40. Flavonoids as biochemical markers in the genus Oryza

1) Laboratoire de Phytochimie, U.E.R. Claude Bernard Lyon 1, 43 Boulevard du 11 Novembre 1918, 69622 Villeurbanne-cedex, and

2) Biologie des Populations et des Peuplements, C.N.R.S. BP 5051, 34033 Montpellier-cedex, France

Our aim is to describe a new biochemical and molecular approach for studying polymorphism in Oryza. Flavonoid compounds are particulaly convenient for this purpose as they are widely distributed among plants and are chemically stable. They show a structural diversity due to differences in oxygenation, methylation and glycosylation processes. Most of the plant samples studied are those analyzed earlier for enzymatic diversity (Second 1982, 1983).

The leaf material to be sampled is immersed in an alcoholic mixture and after a fast purification step, the extract is analysed by two dimensional thin layer chromatography (flavonoid patterns fixed by U.V. photographic process; Gonet 1973), or by high performance liquid chromatography (profiles integrated for the peak heights; Jay et al. 1983). In both cases, the phytochemical data were treated by multivariate analysis.

Two large groups of forms or species were recognized. One of them included the representatives of O. sativa complex, and the other was composed of O. latifolia complex. In the former, different flavonoid patterns could be corresponded to geographical origins or species. In the latter, it was possible to characterize the different genomes reported in this group. Moreover, O. ridleyi and O. meyeriana were distinguishable, and in the latter species the Chinese and South Asiatic forms could be separated.

The flavonoid patterns can be easily obtained from dry samples. The reports by the Phytochemical, Group of Lyon on various plants demonstrate the cogency of the biochemical markers in appreciating plant variability and its phylogenetic significance at species or infraspecific level (Jay et Gorenflot 1980; Jay et al. 1983; Reynaud et ai. 1982).

Gonnet, J. F., 1973. A propos de la photographie en couleurs de chromatographie sur couches minces en lumiere de Wood. J. Chromato. 86: 192.

Jay, M. et R. Corenflot, 1980. Premieres observations relatives a la variation dans l'expression du metabolisme flavonique chex le Phragmites australis (Cav.) Trin. ex Steud. Rev. Gen. Bot. 87: 261-274.

-----, D. Plenet, P. Ardouin, R. Lumaret and P. Jacquard, 1983. Individual polyphenolic variation in 7 tetraploid populations of Dactylis glomerata L. Biochemical Systematics and Ecology (in press).

Reynaud, J., S. Blaise, M. Jay et D. Cartier, 1982. Response du metabolisme flavonique A la pression de selection du milieu sur diverses populations du Lathyrus pratensis L. Taxon 31: 4.

Second, G. 1982. Origin of the genic diversity of cultivated rice (Oryza spp): Study of the polymorphism scored at 40 isozyme loci. Jpn. J. Genet. 57: 25-57.

----- 1983. The study of isozymes in relation to the distribution of the genus Oryza in the palaeoenvironment and the subsequent origin of cultivated rice. Conf. Palaeoenvironment of East-Asia from the Mid-Tertiary. Hongkong, Jan. 7-12, 1983. (Proceedings in press).