深色有隔内生真菌Ochroconis guangxiensis X22诱导子对香蕉的促生和抗枯萎病效果

【目的】从深色有隔内生真菌Ochroconis guangxiensis X22中提取和筛选对香蕉具有促生和抗枯萎病作用的诱导子，为香蕉枯萎病的诱抗剂开发打下理论基础。【方法】通过组培苗接种，评价菌株X22对香蕉枯萎病的室内防治效果；采用匀浆、热解和浸提等方法从菌株X22菌丝体中提取多糖、寡聚糖和激活蛋白3种物质，通过水培试验评价3种提取物对香蕉苗生长和生长激素含量的影响，测定3种提取物对香蕉枯萎病的防治效果及其对香蕉苗抗病防御酶活的影响。【结果】在无菌条件下菌株X22处理香蕉组培苗后再接种病原菌Foc4，枯萎病发生较轻，叶片颜色正常且植株相对健康粗壮，其防治效果为58.9%；多糖、寡聚糖和激活蛋白3种提取物处理香蕉苗后，多糖处理的香蕉苗株高、根长及鲜重与对照相比分别显著增加16.9%、57.8%和3.9%（P<0.05，下同），香蕉叶片IAA和GA₃含量显著提高39.6%、11.8%；寡聚糖处理的香蕉苗对枯萎病防治效果最明显，对地上部分和地下球茎的防效分别为46.24%和54.73%；多糖处理香蕉苗后20 d再接种Foc4，香蕉叶片的超氧化物歧化酶（SOD）、过氧化物酶（POD）、苯丙氨酸解氨酶（PAL）和多酚氧化酶（PPO）含量在9 d内显著高于对照。【结论】菌株X22及其多糖和寡聚糖提取物对香蕉苗具有促生与抗病作用，可作为研制香蕉抗病诱抗剂的重要资源。

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.