Fungal endophytes: A potent biocontrol agent and a bioactive metabolites reservoir

Endophytes protect the host plant for their entire life cycle and they have the ability to act as a biocontrol agent. Organisms protect the host plant through antibiosis, parasitism and competition mechanism in the biocontrol process. The improper and excessive use of agrochemicals makes the phytopathogens insensitive and leads to the development of resistant fungal pathogens. Chemical fungicides are expensive and have many negative impacts on the environment. The use of endophyte as the biocontrol agent is effective in controlling the plant disease and to achieve sustainable agriculture. Endophytes have antagonistic activity against disease-causing phytopathogens and also capable to produce antimicrobial, insecticidal, antioxidant, anti-tumor and anti-viral metabolites. Perfumoid, phomoenamide, joxysporidinone, alantrypinene, alantryleunone, (−)-4,6′-anhydrooxysporidinone and (−)-6-deoxyoxysporidinone are the few alkaloid compounds of endophytic fungi. Nidurufin, sterigmatocystin, averantin, 11a-methoxycurvularin 4, 11b-methoxycurvularin, tenellone H, phomopene and 1-chloro-2,4-dihydroxy-5-methoxy-7-methylanthraquinone are the endophytic fungal compounds reported with cytotoxic activity in the year between 2008-2019. The present review concentrates on the antagonistic activity of endophytes towards phytopathogens and their bioactive secondary metabolites with pharmacological properties.