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

HIRSCH, MAILÉN; BURGES, PABLO L.; WYSS, BEATRIZ; VILLARREAL, NATALIA M.; MARINA, MARÍA

Rosario

Congreso; XXXIV Argentinian Meeting of Plant Phisiology; 2023

Sociedad Argentina de Fisiología Vegetal

 TheBacillus genus comprises several bacteria recognized as biological controlagents and/or plant growth-promoting bacteria. The reinforcement of the cellwall of the host plant is one of the benefits reported for this genus. Theepiphyte HIII11 previously isolated from strawberry leaves (Fragaria xananassa, Duch) showed the ability to promote the growth of A. thalianaplants and to inhibit the in vitro growing of Botrytis cinereaand Rhizopus stolonifer. In the present work, the sequencing of the 16SrRNA, 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 andcontrol plants (mock-inoculated with MgCl2) were used. We isolatedcell walls as alcohol-insoluble residues (AIR). The amount of AIR was higher inHIII11-inoculated plants compared to the control. In addition, the growthcapacity of B. cinerea and R. stolonifer on agar platescontaining the extracted cell walls as the only source of nutrients wasanalyzed. Interestingly, we observed that the growth of both pathogens waslower on plates containing AIR from plants inoculated with HIII11. Besides,through Real Time PCR we measured the expression of genes related to the plantcell wall metabolism. As for the pectin metabolism, we did not observe changesin the expression of a putative polygalacturonase (AtPG1) compared tothe control. However, the relative expression of pectin methylesterase (AtPME3)increased in plants inoculated with the epiphyte. In turn, HIII11 downregulatedthe expression of AtAra1 and AtβGal, which encode an α-arabinofuranosidaseand β-galactosidase, respectively (related to side-chain metabolism). Asregards hemicellulose metabolism, a downregulation of an expansin (AtExp8)was observed. All the results suggest that B. velezensis HIII11 couldpromote cell wall reinforcement in A. thaliana and encourage furtherstudy.