绿色木霉TR-8菌株对尖镰孢的拮抗机制

Antifungal Mechanisms of Trichoderma viride Strain TR-8 against Fusarium oxysporum

对绿色木霉TR 8菌株抑制尖镰孢的拮抗机制进行了研究。平板对峙培养结果表明,绿色木霉生长快于尖镰孢FO G1,接触后FO G1生长停止,TR 8继续生长,覆盖FO G1的菌落并大量产孢,但不形成抑菌圈。观察了TR 8对FO G1的重寄生现象,TR 8菌丝首先向FO G1趋性生长,然后紧贴FO G1菌丝平行生长或穿入菌丝生长,最后FO G1菌丝瓦解。在扫描电镜下可以看到FO G1菌丝原生质凝结,菌丝上有孔洞出现。发酵7d,TR 8发酵液中β1,3 葡聚糖酶的活性为20 15U/ml,几丁质酶的活性为11 67U。发酵原液对FO G1菌丝生长和孢子萌发均无抑制作用,但TR 8的挥发性分泌物对病菌孢子萌发具有一定的抑制作用。含有TR 8分泌物的培养基对病菌孢子萌发有很强的抑制作用,抑制率高达75 06%。

The antifungal mechanism of Trichoderma viride strain TR-8 against Fusarium oxysporum was studied. When TR-8 and F. oxysporum strain FO-G1 were dual-cultured on PDA plate, TR-8 grew faster than FO-G1. After the two kinds of mycelia contacted, mycelial growth of FO-G1 stopped. Later, TR-8 continued to grow, covered FO-G1 colony and produced large number of conidia. Inhibition ring was not found. The mycoparastism of TR-8 against FO-G1 was observed. It was revealed microscopically that at first TR-8 mycelia grew to FO-G1, then developed in parallel or penetrated FO-G1 mycelia, eventually FO-G1 mycelia collapsed. After TR-8 was fermented 7 d, the activities of 1,3-β-glucosidase and chitinase were 20.15U/ml and 11.67U respectively. Low antibiosis of TR-8 was detected. In vitro, fermentative liquid, even which was not diluted, couldn't inhibit both the mycelial growth and spore germination of FO-G1. The volatile substances secreted by TR-8 could inhibit spore germination, with inhibition rate reached 75.06%.