Unravelling the associations between local environmental factors, soil properties and cultivable root-associated endophytes in dry pea (Pisum sativum L.)

Abstract

Endophytic microorganisms in legume roots form an important interface between soil conditions and plant health. However, field-scale evidence remains limited on how cultivable endophytic bacterial and fungal assemblages in pea roots vary with soil and climatic conditions after nodule removal. In this study, 96 healthy pea plants were collected from eight field plots in Palencia, Spain. Cultivable endophytic bacteria and fungi were isolated from surface-disinfected root tissues after nodule removal, and community composition was assessed by Sanger sequencing of 16 S rRNA gene and ITS markers using a 97% OTU workflow. Bacterial communities showed greater compositional variation among plots, although genera such as Pseudomonas , Achromobacter , Peribacillus and Bacillus were repeatedly isolated across sites. In the cultivable fungal fraction, Fusarium was the most frequently isolated genus. Non-metric multidimensional scaling (NMDS)-envfit analysis showed that bacterial community variation was significantly associated with soil silt percentage (r² = 0.87, P = 0.007), whereas fungal community variation was significantly associated with exchangeable magnesium (r² = 0.67, P = 0.046). No climatic variable showed a significant fit at the study scale. Overall, these results provide a culture-based description of recurrent endophytic taxa in healthy pea roots and their preliminary associations with local soil conditions, offering a basis for future strain-based functional studies and more comprehensive microbiome analyses using culture-independent approaches.

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