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The chrysanthemum black spot caused by Alternaria alternata significantly reduced the quality and yield of chrysanthemum. The crude toxin secreted by A. alternata in the metabolic process have elopathic effects on plants, which is the main pathogenic factor for the occurrence of chrysanthemum black spot. The pathogenic fungi A. alternate was isolated from chrysanthemum black spot leaves, The effects of crude toxin on plant height, stem diameter, root length, resistant material content, membrane relative permeability, polyphenol oxidase (PPO), peroxidase (POD), phenylalanine ammonia-lyase (PAL) in different treatments of chrysanthemum 'Jinba' seedlings were investigated. The results showed that the crude toxin of A. alternata had an inhibition effect on plant height, stem diameter and root length. The toxin concentration was positively correlated with the inhibitory effect. 14 days after crude toxin treatment, plant height, stem diameter and root length were significantly inhibited, with an reduction of 28.9%, 21.4% and 23.3%, respectively. The cell membrane permeability of leaf increased with the toxin concentration. Under the same toxin concentration, the cell membrane permeability first increased and then decreased with the treatment duration. The contents of soluble protein, malondialdehyde (MDA) and proline in leaves were significantly increased after treatment with the toxin solution. The increases of PAL, POD and PPO were the most significant in 10 times A. alternatacrude toxin treatment. The pathogenicity of A. alternate crude toxin to the chrysanthemum 'Jinba' seedlings was mainly through inhibi-ting the normal growth of roots and stems, destructing the root cell membrane permeability and increasing the contents of MDA, normal soluble sugar and proline, and promoting the activities of PAL, POD, PPO in leaf tissues.由链格孢菌引起的菊花黑斑病严重降低了菊花的品质和产量.链格孢菌在代谢过程中分泌的粗毒素是菊花黑斑病发生的主要致病因子之一.本文从菊花黑斑病发病叶片中分离筛选出致病真菌链格孢菌1株,研究其粗毒素对菊花幼苗‘神马’生长的影响以及测定盆栽幼苗叶片细胞膜相对透性、抗性物质含量、诱导酶活性及代谢物质含量变化.结果表明: 链格孢菌粗毒素对菊花‘神马’幼苗的株高、茎粗、根长均有抑制作用,毒素浓度与抑制效果呈正相关,且粗毒素原液处理14 d后,菊花幼苗株高、茎粗、根长受到显著抑制,分别比对照减少了28.9%、21.4%和23.3%;链格孢菌粗毒素处理菊花‘神马’幼苗后,根系组织细胞膜透性随着毒素浓度的增加而增加,在同一毒素浓度处理下,菊花幼苗叶片细胞膜透性随着处理时间的增加呈先增大后降低的趋势;毒素原液处理菊花幼苗后,菊花幼苗叶片中抗性物质可溶性蛋白、丙二醛(MDA)以及脯氨酸含量均显著提高.链格孢菌10倍稀释液处理对叶片苯丙氨酸解氨酶(PAL)、过氧化物酶(POD)和多酚氧化酶(PPO)活性的提高最为显著.链格孢菌粗毒素对切花菊‘神马’幼苗的致病作用主要通过抑制菊花幼苗根、茎的正常生长,增加菊花幼苗叶片细胞膜透性,影响切花菊幼苗叶片中抗性物质代谢以及提高叶片保护酶活性而影响植株正常生理代谢. |
