BURKHOLDERIA SP. (AU4i) CHANGES CELL WALL METABOLISM AND DEFENSE GENE EXPRESSION AND PROVOKES BENEFICIAL EFFECTS IN ARABIDOPSIS THALIANA

COLAVOLPE B; GÁRRIZ A; VILLARREAL NM; ROSSI FR; ROMERO FM; RUIZ OA; SAINI A; MARINA M

Congreso; XXXI REUNIÓN ARGENTINA DE FISIOLOGÍA VEGETAL; 2016

Burkholderia sp. (AU4i) is a beneficial strain previously isolated from the pea rhizosphere. In the present work, we demonstrated that AU4i is also able to grow endophytically on A. thaliana, promoting plant growth as evidenced by an increment in plant fresh weight, the length of principal roots as well as thenumber of lateral roots. Direct contact between plant and AU4i is required to increase root length, ruling out the possibility that these effects are provoked by volatile or diffusible compounds. In addition, we evaluated the transcription of plant cell wall metabolism and defense genes during this endophyticinteraction. Our analysis showed the induction of a gene coding for a pectin-methyl esterase enzyme, as well as the jasmonate (JA) responsive gene PDF1.2. By contrast, the expression of PR1, a key component of the salicylic acid signaling was not modulated. The degree and pattern of methyl esterification and hormone signaling activation affects cell wall structure and properties with consequences on pathogens resistance, suggesting that AU4i could be used as a biocontrol agent. As a whole, AU4i causes a variety of beneficial effects in A. thaliana, provably modifying its cell wall metabolism and inducing the JA defense signaling pathway.