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Leaves of the Arabidopsis maltose exporter1 mutant exhibit a metabolic profile with features of cold acclimation in the warm.

Purdy SJ, Bussell JD, Nunn CP, Smith SM - PLoS ONE (2013)

Bottom Line: Grown at 21 °C, mex1-1 plants were much smaller, with fewer leaves, and elevated carbohydrates and amino acids compared to WT.After prolonged growth at 4 °C, the shoot biomass, rosette diameter and number of leaves at bolting were similar in mex1-1 and WT.This may in turn compromise growth of mex1-1 in the warm relative to WT.

View Article: PubMed Central - PubMed

Affiliation: Australian Research Council Centre of Excellence in Plant Energy Biology, The University of Western Australia, Perth, Western Australia, Australia ; Institute of Biological, Environmental & Rural Sciences, Aberystwyth University, Aberystwyth, United Kingdom.

ABSTRACT

Background: Arabidopsis plants accumulate maltose from starch breakdown during cold acclimation. The Arabidopsis mutant, maltose excess1-1, accumulates large amounts of maltose in the plastid even in the warm, due to a deficient plastid envelope maltose transporter. We therefore investigated whether the elevated maltose level in mex1-1 in the warm could result in changes in metabolism and physiology typical of WT plants grown in the cold.

Principal findings: Grown at 21 °C, mex1-1 plants were much smaller, with fewer leaves, and elevated carbohydrates and amino acids compared to WT. However, after transfer to 4 °C the total soluble sugar pool and amino acid concentration was in equal abundance in both genotypes, although the most abundant sugar in mex1-1 was still maltose whereas sucrose was in greatest abundance in WT. The chlorophyll a/b ratio in WT was much lower in the cold than in the warm, but in mex1-1 it was low in both warm and cold. After prolonged growth at 4 °C, the shoot biomass, rosette diameter and number of leaves at bolting were similar in mex1-1 and WT.

Conclusions: The mex1-1 mutation in warm-grown plants confers aspects of cold acclimation, including elevated levels of sugars and amino acids and low chlorophyll a/b ratio. This may in turn compromise growth of mex1-1 in the warm relative to WT. We suggest that elevated maltose in the plastid could be responsible for key aspects of cold acclimation.

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Soluble sugar profile of Col-0 and mex1-1 rosette leaves grown at 21 °C and after cold acclimation at 4 °C for 5 days.A, Fructose, glucose, sucrose and raffinose concentration, B Maltose concentration. Note that the vertical axis is represented on different scales for wild type and mex1-1. C. Fold change of soluble sugars after transfer (cold/warm). D, sum of sugars metabolisable by both genotypes (fructose + glucose + sucrose + raffinose) and E, total soluble sugars (fructose + glucose + sucrose + raffinose + maltose). Concentrations are given as mg g-1 FW and values represent the mean ± SE of five biological replicates. Letters indicate significant differences between genotypes and treatments for each sugar or sugar pool (Student’s T-Test, P ≤ 0.05).
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pone-0079412-g002: Soluble sugar profile of Col-0 and mex1-1 rosette leaves grown at 21 °C and after cold acclimation at 4 °C for 5 days.A, Fructose, glucose, sucrose and raffinose concentration, B Maltose concentration. Note that the vertical axis is represented on different scales for wild type and mex1-1. C. Fold change of soluble sugars after transfer (cold/warm). D, sum of sugars metabolisable by both genotypes (fructose + glucose + sucrose + raffinose) and E, total soluble sugars (fructose + glucose + sucrose + raffinose + maltose). Concentrations are given as mg g-1 FW and values represent the mean ± SE of five biological replicates. Letters indicate significant differences between genotypes and treatments for each sugar or sugar pool (Student’s T-Test, P ≤ 0.05).

Mentions: Under warm conditions mex1-1 contained significantly more fructose, glucose, sucrose and maltose than WT (Figure 2A & B). Previous studies have reported that mex1-1 had a maltose level more than 40-fold that of WT. Our values were substantially more than that, mainly owing to the lower values for WT plants than previously reported [19]. Our finding that mex1-1 contained about 1.2 mg g-1 FW in warm conditions is in agreement with previous reports of 1-2 mg g-1 FW [19], [20] .


