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Fructan synthesis, accumulation, and polymer traits. I. Festulolium chromosome substitution lines.

Gallagher JA, Cairns AJ, Thomas D, Charlton A, Williams P, Turner LB - Front Plant Sci (2015)

Bottom Line: The fructans found as storage carbohydrates in temperate forage grasses have a physiological role in regrowth and stress tolerance.Additionally fescue retained high concentrations of fructan, both polymeric and oligomeric, during conditions of low source/high sink demand.There were indications that major genes involved in the control of some of these traits might be located on fescue chromosome 3 opening the possibility to develop grasses optimized for specific applications.

View Article: PubMed Central - PubMed

Affiliation: Institute of Biological, Environmental and Rural Sciences, Aberystwyth University Aberystwyth, UK.

ABSTRACT
The fructans found as storage carbohydrates in temperate forage grasses have a physiological role in regrowth and stress tolerance. They are also important for the nutritional value of fresh and preserved livestock feeds, and are potentially useful as feedstocks for biorefining. Seasonal variation in fructan content and the capacity for de novo fructan synthesis have been examined in a Festulolium monosomic substitution line family to investigate variation in the polymers produced by grasses in the ryegrass-fescue complex. There were significant differences between ryegrass and fescue. Fescue had low polymeric fructan content and a high oligomer/polymer ratio; synthesis of polymers longer than degree of polymerization 6 (DP6) from oligomers was slow. However, extension of polymer length from DP10/DP20 upward appeared to occur relatively freely, and, unlike ryegrass, fescue had a relatively even spread of polymer chain lengths above DP20. This included the presence of some very large polymers. Additionally fescue retained high concentrations of fructan, both polymeric and oligomeric, during conditions of low source/high sink demand. There were indications that major genes involved in the control of some of these traits might be located on fescue chromosome 3 opening the possibility to develop grasses optimized for specific applications.

No MeSH data available.


Carbohydrate contents (mg/g DM) of leaf material from the chromosome substitution lines and their parents over the growing season. Total WSC, black closed squares; polymeric fructan, black closed circles; oligomeric fructan, black closed triangles; disaccharides, gray closed squares; monosaccharides, gray closed circles. Data are means and SE; n = 11.
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Figure 2: Carbohydrate contents (mg/g DM) of leaf material from the chromosome substitution lines and their parents over the growing season. Total WSC, black closed squares; polymeric fructan, black closed circles; oligomeric fructan, black closed triangles; disaccharides, gray closed squares; monosaccharides, gray closed circles. Data are means and SE; n = 11.

Mentions: The vegetative material removed above a 4 cm cut was predominantly leaf blade with a small percentage of leaf sheath present. The mean total WSC content of this material varied over the growing season in all lines (Figure 1). The significance of these seasonal effects was tested by fitting curves to the data. The curves of best fit (those where the majority of the variation was explained by the curve equation parameters and with the lowest error mean square values) for mean sugar contents were all non-linear, confirming significant variation over the growing season. Third order polynomial curves were the best fit for disaccharide and monosaccharide sugars, but fourth order equations improved the fit for total WSC, polymeric fructan and oligomeric fructan (Table 1). There were no significant differences between the different substitution lines in curve form (as tested with parallel curve analysis using the polynomial curve of best fit for each sugar), indicating that the seasonal pattern was consistent. WSC was highest in the summer during June, July and August (Figure 2). Sucrose constituted the majority of the non-fructan sugar pool and was highest in June when it was the major sugar. Polymeric fructan content peaked later, in August, and was the major sugar in leaf material at this time. The significance of variation over the growing season was further assessed by one-way ANOVA treating date as the fixed effect and without blocking. The effect of date was significant at P < 0.001 for all sugars. The data for total WSC and fructan fell into two distinct groups: one group comprising June, July, and August, with high carbohydrate content, and a second group for April, September, and November, with lower carbohydrate content. With the exceptions of polymeric fructan in June and oligomeric fructan in September, carbohydrate contents were not significantly different from each other within these groups, but were all different from those of the other group.


