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Elucidating the genetic basis of antioxidant status in lettuce (Lactuca sativa).

Damerum A, Selmes SL, Biggi GF, Clarkson GJ, Rothwell SD, Truco MJ, Michelmore RW, Hancock RD, Shellcock C, Chapman MA, Taylor G - Hortic Res (2015)

Bottom Line: Analysis of a QTL on linkage group 3, which accounted for >30% of the variation in AO potential, revealed several candidate genes encoding multiple MYB transcription factors which regulate flavonoid biosynthesis and flavanone 3-hydroxylase, an enzyme involved in the biosynthesis of the flavonoids quercetin and kaempferol, which are known to have powerful AO activity.Follow-up quantitative RT-PCR of these candidates revealed that 5 out of 10 genes investigated were significantly differentially expressed between the wild and cultivated parents, providing further evidence of their potential involvement in determining the contrasting phenotypes.These results offer exciting opportunities to improve the nutritional content and health benefits of lettuce through marker-assisted breeding.

View Article: PubMed Central - PubMed

Affiliation: Centre for Biological Sciences, University of Southampton, Life Sciences , University Road, Southampton SO17 1BJ, UK.

ABSTRACT
A diet rich in phytonutrients from fruit and vegetables has been acknowledged to afford protection against a range of human diseases, but many of the most popular vegetables are low in phytonutrients. Wild relatives of crops may contain allelic variation for genes determining the concentrations of these beneficial phytonutrients, and therefore understanding the genetic basis of this variation is important for breeding efforts to enhance nutritional quality. In this study, lettuce recombinant inbred lines, generated from a cross between wild and cultivated lettuce (Lactuca serriola and Lactuca sativa, respectively), were analysed for antioxidant (AO) potential and important phytonutrients including carotenoids, chlorophyll and phenolic compounds. When grown in two environments, 96 quantitative trait loci (QTL) were identified for these nutritional traits: 4 for AO potential, 2 for carotenoid content, 3 for total chlorophyll content and 87 for individual phenolic compounds (two per compound on average). Most often, the L. serriola alleles conferred an increase in total AOs and metabolites. Candidate genes underlying these QTL were identified by BLASTn searches; in several cases, these had functions suggesting involvement in phytonutrient biosynthetic pathways. Analysis of a QTL on linkage group 3, which accounted for >30% of the variation in AO potential, revealed several candidate genes encoding multiple MYB transcription factors which regulate flavonoid biosynthesis and flavanone 3-hydroxylase, an enzyme involved in the biosynthesis of the flavonoids quercetin and kaempferol, which are known to have powerful AO activity. Follow-up quantitative RT-PCR of these candidates revealed that 5 out of 10 genes investigated were significantly differentially expressed between the wild and cultivated parents, providing further evidence of their potential involvement in determining the contrasting phenotypes. These results offer exciting opportunities to improve the nutritional content and health benefits of lettuce through marker-assisted breeding.

No MeSH data available.


Related in: MedlinePlus

Comparison of relative phenolic concentrations amongst L. serriola, L. sativa and the high and low antioxidant RILs. Relative concentration of phenolics DCTA, Q-3MG, CQA, Q-3G, CTA, DCQA, L-7G, CMA and K-3MG for the parents and the four RILs measured to have the highest (HAO) and lowest (LAO) antioxidant status. Bars represent the mean ± standard error, with letters indicating significant differences (one-way ANOVA; see text for details).
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fig3: Comparison of relative phenolic concentrations amongst L. serriola, L. sativa and the high and low antioxidant RILs. Relative concentration of phenolics DCTA, Q-3MG, CQA, Q-3G, CTA, DCQA, L-7G, CMA and K-3MG for the parents and the four RILs measured to have the highest (HAO) and lowest (LAO) antioxidant status. Bars represent the mean ± standard error, with letters indicating significant differences (one-way ANOVA; see text for details).

Mentions: Relative concentrations of the most abundant metabolites detected in lettuce were compared against L. serriola and L. sativa and for the top four RILs measured to have the highest (denoted HAO lines 1–4) and four RILs with the lowest (LAO lines 1–4) AO potential (Figure 3). DCTA concentration was significantly higher in the wild parent in comparison to the cultivated parent (one-way ANOVA, F3,44 = 26.26, P < 0.001) and this was also seen for CTA (F3,44 = 26.26, P < 0.001). Transgressive segregation of metabolites was often observed with concentrations usually higher in the HAO line than in the cultivated parent, seen for Q-3MG (F3,44 = 6.43, P < 0.01), CQA (F3,44 = 12.34, P < 0.001), Q-3G (F3,44 = 13.97, P < 0.001), CTA, DCQA (F3,44 = 17.39, P < 0.001), L-7G (F3,44=10.31, P < 0.01) and K-3MG (F3,44 = 6.33, P < 0.01), though there were no differences of relative CMA concentration amongst any of the lines (F3,44 = 2.27, P > 0.05). In most cases, the HAO line also had greater metabolite concentrations than the LAO, excluding for CMA. There were no differences in relative metabolite concentration between L. sativa and the LAO line excluding DCQA and no differences were observed between L. serriola and the HAO line.


