Soil Core Bacteria and Main Edaphic Functions in Pecan Nut Trees (Carya illinoinensis) Rhizosphere in an Arid Agroecosystem

Abstract

Microorganisms are fundamental for preserving plant health and productivity, thus knowledge of their composition and metabolism in a particular agroecosystem could be used as a tool to sustainably improve or maintain crop performance. Therefore, this study aimed to identify the bacterial core and its functional characteristics in the rhizosphere of Carya illinoinensis. This study was carried out in the arid north of Mexico (Viesca, Coahuila) in 2022 in an orchard of 20-25-year-old young trees, with a nut production per tree of 20-22 kg. Sampling was carried out at five points in the orchard: the four corners and the center. Metagenomic analyses of the 16S rRNA gene were performed to determine the taxonomic composition of the microbial species. In addition, functional predictions were made using Phylogenetic Community Research by Reconstruction of Unobserved States (PICRUSt) to estimate gene abundance within metabolic pathways. The ASVs of the bacterial population of the studied orchard were classified into 60 phyla, 130 classes, 392 orders, 40 families, 40 genera, and 1766 species. Proteobacteria, Acidobacteriota, and Actinobacteriota were the most abundant phyla. At the genus level, Pararheinheimera (X̅=5.5%) and two unknown genera of the Thermoanaerobaculia class (X̅=3.2% and X̅=2.7%, respectively) were the main taxa. In addition, glucose oxidation, phospholipase, and L-rhamnose production were the main metabolic pathways associated with the bacterial community, which confer plant growth-promoting properties and crop resilience under biotic and abiotic stress conditions. Thus, knowledge of the local bacteriome is a tool to propose the appropriate agronomic management to exploit the potential of key taxa to promote plant growth or isolate specific strains for the generation of biofertilizers.