Endophytic Actinomycetes and Their Interactions with Host Plants

Abstract

Endophytic microbes including bacteria, actinomycetes and fungi are ubiquitous in most plant species, especially in field-grown plants. As of 1997, bacteria isolated from the internal plant tissue of healthy-looking plants were comprised of over 129 species representing over 54 genera1). Although some of the endophytes are pathogenic to host plants and can locally or systemically colonize plant tissues, others latently reside in the internal tissues of nonsymptomatic plants without causing any adverse effects to the plants. Consequently, intimate associations between endophytes and host plants can be formed without harming the plant. Endophytes have been demonstrated to improve and promote growth of host plants as well as to reduce disease symptoms caused by plant pathogens and/or various environmental stresses. The low stress tolerance of axenic plants is commonly believed to result partly from the absence of endophytic microbes1). Management of beneficial microbial communities to favor plant growth could be realized by a deeper understanding of the physiological and molecular interactions between microbes and plants . This research also may have broader economic and environmental impacts.