Abstract
UV-excitation of green leaves induces a red fluorescence (RF) and a blue-green fluorescence (BGF) emitted by chlorophyll and hydroxycinnamic acids (HCA), respectively. The potential use of BGF for crop remote sensing requires the precise knowledge of molecular and anatomical origins of BGF during plant development. In this study, we investigated how cell age and the leaf stage of development influence the BGF signature. We measured the UV-induced fluorescence along the three leaves of 15-days old wheat plants (Triticum aestivum L.) using a UV-PAM fluorimeter. Then, the BGF was described and quantified along the leaves by microscopic fluorescence imaging. The HCA origin of BGF was verified by comparing alkali-induced changes of leaf BGF to pH-induced variation of ferulic acid fluorescence spectra. The decrease of RF from the base towards the tip of all leaves showed that UV-absorbers accumulated as cell aged. Except for the oldest leaf, there was no similar decrease in BGF, which therefore could emanates from leaf surface. We showed that BGF emanates from the wall of each epidermal cell type and from the trichome protoplast. We verified that all these structures contain HCA. Lignified cell wall of sclerenchyma bands contributed also to BGF. Among the three leaves, the oldest one emitted the lowest BGF which was related to the lowest density of trichomes. However, the decrease of BGF along this leaf can not be explained by a reduction in trichomes density. The significance of BGF signatures is discussed considering the spatial distribution of blue-green fluorophores and UV-absorbers
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Claims 7
Claim · model-written summary
Red fluorescence decreased from the leaf base toward the tip of all wheat leaves, indicating UV-absorber accumulation as cells aged.
- Taxon
- wheat
Triticum aestivume0 - Organ / stage
- all leavese1
- Outcome
- RFe1
- Direction
- decreasee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“wheat plants (Triticum aestivum L.)”
e1“The decrease of RF from the base towards the tip of all leaves showed that UV-absorbers accumulated as cell aged”
Claim · model-written summary
Except for the oldest leaf, BGF showed no similar decrease along the leaves.
- Taxon
- wheatTriticum aestivume0
- Outcome
- BGFe2
- Qualifier
- Except for the oldest leafe2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“wheat plants (Triticum aestivum L.)”
e2“Except for the oldest leaf, there was no similar decrease in BGF”
Claim · model-written summary
BGF emanates from the wall of each epidermal cell type and from the trichome protoplast in wheat leaves.
- Taxon
- wheatTriticum aestivume0
- Organ / stage
- trichome protoplaste3
- Outcome
- BGFe3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“wheat plants (Triticum aestivum L.)”
e3“BGF emanates from the wall of each epidermal cell type and from the trichome protoplast”
Claim · model-written summary
The wheat leaf structures emitting BGF all contain HCA.
- Taxon
- wheatTriticum aestivume0
- Outcome
- contain HCAe4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“wheat plants (Triticum aestivum L.)”
e4“We verified that all these structures contain HCA”
Claim · model-written summary
Lignified cell wall of sclerenchyma bands in wheat leaves contributed to BGF.
- Taxon
- wheatTriticum aestivume0
- Organ / stage
- sclerenchyma bandse5
- Outcome
- BGFe5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“wheat plants (Triticum aestivum L.)”
e5“Lignified cell wall of sclerenchyma bands contributed also to BGF”
Claim · model-written summary
The oldest of the three wheat leaves emitted the lowest BGF, which was related to the lowest trichome density.
- Taxon
- wheatTriticum aestivume0
- Organ / stage
- the oldest onee6
- Outcome
- BGFe6
- Direction
- loweste6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“wheat plants (Triticum aestivum L.)”
e6“the oldest one emitted the lowest BGF which was related to the lowest density of trichomes”
Claim · model-written summary
The decrease of BGF along the leaf cannot be explained by a reduction in trichome density.
- Taxon
- wheatTriticum aestivume0
- Organ / stage
- this leafe7
- Outcome
- BGFe7
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“wheat plants (Triticum aestivum L.)”
e7“the decrease of BGF along this leaf can not be explained by a reduction in trichomes density”