Partner or perish: tree microbiomes and climate change.

Understanding the complex relationships between plants, their microbiomes, and environmental changes is crucial for improving growth and survival, especially for long-lived tree species. Trees, like other plants, maintain close associations with a multitude of microorganisms on and within their tissues, forming a 'holobiont'. However, a comprehensive framework for detailed tree-microbiome dynamics, and the implications for climate adaptation, is currently lacking. This review identifies gaps in the existing literature, emphasizing the need for more research to explore the coevolution of the holobiont and the full extent of climate change impact on tree growth and survival. Advancing our knowledge of plant-microbial interactions presents opportunities to enhance tree adaptability and mitigate adverse impacts of climate changes on trees.

Stable isotope probing: technical considerations when resolving (15)N-labeled RNA in gradients.

RNA based stable isotope probing (SIP) facilitates the detection and identification of active members of microbial populations that are involved in the assimilation of an isotopically labeled compound. (15)N-RNA-SIP is a new method that has been discussed in recent literature but has not yet been tested. Herein, we define the limitations to using (15)N-labeled substrates for SIP and propose modifications to compensate for some of these shortcomings. We have used (15)N-RNA-SIP as a tool for analysing mixed bacterial populations that use nitrogen substrates. After incubating mixed microbial communities with (15)N-ammonium chloride or (15)N(2) we assessed the fractionation resolution of (15)N-RNA by isopycnic centrifugation in caesium trifluoroacetate (CsTFA) gradients. We found that the more isotopic label incorporated, the further the buoyant density (BD) separation between (15)N- and (14)N-RNA, however it was not possible to resolve the labeled from unlabeled RNA definitively through gradient fractionation. Terminal-restriction fragment length polymorphism (T-RFLP) analysis of the extracted RNA and fluorescent in situ hybridisation (FISH) analysis of the enrichment cultures provided some insight into the organisms involved in nitrogen fixation. This approach is not without its limitations and will require further developments to assess its applicability to other nitrogen-fixing environments.