression in flowering plants, with the goal to increase tolerance to abiotic stress without altering the normal growth and development of transgenic plants. Transgenic tobacco plants expressing ZmmiR156 from maize were generated, driven either by the cauliflower mosaic virus (CaMV) 35S promoter or the stress-inducible ZmRab17 promoter. Expression of ZmmiR156 led to improved drought and salt tolerance in both and transgenic plants, as shown by more vigorous growth, greater biomass production and higher antioxidant enzyme expression after a long period of drought or salt treatment, when compared to wild type and transgenic vector control plants. However, constitutive expression of ZmmiR156 also resulted in retarded growth, increased branching and delayed flowering of transgenic plants. These undesirable developmental changes could be mitigated by using the stress-inducible ZmRab17 promoter. Furthermore, under drought or salt stress conditions, expression of ZmmiR156 reduced the transcript level of and , the genes potentially targeted by ZmmiR156, as well as that of , , and , the senescence-associated genes in tobacco. Collectively, our results indicate that ZmmiR156 can be temporally manipulated for the genetic improvement of plants resistant to various abiotic stresses.
处于幼年期的植物对不利条件更具耐受性。MicroRNA156（miR156）的组成型表达延长了幼年期并增强了对非生物胁迫的抗性，但也影响了转基因植物的株型。在本研究中，我们探究了在开花植物中精细调控miR156表达的可能性，目的是在不改变转基因植物正常生长发育的情况下提高其对非生物胁迫的耐受性。构建了由花椰菜花叶病毒（CaMV）35S启动子或胁迫诱导型ZmRab17启动子驱动的、表达来自玉米的ZmmiR156的转基因烟草植株。与野生型和转基因载体对照植株相比，ZmmiR156的表达使两种转基因植株的耐旱性和耐盐性均得到提高，这表现为在长期干旱或盐处理后，转基因植株生长更旺盛、生物量积累更多且抗氧化酶表达更高。然而，ZmmiR156的组成型表达也导致转基因植株生长迟缓、分枝增加和开花延迟。使用胁迫诱导型ZmRab17启动子可减轻这些不良的发育变化。此外，在干旱或盐胁迫条件下，ZmmiR156的表达降低了ZmmiR156可能靶向的基因以及烟草中衰老相关基因的转录水平。总体而言，我们的结果表明，可以通过时间调控ZmmiR156来对植物进行遗传改良，使其对各种非生物胁迫具有抗性。
