Determination of Efficiency between Molecular and Phenotypic Photosynthetic Predictors of Salt Stress in Common Bean (Phaseolus vulgaris L.)

• Adelyn Doyle, Marine Science, University of Delaware

• Antonette Todd, Department of Agriculture and Natural Resources, Delaware State University

Saltwater intrusion (SWI) is a pressing issue Delawarean communities and ecosystems face. With Earth warming at a rapid pace, globally rising sea levels will perpetuate SWI and worsen subsequent problems: soil aridity, infrastructure corrosion, coastal groundwater contamination, and crop damage. Conventional phenotypic indication entails observation of wilting, yellowing, and general decay; however, this stage is unideal for viable sample processing and analysis. Common bean (Phaseolus vulgaris L.), a staple crop in many regions, is a salt-sensitive species that is important to Delaware’s economy. To contribute to preventative measures against SWI, this study aims to determine if the effects of SWI can be observed preemptively on the molecular level of the common bean and to establish which method, molecular or phenotypic, is the most effective in early detection of stress. 21 first-trifoliate-stage common bean plants were  treated with assigned saltwater solutions, including control, low, and high salt levels of 0, 100, and 200 mM NaCl respectively. Collection ensued based on assigned time intervals: 0 hours, 6 hours, 12 hours, 24 hours, 48 hours, 72 hours, and 7 days. Photosynthetic efficiency was measured molecularly via RNA extraction, cDNA synthesis, and subsequent qPCR for Photosystem I-related gene expression, and phenotypically with chlorophyll and bulk carotenoid measurements. We expect to find a pattern of molecular responses that display earlier evidence of salt stress than the observed phenotypic parameters, implying that the molecular method is more efficient at identifying salt-induced symptoms. Determining a preemptive protocol to detect the presence of SWI is significant in finding solutions to manage and possibly halt salt stress effects. If a preventative measure is established utilizing molecular methods, scientists will gather the tools to guide farmers and other agricultural figures in adjusting growth processes or breeding salt-tolerant species of vital crop species.