Salinity generates varying chemical and biochemical responses in Physalis ixocarpa (Solanaceae) during different times of exposure

Abstract

Background: Diverse plants respond differently to similar saline conditions. The aim of the current study was to determine the variation in the foliar contents of phenolic compounds, carotenoids, and proline, and the variation of the activities of catalase (CAT) and superoxide dismutase (SOD) of the edible and medicinal Physalis ixocarpa throughout three different times of exposure (24, 42, and 57 d) to three salinity levels (0, 90, and 120 mM NaCl). The specific effects of salt concentration and time of exposure were also assessed.

Results: Proline increase was the only clearly salt-related response, evidencing its significant protective role in salinized P. ixocarpa under either short, medium, or chronic exposure. One phenolic acid, which increased up to 26.26 times its concentration (compared to control, under high salinity at the longest treatment) out of the eight compounds forming the phenolic profile of the species, and CAT and SOD, under 90 and 120 mM NaCl, respectively, and short and medium exposure, also made important contributions. Salt concentration mainly affected total phenolics, tannins, phenolic acids (PA), proline, and SOD, whereas exposure time mainly affected flavonoids, carotenoids, and CAT.

Conclusions: The participation of the different protection mechanisms of P. ixocarpa against salinity is dynamic and complementary, and it is differentially modulated by the salt concentration and the time of exposure. Proline is the main mechanism for the species. The accurate chronic registration of the responses is needed to determine its adaptation potential to salt stress. The results have agronomic and food quality implications.