Is foliar Cl- concentration the cause of photosynthetic decline in grapevine during mild salinity?

Abstract

Moderate levels of Cl- have been associated with grapevine salt tolerance. The hypothesis to be tested in this work is: photosynthesis in grapevine is negatively correlated with foliar Cl- concentration. To further test this hypothesis, multiple mild salinity experiments on four different Vitis genotypes (Cabernet-Sauvignon, Riparia Gloire, Ramsey and SC2) were conducted and photosynthesis, ion concentrations and gene expression responses were quantified. The salt-tolerant rootstock Ramsey had greater Cl- exclusion capabilities than V. vinifera cultivars both during rooted cutting greenhouse experiments and three years of field-grafted experiments; SC2 also excluded Cl-. Differential gene expression indicated that salinity affected transcript abundance more in salt-sensitive genotypes (97.7 % of DEGs in the dataset), especially chloroplast-related transcripts. The transcript abundances of known anion transporters were determined and a family of putative B transporters was associated with the Cl- exclusion phenotype. Photosynthesis and growth were maintained in Ramsey and SC2 under mild salinity. However, photosynthesis declined in Cabernet-Sauvignon with isosmotic 20 mM salt concentrations of NaCl, KCl or NaNO3, independent of the salt type. While foliar Cl- concentrations did correlate with salt tolerance during control and NaCl conditions, it was not found to be the cause of photosynthetic decline in Vitis during mild salinity.

Physiological and Transcriptional Responses to Saline Irrigation of Young ‘Tempranillo’ Vines Grafted Onto Different Rootstocks

“…The generalized reduction found in net photosynthesis (A N ) under saline conditions, regardless of the rootstock ( Figure 2 ), is related to stomatal and mesophyll conductance limitation, as there were no major differences in WUE i beyond those expected, given the differences in water status ( Flexas et al, 2004 ). Reductions are in line with those found by Flexas et al (1999) in ‘Tempranillo’ and Baeza et al (2007) and Baggett et al (2021) in ‘Cabernet-Sauvignon’ cultivars. Moreover, no differences were detected in the ratio of internal to atmospheric CO 2 concentration (Ci/Ca) between treatments (0.76 and 0.75 in Control and Saline treatments, respectively; data not shown).…”

“…This genotype-dependent, though fuzzy, transcriptomic effects agree with our GSEA results, which identified much less statistically significantly (FDR q < 0.25) differentially expressed bins due to WQ in ‘Tempranillo’ grafted onto 1103P as compared to M4 and M1 ( Figure 3 ). Baggett et al (2021) , also similarly observed that salinity affected transcript abundance more in salt-sensitive genotypes than in salt-tolerant ones. Importantly, the leaf Cl – concentrations in our trial are higher than the ones reported by Urdanoz and Aragüés (2009) and Baggett et al (2021) , even though in the range of the ones found in ‘Cabernet Sauvignon’ onto 1103P by Dag et al (2015) using similar WQ.…”

“… Baggett et al (2021) , also similarly observed that salinity affected transcript abundance more in salt-sensitive genotypes than in salt-tolerant ones. Importantly, the leaf Cl – concentrations in our trial are higher than the ones reported by Urdanoz and Aragüés (2009) and Baggett et al (2021) , even though in the range of the ones found in ‘Cabernet Sauvignon’ onto 1103P by Dag et al (2015) using similar WQ.…”

“…It is important to bear this in mind when interpreting the results, especially the transcriptome analyses, because of the combination of two Vitis spp. Genotypes are studied by evaluating only one of them, i.e., Vitis vinifera L. In comparison, most of the grapevine transcriptomics responses reported in the literature have been assessed on a single genotype, i.e., directly in the own-rooted Vitis vinifera ( Cramer et al, 2007 ; Guan et al, 2018 ; Das and Majumder, 2019 ; Lehr et al, 2022 ) or on the rootstock without grafting ( Gong et al, 2011 ; Henderson et al, 2014 ; Meggio et al, 2014 ; Corso et al, 2015 ; Vannozzi et al, 2017 ; Fu et al, 2019 ; Çakır Aydemir et al, 2020 ), and if carried out in both the scion and the rootstock, they have been under highly controlled conditions ( Upadhyay et al, 2018 ; Bianchi et al, 2020 ; Franck et al, 2020 ; Baggett et al, 2021 ), i.e., not under real field-grown conditions.…”

Coastal Wild Grapevine Accession (Vitis vinifera L. ssp. sylvestris) Shows Distinct Late and Early Transcriptome Changes under Salt Stress in Comparison to Commercial Rootstock Richter 110

“…Under the same saline concentration, 50 mM NaCl, Henderson et al [ 60 ] concluded that the salt-exclusion mechanisms in 140 Ruggeri (a close relative to R110 from the same parental background, but featuring higher salt tolerance) were not induced by salinity but, rather, seem to remain constitutively expressed, which could a similar case for R110. Similarly, constitutive gene expression profile was also shown in salt-tolerant variety Ramsey ( Vitis champinii ) against a saline treatment of 25 mM NaCl [ 63 ]. Given AS1B’s higher survival capability under salt stress, its responsive strategy could be an additional alternative to consider, in addition to known strategies in rootstocks showing constitutive expression.…”