水稻种子携带恶苗病菌种类及其致病性研究

 水稻恶苗病是水稻上的一种重要病害,每年给我国的水稻生产造成严重的经济损失。本文旨在探究我国主要稻作区水稻种子携带恶苗病菌的种类及其致病性情况。采用洗涤法和平板培养法对收集我国主要稻作区的66份水稻种子样本进行恶苗病病菌分离,共获得111株病菌分离物,并从中选取24株代表性分离物,采用翻译延伸因子TEF-1α序列、形态学进行鉴定,结果表明,分离物中的优势种为藤仓镰孢菌和层出镰孢菌,分离频率分别为45.94%和52.25%;66份水稻样本中,合计有22份水稻种子携带恶苗病菌,主要携带病原菌的种类为藤仓镰孢菌Fusarium fujikuroi、层出镰孢菌F. proliferatum和F. andiyazi,检出率分别为18.18%、16.67%、1.52%。采用水培法对22份阳性水稻种子进行苗期致病性观察,结果表明,种子内外部均携带恶苗病菌和内部携带该病菌的水稻种子均可引起苗期发病,平均发病率分别为15.56%和3.73%;外部携带恶苗病菌的水稻种子平均发病率为6.5%;另外,携带藤仓镰孢菌的水稻种子比携带层出镰孢菌的种子更易发病。

Fusarium species from rice seeds associated with bakanae disease and their pathogenicity to rice seedlings

Rice bakanae disease is an important disease responsible for serious rice production loss in China. The current study aimed to reveal the species of seedborne rice bakanae pathogens in main rice planting regions. A total of 111 strains of putative Fusarium spp. were isolated from the 66 rice seed samples via the washing method and plate culture method. Based on morphological features, 24 representative strains were selected and further analyzed based on the translation elongation factor 1α gene (TEF-1α) sequences and morphological characteristics. Among the 111 isolates, 45.94% and 52.25% were proved to be Fusarium fujikuroi and F. proliferatum, respectively. There were 22 of the 66 seed samples carrying bakanae pathogens. F. fujikuroi was the most frequent species (18.18%), followed by F. proliferatum (16.67%) and F. andiyazi (1.52%). Hydroponic method was used to nurse the 22 rice seed samples, and the bakanae disease was measured in the seedlings. The pathogens both from interior and exterior of rice seeds were found to be able to cause bakanae disease. The pathogens in the interior, exterior, or both interior and exterior of rice seeds induced diseases at the frequency of 3.73%, 6.5% and 15.56%, respectively, at the seedling stage. In addition, F. fujikuroi-infected seeds induced diseases in the seedlings at higher frequency than F. proliferatum did.