Fructan synthesis, accumulation, and polymer traits. I. Festulolium chromosome substitution lines.

Gallagher JA, Cairns AJ, Thomas D, Charlton A, Williams P, Turner LB - Front Plant Sci (2015)

Carbohydrate contents (mg/g DM) of leaf material from the chromosome substitution lines and their parents over the growing season. Total WSC, black closed squares; polymeric fructan, black closed circles; oligomeric fructan, black closed triangles; disaccharides, gray closed squares; monosaccharides, gray closed circles. Data are means and SE; n = 11.
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Related In: Results  -  Collection

License
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Figure 2: Carbohydrate contents (mg/g DM) of leaf material from the chromosome substitution lines and their parents over the growing season. Total WSC, black closed squares; polymeric fructan, black closed circles; oligomeric fructan, black closed triangles; disaccharides, gray closed squares; monosaccharides, gray closed circles. Data are means and SE; n = 11.
Mentions: The vegetative material removed above a 4 cm cut was predominantly leaf blade with a small percentage of leaf sheath present. The mean total WSC content of this material varied over the growing season in all lines (Figure 1). The significance of these seasonal effects was tested by fitting curves to the data. The curves of best fit (those where the majority of the variation was explained by the curve equation parameters and with the lowest error mean square values) for mean sugar contents were all non-linear, confirming significant variation over the growing season. Third order polynomial curves were the best fit for disaccharide and monosaccharide sugars, but fourth order equations improved the fit for total WSC, polymeric fructan and oligomeric fructan (Table 1). There were no significant differences between the different substitution lines in curve form (as tested with parallel curve analysis using the polynomial curve of best fit for each sugar), indicating that the seasonal pattern was consistent. WSC was highest in the summer during June, July and August (Figure 2). Sucrose constituted the majority of the non-fructan sugar pool and was highest in June when it was the major sugar. Polymeric fructan content peaked later, in August, and was the major sugar in leaf material at this time. The significance of variation over the growing season was further assessed by one-way ANOVA treating date as the fixed effect and without blocking. The effect of date was significant at P < 0.001 for all sugars. The data for total WSC and fructan fell into two distinct groups: one group comprising June, July, and August, with high carbohydrate content, and a second group for April, September, and November, with lower carbohydrate content. With the exceptions of polymeric fructan in June and oligomeric fructan in September, carbohydrate contents were not significantly different from each other within these groups, but were all different from those of the other group.

Bottom Line: The fructans found as storage carbohydrates in temperate forage grasses have a physiological role in regrowth and stress tolerance.Additionally fescue retained high concentrations of fructan, both polymeric and oligomeric, during conditions of low source/high sink demand.There were indications that major genes involved in the control of some of these traits might be located on fescue chromosome 3 opening the possibility to develop grasses optimized for specific applications.

View Article: PubMed Central - PubMed

Affiliation: Institute of Biological, Environmental and Rural Sciences, Aberystwyth University Aberystwyth, UK.

ABSTRACT
The fructans found as storage carbohydrates in temperate forage grasses have a physiological role in regrowth and stress tolerance. They are also important for the nutritional value of fresh and preserved livestock feeds, and are potentially useful as feedstocks for biorefining. Seasonal variation in fructan content and the capacity for de novo fructan synthesis have been examined in a Festulolium monosomic substitution line family to investigate variation in the polymers produced by grasses in the ryegrass-fescue complex. There were significant differences between ryegrass and fescue. Fescue had low polymeric fructan content and a high oligomer/polymer ratio; synthesis of polymers longer than degree of polymerization 6 (DP6) from oligomers was slow. However, extension of polymer length from DP10/DP20 upward appeared to occur relatively freely, and, unlike ryegrass, fescue had a relatively even spread of polymer chain lengths above DP20. This included the presence of some very large polymers. Additionally fescue retained high concentrations of fructan, both polymeric and oligomeric, during conditions of low source/high sink demand. There were indications that major genes involved in the control of some of these traits might be located on fescue chromosome 3 opening the possibility to develop grasses optimized for specific applications.

No MeSH data available.