Metabolomics and Proteomics of Brassica napus Guard Cells in Response to Low CO2

Abstract

Stomatal guard cell response to various stimuli is an important process that balances plant carbon dioxide (CO2) uptake and water transpiration. Elevated CO2 induces stomatal closure, while low CO2 promotes stomatal opening. The signaling process of elevated CO2 induced stomatal closure has been extensively studied in recent years. However, the mechanism of low CO2 induced stomatal opening is not fully understood. Here we report metabolomic and proteomic responses of Brassica napus guard cells to low CO2 using hyphenated mass spectrometry technologies. A total of 411 metabolites and 1397 proteins were quantified in a time-course study of low CO2 effects. Metabolites and proteins that exhibited significant changes are overrepresented in fatty acid metabolism, starch and sucrose metabolism, glycolysis and redox regulation. Concomitantly, multiple hormones that promote stomatal opening increased in response to low CO2. Interestingly, jasmonic acid precursors were diverted to a branch pathway of traumatic acid biosynthesis. These results indicate that the low CO2 response is mediated by a complex crosstalk between different phytohormones.

Hydrotropism in the primary roots of maize

“…Root samples in three biological replicates were freeze‐dried using a lyophilizer from Labconco (Kansas City, MO, USA). Metabolites were extracted as previously described (Geng et al , 2016, 2017). Briefly, an internal standard (10 μl of 100 μM lidocaine) was added to each sample before metabolite extraction.…”

“…The flow rate was 0.5 ml min −1 , and the total analysis time was 1 h. The MS conditions were 30 psi for curtain gas, 50 psi GS1, 55 psi GS2, ion source voltage at 4500 V, and turbo electrospray ionization interface temperature at 350°C. A multiple‐period (segment) method was followed as previously described for metabolomic analysis (Geng et al , 2017). Raw files (.wiff) were imported into MultiQuant software (AB Sciex) for manual integration and quantification.…”

Sugar Beet (Beta vulgaris) Guard Cells Responses to Salinity Stress: A Proteomic Analysis

“…The higher abundance of GDSL protein has been reported in response to biotic and abiotic environmental factors [32]. Increased in GDSL esterase/lipases proteins and stomatal apertures were observed in response to low CO 2 in Arabidopsis [29].…”

“…In most proteomics studies, GCs are not analyzed separately but included in the bulk of the leaf samples, thus masking GC-specific mechanisms underlying stomatal operation under stress conditions. To date, a very limited number of studies have used proteomics to analyze GCs specifically [4,[8][9][10]29] and none have investigated the specific response of GCs to salt stress. In this study, the efficiency of the GC isolation method was validated with a combination of techniques, including microscopic observation, viability tests, and at the proteome level.…”

Metabolomics for understanding stomatal movements

“…High ambient CO 2 concentrations mediate closure of stomatal pores in plants and conversely low ambient CO 2 concentration triggers the opening of stomatal pores. Within the context of the raising atmospheric CO 2 concentration to understand how guard cells adjust their physiology and metabolism in response to CO 2 is a key step for the development of plants better adapted to the shifting climate condition (Geng et al 2017). Indeed, although the whole network of CO 2 response is not fully clear, recent studies have addressed the molecular and cellular mechanisms mediating CO 2 regulation of stomatal movements (Engineer et al 2016;Zhang et al 2018).…”