[背景]辣椒疫霉是一种毁灭性的土传病害,当前主要使用化学合成杀菌剂防治,但容易导致环境污染和食品安全等问题.[目的]筛选可拮抗辣椒疫霉的候选菌株,探究分离菌株拮抗辣椒疫霉的生理生化作用机制.[方法]综合应用形态学、核糖体RNA (rRNA)基因非转录区ITS序列相似性方法鉴定分离菌株,通过对峙实验筛选抑菌效果较高的拮抗菌株,基于比色法测定分离菌株发酵液粗提物对辣椒疫霉菌丝脂质过氧化、纤维素酶、β-葡萄糖苷酶(β-GC)和多聚半乳糖醛酸酶(PG)活性的影响.[结果]从腐木和土壤样品中分离得到11株木霉,分属于绿色木霉(Trichoderma virens)、哈茨木霉(Trichoderma harzianum)、钩状木霉(Trichoderma hamatum)和棘孢木霉(Trichoderma asperellum) 4个种.11株木霉对辣椒疫霉均有一定的抑制作用,抑制率达到90％以上的菌株包括:绿色木霉Tv-1(92.68％)、Tv-2 (95.12％),哈茨木霉Thz-2 (92.68％),钩状木霉Tha-1 (90.24％).以4株高效木霉的发酵液粗提物处理辣椒疫霉菌丝5 d后,因脂质过氧化产生的丙二醛含量显著增加,分别达到1.20、1.48、2.69和3.16 nmol/g,显著高于对照处理的0.77 nmol/g;与对照组相比,β-GC、PG酶活性显著下降,分别降低了12.28％?64.91％、7.2％?15.5％;同时纤维素酶活性呈上升趋势,最显著组为2.647 U/mL,相对于对照组增加了0.831 U/mL.[结论]分离得到4株明显抑制辣椒疫霉菌生长的高效木霉菌,主要通过破坏细胞壁结构、降低致病因子酶活力和增强脂质过氧化等方式起拮抗作用,可为辣椒疫病的生物防治提供理论依据和技术支持.%[Background] Phytophthora capsici is a devastating soil-borne disease. Currently, it is mainly controlled by chemical fungicides, easily leading to environmental pollution and food contamination problems. [Objective] The aim is to isolate effective strains that can antagonize Phytophthora capsici. [Methods] Isolated strains were identified by the sequencing similarity of the internal transcribed spacer regions of rDNA and morphological characteristics. The antagonistic activity of the isolated strains was detected by the dual culture test. After treated with the extract from the isolated strains, malondialdehyde concentration, cellulase, β-glucosidase, and the polygalacturonase activity in Phytophthora capsici were analyzed by the colorimetric method. [Results] All 11 isolated strains inhibited Phytophthora capsici growth. The isolated strains belonged to Trichoderma virens, Trichoderma harzianum, Trichoderma hamatum and Trichoderma asperellum species. Four strains (T. virens, T. harzianum, T. hamatum and T. virens) showed higher inhibition rates, which were 92.68％, 92.68％, 90.24％ and 95.12％, respectively. After treated with the extract from the four isolated strains, the MDA concentration and the cellulase activity in P. capsici hyphae were significantly increased while the β-GC and PG activities were significantly decreased. The highest activity of chitinase was up to 0.831 U/mL with 0.783 U/mL more than that in control group. On the contrary, both of β-GC and PG activities were significantly decreased in the treated groups, in which the reduction rates ranged from 12.28％ to 64.91％ and 7.2％ to 15.5％. [Conclusion] Four isolated Trichoderma spp. inhibited Phytophthora capsici growth by destroying its mycelial cytoderm structure, decreasing the activity of pathogenic factors and increasing the lipid peroxidation. This study provided a theoretical and technology support for resistant the Pepper Phytophthora blight.
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