Identification Of Seed-born Fungi In Rice Cultivated In Hunan

Rice seeds carrying fungi could reduce the germination rate of seeds, and could easily cause seed-borne diseases, even into a phase of the disease, which caused huge losses to rice production. There are as many as150-200rice varieties in Hunan province in recent years. There is a lack of system reports on rice seed fungal flora. Therefore, fungi isolating and identifying work were done on part of promotion rice varieties of Hunan province. We preliminary cleared the fungi species and frequencies of rice seed,which could provide scientific basis for seed introduction and early disease prevention.1、Conventional detection of seed-borne fungi on riceThe Moisturizing microscopy results showed that the fungus-carrying rate of Luoyou8was the highest (11.65%) among the Three-line hybrid rice cvs., while Jinyou463, Zhongyou177and Yiyou701were the lowest(0%). The fungus-carrying rate of Zhuliangyou819was the highest (7.13%) among the two-line hybrid rice cvs.,while Aoliangyou69and Baliangyou18were the lowest(0.27%). Among the conventional rice cvs., the fungus-carrying rate of Xiangzaoxian17was the highest (6.35%) while Huanghuazhan was the lowest(0.18%). The rate of fungus-carrying have no direct relation with the parental species. As to fungi carrying sites, the rate of seed husks is much higher than rice kernels. Cochliobolus miyabeanus, Sarocladium sp., Tilletia horrid, Curvularia sp., Fusarium sp. and Nigrospora sp.were detected from rice growth period, and Magnaporthe oryzae and Ustilaginoidea virens were not found. Storage stage fungi such as Aspergillus sp., Mucor sp., Alternaria sp., Penicillium sp. were also detected, most of which probably cause seedling rot during early season rice seedling, especially under the condition of greenhouse seedlings.2、Molecular identification of seed-borne fungiIsolation, culture and molecular identification of the seed samples were done. The studies show that pathogen rate of Neiwuyou8015and Xiangzaoxian24th are the lowest (2%), and Zhongqingyou2nd, Hualiangyou1206and Yangliangyou6th are the highest (100%). The eukaryotes rDNA-ITS universal primers PCR, sequencing and the BLAST of the product, Seven pathogenic fungi, Cochliobolus miyabeanus, Alternaria padwickii, Nigrospora oryzae, Penicillium citrinum and Aspergillus niger, were found on rice seeds. On the other hand, endophytic fungi were also detected, taking Coprinellus radians, Cladosporium sp., Arthrinium sp., Chaetomium brasiliense, Chaetomium globosum, Cochliobolus australiensis, Arthrobotrys foliicola, and Gelasinospora udagawae as examples.Innovation Points:(1) The moisture cultivation fungus and the fungus-carrying rate of150kinds of rice varieties in hunan province were clear for the first time;(2) The fungus and the separation fungus-carrying of155kinds of rice varieties in hunan province were clear for the first time, sequencing of the isolated strains was done and the rDNA-ITS phylogenetic tree was set up, and the fungi of Gelasinospora udagawae, Coprinellus radians, Chaetomium brasiliense, Cladosporium cladosporioides and Arthrinium sp. were not previously reported on the rice seed.