College of Agronomy, Sichuan Agriculture University, Chengdu 611130, China.
Int J Mol Sci. 2020 Apr 6;21(7):2537. doi: 10.3390/ijms21072537.
Alligator weed is reported to have a strong ability to adapt to potassium deficiency (LK) stress. Leaves are the primary organs responsible for photosynthesis of plants. However, quantitative proteomic changes in alligator weed leaves in response to LK stress are largely unknown. In this study, we investigated the physiological and proteomic changes in leaves of alligator weed under LK stress. We found that chloroplast and mesophyll cell contents in palisade tissue increased, and that the total chlorophyll content, superoxide dismutase (SOD) activity and net photosynthetic rate (PN) increased after 15 day of LK treatment, but the soluble protein content decreased. Quantitative proteomic analysis suggested that a total of 119 proteins were differentially abundant proteins (DAPs). KEGG analysis suggested that most represented DAPs were associated with secondary metabolism, the stress response, photosynthesis, protein synthesis, and degradation pathway. The proteomic results were verified using parallel reaction monitoring mass spectrometry (PRM-MS) analysis and quantitative real-time PCR (qRT-PCR)assays. Additional research suggested that overexpression of cationic peroxidase 1 of alligator weed (ApCPX1) in tobacco increased LK tolerance. The seed germination rate, peroxidase (POD) activity, and K content increased, and the hydrogen peroxide (HO) content decreased in the three transgenic tobacco lines after LK stress. The number of root hairs of the transgenic line was significantly higher than that of WT, and net K efflux rates were severely decreased in the transgenic line under LK stress. These results confirmed that ApCPX1 played positive roles in low-K signal sensing. These results provide valuable information on the adaptive mechanisms in leaves of alligator weed under LK stress and will help identify vital functional genes to apply to the molecular breeding of LK-tolerant plants in the future.
水花生具有较强的耐低钾（LK）胁迫能力。叶片是植物进行光合作用的主要器官。然而，水花生叶片对 LK 胁迫的响应的定量蛋白质组学变化在很大程度上是未知的。在这项研究中，我们研究了 LK 胁迫下水花生叶片的生理和蛋白质组学变化。我们发现，在 LK 处理 15 天后，栅栏组织中的叶绿体和叶肉细胞含量增加，总叶绿素含量、超氧化物歧化酶（SOD）活性和净光合速率（PN）增加，而可溶性蛋白含量下降。定量蛋白质组学分析表明，共有 119 种蛋白质是差异丰度蛋白（DAP）。KEGG 分析表明，大多数代表性 DAPs 与次生代谢、应激反应、光合作用、蛋白质合成和降解途径有关。使用平行反应监测质谱（PRM-MS）分析和定量实时 PCR（qRT-PCR）检测对蛋白质组学结果进行了验证。进一步的研究表明，水花生阳离子过氧化物酶 1（ApCPX1）在烟草中的过表达增加了 LK 耐受性。在 LK 胁迫下，三个转基因烟草系的种子发芽率、过氧化物酶（POD）活性和 K 含量增加，过氧化氢（HO）含量降低。转基因系的根毛数量明显高于 WT，在 LK 胁迫下，转基因系的净 K 外排率严重降低。这些结果证实了 ApCPX1 在低钾信号感应中发挥了积极作用。这些结果为水花生叶片在 LK 胁迫下的适应机制提供了有价值的信息，并将有助于鉴定重要的功能基因，以便将来应用于 LK 耐受植物的分子育种。
