抗蔓枯病甜瓜突变体edr2抗病现象的初步研究

 【目的】蔓枯病常引起甜瓜毁灭性的损失,研究甜瓜与蔓枯病菌互作的功能基因对选育抗蔓枯病的甜瓜品种是非常重要的。【方法】采用农杆菌侵染子叶外植体的方法产生T-DNA插入的甜瓜突变体,人工气候箱内离体和大棚内幼苗接种蔓枯病菌,筛选蔓枯病抗性增强的突变体株系,并且初步研究该突变体的抗病机制。【结果】一个蔓枯病抗性明显增强的突变体,命名为edr2,该突变体是T-DNA单拷贝插入甜瓜染色体引起的,edr2的蔓枯病抗性和标记基因卡那霉素抗性基因共分离。蔓枯病菌在突变体甜瓜edr2上的侵染过程与在野生型甜瓜上相比,分生孢子萌发率降低、芽管的伸长和菌丝的生长较迟缓。蔓枯病菌的侵染能引起edr2突变体发生细胞程序性死亡,但是不引起野生型甜瓜的细胞发生程序性死亡。【结论】edr2突变体抗性增强,不但抑制病菌在植株体内的生长,并且诱导自身的抗性。本研究为选育抗蔓枯病的甜瓜品种提供了新的思路,为挖掘甜瓜－蔓枯病菌互作的基因提供支持。

A Preliminary Investigation of a Mutant Melon Plant edr2 on Resistance to Gummy Stem Blight

【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.