Population Diversity Research On Endophytic Bacteria Of Tian Fu Peanuts

Endophytic bacteria are beneficial microbial resources for improving plant growth and abilities of antidisease and antiadversity. They extensively live in various kinds of plants. Our research investigated the endophytic bacteria resources of Tian Fu peanuts. Their population dynamics and distribution within the plant cultivars and different plant organs were studied. The results revealed the diversity and the occurrence of dominant species of endophytic bacteria. This is the basis for screening of plant growth promoting and plant pathogen antagonistic endophytic bacteria, and their application in sustainable agriculture. The major results are summarized as the following.Four major peanut cultivars were collected for the analysis of endophytic bacteria in Sichuan province. Two hundred and twenty endophytic bacteria stains were isolated from the seeds, and the plant organs at the seeding, flowering and maturing stages. The taxonomic position of the isolates were identified by morphological and biochemical analysis. All the strains were grouped into seventeen genera of bacteria, which were Bacillus, Micrococcus, Erwinia, Acinetobacter, Arthrobacter, Corynebacterium, Alcaligenes, Mycobacterium, Sporosarcina, Enterobacter, Flavobacterium, Kurthia, Pseudomonas, Xantomonas, Proteus, Bradyrhizobium and Streptomyces.The genera of Bacillus, Micrococcus and Erwinia occurred at higher frequenency than the others. Bacillus was the most dominant endophytic bacteria in peanuts with an average isolation frequency of 83.3% in the flowering stage and 57.1% in the maturing stage. Eleven species within the Bacillus genera were identified, which included B.megaterium, B.subtilis, B.pumilus, B.licheniformis, B.cereus, B.firmus, B.coagulans, B.sphaericus, B.mycoides, B.stearothermophilus, B.lentimorbus. B.megaterium was the most prevalent species among the all. Micrococcus genera was occurred in the four peanut cultivars tested.The total number and population diversity of endophytic bacteria isolated from different growing stages of the four peanut varieties vary distinctly, however in the seedling stage, the total number of endophytic bacteria in all of the four peanut varieties achieved their peaks. Meanwhile the population diversity index of endophytic bacteria in seedling stages are the highest ones in almost all peanut varieties except TF12, whose population diversity index in the seed is higher than in seedling stage by 0.02.According to morphological observation, the fifteen actinobacterial isolates were...