Uncovering salt tolerance mechanisms in pepper plants: a physiological and transcriptomic approach

Abstract

Background Pepper is one of the most cultivated crops worldwide, but is sensitive to salinity. This sensitivity is dependent on varieties and our knowledge about how they can face such stress is limited, mainly according to a molecular point of view. This is the main reason why we decided to develop this transcriptomic analysis. Tolerant and sensitive accessions, respectively called A25 and A6, were grown for 14 days under control conditions and irrigated with 70 mM of NaCl. Biomass, different physiological parameters and differentially expressed genes were analysed to give response to differential salinity mechanisms between both accessions. Results The genetic changes found between the accessions under both control and stress conditions could explain the physiological behaviour in A25 by the decrease of osmotic potential that could be due mainly to an increase in potassium and proline accumulation, improved growth (e.g. expansins), more efficient starch accumulation (e.g. BAM1), ion homeostasis (e.g. CBL9, HAI3, BASS1), photosynthetic protection (e.g. FIB1A, TIL, JAR1) and antioxidant activity (e.g. PSDS3, SnRK2.10). In addition, misregulation of ABA signalling (e.g. HAB1, ERD4, HAI3) and other stress signalling genes (e.g. JAR1) would appear crucial to explain the different sensitivity to NaCl in both accessions. Conclusions After analysing the physiological behaviour and transcriptomic results, we have concluded that A25 accession utilizes different strategies to cope better salt stress, being ABA-signalling a pivotal point of regulation. However, other strategies, such as the decrease in osmotic potential to preserve water status in leaves seem to be important to explain the defence response to salinity in pepper A25 plants.

Effects of Conventional and Bokashi Hydroponics on Vegetative Growth, Yield and Quality Attributes of Bell Peppers

“…Although not statistically significant ( p > 0.05), the difference in plant height could be due to the high level of Na+ in the bokashi medium, which could result in salinity stress [ 11 ]. The stunted growth could also be due to nutrient deficiencies.…”

The Effect of Neutral Salt and Alkaline Stress with the Same Na+ Concentration on Root Growth of Soybean (Glycine max (L.) Merr.) Seedlings

“…Regardless of whether plants are exposed to neutral salt or alkaline stress, plants often accumulate a large number of inorganic ions in vacuoles to increase cell osmotic potential and reduce cell water potential [64]. Although it takes far less energy for plants to absorb and accumulate inorganic ions than it does to synthesize organic materials [65], excessive ion intake can cause ion toxicity in cells. Therefore, plants often synthesize organic matter, such as proline, betaine, choline, or organic acids, to regulate the osmotic potential inside and outside the cell [46].…”

Differential gene expression patterns and physiological responses improve adaptation to high salinity concentration in pepper accessions

“…for 10 minutes at 9,000 x g. Leaf and root saps were measured with an osmometer (Digital osmometer, Wescor). Osmolyte content (mmol kg À1 ) was converted into MPa by the Van't Hoff equation (L opez-Serrano et al, 2021) to calculate the osmotic potential in leaf and root (Ψ πL and Ψ πR, respectively).…”