Philippe Lebreton

Differentiation des dihydroxy-5, 7 methoxy-6 ou 8 flavones flavonols et methyl-3 flavonols par spectrometrie de masse

Abstract 5,7-Dihydroxy flavones and flavonols variously methoxylated in the 3-, 6- and/or 8-positions give characteristic fragmentation peaks. The relative abundance of M, M-1 and M-15 peaks and the presence of M-18 peak makes it possible to differentiate the 6-methoxy from the 8-methoxy isomers and three types of 6-methoxyflavones from each other.

Geographical variability of Pinus halepensis Mill. as revealed by foliar flavonoids

Needle flavonoids were used to study the geographical variability of Pinus halepensis Mill. Particular importance was attached to the influence of environment on the expression of these polyphenols in this species. In all trees two proanthocyanins: prodelphinidin and procyanidin, and six flavonols: myricetin, quercetin, larycitrin, kaempferol, isorhamnetin and syringetin, were detected and measured by HPLC. Trees from the same provenance grown at two different experimental plots were found to have similar flavonoid composition. Significant differences however, were observed between individuals harvested in experimental stands and those collected in natural populations. Nevertheless, in experimental stands flavonoid expression was sufficiently stable to allow comparison between trees of different geographical origins. In this context, relative proanthocyanin contents remained constant from one population to another while average myricetin concentrations separated Pinus halepensis into three geographical groups: Greek, North African/Western European and Southern European. The groupings obtained with flavonoid markers were compared with those determined by other genetic traits, namely needle morphology, terpenes and isozymes. The divergence between the population groups was explained on the basis of late tertiary glaciations on the European continent.

GENETIC DIFFERENCES BETWEEN PINUS HALEPENSIS, PINUS BRUTIA AND PINUS ELDARICA BASED ON NEEDLE FLAVONOIDS

A chemosystematic study based on needle flavonoids, was carried out on 324 trees from six populations of Pinus halepensis, six of Pinus brutia and one of Pinus eldarica. Two main flavonoid classes were identified and measured by HPLC: (pro)anthocyanins and flavonols. Relative (pro)anthocyanin contents were constant from one taxon to another, while flavonol aglycones, in particular quercetin and isorhamnetin, allowed complete discrimination of the three taxa. In agreement with previous studies, needle flavonoids show that P. halepensis and P. brutia are two distinct species. Surprisingly, P. brutia subsp. brutia was found to be more distant from P. brutia subsp. eldarica than from P. halepensis. Concerning their phylogenetic relationships, needle flavonoids bring chemical evidence of the common origin of the three pines studied. Early divergence of the progenitor resulted in the appearance of contemporary P. halepensis and P. brutia; subsequent evolution of P. brutia gave P. eldarica. On the basis of the phylogenetic results and taking into account other genetic traits, it is proposed to maintain P. eldarica as a subspecies of the P. brutia complex.

Taxonomy and systematics of the genus Pinus based on morphological, biogeographical and biochemical characters

For a long time, systematists have subdivided the genus Pinus into Diploxylon and Haploxylon according to morpho-anatomy and the number of needles. Nevertheless, divergent views remain regarding the structure of these two subgenera, mainly at the section and subsection levels. We propose to clarify some of these uncertainties by studying 45 Pinus taxa of different origins. Our results, based on morphometric and biochemical (flavonoids) parameters, complement those obtained from classical anatomical and morphological studies, and also modern macro-molecular markers (proteins, DNA). We confirm the subdivision of the genus into Pinusxa0=xa0Diploxylon versus Strobusxa0=xa0Haploxylon and the further sectioning of the first subgenus into sections Pinus and Trifoliae. Moreover, we specify the different subsections, whereby the contents of the methylated flavonol isorhamnetin coupled with needle morphometry play a significant role (subsections Pinus vs. Pinaster in section Pinus, Australesxa0+xa0Ponderosae vs. Contortae in section Trifoliae). Given that isorhamnetin proceeds from quercetin by the irreversible action of an O-methyl-transferase, this methylated flavonol becomes a dynamic marker in such way that the taxa rich in isorhamnetin can be considered as more “derivedxa0=xa0evolved”. In addition, there exists a highly significant negative correlation between methylation index and number of needles. Consequently, the pines from the Holarctic Strobus group (with five needles and low isorhamnetin contents) can be considered as “ancestral”, in reference to a Laurasian origin of the genus. In the subgenus Pinus, the Nearctic group (=section Trifoliae) remains near the ancestral base. On the other hand, the Holarctic subset “densiflorae” is connected to the other members (mainly European) of the polyphyletic subsection Pinus, in particular with series “sylvestres”. Because of their very high contents of isorhamnetin, the Mediterranean pines result from an accentuation of this evolutionary trend (=subsection Pinaster). In fact, the pines growing under hot and dry climates (Mediterranean region) are highly evolved compared to those from cold and/or wet regions (Eurasia and North America but also, to a lesser extent, the south-eastern USA and East Asia). Our dynamic propositions based on plant phenolics data complete those from more modern macromolecular (DNA, proteins) studies.

