琯溪蜜柚炭疽病拮抗放线菌的筛选和鉴定

为筛选出对琯溪蜜柚炭疽病有防治效果的生防菌,以琯溪蜜柚炭疽病菌（Colletotrichum gloeosporioides）为靶标菌,采用平板对峙法进行初筛,用生长速率法和人工接种法对抑菌效果较好的菌株FX28进行抑菌谱及防治效果测定;通过形态学、生理生化特征,结合16S rDNA序列分析等方法研究其分类地位。结果表明：从25份土样中共分离到放线菌105株,对琯溪蜜柚炭疽病菌有较好拮抗作用的放线菌有16株,其中菌株FX28抑菌活性最高,其抑菌带宽度为15.3 mm,抑制率达86.4%,抑菌谱广,对琯溪蜜柚炭疽病菌、琯溪蜜柚黑点病菌、琯溪蜜柚黑斑病菌等14种供试植物病原菌均有抑制作用;其作用机制表现为菌丝分枝增多、变粗、顶端膨大等,对琯溪蜜柚炭疽病的预防效果和治疗效果分别为83.8%和71.1%。根据形态、生理生化特性及16S rDNA序列分析,初步确定菌株FX28为深红紫链霉菌（Streptomyces violaceorubidus）。

Screening and Identification of Antagonistic Actinomycete Against Anthracnose Disease of Guanxi Honey Pomelo Cultivar

This study was conducted to screen resources for the biological control of Colletotrichum gloeosporioides which cause anthracnose disease for Guanxi honey pomelo cultivar. An antagonistic actinomycete of C. gloeosporioides was isolated from the soil samples by the plate-confrontation method and growth speed rate method, and the inoculated fruit was treated with the fermented broth. The taxonomic identification of the strain FX28 was carried out using morphological, physiological and biochemistry characteristics and 16S rDNA sequence. From the 25 soil samples, 16 of 105 antagonistic actinomycete isolates showed againstantifungal activity against C. gloeosporioides. FX28 showed an inhibition zone with a diameter 15.3 mm and strongest inhibition rate 86.4%. FX28 had broad-spectrum inhibition activity to all the 14 plant pathogenic fungi such as C. gloeosporioides, Diaporthe citri, Phyllosticta citriasian. FX28 could break down hyphae, turn hyphal thickened, fractured and enlarged. The protection and curation effects of the fermented broth against C. gloeosporioides were up to 83.8% and 71.1%, respectively. Based on the morphological, physiological-biochemical characteristics and molecular analysis, FX28 was identified as Streptomyces violaceorubidus.