Azospirillum brasilense and ABA improve growth in Arabidopsis thaliana

COHEN A; PONTIN M; BOTTINI R,; PICCOLI P

Puerto Vallarta, Mexico

Congreso; 19 th IPGSA Meeting (The International Plant Growth Substances Association).; 2007

The International Plant Growth Substances Association

Azospirillum brasilense and ABA improve growth in Arabidopsis thaliana Cohen, Ana; Pontin, Mariela; Bottini, Rubén; Piccoli, Patricia. Facultad de Ciencias Agrarias-CONICET, Universidad Nacional de Cuyo, Alte. Brown 500, M5528AHB Chacras de Coria, Argentina; ppiccoli@fca.uncu.edu.ar Azospirillum sp. are plant growth promoting bacteria (PGPB) that increase grain yield in cereals and general plant growth in different species. The beneficial effects of PGPB have been partially attributed to bacterial production of plant hormones, especially “growth promoters” like auxins, gibberellins cytokinins and, more recently, ABA (see Cohen et al. this meeting). In this work 7 days-old A. thaliana plants inoculated with 10 uL 106 CFU.mL-1 of A. brasilense or sprayed with 100 uM ABA, both with and without 10 uM fluridone (inhibitor of carotene synthesis), improved root length. However ABA did not increased root hair density and emergence of lateral roots as Azospirillum did. Leaf area was increased by two-fold in inoculated plants. Interestingly, Azospirillum inoculation enhanced trichome development. These preliminary results suggest that Azospirillum beneficial effects may be mediated by different phytohormones, including ABA.