Abstract:

【Objective】 Most plant defensins involve with defense and exhibit antimicrobial activity against various plant pathogens. Expression of the defensin AlfAFP from Medicago sativa in transgenic potato and tomato plants has been proved to possess high resistance to the pathogen. Study on antimicrobial activity of alfAFP against three main rice disease, blast, bacterial blight and sheath blight, will be significant for further research of disease resistance in transgenic rice. 【Method】 alfAFP was inserted into yeast expression vector pPIC9K, and then transferred into Pichia pastoris GS115 strain by electroporation, and alfAFP was expressed in yeast and utilized to assess antimicrobial activity in vitro. 【Result】 A molecular mass of expressed alfAFP was about 6.5 kD by 15% SDS-PAGE analysis, and the recombinant protein showed certain antimicrobial activity against Rhizoctonia solani, Magnaporthe grisea and Xanthomonas oryzae pv. oryzae, especially for Rhizoctonia solani. 【Conclusion】 Defensin alfAFP was successfully expressed in Pichia pastoris, and antimicrobial activity was detected for rice tested pathogens in vitro, indicating its potential function in breeding rice for disease resistance.

Key words: plant defensin alfAFP, Pichia pastoris, antimicrobial activity, Magnaporthe grisea, Xanthomonas oryzae pv. oryzae, Rhizoctonia solani