Department of Biotechnology, Guru Nanak Dev University, Amritsar, Punjab, India.
Division of Biotechnology, CSIR-Institute of Himalayan Bioresource Technology, Palampur, Himachal Pradesh, India.
Physiol Plant. 2024 Sep-Oct;176(5):e14513. doi: 10.1111/ppl.14513.
Pathogenesis-related proteins (PR), including osmotins, play a vital role in plant defense, being activated in response to diverse biotic and abiotic stresses. Despite their significance, the mechanistic insights into the role of osmotins in plant defense have not been extensively explored. The present study explores the cloning and characterization of the osmotin gene (WsOsm) from Withania somnifera, aiming to illuminate its role in plant defense mechanisms. Quantitative real-time PCR analysis revealed significant induction of WsOsm in response to various phytohormones e.g. abscisic acid, salicylic acid, methyl jasmonate, brassinosteroids, and ethrel, as well as biotic and abiotic stresses like heat, cold, salt, and drought. To further elucidate WsOsm's functional role, we overexpressed the gene in Nicotiana tabacum, resulting in heightened resistance against the Alternaria solani pathogen. Additionally, we observed enhancements in shoot length, root length, and root biomass in the transgenic tobacco plants compared to wild plants. Notably, the WsOsm- overexpressing seedlings demonstrated improved salt and drought stress tolerance, particularly at the seedling stage. Confocal histological analysis of HO and biochemical studies of antioxidant enzyme activities revealed higher levels in the WsOsm overexpressing lines, indicating enhanced antioxidant defense. Furthermore, a pull-down assay and mass spectrometry analysis revealed a potential interaction between WsOsm and defensin, a known antifungal PR protein (WsDF). This suggests a novel role of WsOsm in mediating plant defense responses by interacting with other PR proteins. Overall, these findings pave the way for potential future applications of WsOsm in developing stress-tolerant crops and improving plant defense strategies against pathogens.
与植物防御相关的蛋白（PR），包括渗透素，在植物防御中起着至关重要的作用，它们会被各种生物和非生物胁迫激活。尽管渗透素有如此重要的作用，但渗透素在植物防御机制中的作用的机制见解尚未得到广泛探索。本研究从茄科植物睡茄（Withania somnifera）中克隆和表征渗透素基因（WsOsm），旨在阐明其在植物防御机制中的作用。实时定量 PCR 分析显示，WsOsm 对各种植物激素（如脱落酸、水杨酸、茉莉酸甲酯、油菜素内酯和乙烯利）以及生物和非生物胁迫（如热、冷、盐和干旱）均有显著的诱导。为了进一步阐明 WsOsm 的功能作用，我们在烟草（Nicotiana tabacum）中过表达了该基因，导致对Alternaria solani 病原体的抗性增强。此外，我们观察到，与野生型植物相比，转基因烟草植物的茎长、根长和根生物量增加。值得注意的是，过表达 WsOsm 的幼苗在盐和干旱胁迫下表现出更高的耐受性，尤其是在幼苗阶段。HO 的共聚焦组织学分析和抗氧化酶活性的生化研究表明，过表达系中的水平更高，表明抗氧化防御增强。此外，下拉测定和质谱分析显示 WsOsm 与防御素（一种已知的抗真菌 PR 蛋白（WsDF））之间存在潜在的相互作用。这表明 WsOsm 通过与其他 PR 蛋白相互作用，在介导植物防御反应中发挥新的作用。总之，这些发现为未来利用 WsOsm 开发耐胁迫作物和改善植物防御策略以对抗病原体提供了可能性。
