葫芦种子带菌对幼苗细菌性果斑病发生和侵染途径的影响

Influence of occurrence and infection pathway on cucurbit seeds pathogen for seedling bacterial fruit blotch

采用葫芦砧木种子人工接种燕麦嗜酸菌西瓜亚种(Acidovorax avenae ssp.citrulli,Aac)的方法,观察由Aac经种传方式对葫芦砧木苗期发病的影响和Aac在葫芦砧木苗期的定殖情况,并在温室条件下分析种子中不同带菌量与葫芦砧木幼苗细菌性果斑病发病的关系。结果表明:Aac在随着葫芦砧木幼苗生长过程中先侵染幼苗子叶,随后沿叶脉侵入下胚轴并定殖于下胚轴的韧皮部和木质部中,继而引起幼苗下胚轴发病;随着砧木种子带菌浓度的提高,幼苗发病率和病情指数也越高。

The bacterial fruit blotch(BFB)caused by Acidovorax avenae ssp.citrulli(Aac)is a sort of devastating seed-borne quarantine disease of cucurbits.The impact of seed infection was investigated to the disease severity of cucurbit rootstock seedling and the infection process of Aac during seedling stage through artificially inculcating cucurbit seeds with Aac.In greenhouse condition,the relationship between different carrier amount of bacteria and the disease level of BFB was established.The results indicate that during the seed-borne infection process,the Aac infected the cotyledons firstly,then infected the hypocotyls and colonized in the xylem and phloem,caused the disease of the hypocotyls.Moreover,the higher amount of bacteria the seeds carried,and the higher disease rate and index the young seedling was.