Abstract
Salinity affects plant growth and development as shown with the glycophyte model plant, Arabidopsis thaliana (Arabidopsis). Two Arabidopsis accessions, Wassilewskija (Ws) and Columbia (Col-0), are widely used to generate mutants available from various Arabidopsis seed resources. However, these two ecotypes are known to be salt-sensitive with different degrees of tolerance. In our study, 3-week-old Col-0 and Ws plants were treated with and without 150 mM NaCl for 48, 72, or 96 h, and several physiological and biochemical traits were characterized on shoots to identify any specific traits in their tolerance to salinity. Before salt treatment was carried out, a different phenotype was observed between Col-0 and Ws, whose main inflorescence stem became elongated in contrast to Col-0, which only displayed rosette leaves. Our results showed that Col-0 and Ws were both affected by salt stress with limited growth associated with a reduction in nutrient uptake, a degradation of photosynthetic pigments, an increase in protein degradation, as well as showing changes in carbohydrate metabolism and cell wall composition. These traits were often more pronounced in Col-0 and occurred usually earlier than in Ws. Tandem Mass Tags quantitative proteomics data correlated well with the physiological and biochemical results. The Col-0 response to salt stress was specifically characterized by a greater accumulation of osmoprotectants such as anthocyanin, galactinol, and raffinose; a lower reactive oxygen detoxification capacity; and a transient reduction in galacturonic acid content. Pectin degradation was associated with an overaccumulation of the wall-associated kinase 1, WAK1, which plays a role in cell wall integrity (CWI) upon salt stress exposure. Under control conditions, Ws produced more antioxidant enzymes than Col-0. Fewer specific changes occurred in Ws in response to salt stress apart from a higher number of different fascilin-like arabinogalactan proteins and a greater abundance of expansin-like proteins, which could participate in CWI. Altogether, these data indicate that Col-0 and Ws trigger similar mechanisms to cope with salt stress, and specific changes are more likely related to the developmental stage than to their respective genetic background.
Highlights
Salt stress, which results from natural salt accumulation and inappropriate agricultural practices, is a worldwide environmental issue that affects plant growth and development (Munns and Tester, 2008; FAO, 2018)
To determine the natural variation between Col-0 and Ws, control and salt-treated plants were phenotyped by measuring different parameters including the fresh mass (FM) of the shoots, the shoot water content (SWC), and the tolerant index of the shoots (TI)
A decrease in FM was observed in both ecotypes after a prolonged salt stress exposure (T72 and T96) (Supplementary Figure 1A)
Summary
Salt stress, which results from natural salt accumulation and inappropriate agricultural practices, is a worldwide environmental issue that affects plant growth and development (Munns and Tester, 2008; FAO, 2018). It impairs plant growth by first inducing osmotic stress, due to the excess of salt in the soil resulting in an increased soil osmotic potential, disrupting water uptake by roots (Roy et al, 2014). Salt stress is accompanied by an oxidative stress characterized by an accumulation of reactive oxygen species (ROS) (Miller et al, 2010). All the major plant physiological and biochemical processes are impaired, including photosynthesis mainly characterized by an alteration of chloroplast structure, loss of chlorophyll, and reduction of CO2 uptake due to stomatal closing (Chaves et al, 2009; Stepien and Johnson, 2009; Gao et al, 2019)
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