Bioprospecting cold-adapted plant growth promoting microorganisms from mountain environments

Mountain soils are challenging environments for all kinds of living things, including plants and microorganisms. Many cold-adapted microorganisms colonizing these extreme soils play important roles as promoters of plant growth and development; for that reason, they are called collectively plant growth-promoting microorganisms (PGPM). Even though there is seldom doubt concerning the usefulness of PGPM to develop eco-friendly bioinoculants, including biofertilizers and biocontrollers, a series of aspects need to be addressed in order to make this technology field-applicable. Among these aspects, the ecological and rhizosphere competences of PGPM are of paramount importance, particularly when considering the development of bioinoculants, well suited for the intensification of mountainous agricultural production. Studies on native, cold-adapted PGPM conducted in the Indian Himalayan region (IHR) and the Tropical Andes (TA) lead nowadays the research in this field. Noticeably, some common themes are emerging. For instance, soils in these mountain environments are colonized by many cold-adapted PGPM able to mobilize soil nutrients and to inhibit growth of plant pathogens. Studies aimed at deeply characterizing the abilities of such PGPM is likely to substantially contribute towards a better crop productivity in mountainous environments. The present review focuses on the importance of this microbial resource to improve crop productivity in IHR and TA. We also present a number of successful examples, which emphasize the effectiveness of some bioinoculants-developed from naturally occurring PGPM-when applied in the field.