Leaves of the Arabidopsis maltose exporter1 mutant exhibit a metabolic profile with features of cold acclimation in the warm.

Purdy SJ, Bussell JD, Nunn CP, Smith SM - PLoS ONE (2013)

Soluble sugar profile of Col-0 and mex1-1 rosette leaves grown at 21 °C and after cold acclimation at 4 °C for 5 days.A, Fructose, glucose, sucrose and raffinose concentration, B Maltose concentration. Note that the vertical axis is represented on different scales for wild type and mex1-1. C. Fold change of soluble sugars after transfer (cold/warm). D, sum of sugars metabolisable by both genotypes (fructose + glucose + sucrose + raffinose) and E, total soluble sugars (fructose + glucose + sucrose + raffinose + maltose). Concentrations are given as mg g-1 FW and values represent the mean ± SE of five biological replicates. Letters indicate significant differences between genotypes and treatments for each sugar or sugar pool (Student’s T-Test, P ≤ 0.05).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3818174&req=5

pone-0079412-g002: Soluble sugar profile of Col-0 and mex1-1 rosette leaves grown at 21 °C and after cold acclimation at 4 °C for 5 days.A, Fructose, glucose, sucrose and raffinose concentration, B Maltose concentration. Note that the vertical axis is represented on different scales for wild type and mex1-1. C. Fold change of soluble sugars after transfer (cold/warm). D, sum of sugars metabolisable by both genotypes (fructose + glucose + sucrose + raffinose) and E, total soluble sugars (fructose + glucose + sucrose + raffinose + maltose). Concentrations are given as mg g-1 FW and values represent the mean ± SE of five biological replicates. Letters indicate significant differences between genotypes and treatments for each sugar or sugar pool (Student’s T-Test, P ≤ 0.05).
Mentions: Under warm conditions mex1-1 contained significantly more fructose, glucose, sucrose and maltose than WT (Figure 2A & B). Previous studies have reported that mex1-1 had a maltose level more than 40-fold that of WT. Our values were substantially more than that, mainly owing to the lower values for WT plants than previously reported [19]. Our finding that mex1-1 contained about 1.2 mg g-1 FW in warm conditions is in agreement with previous reports of 1-2 mg g-1 FW [19], [20] .

Bottom Line: Grown at 21 °C, mex1-1 plants were much smaller, with fewer leaves, and elevated carbohydrates and amino acids compared to WT.After prolonged growth at 4 °C, the shoot biomass, rosette diameter and number of leaves at bolting were similar in mex1-1 and WT.This may in turn compromise growth of mex1-1 in the warm relative to WT.

View Article: PubMed Central - PubMed

Affiliation: Australian Research Council Centre of Excellence in Plant Energy Biology, The University of Western Australia, Perth, Western Australia, Australia ; Institute of Biological, Environmental & Rural Sciences, Aberystwyth University, Aberystwyth, United Kingdom.

ABSTRACT

Background: Arabidopsis plants accumulate maltose from starch breakdown during cold acclimation. The Arabidopsis mutant, maltose excess1-1, accumulates large amounts of maltose in the plastid even in the warm, due to a deficient plastid envelope maltose transporter. We therefore investigated whether the elevated maltose level in mex1-1 in the warm could result in changes in metabolism and physiology typical of WT plants grown in the cold.

Principal findings: Grown at 21 °C, mex1-1 plants were much smaller, with fewer leaves, and elevated carbohydrates and amino acids compared to WT. However, after transfer to 4 °C the total soluble sugar pool and amino acid concentration was in equal abundance in both genotypes, although the most abundant sugar in mex1-1 was still maltose whereas sucrose was in greatest abundance in WT. The chlorophyll a/b ratio in WT was much lower in the cold than in the warm, but in mex1-1 it was low in both warm and cold. After prolonged growth at 4 °C, the shoot biomass, rosette diameter and number of leaves at bolting were similar in mex1-1 and WT.

Conclusions: The mex1-1 mutation in warm-grown plants confers aspects of cold acclimation, including elevated levels of sugars and amino acids and low chlorophyll a/b ratio. This may in turn compromise growth of mex1-1 in the warm relative to WT. We suggest that elevated maltose in the plastid could be responsible for key aspects of cold acclimation.

Show MeSH
Related in: MedlinePlus