Ronald Koes - Academia.edu (original) (raw)

Papers by Ronald Koes

Nature Cell Biology, 2008

The regulation of pH in cellular compartments is crucial for intracellular trafficking of vesicle... more The regulation of pH in cellular compartments is crucial for intracellular trafficking of vesicles and proteins and the transport of small molecules, including hormones. In endomembrane compartments, pH is regulated by vacuolar H + -ATPase 1 (V-ATPase), which, in plants, act together with H + -pyrophosphatases 2 (PPase), whereas distinct P-type H + -ATPases in the cell membrane control the pH in the cytoplasm and energize the plasma membrane 3 . Flower colour mutants have proved useful in identifying genes controlling the pH of vacuoles where anthocyanin pigments accumulate 4,5 . Here we show that PH5 of petunia encodes a P 3A -ATPase proton pump that, unlike other P-type H + -ATPases, resides in the vacuolar membrane. Mutation of PH5 reduces vacuolar acidification in petals, resulting in a blue flower colour and abolishes the accumulation of proanthocyanindins (condensed tannins) in seeds. Expression of PH5 is directly activated by transcription regulators of the anthocyanin pathway, in conjunction with PH3 and PH4. Thus, flower coloration, a key-factor in plant reproduction, involves the coordinated activation of pigment synthesis and a specific pathway for vacuolar acidification.

Development, 2007

Petals of animal-pollinated angiosperms have adapted to attract pollinators. Factors influencing ... more Petals of animal-pollinated angiosperms have adapted to attract pollinators. Factors influencing pollinator attention include colour and overall size of flowers. Colour is determined by the nature of the pigments, their environment and by the morphology of the petal epidermal cells. Most angiosperms have conical epidermal cells, which enhance the colour intensity and brightness of petal surfaces. The MYB-related transcription factor MIXTA controls the development of conical epidermal cells in petals of Antirrhinum majus. Another gene encoding an R2R3 MYB factor very closely related to MIXTA, AmMYBML2, is also expressed in flowers of A. majus. We have analysed the roles of AmMYBML2 and two MIXTA-related genes, PhMYB1 from Petunia hybrida and AtMYB16 from Arabidopsis thaliana, in petal development. The structural similarity between these genes, their comparable expression patterns and the similarity of the phenotypes they induce when ectopically expressed in tobacco, suggest they share homologous functions closely related to, but distinct from, that of MIXTA. Detailed phenotypic analysis of a phmyb1 mutant confirmed the role of PhMYB1 in the control of cell morphogenesis in the petal epidermis. The phmyb1 mutant showed that epidermal cell shape affects petal presentation, a phenotypic trait also observed following re-examination of mixta mutants. This suggests that the activity of MIXTA-like genes also contributes to petal form, another important factor influencing pollinator attraction.

Plant physiology, Jan 15, 2014

Anthocyanins are a chemically diverse class of secondary metabolites that color most flowers and ... more Anthocyanins are a chemically diverse class of secondary metabolites that color most flowers and fruits. They consist of three aromatic rings that can be substituted with hydroxyl, sugar, acyl, and methyl groups in a variety of patterns depending on the plant species. To understand how such chemical diversity evolved, we isolated and characterized METHYLATION AT THREE2 (MT2) and the two METHYLATION AT FIVE (MF) loci from Petunia spp., which direct anthocyanin methylation in petals. The proteins encoded by MT2 and the duplicated MF1 and MF2 genes and a putative grape (Vitis vinifera) homolog Anthocyanin O-Methyltransferase1 (VvAOMT1) are highly similar to and apparently evolved from caffeoyl-Coenzyme A O-methyltransferases by relatively small alterations in the active site. Transgenic experiments showed that the Petunia spp. and grape enzymes have remarkably different substrate specificities, which explains part of the structural anthocyanin diversity in both species. Most strikingly...

