西瓜种传镰刀菌形态和分子鉴定及其对种子发芽的影响

 采用洗涤检验法和PDA培养基法,从京欣一号和新京欣一号西瓜种子的种壳上分离得到镰刀菌,通过形态学观察和分子检测进行了鉴定,并研究了其对种子发芽的影响。通过菌落形态、色素颜色、菌落生长速率、大型分生孢子、小型分生孢子、厚垣孢子以及分生孢子梗等形态学观察,初步认为其为尖孢镰刀菌;采用真菌rDNA ITS区的通用引物、镰刀菌属特异性引物和尖孢镰刀菌特异性引物对其DNA进行PCR扩增,PCR产物经连接转化并验证后测序,将测序结果登录GenBank进行BLAST分析,分子检测结果与形态学观察结果一致,表明西瓜种子种壳携带的镰刀菌为尖孢镰刀菌,此结果为国内首次报道。用种传尖孢镰刀菌孢子悬浮液处理西瓜种子后,发芽势、发芽率和发芽指数均显著降低。

Morphological and molecular identification of seedborne Fusarium of watermelon and its effect on seed germination

An isolate of Fusarium sp. was obtained from seed coat of watermelon (cvs. Jingxin No.1 and Xinjingxin No.1) using seed washing test and PDA plate methods. The isolate was identified through morphological observation and molecular detection. Effects on the seed germination were also studied. After observation of morphology, color and growth rate of the colonies, and morphology of macroconidia, microconidia, chlamydospores and conidiophores, it was preliminarily identified as Fusarium oxysporum. DNA of the fungus was amplified by universal primers of fungal rDNA ITS, specific primers of genus Fusarium rDNA ITS and specific primers of F. oxysporum rDNA ITS, respectively. After PCR products were ligated, transformed and confirmed, inserted sequences of the recombinant plasmids were analyzed. The sequencing results were logged in GenBank to BLAST. The results of molecular detection and morphologic observation all showed that the Fusarium isolate should be F. oxysporum. It is the first report of seedborne F. oxysporum isolated from seed coat of watermelon in China. Moreover, the germination energy, percentage germination and germination index of watermelon seeds all decreased significantly after treated with the spore suspension of seedborne F. oxysporum.