Effects of dark septate endophyte Ochroconis guangxiensis X22 elicitor on banana growth promotion and Fusarium wilt resistance

【Objective】 To extract and screen elicitors with growth promotion and Fusarium wilt resistance function for banana from the dark septate endophyte Ochroconis guangxiensis X22, so as to provide theoretical basis for banana Fusarium wilt inducer development.【Method】 Effects of O. guangxiensis X22 on banana Fusarium wilt resistance in indoor environment were evaluated by tissue culture inoculation. Polysaccharide, oligosaccharide and harpin were extracted from O. guangxiensis X22 mycelium by methods such as homogenization, pyrolysis and extraction. Effects of these extracts on growth and growth hormone content of banana seedlings were evaluated by hydroponic experiment. Control effects of these three extracts on banana Fusarium wilt and their effects on defense enzyme activity of banana seedling were determined.【Result】Under the aseptic condition, when pathogen Foc4 was inoculated with strain X22 after the treatment of banana tissue culture seedlings, Fusarium wilt occurred less, the leaves were normal, the plants were relatively healthy and robust, and the control effect was 58.9%. Compared with the control, the plant height, root length and fresh weight of banana seedlings treated with polysaccharide, oligosaccharide and harpin were significantly increased by 16.9%, 57.8% and 3.9%(P<0.05, the same below) respectively. Content of IAA and GA₃ were significantly increased by 39.6% and 11.8% respectively. Oligosaccharide-treated banana seedlings had better Fusarium wilt resistance, and their control effects of above-ground part and corm were 46.24% and 54.73% respectively. After 20 d of polysaccharide treatment, banana seedlings were inoculated with Foc4 and content of superoxide dismutase(SOD), peroxidase(POD), phenylalanine ammonia lyase(PAL) and polyphenol oxidase(PPO) in leaves were significantly higher than those in the control within 9 d.【Conclusion】Strain X22 and its oligosaccharide extract have growth promotion and Fusarium wilt resistance function for banana seedlings, which can be used as important resources for biocontrol preparation of banana Fusarium wilt.