梨灰霉病拮抗放线菌L-30的筛选、鉴定及作用机制研究

Selection,Identification and Characterization of Actinomyces L-30 for the Biocontrol of Pear Gray Mold

采用平板对峙培养法从果树根际土壤中筛选出对梨灰霉病菌(Botrytis cinerea)及10种常见果实采后病害具有抑制活性的放线菌株L-30,同时利用分子方法结合形态观察对其进行鉴定,并测定其对B.cinerea孢子萌发的抑制作用、对‘皇冠’梨的诱导抗性和果实防御酶系活性的影响。结果表明,菌株L-30对梨灰霉病菌的活体抑制活性达到40%以上,基于16S rDNA核酸一致性和系统发育分析及培养特性证明L-30为链霉菌属(Streptomyces)的多产色链霉菌(S.polychromogenes)。L-30稀释100倍发酵液对梨灰霉病孢子萌发抑制率为52.04%。L-30处理皇冠梨果实能显著降低梨灰霉病菌的扩展,并提高果实的过氧化物酶(POD)、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和苯丙氨酸解氨酶(PAL)活性。

Strain L-30，with effective inhibitory activity against Botrytis cinerea and 10 other postharvest fruit diseases，was selected from rhizosphere of pear orchard by dual-culture method. The morphological characters and 16S rDNA sequence analysis were used to identify the selected strain. The mechanisms involved in the biocontrol process of strain L-30 against B. cinerea were also investigated. Results showed that the control efficacy of strain L-30 against pear gray mold reached 40% on ‘Huangguan’pears. Based on morphological characters and 16S rDNA sequence analysis，L-30 was identified as Streptomyces polychromogenes. The supernatant of strain L-30’s fermentation could effectively reduce the germination of B. cinerea spores，the inhibitory efficiency of its 100-fold dilution reached 50.14%. In addition，S. polychromogenes L-30 could significantly induce the resistance of‘Huangguan’pear against pear gray mold，and also increase the activities of peroxidase（POD），superoxide dismutase（SOD），catalase（CAT）and phenylalanine ammonia lyase（PAL）.