黑星病菌在苹果叶片上的发育过程研究(英文)

DEVELOPMENT OF VENTURIA INAEQUALIS ON APPLE LEAVES OBSERVED BY ELECTRON MICROSCOPE

采用电子显微镜技术,研究了苹果黑星病菌在苹果叶片上发育过程。扫描电子显微镜观察结果表明,接种后12 h 分生孢子即可萌发并形成附着胞,统计结果显示其孢子萌发率在6 h和12 h分别为83% 和95%,附着胞形成率在12 h和24 h 分别为93% 和95%。透射电子显微镜观察结果表明,黑星病菌侵入以后在寄主角质层下和表皮细胞之间扩展、定殖并可形成子座。接种后12d,病菌开始从子座上产生分生孢子梗和分生孢子,分生孢子梗顶端每产生一个单生的分生孢子就形成一个环痕并延伸其长度。分生孢子梗和分生孢子主要沿叶脉形成,在叶片上呈网状扩展,此时叶片表现明显的病害症状。

Development of apple scab pathogen, Venturia inaequalis, on the leaves were examined by means of scanning and transmission electron microscopy. The results showed that the conidia of V. inaequalis germinated and developed appressoria within 12 h after inoculation. The germination percentages of conidia examined at 6 h and 12 h after inoculation were 83% and 95% respectively. The frequency of appressorium formation of the germinated conidia were 93% and 95% 12 h and 24 h after inoculation respectively. The TEM observations revealed that after penetration of the cuticle growth of the pathogen was entirely subcuticular during the stages of parasitism. The sporulation of the fungus started with the formation of conidia 12 days after inoculation in the apple leaves. With the initiation of the conidiogenesis the enlarged stroma forced the cuticle outward until rupture. Each new proliferation lengthens the annellide and normally produces a single terminal conidium. Production of annelids and conidia occurs in narrow thread-like lines which radiate irregularly from one or more centers of origin (site of initial infections) and branch repeatedly, forming a network over the leaf surface , often paralleling a leaf vein. The typical scab symptom was observed at this sampling time.