Structural and functional microbial diversity determined by shrubs ecophysiological adaptation in Negev desert

Background/Question/Methods

Microbial function, composition and distribution play fundamental roles in ecosystem ecology. Interaction between microbes and plants reciprocally influence both their ecophysiologies. Therefore, adaptation of desert plants to the hot and arid environment may be greatly affected by their associated microbes. Yet it is not clear to what degree the structure and function of the microbial communities contribute to the adaptation of desert plant and vice versa what is the specific effect of the plant on bacterial desert community. 

In this study we correlate between specific pattern of microbial communities and their associated desert plants to assess the potential effect on their ecophysiology. Three desert shrubs typical to the Israeli desert having different ecophysiological adaptations, Atriplex halimus, Artemisa herba-alba, and Hammada scoparia, were evaluated physiologically and their below-canopy and above-canopy composition of the microbial community were determined.

Microbial functional diversity, microbial biomass, CO₂ evolution, and community-level physiological profile (CLPP) in soil and leaves were detected using the MicroResp™ method and compared with interplant open area that was used as a control (CO). We extracted DNA from leaf surfaces and soil samples beneath the shrubs to study associated microbial structural diversity. To study plant-associated microbial structural diversity bacterial and fungal communities were determined using Ion Torrent sequencing of 16S rRNA and ribosomal ITS1 genes multi reads, respectively.  

Results/Conclusions

The results demonstrated the importance and advantage of plant ecophysiological adaptations, which play an important role as abiotic environmental mediators and microbial-community 'temporary hosts', determining microbial biomass, CO₂ evolution, CLPP, functional and structural diversity. Identified operational taxonomic units (OTUs) revealed distinct microbial order composition is plant-type specific indicating that the plants provide suitable and unique microenvironment. The effect each shrub has on its associated microbial composition together with distinct micro-environmental properties strongly points to a role of adaptation in shaping microbial diversity.

Based on our data it can be concluded that each of the three shrubs provide unique microenvironment effecting the composition of microbial phyllosphere and laimosphere communities. This raises the possibility that microbial diversity is dictated by the specific ecophysiological adaptation of the plants, and that it might play a positive role in its plasticity.   

Overall, our findings contribute to a better understanding of the link between plant ecophysiological adaptation as a 'temporary host' and the biotic-community parameters in extreme xeric environments.