Proceedings of the National Academy of Sciences, 1995

Establishment of loss-of-function phenotypes is often a key step in determining the biological fu... more Establishment of loss-of-function phenotypes is often a key step in determining the biological function of a gene. We describe a procedure to obtain mutant petunia plants in which a specific gene with known sequence is inactivated by the transposable element dTphl. Leaves are collected from batches of 1000 plants with highly active dTphl elements, pooled according to a three-dimensional matrix, and screened by PCR using a transposon-and a gene-specific primer. In this way individual plants with a dTphl insertion can be identified by analysis of about 30 PCRs. We found insertion alleles for various genes at a frequency of about 1 in 1000 plants. The plant population can be preserved by selfing all the plants, so that it can be screened for insertions in many genes over a prolonged period.

Cell Reports, 2014

The acidification of endomembrane compartments is essential for enzyme activities, sorting, traff... more The acidification of endomembrane compartments is essential for enzyme activities, sorting, trafficking, and trans-membrane transport of various compounds. Vacuoles are mildly acidic in most plant cells because of the action of V-ATPase and/or pyrophosphatase proton pumps but are hyperacidified in specific cells by mechanisms that remained unclear. Here, we show that the blue petal color of petunia ph mutants is due to a failure to hyperacidify vacuoles. We report that PH1 encodes a P 3B -ATPase, hitherto known as Mg2 + transporters in bacteria only, that resides in the vacuolar membrane (tonoplast). In vivo nuclear magnetic resonance and genetic data show that PH1 is required and, together with the tonoplast H + P 3A -ATPase PH5, sufficient to hyperacidify vacuoles. PH1 has no H + transport activity on its own but can physically interact with PH5 and boost PH5 H + transport activity. Hence, the hyperacidification of vacuoles in petals, and possibly other tissues, relies on a heteromeric P-ATPase pump.

Plant Molecular Biology Reporter, 1988

... Genetic Resources Cloned Genes of Phenylpropanoid Metabolism in Plants Joseph NM Mol, Toon R.... more ... Genetic Resources Cloned Genes of Phenylpropanoid Metabolism in Plants Joseph NM Mol, Toon R. Stuitje, Anton GM Gerats and Ronald E. Koes ... USA. 83: 9631-9635. Cramer, CL, K. Edwards, M. Dron, X. Liang, SL Dildine, GP Bolwell, RA Dixon, CJ. Lamb and W. Schuch. ...

Trends in Biotechnology, 1995

‘Classical’ flower breeding by continuous crossing and selection has its limitations; for example... more ‘Classical’ flower breeding by continuous crossing and selection has its limitations; for example, no one has succeeded in breeding a blue rose or an orange petunia. However, the ability to introduce individual genes into plants (molecular breeding) has made the development of plant species with novel aesthetic properties possible. This review summarizes recent developments in the molecular breeding of flowers, indicates novel traits and strategies, and discusses some of the problems that must be tackled before transgenic ornamental plants can reach the marketplace.

Current Opinion in Biotechnology, 1999

The floricultural industry has focused its attention primarily on the development of novel colour... more The floricultural industry has focused its attention primarily on the development of novel coloured and longer living cut flowers. The basis for this was laid down some years ago through the isolation of ‘blue’ genes and ethylene biosynthesis genes. Recently, a novel ‘blue’ gene has been discovered and yellow pigments were produced in petunias by addition of a new branch

The Plant Cell, 2000

... Cornelis Spelt a , Francesca Quattrocchio a , Joseph NM Mol a , and Ronald Koes a a Departmen... more ... Cornelis Spelt a , Francesca Quattrocchio a , Joseph NM Mol a , and Ronald Koes a a Department of Genetics, Institute for Molecular Biological Sciences, Vrije Universiteit, Biocentrum Amsterdam, de Boelelaan 1087, 1081 HV Amsterdam, The Netherlands ...

Trends in Plant Science, 2005

Trends in Plant Science, 1998

Mutant analyses have given insight into the various parameters that contribute to flower colour a... more Mutant analyses have given insight into the various parameters that contribute to flower colour and pattern, which is so important for pollination. One important factor is the accumulation of orange, red and purple anthocyanin pigments in the cell vacuolepatterns arise by cell-specific expression of combinations of regulatory proteins. The overall colour perceived is also influenced by vacuolar pH, co-pigmentation and the shape of the petal cells. Although understanding of the biochemistry and genetics of anthocyanin and flavonol biosynthesis is well developed, this is not the case for pH and cellshape control.

