Interaction between IAA and ET in ISR-expressing strawberry plants inoculated with Azospirillum brasilense

GUERRERO-MOLINA, MF.; ELÍAS, JM.; PERATO SM.; PEDRAZA R.O.; DÍAZ RICCI, JC

Foz do Iguazú

Congreso; 11th International Congress of Plant Molecular Biology Iguazú Falls (Argentina - Brazil). 25-30 October.; 2015

International Plant Molecular Biology

Plant growth-promoting bacteria (PGPB) colonization isoften associated with the activation of plant induced systemic resistance (ISR)dependent of ethylene (ET) and jasmonic acid. The strain REC3 of Azospirillumbrasilense is a PGPB capable of inducing growth of strawberry plants (Fragariaananassa) in controlled and field conditions. The auxin, indol-3-aceticacid (IAA), is implicated in plant growth and defence, and can be synthesizedby A. brasilense. Since modulation of plant growth and immunity areregulated by hormonal signals, we were interested in investigating theparticipation of IAA and ET in the interaction of A. brasilense withstrawberry plants. In-vitro micropropagated strawberry plants were grownin hydroponic culture and inoculated with REC3 (106 CFU·ml-1). IAA productionwas quantified by HPLC and ET by GC, at different hours post inoculation (hpi):6 to 120. The expression of IAA and ET related genes was measured by qPCR. Theevolution of IAA content in REC3-inoculated plants in comparison tonon-inoculated plants (control), exhibited a biphasic behavior with a firstpeak at 12 hpi (105%) and the second at 120 hpi (136%), whereas the ETproduction rate was higher during the first 12 hpi (47%) and decreasedafterwards. Also at 12 hpi, there was a positive regulation of auxin relatedgenes, Faami1 and Faaux1, and genes implicated in ET perceptionand synthesis: Faetr1, Faers1 y Faein4, Faaco2 and Faacs1.Results obtained suggest that IAA modulates ET response in strawberry plantsshortly after inoculation with A. brasilense REC3.