短密木霉菌株GAS1-1的分离鉴定、拮抗作用及其生物学特性

Isolation, identification, antagonistic effect and biological characteristics of Trichoderma brevicompactum strain GAS 1-1

为了解短密木霉Trichoderma brevicompactum对植物病害的生防作用及其生物学特性,利用稀释平板分离法从甘肃省景泰县马铃薯连作田植株根际土壤中分离获得1株木霉菌株GAS1-1,经形态观察、rDNA-ITS和EF-1α序列分析明确其分类地位;用生物学方法研究该菌的营养生长和产孢条件;采用对峙培养法测定该菌株对5种植物病原真菌的抑制作用。结果表明,基于形态学特征和基因序列分析结果,菌株GAS1-1被鉴定为短密木霉Trichoderma brevicompactum,为甘肃省木霉新记录种。该菌株对玉米镰孢茎腐病菌Fusarium graminearum、玉米穗腐病菌F. verticillioides、棉花枯萎病菌F. oxysporum、玉米腐霉茎腐病菌Pythium inflatum和灰葡萄孢霉Botrytis cinerea均具有较好的拮抗效果,尤其对玉米腐霉茎腐病菌的抑制作用最好,抑菌率达100.00%。该菌株营养生长和产孢的最适碳源和氮源分别为葡萄糖和酵母膏;其在15～35℃均可生长,菌丝最适生长温度为30℃,最佳产孢温度为25℃;在pH 5～12的培养基上菌丝均可生长,菌丝最适生长和产孢的pH均为5;24 h黑暗条件下菌丝营养生长最快,12 h光暗交替条件有利于产孢;孢子致死温度为69℃,10 min。表明短密木霉菌株GAS1-1具有较好的生防应用潜力。

In order to investigate the biological characteristics of Trichoderma brevicompactum and biocontrol of T. brevicompactum against plant diseases, a Trichoderma strain GAS1-1 was isolated from rhizosphere soils of continuously cropped potato in Jingtai County, Gansu Province. The taxonomic status of strain GAS1-1 was confirmed with morphologic observation, rDNA-ITS and EF-1α sequence analysis. Nutritional growth and sporulation conditions of strain GAS1-1 were ascertained by using biological method. The inhibitory effect of the strain GAS1-1 against five plant pathogenic fungi was determined by dual culture. The results of morphological and sequence analysis showed that the strain GAS1-1 was identified as T. brevicompactum, which is a firstly recorded Trichoderma species in Gansu. The strain showed strong antagonistic activity against Fusarium graminearum, F. verticillioides, F. oxysporum, Pythium inflatum and Botrytis cinerea. In particular, it produced the highest antifungal activity against P. inflatum with an inhibition ratio of 100.00%. The study of biological characteristics showed that the optimum carbon and nitrogen sources of the strain were glucose and yeast extract for mycelial growth and sporulation, respectively. The strain could grow at 15-35℃, and the optimal hyphal growth and sporulation temperatures were 30℃ and 25℃, respectively. The strain could grow at pH 5-12, and the optimal pH value for hyphal growth and sporulation was pH 5. The most favorable condition for mycelial growth was 24 h dark photoperiod, while the condition of alternative 12 h light and 12 h dark was the most favorable to its sporulation. The lethal temperature for spores was 69℃ for 10 min. It suggested that this strain of T. brevicompactum has biocontrol potential against plant diseases.