|Cornacchione, Monica - Estacion Experimental Agroindustrial Obispo Colombres (EEAOC)|
|Kaundal, Amita - University Of California - Cooperative Extension Service|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 8/28/2018
Publication Date: N/A
Technical Abstract: Salinity is one of the most important abiotic stresses that adversely affects plant growth and productivity worldwide. About 1/5th of the irrigated land used for agriculture is affected by salt. Salinity affects plants in two important ways: through osmotic and/or ionic stress. Osmotic stress is considered the first adverse effect on plant growth as a plant is exposed to salinity, with ion toxicity contributing in later stages. Plants respond to salinity stress through a complex network of physiological, biochemical, and ecological strategies. Although several genomic resources have been developed in most crop plants, the functional characterization of genes involved in salt tolerance is still lacking. In order to manage the salinity problem, it is important to link the biochemical and physiological responses with the underlying genetic determinants, which will be the key in developing genetic material tolerant to salt. Studies on alfalfa (Medicago sativa) showed that the most salt-tolerant genotypes that were top performers for biomass accumulated low Na+ and Cl-. Foliar leaf area, photosynthesis, transpiration and stomatal conductance were reduced in most genotypes under salinity. Various genes that are known to play important roles in different components of the salt tolerance mechanism were upregulated during salt stress. Gene expression analyses were used to classify genotypes based on component traits. Na+/H+ exchangers (NHX) that are known to play important role in sequestration of Na+ into vacuole and keeping cytoplasmic Na+ concentration low also played critical role in alfalfa salt tolerance. Bioinformatics and phylogenetic analyses of Arabidopsis NHX genes enabled us to characterize corresponding genes in Medicago truncatula. Na+ exclusion was found to be responsible for the relatively smaller increase in Na+ concentration compared to Cl-, in roots under salt stress. This new knowledge gained from M. truncatula may become instrumental in characterizing salt tolerance responses in alfalfa. Development of new salt-tolerant varieties will allow farmers to grow alfalfa in marginal lands and sustain high-value agricultural production even by using poor quality irrigation water.