Microbial Endophytes: Future Challenges

Endophytes are represented by a diverse group of prokaryotic (bacteria or cyanobacteria) or eukaryotic (fungi or parasitic vascular plants) organisms that form lifelong associations within tissues of plants. Ecologically, these associations are viewed as

  • PDF / 142,736 Bytes
  • 11 Pages / 504.57 x 720 pts Page_size
  • 71 Downloads / 201 Views

DOWNLOAD

REPORT


22

Charles W. Bacon and Dorothy M. Hinton

Abstract

Endophytes are represented by a diverse group of prokaryotic (bacteria or cyanobacteria) or eukaryotic (fungi or parasitic vascular plants) organisms that form lifelong associations within tissues of plants. Ecologically, these associations are viewed as mutualistic and as sources of secondary metabolites capable of serving as novel medicinals and agrichemicals. It is this area that serve to stimulate the large research investigations from all parts of the planet. The challenges as we see them are multifaceted. These include an understanding of the genetics nature of microbial endophytes, how endophytes communicate and partition themselves within hosts, how do these biotrophic organisms obtain nutrients, and are specific nutrient acquisitions key to the final effects observed? Further, are there basic difference between bacterial endophytes and fungal endophytes? What influence the host interactions to produce the desired effects, and how is the stability of the system affected. Thus, future challenges are dependent on identifying, delineating, dissecting, and defining the mechanisms whereby hosts and their symbionts accomplish this curious lifestyle. Defining these biological mechanisms will ensure the present and future successful technological applications of microbial endophytes.

1

C.W. Bacon (*) • D.M. Hinton Toxicology and Mycotoxin Research Unit, USDA, Agriculture Research Service, Russell Research Center, 950 College Station Road, Athens, GA 30605, USA e-mail: [email protected]

Introduction

The emphasis in greater sustainability and an increase in public concern for hazards associated with synthetic chemical pesticides and transgenic plants have produced a resurgence of interest in the use of introduced microorganisms for biological control of plant pathogens. Most of these microorganisms are inconsistent in their performance in biological control resulting in reduced commercial

V.C. Verma and A.C. Gange (eds.), Advances in Endophytic Research, DOI 10.1007/978-81-322-1575-2_22, © Springer India 2014

441

442

development and widespread use. The major reason for this lack of performance is inadequate colonization of the target site, variation in expression of control at that site, and need for numerous applications. Most of the biocontrol organisms are either soil or surface dwellers and have very little affinity to plants as specific colonizers as evidenced by ineffective controls of disease following repeated applications (see Thomashow and Weller 1996; Hallmann et al. 1997; Hallmann 2001 for review). However, we are concerned with here a unique group of microbial organisms that form endophytic associations within plants, and several of these have been discussed in other chapters in this book. Microbial endophytes actively colonize below and aboveground host tissues and establish long-term associations, actually lifelong natural associations, without imposing any obvious harm to the host. Since the work demonstrating the production of ru