三种松树内生真菌的分离鉴定及其对红脂大小蠹伴生真菌的拮抗作用

Isolation and identification of endophytic fungi of three pine species and their antagonistic effect on the associated fungi of Dendroctonus valens

摘要:

【背景】松树的内生真菌会影响红脂大小蠹及其伴生真菌的生长及扩散，从而影响红脂大小蠹的入侵。【目的】掌握赤峰地区红脂大小蠹寄主树种内生真菌的物种多样性，筛选对其伴生菌有拮抗作用的菌株，为红脂大小蠹的生物防治提供资源。【方法】采用组织分离法、形态学鉴定和internal transcribed spacer (ITS)序列分析相结合的方法对红脂大小蠹寄主树种油松、樟子松和潜在寄主落叶松进行内生真菌多样性研究，并用两点对峙法进行拮抗菌株筛选。【结果】松树内生真菌鉴定为2门6纲10目18科19属，其中落叶松韧皮部分离到的内生真菌数量最多，为39株，隶属于9属12种，真菌检出率为43.33%；油松次之，为30株，隶属于7属8种，真菌检出率为33.33%；樟子松最少，为29株，隶属于10属13种，真菌检出率为32.22%。3个树种的内生真菌相似性较低，无共有的菌种，青霉属(Penicillium)和篮状菌属(Talaromyces)是唯二的共有菌属，且青霉属在3个树种中均为优势菌属。平板对峙结果表明90%以上的树木内生真菌均能够与伴生真菌形成稳定的对峙，抑制率在50%-86%之间，且Phialocephala sp.和Pochonia bulbillosa对伴生菌的抑制率能高达93.7%。【结论】松树韧皮部的内生真菌具有较高的生防潜力，Phialocephala sp.和P. bulbillosa对红脂大小蠹伴生菌有较好的抑制效果，可作为红脂大小蠹的生防资源。

Abstract:

[Background] Endophytic fungi of pine trees can affect the growth and spread of Dendroctonus valens and its associated fungi, thus further influencing the invasion of D. valens. [Objective] To investigate the diversity of endophytic fungi in the hosts of D. valens in Chifeng, Inner Mongolia in northern China, and to screen strains against its associated fungi for the control of this destructive forest pest. [Methods] The endophytic fungi in the hosts Pinus tabuliformis and Pinus sylvestris var. mongolica and potential host Larix gmelinii were explored by tissue isolation, morphological identification, and ITS sequence analysis, and the antagonistic strains were screened with the plate confrontation method. [Results] The endophytic fungi in 19 genera, 18 families, 10 orders, 6 classes, and 2 phyla were identified from the three pine species. L. gmelinai topped the three species in the number of isolated strains (39 strains of 12 species in 9 genera), with fungal detection rate of 43.33%, followed by P. tabuliformis (30 strains of 8 species in 7 genera), with fungal detection rate of 33.33%, and coming in the third was P. sylvestris var. mongolica (29 strains of 13 species in 10 genera), with fungal detection rate of 32.22%. The three pine species had no common strains but had the common genera of Penicillium and Talaromyces. Penicillium dominated the fungi in all three pine species. The results of plate confrontation indicated that more than 90% of the endophytic fungi showed stable confrontation against the associated fungi, and the inhibition rate ranged from 50% to 86%. Particularly, the associated fungi-inhibiting rate of Phialocephala sp. and Pochonia bulbillosa stood at 93.7%. [Conclusion] The endophytic fungi in the bast of pine trees have high potential for biocontrol, and Phialocephala sp. and P. bulbillosa have satisfactory inhibitory effect on the concomitant fungi of D. valens and can be used for controlling D. valens.