Trends in Plant Science, 2013

Trends in Plant Science, 2010

The LEAFY (LFY) gene of Arabidopsis and its homologs in other angiosperms encode a unique plant-s... more The LEAFY (LFY) gene of Arabidopsis and its homologs in other angiosperms encode a unique plant-specific transcription factor that assigns the floral fate of meristems and plays a key role in the patterning of flowers, probably since the origin of flowering plants. LFY-like genes are also found in gymnosperms, ferns and mosses that do not produce flowers, but their role in these plants is poorly understood. Here, we review recent findings explaining how the LFY protein works and how it could have evolved throughout land plant history. We propose that LFY homologs have an ancestral role in regulating cell division and arrangement, and acquired novel functions in seed plants, such as activating reproductive gene networks.

The Plant Journal, 1994

Anthocyanin biosynthesis in flowers of Petunia hybrida is controlled by the regulatory genes an1,... more Anthocyanin biosynthesis in flowers of Petunia hybrida is controlled by the regulatory genes an1, an2 and an11. Seven classes of cDNA clones homologous to transcripts that are down-regulated in an1-, an2and an11mutants were isolated via differential cDNA cloning. Genetic mapping, antisense RNA experiments and analyses of mutant alleles demonstrated that one class of clones originated from the Rt locus. The rt gene has no introns and encodes a protein with homology to mammalian glucuronosyl transferases and flavonoid 3-O-glucosyltransferase (UF3GT) encoded by the bzl gene from Zea mays. As the Rt locus controls the rhamnosylation of reddish anthocyanin-3-O-glucosides which is the first in a series of modifications that finally yield magenta or blue/purple coloured anthocyanins, this suggests that rt encodes an anthocyanin rhamnosyl transferase. Molecular analysis of two mutant rt alleles showed that their expression is blocked by different DNA insertion elements. Mutability of the rt-vu15 allele results from the presence of a 284 bp transposable element (dTphl) in the rt promoter region, causing a block in transcription. The protein coding region of the rt.r27 allele contains a 442 bp insertion (dTph3) resulting in premature polyadenylation of rt transcripts. Although dTph3 cannot transpose, it has sequence characteristics of transposable elements, suggesting that it is a defective member of a new family of transposable elements.

The Plant Journal, 1995

The Petunia hybrida line W138 contains more than 200 copies of the transposable element dTphl. In... more The Petunia hybrida line W138 contains more than 200 copies of the transposable element dTphl. In W138 progeny these elements give rise to new unstable mutations at high frequency. With the aim of isolating these mutated genes a method was developed to isolate dTphl flanking sequences unique for mutant plants. This method is based on differential screening of cloned inverse polymerese chain reaction (IPCR) products originating from the mutated plant. It directly yields e probe for the mutated gene which can be used to screen pre-existing cDNA and genomic libraries. This method may be generally applicable to isolate genes tagged by other high copy number transposable elements, like Mutator (Mu) or Dissociation (Ds) in Zea mays.

The Plant Journal, 1998

The regulatory anthocyanin loci, an1, an2, an4 and an11 of Petunia hybrida, and r and c1 from Zea... more The regulatory anthocyanin loci, an1, an2, an4 and an11 of Petunia hybrida, and r and c1 from Zea mays, control transcription of different sets of target genes. Both an2 and c1 encode a MYB-type protein. This study reports the isolation of a P. hybrida gene, jaf13, encoding a basic helix-loop-helix protein that, on the basis of sequence homology and intron/exon structure, represents the P. hybrida orthologue of the Z. mays r genes. Ectopic expression of an2 and jaf13 is sufficient for activation of the dihydroflavonol 4-reductase-A (dfrA) promoter and enhanced pigment accumulation in P. hybrida. This indicates that an2 and jaf13 play a key role in determining the tissue-specific expression pattern of structural genes. However, because chalcone synthase (chs) and flavanone-3-hydroxylase (f3h) are not activated, the pattern of pigmentation is not fundamentally altered. Expression of an2 in Z. mays complements a mutation in pl, a c1 paralogue, indicating that an2 activates a wider set of target genes in this host. Transient expression assays in Z. mays and P. hybrida tissues showed that C1 and R or AN2 and JAF13 can activate the promoter of the c2 gene, encoding Z. mays CHS, but not the chsA promoter from P. hybrida. These results indicate that regulatory anthocyanin genes are conserved between species and that divergent evolution of the target gene promoters is responsible for the species-specific differences in regulatory networks.

