Genotypic variation in water-soluble carbohydrate accumulation in wheat

Abstract

The water-soluble carbohydrate (WSC) that accumulates in the stems of wheat during growth can be an important contributor to grain filling, particularly under conditions when assimilation is limited, such as during end-of-season drought. WSC concentration was measured at anthesis across a diverse set of wheat genotypes over multiple environments. Environmental differences in WSC concentration were large (means for the set ranging between 108 and 203 mg g–1 dry weight), and there were significant and repeatable differences in WSC accumulation among genotypes (means ranging from 112 to 213 mg g–1 dry weight averaged across environments), associated with large broad-sense heritability (H = 0.90 ± 0.12). These results suggest that breeding for high WSC should be possible in wheat. The composition of the WSC, examined in selected genotypes, indicated that the variation in total WSC was attributed mainly to variation in the fructan component, with the other major soluble carbohydrates, sucrose and hexose, varying less. The degree of polymerisation (DP) of fructo-oligosaccharides was up to ~13 in samples where higher levels of WSC were accumulated, owing either to genotype or environment, but the higher DP components (DP > 6) were decreased in samples of lower total WSC. The results are consistent with fructan biosynthesis occurring via a sequential mechanism that is dependent on the availability of sucrose, and differences in WSC contents of genotypes are unlikely to be due to major mechanistic differences.

A Novel Isoform of Sucrose Synthase Is Targeted to the Cell Wall during Secondary Cell Wall Synthesis in Cotton Fiber

“…An active apoplastic Sus could function in much the same way as cell wall-associated invertase (for review, see Koch, 2004); however, it would require apoplastic UDP as a substrate in addition to Suc. The sugar composition of the apoplastic fluid of cotton locules 18 to 20 was determined here using a protocol developed for leaves (Nadwodnik and Lohaus, 2008; data not shown) and HPLC-pulsed-amperometric detection (Ruuska et al, 2006). While UDP could not be measured in this system, Suc, Glc, and Fru were abundant (data not shown).…”

Differential response of wild and cultivated wheats to water deficits during grain development: changes in soluble carbohydrates and invertases

“…Further, fructans, the major carbohydrate portion of WSCs, might act as osmolytes enhancing water retention (Kawakami et al 2008) and protect plants from drought and cold stress by stabilizing cellular membranes (Hincha et al 2008). Stem WSCs accumulation is influenced by the environmental factors (Ruuska et al 2006). Considerable genotypic variation in stem WSCs has been observed in wheat and barley.…”

“…Genetic variation exists for WSC accumulation in the stem at anthesis (Ruuska et al 2006) and it has been suggested that breeding for high WSC should be possible due to its high heritability, though the trait appears to be controlled by complex polygenic regulation (Rebetzke et al 2008). Stem reserves and their contribution to grain can be estimated by measuring post-anthesis changes in internode dry matter (Cruz-Aguado et al 2000), changes in internode WSCs content (Shakiba et al 1996) and/or estimated by determining sink activity (Gupta et al 2011) during grain-filling period.…”

Genetic Dissection of Stem Water-Soluble Carbohydrates and Agronomic Traits in Wheat under Different Water Regimes

“…9, No. 3; environmental factors (Blum, 1998;Ruuska et al, 2008;Ruuska et al, 2006). However, considerable genotypic variation in stem WSC concentration has been observed in wheat (Ruuska et al, 2006;Xue et al, 2008).…”