Abstract
BACKGROUND AND AIMS: Caffeoylquinic acids are cinnamate conjugates derived from the phenylpropanoid pathway. They are generally involved in plant responses to biotic and abiotic stress and one of them, chlorogenic acid (5-O-caffeoylquinic acid, 5-CQA), is an intermediate in the lignin biosynthesis pathway. Caffeoylquinic acids, and particularly 5-CQA, are accumulated in coffee beans, where they can form vacuolar complexes with caffeine. Coffea canephora beans are known to have high caffeoylquinic acid content, but little is known about the content and diversity of these compounds in other plant parts. To gain new insights into the caffeoylquinic acid metabolism of C. canephora, caffeoylquinic acid content and in situ localization were assessed in leaves at different growth stages. METHODS: HPLC analyses of caffeoylquinic acid content of leaves was conducted in conjunction with detailed histochemical and microspectrofluorometrical analysis. KEY RESULTS AND CONCLUSIONS: HPLC analyses revealed that caffeoylquinic acid content was 10-fold lower in adult than in juvenile leaves. The most abundant cinnamate conjugate was 5-CQA, but dicaffeoylquinic acids (particularly in juvenile leaves) and feruloylquinic acids were also present. Using specific reagents, histochemical and microspectrofluorometrical analysis showed that caffeoylquinic acids (mono- and di-esters) were closely associated with chloroplasts in very young leaves. During leaf ageing, they were found to first accumulate intensively in specific chlorenchymatous bundle sheath cells and then in phloem sclerenchyma cells. The association with chloroplasts suggests that caffeoylquinic acids have a protective role against light damage. In older tissues, their presence in the leaf vascular system indicates that they are transported via phloem and confirms their involvement in lignification processes. In accordance with the hypothesis of a complex formation with caffeine, similar tissue distribution was observed for alkaloids and this is further discussed.
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Claims 11
Claim · model-written summary
Caffeoylquinic acid content was tenfold lower in adult than juvenile leaves.
- Taxon
- Coffea canephora
Coffea canephorat0 - Organ / stage
- adulte0
- Outcome
- caffeoylquinic acid contente0
- Direction
- lowere0
- Value
- 10-folde0
- Comparator
- juvenile leavese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“caffeoylquinic acid content was 10-fold lower in adult than in juvenile leaves”
t0“Coffea canephora”
Claim · model-written summary
5-CQA was the most abundant cinnamate conjugate.
- Taxon
- Coffea canephoraCoffea canephorat0
- Outcome
- most abundant cinnamate conjugate was 5-CQAe0
- Direction
- most abundante0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The most abundant cinnamate conjugate was 5-CQA”
t0“Coffea canephora”
Claim · model-written summary
Dicaffeoylquinic acids were present, particularly in juvenile leaves.
- Taxon
- Coffea canephoraCoffea canephorat0
- Organ / stage
- juvenile leavese0
- Outcome
- dicaffeoylquinic acids (particularly in juvenile leaves)e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“dicaffeoylquinic acids (particularly in juvenile leaves) and feruloylquinic acids were also present”
t0“Coffea canephora”
Claim · model-written summary
Feruloylquinic acids were present in leaves.
- Taxon
- Coffea canephoraCoffea canephorat0
- Organ / stage
- Leaft0
- Outcome
- feruloylquinic acids were also presente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“feruloylquinic acids were also present”
t0“Coffea canephora Leaf”
Claim · model-written summary
Caffeoylquinic acids were closely associated with chloroplasts in very young leaves.
- Taxon
- Coffea canephoraCoffea canephorat0
- Organ / stage
- very young leavese0
- Outcome
- closely associated with chloroplastse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“caffeoylquinic acids (mono- and di-esters) were closely associated with chloroplasts in very young leaves”
t0“Coffea canephora”
Claim · model-written summary
During leaf ageing, caffeoylquinic acids first accumulated in chlorenchymatous bundle sheath cells.
- Taxon
- Coffea canephoraCoffea canephorat0
- Organ / stage
- chlorenchymatous bundle sheath cellse0
- Outcome
- accumulate intensivelye0
- Direction
- accumulatee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“During leaf ageing, they were found to first accumulate intensively in specific chlorenchymatous bundle sheath cells”
t0“Coffea canephora”
Claim · model-written summary
During leaf ageing, caffeoylquinic acids subsequently accumulated in phloem sclerenchyma cells.
- Taxon
- Coffea canephoraCoffea canephorat0
- Organ / stage
- phloem sclerenchyma cellse0
- Outcome
- then in phloem sclerenchyma cellse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“and then in phloem sclerenchyma cells”
t0“Coffea canephora”
Claim · model-written summary
Chloroplast association suggests a protective role for caffeoylquinic acids against light damage.
- Taxon
- Coffea canephoraCoffea canephorat0
- Outcome
- protective role against light damagee0
- Qualifier
- association with chloroplastse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The association with chloroplasts suggests that caffeoylquinic acids have a protective role against light damage”
t0“Coffea canephora”
Claim · model-written summary
Their presence in older leaf vascular tissue indicates phloem transport.
- Taxon
- Coffea canephoraCoffea canephorat0
- Organ / stage
- leaf vascular systeme0
- Outcome
- transported via phloeme0
- Qualifier
- their presence in the leaf vascular systeme0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In older tissues, their presence in the leaf vascular system indicates that they are transported via phloem”
t0“Coffea canephora”
Claim · model-written summary
Their presence in older vascular tissue supports involvement in lignification.
- Taxon
- Coffea canephoraCoffea canephorat0
- Outcome
- involvement in lignification processese0
- Qualifier
- lignification processese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“confirms their involvement in lignification processes”
t0“Coffea canephora”
Claim · model-written summary
Alkaloids showed a similar tissue distribution to caffeoylquinic acids.
- Taxon
- Coffea canephoraCoffea canephorat0
- Outcome
- similar tissue distribution was observed for alkaloidse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“similar tissue distribution was observed for alkaloids”
t0“Coffea canephora”