Abstract
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.
Highlights
Soil salinity is a recurring problem in several parts of the world, with a predominance in arid and semi-arid regions (Food and Agricultural Organization of The United Nations, FAO, 2019)
The increase in electric conductivity (EC) led to a linear decrease in the seed germination percentage, which dropped from 100% in the control treatment to around 70% in the highest NaCl concentration (Figure 1B)
There are some similarities between this present study and their study, Guo and colleagues did not report the specific accession of green foxtail millet that was employed in their study; making it difficult to explain this difference in the results
Summary
Soil salinity is a recurring problem in several parts of the world, with a predominance in arid and semi-arid regions (Food and Agricultural Organization of The United Nations, FAO, 2019). More than a hundred countries are affected by the presence of salt in their soils, and the global trend indicates even more areas to be affected with the current climatic changes (Zaman; Shahid; Heng, 2018). 20% of the agricultural land in the world has saline and/or sodium soils, among which 25% to 30% of the irrigated land is commercially unproductive due to the salinity conditions of the soil (Shahid; Zaman; Heng, 2018). In Brazil, the saline and sodium soils occur in the State of Rio Grande do Sul, in the Pantanal region of the State of Mato Grosso and, with predominance in the semiarid part of the Northeast Region. A priori, soils that have electrical conductivity (CE) of the saturation extract >4 dS/m at 25 °C are considered as saline; since many fruits, vegetables, and ornamental species suffer from the adverse effects of salinity in a range of 2 to 4 dS/m, soils with CE> 2 dS/m at 25 °C are considered to be saline (Bresler; Mc Neal; Carter, 1982)
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