Arabidopsis Defense Response Triggered By Sm1from Trichoderma And The Association With Reactive Oxygen Species Signaling Pathway

Trichoderma spp. that can secrete small molecular proteins has been recognized as oneimportant fungal biocontrol agent in crop protection. The small proteins induce plant diseaseresistance by triggering the plant immunity. In this study, Sm1gene was cloned from Trichodermavirens (YZ2612). Sequence analysis showed that the cDNA fragment had an ORF with length of414bp encoding138amino acid residues. Southern blot analysis showed that Sm1gene has onesingle copy in Trichoderma virens genome. The recombinant prokaryotic expression vectorpET-28a(+)-Sm1was constructed, and then transformed into Escherichia coli BL21(DE3). IPTGconcentration, induction time and temperature were optimized for enhancing fusion proteinexpression, It was revealed that the best expression was achieved under conditions of24℃and1mmol/L of IPTG for4hours. The recombinant protein was solubilized, denatured, refolded, andpurified. The study on the role of Sm1protein on the plant growth and induced resistance inArabidopsis as model plant has been investigated. The results showed that the ROS signalingpathway of Arabidopsis leaves was activated and the induced resistance to bacterial pathogen(Pseudomonas syringae pv. tomato DC3000) was enhanced with Sm1treatment. Also, Thedefensin gene PDF1.2and ROS scavenging enzyme-related genes SOD、POD、LOX2weresignificantly higher indicating that Sm1protein may play a large role in the ROS and JA/ETdefense signaling pathway. The maize leaf spot disease symptom reduced to some exent with Sm1treatment when inoculated with Curvularia lunata.The vector pBI121-Sm1-eGFP was constructedfor the transient expression of Sm1gene in onion epidermis cells. The result showed thatsub-cellular location of Sm1protein was in onion nucleus. The research preliminarily uncoveredthe correlation between Sm1-induced plant disease defense response and ROS signaling pathwaywhich would lay a foundation for the further study of the mechanism of Sm1-induced plantresistance.