Panax notoginseng snakin gene increases resistance to Fusarium solani in transgenic tobacco

Abstract

Snakins are cysteine-rich plant antimicrobial peptides that are important for plant defense responses to diverse pathogens, and a snakin gene, PnSN1, was cloned from Panax notoginseng to explore the role of snakin in the disease resistance mechanism of P. notoginseng. A gene expression analysis by quantitative real-time PCR revealed that PnSN1 expression was responsive to a Fusarium solani infection and was induced by four signaling molecules (methyl jasmonate, ethephon, salicylic acid, and hydrogen peroxide). A subcellular localization revealed that the PnSN1-GFP fusion protein was present only in the plant cell wall. Moreover, recombinant PnSN1 expressed in Escherichia coli was inhibitory toward the mycelial growth of four plant pathogenic fungi (F. solani, F. oxysporum, F. verticillioides, and Botryosphaeria dothidea), with increasing protein concentrations resulting in greater antifungal activities. The recombinant protein also inhibited F. solani spore germination. Additionally, the overexpression of PnSN1 in the model plant tobacco considerably increased the resistance to F. solani. Furthermore, the transient expression of the PnSN1 RNA interference construct increased the susceptibility of young P. notoginseng leaves to F. solani. These findings confirmed the importance of PnSN1 for the disease resistance of P. notoginseng.