Plant Physiol, October 2002, Vol. 130, pp. 729-739
Expression of Genes Involved in Anthocyanin Biosynthesis in
Relation to Anthocyanin, Proanthocyanidin, and Flavonol Levels during
Bilberry Fruit Development1
Laura
Jaakola,*
Kaisu
Määttä,
Anna Maria
Pirttilä,2
Riitta
Törrönen,
Sirpa
Kärenlampi, and
Anja
Hohtola
Department of Biology/Botany, University of Oulu, FIN-90014 Oulu,
Finland (L.J., A.M.P., A.H.); Institute of Applied Biotechnology (K.M.,
R.T.), Food and Health Research Centre (R.T.), and Department of
Biochemistry (S.K.), University of Kuopio, FIN-70211 Kuopio,
Finland
The production of anthocyanins in fruit tissues is
highly controlled at the developmental level. We have studied the
expression of flavonoid biosynthesis genes during the development of
bilberry (Vaccinium myrtillus) fruit in relation to the
accumulation of anthocyanins, proanthocyanidins, and flavonols in wild
berries and in color mutants of bilberry. The cDNA fragments of five
genes from the flavonoid pathway, phenylalanine ammonia-lyase, chalcone synthase, flavanone 3-hydroxylase, dihydroflavonol 4-reductase, and
anthocyanidin synthase, were isolated from bilberry using the
polymerase chain reaction technique, sequenced, and labeled with a
digoxigenin-dUTP label. These homologous probes were used for
determining the expression of the flavonoid pathway genes in
bilberries. The contents of anthocyanins, proanthocyanidins, and
flavonols in ripening bilberries were analyzed with high-performance liquid chromatography-diode array detector and were identified using a
mass spectrometry interface. Our results demonstrate a correlation
between anthocyanin accumulation and expression of the flavonoid
pathway genes during the ripening of berries. At the early stages of
berry development, procyanidins and quercetin were the major
flavonoids, but the levels decreased dramatically during the progress
of ripening. During the later stages of ripening, the content of
anthocyanins increased strongly and they were the major flavonoids in
the ripe berry. The expression of flavonoid pathway genes in the color
mutants of bilberry was reduced. A connection between flavonol and
anthocyanin synthesis in bilberry was detected in this study and also
in previous data collected from flavonol and anthocyanin analyses from
other fruits. In accordance with this, models for the connection
between flavonol and anthocyanin syntheses in fruit tissues are presented.
1
This work was supported by the Eemil Aaltonen
foundation and by the Oscar Öflund foundation. The research is a
part of the Cooperation Program of the University of Oulu and Kuusamo
Town and was financed by the European Union (to E.S.F.), by the
Regional Council of Northern Ostrobothnia, and by Kuusamo Town.
2
Present address: Department of Botany and Plant
Pathology, Woloshuk Lab, 1155 Lilly Hall, Purdue University, West
Lafayette, IN 47907-1155.
*
Correspondending author; e-mail Laura.Jaakola{at}oulu.fi; fax
358-8-553-1500.
© 2002 American Society of Plant Physiologists
