PhD student Louisiana State University BATON ROUGE, Louisiana
Body of Abstract: High salinity is one of the most severe abiotic stresses causing agricultural losses worldwide due to detrimental effects on arable land and crop yield. As the first organ encountering salt in the soil, roots play a critical role in adjusting to salt-resilient growth. Therefore, understanding how roots could tolerate high salinity is a priority when designing robust crops adapted to saline soils. However, few studies have explored cellular responses in roots of wild plants from saline environments to detect novel mechanisms naturally selected to cope with high salinity. We have used the extremophyte model Schrenkiella parvula and its relative salt-sensitive model Arabidopsis thaliana, to identify root developmental responses to high salinity. We first assessed the accumulation of sodium in different cell populations in the roots when treated with varying salinities in both model species. We then examined if cell death coincided with Na accumulation and excessive production of reactive oxygen species. Our results suggest that the extremophyte is able to accumulate sodium in root cells without cell death at high salinities in distinct root zones critical to sustaining growth under stress. Contrastingly, Arabidopsis was unable to maintain sodium influx while keeping the majority of cells active when exposed to salinity levels reaching 200 mM NaCl. S. parvula roots were able to continue generating new lateral roots and increase their rate of lateral root initiation with increasing salinities up to 400 mM NaCl surpassing the rate of cell death observed in mature root tips. Our study highlights the resilient cell populations generated as a result of developmental adjustments in the extremophyte compared to more vulnerable root zones to cell death in maladapted plants to high salinities.