Elucidating the genetic basis of antioxidant status in lettuce (Lactuca sativa).

Damerum A, Selmes SL, Biggi GF, Clarkson GJ, Rothwell SD, Truco MJ, Michelmore RW, Hancock RD, Shellcock C, Chapman MA, Taylor G - Hortic Res (2015)

Comparison of relative phenolic concentrations amongst L. serriola, L. sativa and the high and low antioxidant RILs. Relative concentration of phenolics DCTA, Q-3MG, CQA, Q-3G, CTA, DCQA, L-7G, CMA and K-3MG for the parents and the four RILs measured to have the highest (HAO) and lowest (LAO) antioxidant status. Bars represent the mean ± standard error, with letters indicating significant differences (one-way ANOVA; see text for details).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4660231&req=5

fig3: Comparison of relative phenolic concentrations amongst L. serriola, L. sativa and the high and low antioxidant RILs. Relative concentration of phenolics DCTA, Q-3MG, CQA, Q-3G, CTA, DCQA, L-7G, CMA and K-3MG for the parents and the four RILs measured to have the highest (HAO) and lowest (LAO) antioxidant status. Bars represent the mean ± standard error, with letters indicating significant differences (one-way ANOVA; see text for details).
Mentions: Relative concentrations of the most abundant metabolites detected in lettuce were compared against L. serriola and L. sativa and for the top four RILs measured to have the highest (denoted HAO lines 1–4) and four RILs with the lowest (LAO lines 1–4) AO potential (Figure 3). DCTA concentration was significantly higher in the wild parent in comparison to the cultivated parent (one-way ANOVA, F3,44 = 26.26, P < 0.001) and this was also seen for CTA (F3,44 = 26.26, P < 0.001). Transgressive segregation of metabolites was often observed with concentrations usually higher in the HAO line than in the cultivated parent, seen for Q-3MG (F3,44 = 6.43, P < 0.01), CQA (F3,44 = 12.34, P < 0.001), Q-3G (F3,44 = 13.97, P < 0.001), CTA, DCQA (F3,44 = 17.39, P < 0.001), L-7G (F3,44=10.31, P < 0.01) and K-3MG (F3,44 = 6.33, P < 0.01), though there were no differences of relative CMA concentration amongst any of the lines (F3,44 = 2.27, P > 0.05). In most cases, the HAO line also had greater metabolite concentrations than the LAO, excluding for CMA. There were no differences in relative metabolite concentration between L. sativa and the LAO line excluding DCQA and no differences were observed between L. serriola and the HAO line.

Bottom Line: Analysis of a QTL on linkage group 3, which accounted for >30% of the variation in AO potential, revealed several candidate genes encoding multiple MYB transcription factors which regulate flavonoid biosynthesis and flavanone 3-hydroxylase, an enzyme involved in the biosynthesis of the flavonoids quercetin and kaempferol, which are known to have powerful AO activity.Follow-up quantitative RT-PCR of these candidates revealed that 5 out of 10 genes investigated were significantly differentially expressed between the wild and cultivated parents, providing further evidence of their potential involvement in determining the contrasting phenotypes.These results offer exciting opportunities to improve the nutritional content and health benefits of lettuce through marker-assisted breeding.

View Article: PubMed Central - PubMed

Affiliation: Centre for Biological Sciences, University of Southampton, Life Sciences , University Road, Southampton SO17 1BJ, UK.

ABSTRACT
A diet rich in phytonutrients from fruit and vegetables has been acknowledged to afford protection against a range of human diseases, but many of the most popular vegetables are low in phytonutrients. Wild relatives of crops may contain allelic variation for genes determining the concentrations of these beneficial phytonutrients, and therefore understanding the genetic basis of this variation is important for breeding efforts to enhance nutritional quality. In this study, lettuce recombinant inbred lines, generated from a cross between wild and cultivated lettuce (Lactuca serriola and Lactuca sativa, respectively), were analysed for antioxidant (AO) potential and important phytonutrients including carotenoids, chlorophyll and phenolic compounds. When grown in two environments, 96 quantitative trait loci (QTL) were identified for these nutritional traits: 4 for AO potential, 2 for carotenoid content, 3 for total chlorophyll content and 87 for individual phenolic compounds (two per compound on average). Most often, the L. serriola alleles conferred an increase in total AOs and metabolites. Candidate genes underlying these QTL were identified by BLASTn searches; in several cases, these had functions suggesting involvement in phytonutrient biosynthetic pathways. Analysis of a QTL on linkage group 3, which accounted for >30% of the variation in AO potential, revealed several candidate genes encoding multiple MYB transcription factors which regulate flavonoid biosynthesis and flavanone 3-hydroxylase, an enzyme involved in the biosynthesis of the flavonoids quercetin and kaempferol, which are known to have powerful AO activity. Follow-up quantitative RT-PCR of these candidates revealed that 5 out of 10 genes investigated were significantly differentially expressed between the wild and cultivated parents, providing further evidence of their potential involvement in determining the contrasting phenotypes. These results offer exciting opportunities to improve the nutritional content and health benefits of lettuce through marker-assisted breeding.

No MeSH data available.


Related in: MedlinePlus