Stem carbohydrate dynamics and expression of genes involved in fructan accumulation and remobilization during grain growth in wheat (Triticum aestivum L.) genotypes with contrasting tolerance to water stress.

Alejandra Yáñez,Gerardo Tapia,Fernando Guerra,Alejandro Del Pozo,Aimin Zhang

doi:10.1371/journal.pone.0177667

Alejandra Yáñez, Gerardo Tapia + Show 3 more

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https://doi.org/10.1371/journal.pone.0177667

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Abstract

The genetic and physiological mechanisms underlying the relationship between water-soluble carbohydrates (WSC) and water stress tolerance are scarcely known. This study aimed to evaluate the main WSC in stems, and the expression of genes involved in fructan metabolism in wheat genotypes growing in a glasshouse with water stress (WS; 50% field capacity from heading) and full irrigation (FI; 100% field capacity). Eight wheat genotypes (five tolerant and three susceptible to water stress) were evaluated initially (experiment 1) and the two most contrasting genotypes in terms of WSC accumulation were evaluated in a subsequent experiment (experiment 2). Maximum accumulation of WSC occurred 10–20 days after anthesis. Under WS, the stress-tolerant genotype exhibited higher concentrations of WSC, glucose, fructose and fructan in the stems, compared to FI. In addition, the stress-tolerant genotype exhibited higher up-regulation of the fructan 1-fructosyltransferase B (1-FFTB) and fructan 1-exohydrolase w2 (1-FEHw2) genes, whereas the susceptible cultivar presented an up-regulation of the fructan 6-fructosyltransferase (6-SFT) and fructan 1-exohydrolase w3 (1-FEHw3) genes. Our results indicated clear differences in the pattern of WSC accumulation and the expression of genes regulating fructan metabolism between the tolerant and susceptible genotypes under WS.

Highlights

Water deficit is an important abiotic stress factor that limits the growth and productivity of major crop species, including wheat [1]
The apparent water-soluble carbohydrates (WSC) remobilization (DWSC) under water stress (WS) conditions, estimated as the difference between the maximum and minimum, was linearly related to the yield tolerance index, the latter determined in field conditions (Table 1; Fig 1B)
In genotype ‘LE 2384’, the stem WSCs under WS conditions were at their maximum at 14– 20 daa and significantly higher (P

Summary

Introduction

Water deficit is an important abiotic stress factor that limits the growth and productivity of major crop species, including wheat [1]. Water deficit in Mediterranean climates usually occurs from heading and continues during grain formation (i.e. terminal drought), which reduces both the number of kernels per spike, grain weight and yield [6, 7] Considering this impact on crop productivity, it is essential to identify robust physiological, biochemical and molecular traits that allow selection of water stress-tolerant genotypes for use in breeding programs [1, 8]. Plants use different mechanisms to tolerate water stress and avoid damage One of those present in cereals is the accumulation of water-soluble carbohydrates (WSCs) in the stem and leaf sheath up to anthesis, which are translocated to the spike and grains during grain filling [12, 13]. The highest WSC levels are located between the peduncle and penultimate internode [15, 16, 17]

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