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 (ΦPSII), 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 ΦPSII 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 ΦPSII. 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.
Highlights
Introduction published maps and institutional affilUnlike animals, plants are sessile organisms that must deal with an ever-changing environment from which they cannot escape
Salt stress profoundly reduces the efficiency of photosynthesis; we wished to verify if Arabidopsis thaliana SYNAPTOTAGMIN 1 (AtSYT1) has a role in the tolerance to salt stress in regard to this essential physiological process in green plants
We investigated gas exchange and chlorophyll a fluorescence in wild-type (WT) and atsyt1 plants watered for 48 h with 150 mM NaCl and compared them with plants irrigated with tap water
Summary
Plants are sessile organisms that must deal with an ever-changing environment from which they cannot escape. They have developed diverse survival mechanisms, and plenty of genes, including plant synaptotagmins (SYTs) that help them to last in adverse conditions have been identified [1]. SYTs, well-known calcium sensors that participate in the release of neurotransmitters at the synapses of their neuronal systems [2], and recently discovered extended SYTs (E-SYTs) [3]. PSYTs contain, to classical SYTs, an N-terminal transmembrane sequence and two closely spaced C2 domains and an additional synaptotagmin-like mitochondrial-lipid binding protein (SMP) domain, which is characteristic of E-SYTs. E-SYTs contain three or five tandem C2 domains [3].
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