The tetrahydrofolate-dependent nitric oxide synthase from the green alga Ostreococcus tauri increases tolerance to abiotic stresses and influences stomatal development in Arabidopsis.

FORESI NOELIA PAMELA; MAYTA MARTIN; LODEYRO ANABELA; SCUFFI DENISE; CORREA ARAGUNDE NATALIA; GARCÍA-MATA CARLOS; CASALONGUÉ, CLAUDIA; CARRILLO NESTOR; LAMATTINA LORENZO

PLANT JOURNAL

WILEY-BLACKWELL PUBLISHING, INC

Año: 2015 vol. 22 p. 3816 - 3830

0960-7412

Nitric oxide (NO) is a signaling molecule with diverse biological functions in plants. NO plays a crucial role in growth and development, from germination to senescence, and is also involved in plant responses to biotic and abiotic stresses. In animals, NO is synthesized through well described nitric oxide synthase (NOS) enzymes. NOS activity has also been detected in higher plants, but no gene coding for a NOS protein, or for the enzymes required for the synthesis of tetrahydrobiopterin, an essential cofactor of mammalian NOS activity, have been identified so far. Recently, a NOS gene from the unicellular marine alga Ostreococcus tauri (OtNOS) has been discovered and characterized. Arabidopsis thaliana plants were transformed with OtNOS under the control of the inducible short promoter fragment (SPF) of the sunflower (Helianthus annuus) Hahb-4 gene, which responds to abiotic stresses and abscisic acid. Transgenic plants expressing OtNOS accumulated higher NO concentration compared to siblings transformed with the empty vector (EV), and displayed enhanced salt, drought and oxidative stress tolerance. Moreover, transgenic OtNOS lines exhibited increased stomatal development compared with plants transformed with the EV. Both in vitro and in vivo experiments indicate that OtNOS, unlike mammalian NOS, can efficiently use tetrahydrofolate as a cofactor in Arabidopsis plants. The modulation of NO production for alleviating abiotic stress disturbances in higher plants highlights the potential of the genetic manipulation directed to influence the NO metabolism as a tool to improve plant fitness under adverse growth conditions.