青藏高原矮火绒草内生细菌多样性及生物功能分析

文章编号：2095-1191（2019）10-2222-12

Diversity and biological function of endophytic bacteria in Leontopodium nanum of Qinghai-Tibetan Plateau

CHENG Liang1，2

（1Institute of Plant Protection， Qinghai Academy of Agriculture and Forestry Science， Xining  810016， China;

2Key Laboratory of Agricultural Integrated Pest Management of Qinghai Province， Xining  810016， China）

Abstract：【Objective】The diversity and function of endophytic bacteria of Leontopodium nanum were explored to provide reference for developing biological bacterium agent with related functions and to provide valuable endophytic bacteria resources for ecological agriculture and animal husbandry production in Qinghai-Tibet Plateau. 【Method】The endophytic bacteria of L. nanum were isolated and purified by tissue isolation method. The phylogenetic status of the isolated strains was preliminarily determined based on 16S rDNA sequence analysis. The antagonistic activity of the strains against pathogenic fungi was detected by plate confrontation method. The indoleacetic acid（IAA） secretion， phosphate solubilization and nitrogen fixation abilities of the strains were tested. The herbicidal activity， low temperature suitability and seed germination characteristics were also determined. 【Result】Results showed that 52 endophytic bacteria that belonged to 28 genera， 14 families， 10 orders， 7 classes， 4 phyla were isolated from the root， stem leaf， and seed of L. nanum based on their 16S rDNA sequences. 52.17% isolates were identified as Pseudomonas， which was the most dominant genus in the roots of L. nanum. Bacillus was the most dominant genera in the stems of L. nanum， which accounted for 41.18% of the total. The quantitative distribution of endophytic bacteria in different parts of L. nanum was root>stem>seed>leaf. Furthermore， out of 52 isolates， 11 strains confirmed to have antifungal activity， 10 strains showed IAA-producing activity， 7 strains turned out to have phosphate-solubilizing activity，7 strains were proved to be azotobacter， 20 strains showed herbicidal activity， 13 strains showed low temperature tolerance and 8 strains exhibited growth-promoting effects. Seven types of functional endophytic bacteria were found in the root， stem， leaf and seed of L. nanum. Isolates with antagonistic and herbicidal activity had a relatively large proportion in the roots of L. nanum. The proportion of strains with phosphate-solubilizing activity in all plant parts was relatively small. Isolates with antagonistic， IAA-producing， nitrogen-fixing and growth-promoting activity were not discovered in the leaves of L. nanum. The functional endophytic bacteria were distribu-ted in 17 different genera and had high population diversity. The isolates from Pseudomonas and Bacillus were multi-functional strains with a high proportion in the four parts of seedlings. 【Conclusion】The number and distribution of endophytic bacteria in different parts of L. nanum plant are different， but can be isolated into different functional types. The functional strains consist of 17 genera， of which Pseudomonas and Bacillus are dominant genus.