Orchid mycorrhizal fungi (OMF) are vital biocontrol agents, especially for Odontoglossum ringspot virus (ORSV). The promising study helped identify the mycorrhiza isolate from native tropical orchids and determine its potential as a biocontrol. Sample collection of healthy roots of Phalaenopsis amabilis emanated in Yogyakarta, Indonesia, carrying out molecular identification with rDNA-ITS amplification using a set of universal primers ITS1 and ITS4. In vivo, antagonist tests began by inoculating viruses and mycorrhiza to determine the effect of growth and induction of secondary metabolites. The result showed one isolate of Trichoderma sp. associated with the molecular analysis has amplified the ITS1-5.8S-ITS4 section by 600–750 bp DNA. The sequenced products revealed insertion and substitution occurrences, which may have caused the variance by strain diversity and potential severity. Indonesian isolates have undergone speciation and separation from other isolates by a substantial distance. The considerable effects were the increase in leaf length, leaf width, root length, leaf count, the number of roots, fresh weight, and a lowering of the virus content. The analysis of the plant growth parameters and virus concentrations provided significant differences among the treatments inoculated with orchid mycorrhiza (Mycorrhiza [M], Mycorrhiza + Virus [MV], and Virus + Mycorrhiza [VM]) and those without orchid mycorrhiza inoculation (Control [C] and Virus [V]). The orchid resistance suggested that the virus infecting plant leaves contain more phenolic chemicals. This study is the first-ever report of the Trichoderma sp. isolated from native tropical orchids in Indonesia.
Antagonistic test, biocontrol, orchid mycorrhiza fungi, Phalaenopsis amabilis, phenolic chemicals, rDNA-ITS
Molecular characterization of mycorrhizal isolates on the roots of Phalaenopsis amabilis from Yogyakarta, Indonesia, based on rDNA-ITS has a DNA product size of 600–750 bp located on ITS1-5.8S-ITS4, which is a Trichoderma sp. The phylogenetic tree reconstruction showed the isolate has undergone speciation. The results of the mycorrhizal antagonist test against ORSV infection revealed considerable growth of leaf length, width, root length, number of leaves, root volume, fresh weight, and phenolic chemicals.