The Impact of Genotype and Salinity on Physiological Function, Secondary Metabolite Accumulation, and Antioxidative Responses in Lettuce

Abstract

Salinity inhibits plant growth due to osmotic and ionic effects. However, little is known about the impact of genotype and salinity on biochemical and molecular processes in the leafy vegetable lettuce. We report here evaluations of two lettuce types, Verte (NaCl tolerant) and Romaine (NaCl sensitive), under iso-osmotic 100 mM NaCl and 77 mM Na(2)SO(4) treatments. As compared to Romaine, NaCl-treated Verte displayed better growth, contained lower levels of inorganic cations in leaves, and possessed superior antioxidative capacity due to enhanced carotenoid and phenolics biosynthesis and more active antioxidative enzymes resulting in reduced membrane damage. Both genotypes had relatively similar growth patterns under Na(2)SO(4) treatment, but Romaine showed enhanced root lignification, greater malondialdehyde formation, and suppressed Fe-superoxide dismutase expression in roots as compared with Verte.

Application timing of nitric oxide ameliorates on deleterious effects of salinity on growth and fruit quality of strawberry cv. ‘Selva’

“…Khayat et al [50] could improve strawberry TSS and ascorbic acid concentration with moderate salinity and supplementary calcium. NO application without combination with salinity increased antioxidant compounds like total anthocyanins and polyphenol in our research, which are in accordance with experiments on other plant species indicating increment of plant enzymatic and non-enzymatic antioxidant system under adverse abiotic stress conditions [51][52][53][54]. NO, is an important bioactive signaling molecule that is involved in regulation of plant responses under stress conditions [13], and under salinity conditions synthesis of this molecule increases [8].…”

The effects of salt and drought stress on phenolic accumulation in greenhouse-grown Hypericum pruinatum

“…Similarly, total phenolic content decreased by 30, 54, and 61% in response to 20, 40, and 60 μM NaCl treatments in Nigella sativa (Bourgou et al, 2010). The differential accumulation of phenolic fractions under different salt treatments in the plant species with different salinity resistance suggests that salt resistant species and varieties may employ phenolic compounds, especially phenolic acids and flavonoids differentially to adapt to contrasting salinities (Mahmoudi et al, 2010). This phenomenon was confirmed by Salah et al, (2011) who reported that The salt-tolerant Medicago ciliaris line TNC 1.8 was more efficient at managing salt-induced oxidative damage in leaves and in roots than the saltsensitive line TNC 11.9, by preserving higher phenolic compound levels in both organs.…”

Varied tolerance to NaCl salinity is related to biochemical changes in two contrasting lettuce genotypes

“…In a previous study, we reported significant differences in tissue antioxidants and ion contents between Verte and Romaine lettuce seedlings grown under 0, 100 mM NaCl and 77 mM Na 2 SO 4 (Mahmoudi et al 2010). Lettuce seedlings can tolerate relatively high concentrations of NaCl for a short time period without developing obvious symptoms (Kim et al 2008).…”

“…Extraction and quantification of carotenoids from leaf tissue (0.1 g) by HPLC was carried as previously described (Mahmoudi et al 2010). Total phenolics were extracted from fresh leaves (0.5 g) with 80% methanol (v/v) and quantified by HPLC as described in Annalisa et al (2002).…”

“…Net photosynthesis decreases in response to salinity in different plants including lettuce (Dubey 2005;M'rah et al 2006;Mahmoudi et al 2010). A close link between growth and photosynthetic rate was also shown in two wheat (Triticum aestivum L.) genotypes differing in salt tolerance (El-Hendawy et al 2005).…”