MINI-REVIEW Plant-endophyte symbiosis, an ecological perspective Zahoor Ahmed Wani & Nasheeman Ashraf & Tabasum Mohiuddin & Syed Riyaz-Ul-Hassan Received: 13 January 2015 /Revised: 13 February 2015 /Accepted: 15 February 2015 # Springer-Verlag Berlin Heidelberg 2015 Abstract Endophytism is the phenomenon of mutualistic as- sociation of a plant with a microorganism wherein the microbe lives within the tissues of the plant without causing any symp- toms of disease. In addition to being a treasured biological resource, endophytes play diverse indispensable functions in nature for plant growth, development, stress tolerance, and adaptation. Our understanding of endophytism and its ecolog- ical aspects are overtly limited, and we have only recently started to appreciate its essence. Endophytes may impact plant biology through the production of diverse chemical entities including, but not limited to, plant growth hormones and by modulating the gene expression of defense and other second- ary metabolic pathways of the host. Studies have shown dif- ferential recruitment of endophytes in endophytic populations of plants growing in the same locations, indicating host spec- ificity and that endophytes evolve in a coordinated fashion with the host plants. Endophytic technology can be employed for the efficient production of agricultural and economically important plants and plant products. The rational application of endophytes to manipulate the microbiota, intimately asso- ciated with plants, can help in enhancement of production of agricultural produce, increased production of key metabolites in medicinal and aromatic plants, as well as adaption to new bio-geographic regions through tolerance to various biotic and abiotic conditions. However, the potential of endophytic biol- ogy can be judiciously harnessed only when we obtain insight into the molecular mechanism of this unique mutualistic rela- tionship. In this paper, we present a discussion on endophytes, endophytism, their significance, and diverse functions in na- ture as unraveled by the latest research to understand this universal natural phenomenon. Keywords Endophytes . Endophytism . Multitrophic interaction . Phytoremediation . Plant adaptation . Systems biology approach Introduction Endophytic biology is pursued in research with multitude of objectives that can be broadly classified into two categories— bioprospecting and plant-microbe symbiosis (Fig. 1). The bioprospecting aspect of endophytism has been extensively reviewed (Aly et al. 2011; Porras-Alfaro and Bayman 2011; Mousa and Raizada 2013; Chen et al. 2014; Brader et al. 2014; Strobel 2015). However, the other aspect, i.e., plant- microbe symbiosis, at molecular level, has been poorly under- stood (Rodriguez and Roossinck 2012; Saikkonen et al. 1998; Ryan et al. 2008). Plant-microbe interactions are ubiquitous and diverse in nature (Redman et al. 2002; Kuldau and Bacon 2008; Mitter et al. 2013). In fact, each plant is a complex community, rather than a single organism, owing to its en- gagement in diverse heterospecific associations (Kiers and Denison 2008; Rodriguez et al. 2009; Rey and Schornack 2013). The complex interplay of diverse array of microbial communities with the host plant affects its ecophysiology such Z. A. Wani : S. Riyaz-Ul-Hassan Microbial Biotechnology Division, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu Tawi 180 001, India N. Ashraf : T. Mohiuddin Plant Biotechnology Division, CSIR-Indian Institute of Integrative Medicine, Sanat Nagar, Srinagar 190 005, India Z. A. Wani : N. Ashraf : T. Mohiuddin : S. Riyaz-Ul-Hassan (*) Academy of Scientific and Innovative Research, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu Tawi 180 001, India e-mail: srhassan@iiim.ac.in S. Riyaz-Ul-Hassan e-mail: riyaz.andrabi@gmail.com Appl Microbiol Biotechnol DOI 10.1007/s00253-015-6487-3