Chimiotaxinomie flavonique des fluviales

Abstract The flavonoid patterns of twenty-three species of Fluviales (= Helobieae) were determined. Flavonols and pro-anthocyanidins are uncommon and trihydroxy derivatives are absent. In contrast, flavones (luteolin and chrysoeriol derivatives) are common, often as C -glycosides (Alismataceae, Butomaceae, Potamogetonaceae). From a taxonomic point of view the results suggest that the Fluviales can be divided into two groups: Potamogetonaceae. Zosteraceae, Ruppiaceae, Zanichelliaceae and Juncaginaceae forming the first, and Hydrocharitaceae, Butomaceae. Alismataceae and Aponogetonaceae the second. This arrangement agrees for the most part with the views of Emberger and Takhtajan.

Reconnaissance chimiosystématique et biométrique du pin de tourbière Pinus x uliginosa (Neumann)

Resume Les pins de tourbiere Pinus uliginosa Neumann de Pologne et ceux de France ont une composition flavonique (faible teneur en quercetine) proche de celle des pins mugo P. mugo Turr. et a crochet P. uncinata Ram., non distinguables a cet egard. La presence minoritaire dindividus de type chimique sylvestris (forte teneur en quercetine) est cependant notable ; en outre nombreux peuvent etre les individus a teneur intermediaire, revelant un processus dhybridation, en bon accord avec la loi de Hardy-Weinberg. La biometrie foliaire (indice dallongement L/P) tend vers le type uncinatalmugo . Si lon veut reconnaitre au pin de tourbiere la dignite specifique, on doit admettre quil resulte de la persistance dans un tel biotope de croisements du pin a crochet/mugo avec le pin sylvestre (plus precisement son chimiomorphe T-, taxifoline absente), le second subordonne au premier. La comparaison est faite avec les phenomenes dhybridation/introgression actuels donnant naissance en altitude, a partir des memes especes parentales, au pin de Bouget Pinus bougeti Flous.

Discrimination and identification of coastal Douglas-fir clones using needle flavonoid fingerprints.

This paper describes a method for discriminating and identifying 10 successful Douglas-fir (Pseudotsuga menziesii var. menziesii) clones using foliar flavonoids. All the 101 individuals analyzed by high performance liquid chromatography contained two proanthocyanidins: prodelphinidin and procyanidin and six flavonols: myricetin, quercetin, larycitrin, kaempferol, isorhamnetin and syringetin, but in different proportions. The experimental protocol used was very reproducible since the variation coefficients for each flavonoid did not exceed 9%. Submission of the flavonoid data to multivariate discriminant analysis allowed excellent discrimination of the 10 clones with 89% of the individuals being well-grouped. Then a clonal bank was established in which the fingerprint of each clone is defined by its position in the multidimensional space of the discriminant analysis. The clonal identity of several unknown individuals was determined with success by projecting their flavonoid data in a subsequent discriminant analysis.

Genetic variation in the needle flavonoid composition of Pinus brutia var. brutia populations

In this paper, the variability of six Pinus brutia var. brutia populations was analyzed in relation to their needle flavonoid composition. In all trees, two proanthocyanidins: prodelphinidin and procyanidin, and six flavonols: myricetin, quercetin, larycitrin, kaempferol, isorhamnetin and syringetin were detected and measured by HPLC. The relative proanthocyanidin composition was remarkably constant from one provenance to another. On the other hand, total proanthocyanidin concentrations as well as relative isorhamnetin contents showed significant differences between the populations studied. Total proanthocyanidin contents distinguished two populations from Crete and Turkey from all the others, whereas relative isorhamnetin contents split the species into two main eastern and western groups in accordance with terpene and isozyme data.

Apports de la biochimie à la définition des Agavacées

ResumeCompletant le travail de Williams (1975), lanalyse flavonique (flavonols, C-glycosyl-flavones, proantlioeyanes) dune trentaine de Liliiflores, dont une douzaine dAgavacees sensu lato, a souligne loriginalite, donc lautonomie, de cette famille.Les divers criteres (incluant la caryologie et la biogeographie) permettent de comprendre ici le taxon au sens le plus large, et de le structurer en 5 sous-familles: Agavoidees, Dracenoidees, Phormioidees, Doryanthoidees et Xanthorrhoeoidees.Les relations avec dautres Liliiflores sont probablement plus etroites avec les Amaryllidacees quavec les Liliacees, notamment sur des criteres biochimiques, flavoniques ou non.