Differential analysis of host small RNAs identified conserved and new miRNAs that affect nodulation and strain selectivity in the Phaseolus vulgaris‐ Rhizobium etli symbiosis

CASTAINGTS, MELISSE; KIROLINKO, CRISTINA; RIVERO, CLAUDIO; VILLAGRA MANCINI, ULISES; BLANCO, FLAVIO ANTONIO; ZANETTI, MARÍA EUGENIA

NEW PHYTOLOGIST

WILEY-BLACKWELL PUBLISHING, INC

Año: 2022

0028-646X

Phaseolus vulgaris plants from the Mesoamerican center of genetic diversificationestablish a preferential and more efficient root nodule symbiosis with sympatric Rhizobiumetli strains. This is mediated by changes in host gene expression, which might occur eitherat transcriptional or post-transcriptional level. However, the implication of small RNAs(sRNAs)-mediated control of gene expression in strain selectivity has remained elusive. sRNA sequencing was used to identify host microRNAs (miRNAs) differentially regulatedin roots at early stages of the symbiotic interaction, which were further characterized byapplying a reverse genetic approach. In silico analysis identified known and new miRNAs that accumulated to higher levels inthe preferential and more efficient interaction. One of them, designated as Pvu-miR5924,participates in the mechanisms that determine the selection of R. etli strains that willcolonize the nodules. In addition, functional analysis of Pvu-miR390b verified that thismiRNA is a negative modulator of nodule formation and bacterial infectionThis study not only extended the list of miRNAs identified in P. vulgaris, but also enabledthe identification of miRNAs that play relevant functions in nodule formation, rhizobiainfection and the selection of the rhizobia strains that will occupy the nodule.