桃褐腐病菌的分离鉴定及其生物防治

Isolation, identification, and biocontrol of Monilinia fructicola

摘要:

【背景】桃褐腐病是桃树重要病害之一，其严重危害花、枝条、叶片和果实，给桃树种植业带来了巨大的经济损失。【目的】明确桃褐腐病病原菌的种类，探究其生物学特性并研究防御假单胞菌(Pseudomonas protegens) QNF1对褐腐病的抑制作用，为桃褐腐病的科学正确防控提供理论依据。【方法】以贮藏期发病的桃果实为试材，从致病果实中分离病原菌，根据柯赫氏法则验证其致病性。同时，结合形态学和分子生物学手段鉴定病原菌种类，深入探究其生物学特性。采用体外培养和体内接种试验系统研究防御假单胞菌QNF1对桃果实致病菌的抑制作用及其对病原菌菌丝结构的破坏情况。【结果】从发病桃果实中分离到病原菌菌株HF，菌落颜色为棕褐色或灰白色，产生大量白色孢子，呈同心轮状；病原菌菌丝结构大多数为典型的二叉状分枝，少数不分枝，菌丝间互相交错；分生孢子为无色单孢，呈卵圆形或近圆形；病原菌接种健康桃果实，其致病性与自然发病果实一致。根据ITS和18S rRNA基因测序结果构建了系统发育树，表明该菌株属于美澳型核果链核盘菌(Monilinia fructicola)。该病原菌在pH 5.0-11.0均可生长，弱酸性环境生长情况最佳，菌丝生长最佳温度为20-28 ℃。进一步试验表明，防御假单胞菌QNF1发酵液可导致桃褐腐病菌菌丝结构发生断裂、膨大等异常变化，对桃果实褐腐病发生的抑制率可高达88.17%。【结论】分离出桃褐腐病病原菌，并对其进行鉴定、生物学特性及生物防治研究，进而为制定科学防控策略提供重要的科学依据，对于促进桃产业的健康可持续发展具有重要意义。

Abstract:

[Background] Peach brown rot, one of the major diseases of peach plants, seriously jeopardizes the flowers, branches, leaves, and fruits, causing great economic losses to the peach industry. [Objective] Identify the pathogenic fungus causing peach brown rot, investigate its biological characteristics, and study the inhibitory effect of Pseudomonas protegens QNF1 on the pathogen, and provide theoretical basis for the scientific and precise prevention and control of peach brown rot. [Methods] The pathogenic fungus causing peach brown rot was isolated from the diseased peach fruits, and its pathogenicity was tested according to Koch’s postulates. We employed morphological and molecular biological methods to identify the pathogen fungus and characterized its biological properties. In vitro culture and in vivo inoculation experiments were carried out to investigate the inhibitory effect of QNF1 on Monilinia fructicola and its damage to the mycelial structure. [Results] The isolated strain HF had colonies with a brown or gray-white color, producing a large number of white spores in a concentric ring. The mycelial were mostly typical binary branching, with a few unbranched, and intertwined with each other. The conidia were colorless single spores that were oval or nearly round. The pathogenicity on healthy peach fruits was consistent with that of naturally diseased fruits. The phylogenetic tree constructed based on the ITS and 18S rRNA gene sequencing indicated that HF belonged to M. fructicola. The pathogen could grow at pH 5.0-11.0, with robust growth in a weakly acidic environments, and the optimal temperature for mycelial growth was 20-28 ℃. Further experiments showed that QNF1 could cause abnormal changes in the mycelial structure of the brown rot fungus, such as breakage and swelling, and the inhibition rate of brown rot on peach fruits reached up to 88.17%. [Conclusion] The study isolated and identified the peach brown rot pathogen and carried out research on its biological characteristics and biocontrol, providing important scientific basis for the precise prevention and control of the disease, which is of great significance for promoting the healthy and sustainable development of the peach industry.