Molecular characterization and plant growth promotion of endophytic diazotrophs isolated from Cymbopogon caesius and Miscanthus floridulus

• 1、College of Agriculture, South China Agricultural University, Guangzhou 510642
• 2、College of Resources and Environment, South China Agricultural University, Guanzhou 510642
• 3、Department of Life Sciences, College of Yuncheng, Yuncheng 044000

Abstract：Cymbopogon caesius and Miscanthus floridulus, which used as forage for various livestock, are perennial plants and the pioneer vegetation grown on barren hillside. Sixty-six endophytic diazotrophs were obtained from C. caesius and M. floridulus by using two selective medium without nitrogen sources in combination with acetylene reduction methods. Thirty strains were isolated from C. caesius vs. thirty-six strains from M. floridulus. Sixty-six endophytic diazotrophs were grouped into 10 groups (I to X) by analysis of SDS-PAGE patterns of whole-cell protein electrophoresis and IS-PCR (Insertion sequence-based PCR) DNA fingerprinting. 16S rDNA sequencing analysis of representative strains of each group showed that these strains are closely related to Burkholderia cepacia, Enterobacter cloacae, Phytobacter diazotrophicus, Enterobacter asburiae, Herbaspirillum seropedicae, Cronobacter sakazakii, Enterobacter oryzae, Klebsiella pneumoniae, Enterobacter dissolvens, Azospirillum amazonense, which indicated the great diversity of endophytic diazotrophs colonized in the host plants of C. caesius and M. floridulus. The results of physiological and biochemical tests showed that some isolates have the ability of secreted ammonia, produced indole, dissolved phosphorus and potassium. The selected endophytic diazotrophs inoculated with rice and corn significantly promote the growth of plants.

Keywords： Cymbopogon caesius Miscanthus floridulus endophytic diazotrophs molecular characterization plant growth promotion