Identification And Detection Of Seed-born Bacterium In Rice

Rice seeds carrying bacterium could cause rice seeds discoloring, inhibited their sprouting, influence growth during the growing period of rice and could easily lead to seed-borne diseases, which caused serious losses to rice yield. But beneficial bacterium could promote the growth of rice or inhibit the growth of pathogenic bacteria by breeding in rice. There are a variety of rice in Hunan province in recent years. But the reports of seed-borne bacteria are few.Therefore, isolation and identification of bacteria were done on some rice varieties of Hunan province and other areas.We preliminary cleared the species and frequencies of seed-borne bacteria, which could provide effective information and strain resources for developing beneficial bacterium. Simultaneously,it could establish theoretical basis for bacteriologic test and disease prevention.1、Detection of seed-borne bacterium on riceThe results of bacterial isolation showed that bacterium were detected in all species,but the bacterium-carrying rate were different among rice varieties.The bacterium-carrying rate of Jinyou217(14.29%)、Shenyou9512(16.67%)、Eryou838(16.67%) were lower than other three-line indica hybrid rice,while Qingyou109(95.24%), Tyou109(92.86%) were higher. The bacterium-carrying rate of Cliangyou501(19.05%)、Yliangyou696(19.05%) were lower than other two-line indica hybrid rice,while Lingliangyou211(85.71%) was the highest. The bacterium-carrying rate of Nongxiang18(28.57%) was the lowest, Wuyoudao1(59.52%) and Xiangwanshan12(59.52%) were the highest among conventional hybrid rice. The same species of rice seeds from different sources have different bacterium-carrying rate.The bacterium-carrying rate of seed have no direct relationship with the hybrid parents. The results showed that bacterium were high frequency detected.Many rice seeds surface discoloring showed that bacterium could reduce the quality of rice during storage period. These bacterium probably cause seedling rot during early season rice seedling, especially under the condition of greenhouse seedlings.2、Identification of seed-borne bacteriumThe work of isolation and identification for bacterium were done.The results showed that the frequency of Pcntoea was the highest in all bacterium.The frequency of Bacillus.Methylobacterium, Burkholderia glumae, Acidovorax (0.04%),were the lowest.The bacterium rDNA-16S PCR, sequence alignmenting for the product. Three Pathogenic bacteria, Xanthomonas, Burkholderia glumae, Pantoea agglomerans were found on rice seeds.And some endophytic bacteria were detected,there were Pseudomonas, Agrobacterium, Curtobacterium, Bacillus, Sphingonomonas yabuuchiae, Escherichia hermannii, Methylobacterium, Acidovorax, Enterobacter, Pseudacidovorax iniermedius, Microbactium. The frequency of same bacterium were different on different varieties of rice seeds.Rice seeds carrying bacterium could spread bacterial disease, and influence normal growth of rice.Fristly, Pantoea caused rice seedling blight in the seedling stage. Pantoea not only inhibited rice seeds sprouting, but also influenced the development and maturation of rice seeds; During heading and booting stage, it delayed rice heading, caused leaf and rice seedlings necrosis. Secondly, rice bacterial leaf streak and bacterial leaf blight caused leaf disease. Bacteria-bearing seeds caused serious rice quarantine disease in the field period, which leaf wilting and spike of rice unplumpness.Innovation Points:(1) The bacterium-carrying rate of118varieties of rice in hunan province and other areas were clear for the first time;(2) The bacterium-carrying rate and distribution structure of different rice varieties in hunan province and other areas were clear for the first time,sequencing of the isolated strains was done and the rDNA-16S phylogenetic tree was set up.