Effect of salinity stress in Setaria viridis (L.) P. Beauv. accession A10.1 during seed germination and plant development

Effeito do estresse salino em Setaria viridis (L.) P. Beauv. acesso A10.1 durante a germinação das sementes e desenvolvimento das plantas

ABSTRACT

Setaria viridis (L.) P. Beauv. is a species proposed to be used as model plant in reverse genetics studies for the validation of gene function. Soil salinity is a recurring problem present in more than a 100 countries worldwide, and approximately 20% of the agricultural land in the world has saline and/or sodium soils. Saline stress affects all the main processes of the plant, such as germination, growth, and, consequently, the yield. The present study aimed at determining the tolerance levels of S. viridisA10.1 to saline stress and identify its potential as a model plant to validate salt-tolerance candidate genes/alleles as well as promoter sequences from salt-responsive genes. In an initial experiment, the seeds of the plant were sown on a germination medium containing an increasing concentration of NaCl (0, 30, 60, 90, 120, or 150 mM), and maintained there during the initial growth stage; and, in another experiment, the plants at the vegetative growth stage were submitted to increasing doses of NaCl (0.0, 0.2, 0.4, 0.6, 0.8, and 1.0g per 100g of the substrate). The germination rate was found to be affected a little by the salinity, while the seedlings development was impaired right after germination. Plant in the vegetative growth stage experienced a reduction in the evapotranspiration rates and pigment levels, along with an impairment in the system of capture and use of light, and a decrease in the leaf gas exchange rates, resulting in less accumulation of dry and fresh plant biomass proportional to the salt dose used. Plants started to die within a week at doses ≥19.4 dS/m. In conclusion, A10.1 is a glycophyte plant with some level of salt-tolerance and might be used as a model plant to validate salt-tolerance candidate genes/alleles, as well as promoters salt-responsive genes, depending on the right combination of plant age and level of stress. As seed germination is affected only little by salt stress at NaCl doses of about 15 dS/m or less, A10.1 might not be used to validate genes/alleles with a putative role regarding this trait.

Index terms:
Abiotic stress; phenomics; biosaline agriculture; plant biotechnology; salt responsive genes.