Stable expression of nitric oxide synthase (NOS) from Ostreococcus tauri increases growth rate and seed production in Nicotiana tabacum

NEJAMKIN ANDRÉS; DEL CASTELLO, FIORELLA; CARILLO, NESTOR; FORESI NOELIA; MAYTA, MARTIN; LAMATTINA, LORENZO; CORREA-ARAGUNDE, NATALIA; LODEYRO, ANABELLA

Rosario

Simposio; Simposio de genomica funcional de Plantas; 2017

Nitric oxide (NO) is a signaling free radical involved in many physiological processes in species from all kingdoms of life. In plants, NO acts, as a growth regulator, stimulating root development and many growth-associated processes. While in animals, NO is synthesized by NO synthase (NOS) using L-arginine as substrate, in higher plants, no gene or protein homologous to NOS was identified. Our laboratory was the first in characterizing a NOS from the plant kingdom in the unicellular green alga Ostreococcus tauri (OtNOS). We found that recombinant OtNOS possess high activity in vitro, which is comparable to animal inducible NOS enzyme. OtNOS was cloned under the control of the constitutive 35S promoter, expressed in Nicotiana tabacum and the generated transgenic tobacco lines were analyzed. Transgenic tobaccos show increased biomass, number of flowers and seed production than plants transformed with the empty vector. High level of NO and an increased expression of non-symbiotic hemoglobin (non-sym-Hb, it converts NO to NO3-), was detected in roots of transgenic lines. We are currently studying the effect of OtNOS expression on the metabolism of nitrogen (N) and carbon. In plants, N is the major macronutrient for growth and productivity, and is mainly stored as L-Arginine. We postulate that OtNOS expression increases N use efficiency (NUE) by improving fixing, assimilation and N recycling in tobacco.