杨凌糖丝菌蛋白激发子HSyp1和HSyp2诱导植物抗病功能

Protein elicitors HSyp1 and HSyp2 from Saccharothrix yanglingensis Hhs.015 enhance disease resistance of plants

摘要:

【目的】前期研究从杨凌糖丝菌(Saccharothrix yanglingensis) Hhs.015全基因组中初步筛选出4种能够诱导烟草发生过敏反应(hypersensitive response)的蛋白激发子，本研究进一步探讨引发明显HR的2个激发子及其相关的免疫机理，为深入研究Hhs.015诱导植物抗病性的分子机制提供依据。【方法】通过过敏反应和活性氧检测等方法筛选能够诱发植物免疫反应的蛋白激发子。使用原核表达系统纯化蛋白，通过观察病斑表型、测定防御相关酶活性及分析防御基因表达，验证这些激发子在诱导植物抗病性方面的功能。同时，将蛋白激发子应用于苗期拟南芥(Arabidopsis thaliana)，以观察其促生效果。【结果】从Hhs.015中筛选出能够引起烟草(Nicotiana benthamiana)过敏反应、促进胼胝质和活性氧沉积、防御基因上调，且能够以可溶性形式表达的蛋白激发子HSyp1和HSyp2。植物抗病性检测结果表明，HSyp1和HSyp2能够提高不同植物对核盘菌(Sclerotinia sclerotiorum)、黑杆病菌(Phytophthora capsica)以及黑腐皮壳菌(Valsa mali)的抗病性。此外，研究还发现HSyp1和HSyp2对苗期拟南芥的子叶和根部发育具有一定的促生作用，其中HSyp2的促生效果比HSyp1更为显著。【结论】本研究筛选出2个蛋白激发子HSyp1和HSyp2，能够激发植物免疫反应，提高植物抗病能力，并具有促生作用。这些发现为开发新型生物农药提供了理论基础，也为其未来的田间应用提供了实验依据。

Abstract:

[Objective] Preliminary studies have identified four protein elicitors from the whole genome of Saccharothrix yanglingensis Hhs.015 that can induce a hypersensitive response (HR) in Nicotiana benthamiana. This study investigated the two elicitors capable of triggering a strong HR and their associated immune mechanisms, aiming to provide a basis for probing into the molecular mechanisms by which Hhs.015 enhances the disease resistance of plants. [Methods] The protein elicitors capable of inducing the immune responses of plants were screened based on the HR and reactive oxygen species (ROS) levels. A prokaryotic expression system was used to purify the proteins. Furthermore, we verified the roles of the protein elicitors in inducing plant disease resistance by observing the disease spots, measuring the activities of defense-related enzymes, and analyzing the expression of defense genes. Additionally, we treated Arabidopsis thaliana seedlings with the protein elicitors to evaluate the plant growth-promoting effects of the elicitors. [Results] The protein elicitors HSyp1 and HSyp2 from Hhs.015 that could induce a HR, callose and ROS deposition, and upregulation of defense genes in N.benthamiana, were screened and found to be soluble. HSyp1 and HSyp2 enhanced the resistance of different plants to Sclerotinia sclerotiorum, Phytophthora capsica, and Valsa mali. Furthermore, HSyp1 and HSyp2 promoted the cotyledon and root development of A. thaliana seedlings, and HSyp2 exhibited stronger plant growth-promoting effect than HSyp1. [Conclusion] This study identified two protein elicitors HSyp1 and HSyp2 capable of triggering immune responses, enhance disease resistance, and promoting growth of plants. The findings provide a theoretical basis for the development of new biocontrol agents and offer experimental evidence for their future field application.