| Wet bubble disease caused by Mycogone perniciosa Magn has been an important disease of Agaricus bisporus:it was very contagious and results in severe crop loss. In this paper, research on the interaction between M. perniciosa Magn hyphae and A. bisporus hyphae, germination condition and method of M. perniciosa Magn chlamydospore, histopathologic observation of Wet bubble disease and the resistance of A. bisporus to M. perniciosa Magn on the basis of physiology and biochemistry were studied. Also the pathogenesis factors of this disease were studied. In this study, the interaction relationship between A. bisporus and M. perniciosa Magn was researched comprehensively. The experimental results are summarized as follows:1 The research of the interaction between M. perniciosa Magn hyphae and A. bisporus hyphae on PDA mediaThere were two kinds of results in trials of confrontation between M. perniciosa Magn hyphae and A. bisporus hyphae. One result was no antagonism between M. perniciosa Magn hyphae and A. bisporus hyphae and they can grow cross each other; the other results was A. bisporus hyphae become yellow, languish, and be degraded into hyphae clips when come into contact with M. perniciosa Magn hyphae,but M. perniciosa Magn hyphae grew normal.Growth of M. perniciosa Magn and A. bisporus on PDA media in dual plate was studied to research the effect of volatile compounds to each other. The result showed that M. perniciosa Magn hyphae could produce volatile substance to inhibit A. bisporus hyphae growth; and A. bisporus hyphae could produce some volatile material to promote the growth of M. perniciosa Magn hyphae.2 Germination of M. perniciosa Magn chlamydosporeIn this paper, we also researched the germination nutrition conditions and method of M. perniciosa Magn chlamydospore. Results showed that M. perniciosa Magn chlamydospore did not germination in general fungal medium. Some chlamydospore germinated when the A. bisporus extract was added into the medium, but the germination rate was very low, all less than 5%. This could explain mushroom fruit body extract can induce germination of M. perniciosa Magn chlamydospore. Secondly, in the five spore germination method, ordinary Petri dish method and suspended drops germination rate of minimum, only 3.6%, the germination rate of slide-slip method was 4.0%, mushroom hyphae gas induced method was 4.2%, improved Petri dish method can reach 5.0%. Thus, we draw the conclusion that in the five kinds of spore germination method, improved Petri dish method was the best germination method of M. perniciosa Magn chlamydospore.3 Histopathological observation of wet bubble disease mushroomThe result showed that there were some M. perniciosa Magn hyphae on the wet bubble diseased mushroom preface, and the A. bisporus hyphae cell wall was degraded, leading the leakage of cell inclusion. Thus, we can speculated that the wet bubble disease of A. bisporus fruit body infection is mainly caused by a series of enzymes produced from the M. perniciosa Magn, which could degrade A. bisporus hyphae cell wall and make A. bisporus hyphae cells lose protection function. Then the A. bisporus cellular structure was destroyed, and its cell inclusions exudates providing nutrition for M. perniciosa Magn growth, ultimately leading the A. bisporus hyphae to the disintegration and collapse.4 Study on the physiological and biochemical mechanism of A. bisporus to M. perniciosa MagnBy biochemical methods,we mensurated the content of protein, total soluble sugar and malondialdehyde(MDA) in A. bisporus fruits infected by M.perniciosa Magn with different times, and then analyzed the relationship between the change of these biochemical substances and the resistance of host. The results showed that when A. bisporus fruits have been infected by M. perniciosa Magn, the content of protein and total soluble sugar will increased on earlier, then gradually reduce and eventually was far below than CK; the content of malondialdehyde(MDA) in wet bubble diseased mushroom will gradually reduced.By means of mensuration the biochemical characters, A. bisporus fruit infected by M. perniciosa Magn with different times, the changes of activities of phenylalanine ammonia-lyase (PAL), polyphenoloxidase (PPO), peroxidase (POD), superoxide dismutase (SOD) and catalase (CAT) were studied. The results showed that when A. bisporus fruits have been infected by M. perniciosa Magn, the activities of PAL, PPO, POD and SOD were all induced in infected earlier, and were all higher than CK. In the second day of wet bubble disease, the activities of POD achieve the highest; the activities of PAL would reach highest in the fourth day and the sixth day; the activities of PPO and SOD would reach the highest value in the fifth day. Then, with the development of the wet bubble disease, the activities of all these enzymes start gradually increased.5 Study on the pathogenesis factors of wet bubble diseaseUse transparent circle method to detect the ability of four fungi cell-wall degradation enzymes (chitinase, cellulose enzyme, protease and beta 1,3-glucan enzyme) from M. perniciosa Magn production in vitro.The results showed that M. perniciosa Magn could produce the four cell-wall degradation enzymes after induction in vitro. Secondly, the determination of the activities of these four cell-wall degradation enzyme in mushroom fruiting body from different period of the disease, the activity of these four enzymes were improved. Therefore, we made it clearlly that these four cell-wall degradation enzymes plays a key role in the process of M. perniciosa Magn infect A. bisporus. Combined with the results of the histopathological observation, we can initially conclude that the cell wall degrading enzymes may be an important pathogenic factor warts spore fungal infection of A. bisporus.Extracted the secondary metabolites residuing from the M.perniciosa Magn in the diseased fruiting body of A. bisporus and tested its pathogenicity activities, the result showed that crude toxin has certain pathogenic capability. For another, the crude toxin of high temperature resistant and pathogenic active ingredient was preliminary performed and the result demonstrated that: pathogenic crude toxin after the high-temperature processing still has low pathogenic activity, pathogenic toxin’s active ingredient mainly were macromolecular material, part of the active ingredient for the enzymes material, specific what is material, it could be studying further. |
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