Studies on diversity and antimicrobial potential of endophytic fungi from some medicinal plants

Abstract

An endophyte, by definition, is a microbe that lives within the tissues of a plant with no noticeable symptoms or signs of its presence in it. The association may range from symbiotic to one bordering on pathogenic, producing substances that help the plant by warding off pathogens. These endophytes also modify biology of plant enabling it to survive in environmental extremes, not usual for the species. Since last decade, fungal endophytes have received considerable attention as potential producers of biologically active (known/novel) products and various aspects of benefits to the plants has been demonstrated. The property of fungal endophytes to acquire ability to synthesize plant metabolites has gained attention in recent years. These studies has surged interests in biology of endophytes and whole approach of screening the plants of medicinal value has changed. Moreover the strategy to find endophytic fungi inside these plants is scaling new heights, especially in tropical regions. It is considered that the tropics harbor more than half of living species worldwide, and a large number of biologically active metabolites are probably produced in these ecosystems. Endophytes are an important component of fungal biodiversity that play important role in revealing estimated number of fungi on this earth (Hawksworth 2001). It is assumed that endophytes are biologically diverse in those areas where plants are unusual and diverse. Certainly, India is one among these regions. About 17,527 plants are known from India (Karthikeyan 2009). Considering such a vast plant diversity and a wide range of vegetation distributed along with the ‘Western Ghats’ forests (biodiversity hot spot of India) forests, it is presumed that a high degree of endophytic fungal diversity may be present, which may serve as valuable germplasm for exploring biologically active compounds. Many endophytes and their secondary products remain unknown to science and may hold promise for medicinal, agricultural or industrial uses. Survey of literature revealed that about 120 host plants belonging to 75 families have been studied so far and their associated endophytic fungal diversity reported. However, out of these, only a few hosts have been studied relative to their comprehensive endophytic fungal diversity, biology and potential. As such the available information on endophytic fungi from India is scanty.