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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 the phenolic profiles of L. serriola and L. sativa. LC-MS profiles of the RIL parents, Lactuca serriola and L. sativa. Figure shows the relative maxima of absorbance of samples against retention time in (minutes), also displayed above each peak. Peaks: (1) CTA; (2) 5-CoQA (5-p-coumaroylquinic acid); (3) caffeoyl quinic acid; (4) caffeoyl malic acid; (5) di-CTA; (6) di-pCT; (7) dicaffeoyl quinic acid; (8) kaempferol glucuronide; (9) quercetin-3-glucuronide; (10) quercetin-3-malonylglucoside; (11) kaempferol-3-malonylglucoside. Multiple peaks for the same compound indicate isoforms.
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fig2: Comparison of the phenolic profiles of L. serriola and L. sativa. LC-MS profiles of the RIL parents, Lactuca serriola and L. sativa. Figure shows the relative maxima of absorbance of samples against retention time in (minutes), also displayed above each peak. Peaks: (1) CTA; (2) 5-CoQA (5-p-coumaroylquinic acid); (3) caffeoyl quinic acid; (4) caffeoyl malic acid; (5) di-CTA; (6) di-pCT; (7) dicaffeoyl quinic acid; (8) kaempferol glucuronide; (9) quercetin-3-glucuronide; (10) quercetin-3-malonylglucoside; (11) kaempferol-3-malonylglucoside. Multiple peaks for the same compound indicate isoforms.

Mentions: Clear differences in total phenolic content were detected between wild and cultivated lettuce (38.76 ± 4.65 vs. 22.25 ± 1.25 catechin equivalent, mg/g dry weight, respectively; two-sample t-test, t(8)=–3.43, P ≤ 0.01). Individual phenolic compounds were further quantified by LC/MS/MS. Visual inspection of the LC-MS profiles revealed clear qualitative and quantitative differences in phenolic composition for the two parent lines (Figure 2). Metabolites such as caffeoyl tartaric acid (CTA), 5-p-coumaroylquinic acid (5-CoQA), caffeoyl quinic acid (CQA), di-pCT, kaempferol glucuronide (K-3Gc), quercetin-3-glucoronide (Q-3Gc), quercetin-3-malonylglucoside (Q-3MG) and kaempferol-3-malonylglucoside (K-3MG; peaks 1–3, 6 and 8–11, respectively, on Figure 2) were present at greater concentrations in L. serriola than L. sativa, whilst concentrations of di-CTA (DCTA; chicoric acid) and dicaffeoyl quinic acid (DCQA; peaks 5 and 7, respectively; Figure 2) were comparable and caffeoyl malic acid (peak 4; Figure 2) was the only phenolic compound noticeably present at greater abundance in L. sativa.


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 the phenolic profiles of L. serriola and L. sativa. LC-MS profiles of the RIL parents, Lactuca serriola and L. sativa. Figure shows the relative maxima of absorbance of samples against retention time in (minutes), also displayed above each peak. Peaks: (1) CTA; (2) 5-CoQA (5-p-coumaroylquinic acid); (3) caffeoyl quinic acid; (4) caffeoyl malic acid; (5) di-CTA; (6) di-pCT; (7) dicaffeoyl quinic acid; (8) kaempferol glucuronide; (9) quercetin-3-glucuronide; (10) quercetin-3-malonylglucoside; (11) kaempferol-3-malonylglucoside. Multiple peaks for the same compound indicate isoforms.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig2: Comparison of the phenolic profiles of L. serriola and L. sativa. LC-MS profiles of the RIL parents, Lactuca serriola and L. sativa. Figure shows the relative maxima of absorbance of samples against retention time in (minutes), also displayed above each peak. Peaks: (1) CTA; (2) 5-CoQA (5-p-coumaroylquinic acid); (3) caffeoyl quinic acid; (4) caffeoyl malic acid; (5) di-CTA; (6) di-pCT; (7) dicaffeoyl quinic acid; (8) kaempferol glucuronide; (9) quercetin-3-glucuronide; (10) quercetin-3-malonylglucoside; (11) kaempferol-3-malonylglucoside. Multiple peaks for the same compound indicate isoforms.
Mentions: Clear differences in total phenolic content were detected between wild and cultivated lettuce (38.76 ± 4.65 vs. 22.25 ± 1.25 catechin equivalent, mg/g dry weight, respectively; two-sample t-test, t(8)=–3.43, P ≤ 0.01). Individual phenolic compounds were further quantified by LC/MS/MS. Visual inspection of the LC-MS profiles revealed clear qualitative and quantitative differences in phenolic composition for the two parent lines (Figure 2). Metabolites such as caffeoyl tartaric acid (CTA), 5-p-coumaroylquinic acid (5-CoQA), caffeoyl quinic acid (CQA), di-pCT, kaempferol glucuronide (K-3Gc), quercetin-3-glucoronide (Q-3Gc), quercetin-3-malonylglucoside (Q-3MG) and kaempferol-3-malonylglucoside (K-3MG; peaks 1–3, 6 and 8–11, respectively, on Figure 2) were present at greater concentrations in L. serriola than L. sativa, whilst concentrations of di-CTA (DCTA; chicoric acid) and dicaffeoyl quinic acid (DCQA; peaks 5 and 7, respectively; Figure 2) were comparable and caffeoyl malic acid (peak 4; Figure 2) was the only phenolic compound noticeably present at greater abundance in L. sativa.

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