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

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.