THE PLANT CELL ONLINE, 1990

Chalcone synthase (CHS) catalyzes the first step in the biosynthesis of flavonoids that function ... more Chalcone synthase (CHS) catalyzes the first step in the biosynthesis of flavonoids that function in flower pigmentation, protection against stress, and induction of nodulation. The petunia genome contains eight complete chs genes, of which four are differentially expressed in floral tissues and UV-light-induced seedlings. The 5'-flanking regions of these four chs genes were fused to the 8-glucuronidase (GUS) reporter gene and introduced into petunia plants by Agrobacterium-mediated transformation. We show that expression of each construct is identical to the expression of the authentic chs gene, implying that the differences in expression pattern between these chs genes are caused at least in part by their promoters. Histochemical analyses of GUS expression show that chs promoters are not only active in pigmented cell types (epidermal cells of the flower corolla and tube and [sub] epidermal cells of the flower stem) but also in a number of unpigmented cell types (mesophylic cells of the corolla, several cell types in the ovary and the seed coat). Comparison of chs-GUS expression and flavonoid accumulation patterns in anthers suggests that intercellular transport of flavonoids and enzymes occurs in this organ. Analysis of the flavonoids accumulated in tissues from mutant lines shows that only a subset of the genes that control flavonoid biosynthesis in the flower operates in the ovary and seed. This implies that (genetic) control of flavonoid biosynthesis is highly tissue specific.

THE PLANT CELL ONLINE, 2002

ANTHOCYANIN1 (AN1) of petunia is a transcription factor of the basic helix-loop-helix (bHLH) fami... more ANTHOCYANIN1 (AN1) of petunia is a transcription factor of the basic helix-loop-helix (bHLH) family that is required for the synthesis of anthocyanin pigments. Here, we show that AN1 controls additional aspects of cell differentiation: the acidification of vacuoles in petal cells, and the size and morphology of cells in the seed coat epidermis. We identified an1 alleles, formerly known as ph6 , that sustain anthocyanin synthesis but not vacuolar acidification and seed coat morphogenesis. These alleles express truncated proteins lacking the C-terminal half of AN1, including the bHLH domain, at an ‫ف‬ 30-fold higher level than wild-type AN1. An allelic series in which one, two, or three amino acids were inserted into the bHLH domain indicated that this domain is required for both anthocyanin synthesis and vacuolar acidification. These findings show that AN1 controls more aspects of epidermal cell differentiation than previously thought through partially separable domains.

THE PLANT CELL ONLINE, 2006

The Petunia hybrida genes ANTHOCYANIN1 (AN1) and AN2 encode transcription factors with a basic-he... more The Petunia hybrida genes ANTHOCYANIN1 (AN1) and AN2 encode transcription factors with a basic-helix-loop-helix (BHLH) and a MYB domain, respectively, that are required for anthocyanin synthesis and acidification of the vacuole in petal cells. Mutation of PH4 results in a bluer flower color, increased pH of petal extracts, and, in certain genetic backgrounds, the disappearance of anthocyanins and fading of the flower color. PH4 encodes a MYB domain protein that is expressed in the petal epidermis and that can interact, like AN2, with AN1 and the related BHLH protein JAF13 in yeast two-hybrid assays. Mutation of PH4 has little or no effect on the expression of structural anthocyanin genes but strongly downregulates the expression of CAC16.5, encoding a protease-like protein of unknown biological function. Constitutive expression of PH4 and AN1 in transgenic plants is sufficient to activate CAC16.5 ectopically. Together with the previous finding that AN1 domains required for anthocyanin synthesis and vacuolar acidification can be partially separated, this suggests that AN1 activates different pathways through interactions with distinct MYB proteins. falw.vu.nl; fax 31-20-5987155.