Influence of the epiphyte Bacillus velezensis HIII11 isolated from strawberry on the metabolism of Arabidopsis thaliana cell wall

HIRSCH MAILÉN; BURGES PABLO; WYSS BEATRIZ; VILLARREAL NATALIA; MARINA MARÍA

Rosario

Conferencia; RAFV Conference 2023. XXXIV Argentinian Meeting of Plant Physiology; 2023

Sociedad Argentina de Fisiología Vegetal (SAFV)

The Bacillus genus comprises several bacteria recognized as biological control agents and/or plant growth-promoting bacteria. The reinforcement of the cell wall of the host plant is one of the benefits reported for this genus. The epiphyte HIII11 previously isolated from strawberry leaves (Fragaria x ananassa, Duch) showed the ability to promote the growth of A. thaliana plants and to inhibit the in vitro growing of Botrytis cinerea and Rhizopus stolonifer. In the present work, the sequencing of the 16S rRNA, recA, and recN genes, identified HIII11 as Bacillus velezensis. Therefore, we decided to evaluate whether HIII11 generates changes in the cell wall of A. thaliana plants. Col-0 plants previously inoculated with the bacteria and control plants (mock-inoculated with MgCl2) were used. We isolated cell walls as alcohol-insoluble residues (AIR). The amount of AIR was higher in HIII11-inoculated plants compared to the control. In addition, the growth capacity of B. cinerea and R. stolonifer on agar plates containing the extracted cell walls as the only source of nutrients was analyzed. Interestingly, we observed that the growth of both pathogens was lower on plates containing AIR from plants inoculated with HIII11. Besides, through Real Time PCR we measured the expression of genes related to the plant cell wall metabolism. As for the pectin metabolism, we did not observe changes in the expression of a putative polygalacturonase (AtPG1) compared to the control. However, the relative expression of pectin methylesterase (AtPME3) increased in plants inoculated with the epiphyte. In turn, HIII11 downregulated the expression of AtAra1 and AtβGal, which encode an α-arabinofuranosidase and β-galactosidase, respectively (related to side-chain metabolism). As regards hemicellulose metabolism, a downregulation of an expansin (AtExp8) was observed. All the results suggest that B. velezensis HIII11 could promote cell wall reinforcement in A. thaliana and encourage further study.