Impact of carbon dioxide enrichment on the responses of maize leaf transcripts and metabolites to water stress

Abstract

Maize (Zea mays) was grown in indoor chambers with ambient (38 Pa) and elevated (70 Pa) CO(2) . Drought treatments were imposed 17 days after sowing by withholding nutrient solution. Decreases of soil water content, leaf water potential, net CO(2) assimilation and stomatal conductance as a result of drought were delayed approximately 2 days by CO(2) enrichment. Concentrations of 28 of 33 leaf metabolites were altered by drought. Soluble carbohydrates, aconitate, shikimate, serine, glycine, proline and eight other amino acids increased, and leaf starch, malate, fumarate, 2-oxoglutarate and seven amino acids decreased with drought. Drought-dependent decreases of nitrate, alanine and aspartate were impacted by limiting nitrogen. Transcript levels of 14 stress-related maize genes responded to drought but this was delayed or modified by CO(2) enrichment. Overall, CO(2) enrichment eliminated many early responses of maize metabolites and transcripts to water stress but was less effective when drought was severe. Four metabolite groupings were identified by clustering analysis. These groupings included compounds that decreased with water stress, compounds involved in osmotic adjustment and aromatic compounds that alleviate oxidative stress. Metabolite changes also supported the suggestion that water stress inhibited C(4) photosynthesis and induced photorespiration.

Metabolite profiles of maize leaves in drought, heat and combined stress field trials reveal the relationship between metabolism and grain yield

“…These metabolites were also accumulated in maize in both greenhouse and field trials under all stress conditions tested, although Thr and GABA were not annotated in greenhouse samples (Sicher and Barnaby, 2012;Witt et al, 2012;Barnaby et al, 2013). Other amino acids, such as Pro, Phe, and Trp, also accumulated under DS in both conditions (Sicher and Barnaby, 2012;Witt et al, 2012;Barnaby et al, 2013) as well as in Arabidopsis (Urano et al, 2009). The accumulation of these metabolites was much lower in this field study than in the other greenhouse studies (Sicher and Barnaby, 2012;Witt et al, 2012;Barnaby et al, 2013), most likely depending on the severity of DS due to the soil structure and coincident rainfalls.…”

“…Other amino acids, such as Pro, Phe, and Trp, also accumulated under DS in both conditions (Sicher and Barnaby, 2012;Witt et al, 2012;Barnaby et al, 2013) as well as in Arabidopsis (Urano et al, 2009). The accumulation of these metabolites was much lower in this field study than in the other greenhouse studies (Sicher and Barnaby, 2012;Witt et al, 2012;Barnaby et al, 2013), most likely depending on the severity of DS due to the soil structure and coincident rainfalls. As the accumulation of amino acids under DS has been reported in various plant species (Evers et al, 2010;Degenkolbe et al, 2013;Barchet et al, 2014;Hatzig et al, 2014;Suguiyama et al, 2014), it can be considered as a wellconserved and robust metabolic response to DS in plants.…”

“…The accumulation of amino acids, including Ile, Val, Thr, and GABA, is a metabolic response common in many abiotic stress environments in Arabidopsis (Obata and Fernie, 2012). These metabolites were also accumulated in maize in both greenhouse and field trials under all stress conditions tested, although Thr and GABA were not annotated in greenhouse samples (Sicher and Barnaby, 2012;Witt et al, 2012;Barnaby et al, 2013). Other amino acids, such as Pro, Phe, and Trp, also accumulated under DS in both conditions (Sicher and Barnaby, 2012;Witt et al, 2012;Barnaby et al, 2013) as well as in Arabidopsis (Urano et al, 2009).…”

Plant Abiotic Stress:‘Omics’ Approach

“…The major approaches that are used in plant metabolomics research includes metabolic fingerprinting which involves separation of metabolites based on the physical and chemical properties using various analytical tools and technologies, metabolite profiling which includes the study of the alterations in metabolites pool that are induced by stress and finally target analyses. Sicher et al [13] conducted an experiment in maize to understand the combined effect of enhanced atmospheric CO 2 and drought response by monitoring foliar metabolites. The concentration of leaf metabolites were found to be altered.…”

Metabolomics applied in bioenergy

“…Major efforts have been taken to understand and manipulate the pathways involved in carbohydrate storage and partitioning (for review, see [2]). In this sense, few descriptive metabolomics studies attempted to unravel the correlation between metabolites, developmental stages, and sucrose accumulation pattern in sugarcane [95] or the impact of environmental stress in different species used for bioenergy [96,97].…”