INVESTIGADORES
COHEN Ana Carmen
congresos y reuniones científicas
Título:
Study of the crtZ in Pseudomonas fluorescens isolated from grape roots as related to bacterial synthesis of abscisic acid
Autor/es:
JOHANA DOMINGUEZ; SANDRA GARCIA LAMAPZONA; ANA C. COHEN; M. VICTORIA SALOMON; PATRICIA PICCOLI
Lugar:
Tucuman
Reunión:
Congreso; VII Congreso Argentino de Microbiologia General. SAMIGE DEL BICENTENARIO; 2011
Institución organizadora:
Sociedad Argentina de Microbiologia General
Resumen:
Plant growth-promoting rhizobacteria (PGPR) colonize the root system of several plants with the
effect of increasing yield. Among the mechanisms proposed to explain such beneficial effect is
the production of phytohormones by the bacteria, including abscisic acid (ABA). In this regard
Pseudomonas fluorescens has received particular attention. We have previously isolated P.
fluorescens from roots of Vitis vinifera (cv. Malbec L.) and demonstrated that it produces ABA in
chemically-defined medium. The aim of this work was to study if the crtZ gene, which encodes a
crucial enzyme in the biosynthesis of zeaxanthin in bacteria, is present in P. fluorescens. The
crtZ gene encodes the enzyme â carotene hydroxylase, an oxidoreductase involved in the
biosynthesis of zeaxanthin from â carotene hydroxylation. In plants, zeaxanthin is a key
intermediate in the biosynthesis of ABA. Specific primers were designed from the crtZ gene
sequence presents in Pseudomonas putida KT 2440. The expected gene was amplified by PCR
and then cloned into competent cells. Plasmidic DNA was extracted and sequenced. Homology
searches were done using the basic local alignment Search Tool BLAST program showing 98%
homology with the crtZ gene found in Pseudomonas putida KT 2440. This result shows that crtZ
gene is present in Pseudomonas fluorescens, which strongly suggests that the ABA
biosynthetic pathway in bacteria is via 1-deoxy-D-xylulose-5-phosphate (DXP) by carotenoid
breakdown, as it happens in plastids of plants.