菊花枯萎病病原菌的分离和鉴定及其粗毒素对切花菊‘神马’幼苗生长的影响

[目的]本文旨在通过对菊花枯萎致病菌的分离和鉴定，研究其粗毒素对切花菊‘神马’幼苗的化感作用。[方法]观察切花菊‘神马’枯萎病的田间发病症状，采用组织分离培养法从菊花病株上分离到1株致病真菌CFD-B2，提取CFD-B2粗毒素，设5个不同稀释倍数的粗毒素处理：对照、粗毒素原液（168.12 μg？mL-1）、粗毒素稀释5倍、粗毒素稀释10倍和粗毒素稀释25倍，测定不同处理中切花菊‘神马’幼苗株高、根长、茎粗，抗性物质含量，细胞膜相对透性以及根系过氧化物酶（POD）、苯丙氨酸解氨酶（PAL）和多酚氧化酶（PPO）活性的变化。[结果]通过ITS基因核酸序列分析，鉴定CFD-B2为镰刀菌属尖孢镰刀菌（Fusarium oxporum）。尖孢镰刀菌CFD-B2不同稀释倍数的粗毒素处理对切花菊‘神马’幼苗的株高、茎粗、根长均有抑制作用，抑制程度由强到弱依次为：粗毒素原液处理、粗毒素稀释5倍处理、粗毒素稀释10倍处理、粗毒素稀释25倍处理。处理7 d时，粗毒素原液对菊花幼苗株高、茎粗、根长抑制效果最显著，比对照分别减少了28.87%、7.31%和42.48%。不同稀释倍数的粗毒素处理能增加切花菊‘神马’幼苗根系组织细胞膜透性及丙二醛（MDA）、可溶性糖和脯氨酸含量。不同稀释倍数的粗毒素处理能够增加根系保护酶活性，且效果从高到低表现为：粗毒素原液处理、粗毒素稀释5倍处理、粗毒素稀释10倍处理、粗毒素稀释25倍处理。同一稀释倍数的粗毒素处理短期内能够增加根系保护酶活性。粗毒素原液处理12 d时，PAL、POD和PPO活性达到最高，比对照分别提高了44.39%、36.96%和35.38%。[结论]尖孢镰刀菌CFD-B2粗毒素对切花菊‘神马’幼苗的化感作用主要表现在可抑制切花菊幼苗根、茎的正常生长，增加切花菊幼苗根系的细胞膜透性以及根系组织中MDA、可溶性糖和脯氨酸的含量，在短期内提高根系保护酶PAL、POD和PPO活性。
[Objectives]The paper aims to study the allelopathic effects of Fusarium oxysporum crude toxin on cut-chrysanthemum seedlings through the isolation and identification of cut-chrysanthemum Fusarium wilt pathogenic fungal.[Methods]Fusarium wilt symptoms in cut-chrysanthemum ‘Jimba’ were observed,then the tissue culture method was used to isolate the pathogenic fungi. The pathogenic fungus CFD-B2 was isolated. The crude toxin of CFD-B2 was extracted and diluted as below:CK,the crude toxin,5 times dilution,10 times dilution,15 times dilution,and 25 times dilution. The steam height,stem diameter,root length,resistant material content,membrane relative permeability,and activities of polyphenol oxidase(PPO),peroxidase(POD)and phenylalanine ammonia-lyase(PAL)in different treatments were investigated at different times.[Results]The results indicated that the strain CFD-B2 was isolated and identified as Fusarium oxysporum by ITS sequencing. The F. oxysporum crude toxin had significant effect on inhibiting the steam height,stem diameter and root length of cut-chrysanthemum seedlings. The inhibiting effect from strong to weak was:crude toxin,diluted 5 times,diluted 10 times,and diluted 25 times. Seven days after crude toxin spraying,the plant height,stem diameter and root length decreased by 28.87%,7.31% and 42.48% respectively when compared to the CK. The CFD-B2 crude toxin could increase the root cell membrane permeability,the content of MDA,soluble sugar and proline content in the root tissue. The CFD-B2 crude toxin had significant promotion effects on increasing the activities of the root cell protective enzyme PAL,POD and PPO. And the promoting effect from strong to weak was:crude toxin,diluted 5 times,diluted 10 times,and diluted 25 times. Compared