Plant growth-promoting and biocontrol potential of endophytic fungi isolated from terrestrial orchids in Mount Gede Pangrango National Park (TNGGP)

Terrestrial orchids harbor diverse endophytic fungi that produce bioactive compounds mimicking their hosts' metabolites, including alkaloids, flavonoids, and phenolics. These endophytes offer potential as dual-function biological agents that promote plant growth and suppress disease. This study aimed to isolate and evaluate endophytic fungi from terrestrial orchids for their ability to enhance plant growth and control Phytophthora capsici, a major pathogen in chili (Capsicum annuum). A total of 34 fungal isolates were obtained and screened for plant growth-promoting activity using chinese cabbage (Brassica rapa var. pekinensis) on oatmeal agar. The three most effective isolates, i.e., SIG 10.2, GG 5.2, and GG 14.2, were further tested in vivo against P. capsici in chili plants. All three isolates significantly improved plant biomass and reduced disease symptoms, with SIG 10.2 showing the highest efficacy. Molecular identification revealed that the isolates belonged to Colletotrichum arxii (SIG 10.2), Colletotrichum gloeosporioides (GG 5.2), and Chaetomium globosum (GG 14.2). These results highlight the potential of orchid-derived endophytes as sustainable biofertilizers and biocontrol agents in horticultural crops.