防治木薯细菌性枯萎病的生防菌株筛选和防效测定

从木薯8个不同生境分离到298株细菌,测定其产酶、次生代谢物和颉颃活性,结果表明,产蛋白酶、纤维素酶、葡聚糖酶和生长素的菌株和比例分别为160(53.69%)、57(19.13%)、11(3.69%)和150(50.34%),产嗜铁素菌株最多203个,比例达68.12%;产几丁质酶的菌株最少7株,比例仅为2.35%;其中,9株菌株对木薯细菌性枯萎病菌具有颉颃活性,比例为3.02%。通过赋值选择88个得分较高的菌株,对其16S r RNA测序及ARDRA-PCR和BOX-PCR聚类分析,发现可分成21个簇,且每个簇的种群丰度较高。优选11个菌株进行日光温室大棚盆栽防效测定,其中,HWY-3-1防效为100%,防效在60%以上的菌株有DBS-5(85.96%)、HS-4-3(82.88%)、DHWP-1(79.37%)、HWYT-3-2(77.88%)、HWS-4-3(77.84%)、DHNS-3-5(65.34%)、DHWR-5-1(61.83%),和对照防效相比,差异显著;进一步选择5个防效较好的潜力菌株测定其田间防效,结果显示,HWY-3-1(Bacillus pumilus)平均防效为38.11%,与对照的防效存在显著差异。试验筛选策略可行,初步找到1株对CBB防效较稳定的生防菌株Bacillus pumilus。

Selection and Identification of Biocontrol Agents Against Cassava Blight Bacteria

298 bacterial isolates were recovered from eight different microenvironments of field-grown cassava plants. of that, 160 (53.69%) expressed protease, 57 (19.13%) produced cellulase, 7 (2.35%) expressed chitinase, and 203 (68.12%) secreted siderophores; 11 (3.69%) produced glucanase, 150 (50.34%) expressed IAA, and only 9 (3.02%) representative isolates were for in vitro antagonism. ARDRA and identification of antagonistic bacteria identified 21 distinct groups ( G1-21) with the similarity coefficient of 50% among the 298 isolates, BOX-PCR fingerprint analysis revealed that isolates in different ARDRA groups had dissimilar genotypes. Eleven representative isolates were evaluated for their efficacy against cassava blight bacterial mildew caused by Xanthomonas axonopodis pv. Manihotis in the greenhouse, the isolates showed biocontrol efficacy ranging from 44.14% to 100%. Eight of them (HWY-3-1 (100%), DBS-5 (85.96%), HS-4-3 (82.88%), DHWP-1 (79.37%), HWYT-3-2 (77.88%), HWS-4-3 (77.84%), DHNS-3-5 (65.34%), DHWR-5-1 (61.83%) attained the efficacy over 60%. HWYT-3-2 and HNR-3-7 significantly suppressed the disease at 30 dpt, and HWYT-3-2 provided significant disease protection from 30-40 dpt, the average bio control efficiency was 38.11%. The strategy of the study was feasible, and found one strains HWYT-3-2 Bacillus pumilus of BCAs against CBB control.