The Absence of the AtSYT1 Function Elevates the Adverse Effect of Salt Stress on Photosynthesis in Arabidopsis

Abstract

Arabidopsis thaliana SYNAPTOTAGMIN 1 (AtSYT1) was shown to be involved in responses to different environmental and biotic stresses. We investigated gas exchange and chlorophyll a fluorescence in Arabidopsis wild-type (WT, ecotype Col-0) and atsyt1 mutant plants irrigated for 48 h with 150 mM NaCl. We found that salt stress significantly decreases net photosynthetic assimilation, effective photochemical quantum yield of photosystem II (ФPSII), stomatal conductance and transpiration rate in both genotypes. Salt stress has a more severe impact on atsyt1 plants with increasing effect at higher illumination. Dark respiration, photochemical quenching (qP), non-photochemical quenching and ФPSII measured at 750 µmol m−2 s−1 photosynthetic photon flux density were significantly affected by salt in both genotypes. However, differences between mutant and WT plants were recorded only for qP and ФPSII. Decreased photosynthetic efficiency in atsyt1 under salt stress was accompanied by reduced chlorophyll and carotenoid and increased flavonol content in atsyt1 leaves. No differences in the abundance of key proteins participating in photosynthesis (except PsaC and PsbQ) and chlorophyll biosynthesis were found regardless of genotype or salt treatment. Microscopic analysis showed that irrigating plants with salt caused a partial closure of the stomata, and this effect was more pronounced in the mutant than in WT plants. The localization pattern of AtSYT1 was also altered by salt stress.

Integrated GWAS and transcriptomic analysis reveal the candidate salt-responding genes regulating Na+/K+ balance in barley (Hordeum vulgare L.)

“…However, the DEGs HORVU6Hr1G016120 and HORVU5Hr1G124800 showed no difference in their expression level between the salt-sensitive and salt-tolerant varieties. In all, our data suggest that the above genes could be promising candidates genes as their orthologs also play a role in salt tolerance in other species ( Hu et al., 2012 ; Liu et al., 2013 ; Joshi et al., 2016 ; Lee et al., 2019 , Krausko et al., 2022 , Myo et al., 2020 , Wang et al., 2020 ).…”

“…In Arabidopsis , the stress-induced SYT3 is an endoplasmic reticulum-plasma membrane (ER-PM) tether that also participates in maintaining PM integrity along with SYT1 ( Ruiz-Lopez et al., 2021 ). Under salt stress, loss of AtSYT1 function resulted in a decrease in photosynthetic efficiency accompanied by a decrease in chlorophyll and carotenoids and an increase in flavonol content in leaves, aggravating the adverse effects of salt stress ( Krausko et al., 2022 ). However, analysis of the above genes in barley salt tolerance has not been reported.…”

Membrane Proteomic Profiling of Soybean Leaf and Root Tissues Uncovers Salt-Stress-Responsive Membrane Proteins

“…In rice, a Na + /H + exchanger protein is the sole Na + efflux transporter and its loss-of-function mutant displayed exceptional salt sensitivity [ 38 ]. In Arabidopsis, synaptotagmin-1 mutant plants were severely affected by salt stress since this protein is required for the maintenance of plasma membrane integrity [ 39 , 40 ]. During salinity stress, V-ATPases facilitate the sequestration of Na + in the vacuole by establishing an electrochemical proton gradient across the tonoplast [ 41 ], and their abundances and activities are usually increased during salinity stress.…”