Abstract:

【Objective】 Gummy stem blight is a prevalence destructive disease of melon. To identify the genes involved in the disease resistance to Didymella bryoniae is the crucial step for breeding resistant melon. 【Methods】 Agrobacterium mediated T-DNA insertion method was used to generate transgenic mellon plants from tissue of cotyledon. The levels of disease resistance of the melon plants were measured and detemined by inoculation of Didymella bryoniae in vitro and in vivo. 【Results】 A melon plant with enhanced resistance to gummy stem blight, named edr2, was identified from 2000 transgenic plants obtained. The mutant has one copy of T-DNA inserted in its genome, and the co-segregation was found between the resistance to gummy stem blight and resistance to kanamycin gene nptII. The germination rate of the spores and growth of germ tubes and hypha were slower in edr2 mutant plant than in wild type plant when Didymella bryoniae was inoculated. Programmed cell death was observed on the leaves of edr2 mutant plant leaves, but not on the ones of wild type melon plant. 【Conclusion】 The edr2 mutant melon plant obtained from T-DNA insertion demonstrated a higher level of disease resistance. The results provide useful information for breeding new melon varieties for disease resistance, and understanding of the functions of the genes involving interaction of melon- Didymella bryoniae.

Key words: melon')">melon, gummy stem blight, mutant, resistance mechanism