甜瓜种子携带的链格孢菌种类鉴定及其致病性研究

 采用洗涤检验法和马铃薯葡萄糖琼脂培养基法,从甜瓜种子上分离得到14个链格孢菌分离物。通过菌落形态、产孢表型、分生孢子以及分生孢子梗等形态学观察,结合分析ITS-rDNA和histone 3基因序列,对链格孢菌分离物的种类进行鉴定;甜瓜种子携带的链格孢菌种类分别为细极链格孢(Alternaria tenuissima)、交链格孢(A. alternata)和倒果链格孢(A. obovoidea)。还研究了这些链格孢菌分离物对甜瓜离体叶片的致病性及其对种子发芽的影响;结果表明,除A. obovoidea外,另外两种链格孢菌均对甜瓜离体叶片具有致病性;A. tenuissima和A. alternata的孢子悬浮液对甜瓜种子发芽均有一定的抑制作用。这是国内首次围绕甜瓜种子传带链格孢菌的种类及其致病性开展详细的研究。

Studies on the identification and pathogenicity of Alternaria spp. associated with muskmelon seeds

The fourteen Alternaria isolates were obtained from muskmelon seeds using washing tests and potato dextrose agar (PDA) plate methods. After the morphological observations on colony morphology, sporulation pattern, conidia, and conidiophores, combined with sequences analysis of ITS-rDNA and the partial histone 3 gene, the results showed that Alternaria species associated with muskmelon seeds were A. tenuissima, A. alternata, and A. obovoidea. Furthermore, the pathogenicity of these Alternaria isolates on the detached leaves of muskmelon and the effect of their spore suspensions on the muskmelon seed germination were also studied. Except for A. obovoidea, the other two Alternaria species including A. tenuissima and A. alternata were pathogenic to the detached leaves of muskmelon. The conidia suspensions of A. tenuissima and A. alternata showed inhibitory effects on muskmelon seed germination. To our knowledge, this is the first detailed report about species identification and pathogenicity tests of muskmelon seedborne Alternaria spp. in China.