Esterified carotenoids are synthesized in petals of carnation (Dianthus caryophyllus) and accumulate in differentiated chromoplasts

Although yellow and orange petal colors are derived from carotenoids in many plant species, this has not yet been demonstrated for the order Caryophyllales, which includes carnations. Here, we identified a carnation cultivar with pale yellow flowers that accumulated carotenoids in petals. Additionally, some xanthophyll compounds were esterified, as is the case for yellow flowers in other plant species. Ultrastructural analysis showed that chromoplasts with numerous plastoglobules, in which flower-specific carotenoids accumulate, were present in the pale yellow petals. RNA-seq and RT-qPCR analyses indicated that the expression levels of genes for carotenoid biosynthesis and esterification in pale yellow and pink petals (that accumulate small amounts of carotenoids) were similar or lower than in green petals (that accumulate substantial amounts of carotenoids) and white petals (that accumulate extremely low levels of carotenoids). Pale yellow and pink petals had a considerably lower level of expression of genes for carotenoid degradation than white petals, suggesting that reduced degradation activity caused accumulation of carotenoids. Our results indicate that some carnation cultivars can synthesize and accumulate esterified carotenoids. By manipulating the rate of biosynthesis and esterification of carotenoids in these cultivars, it should be feasible to produce novel carnation cultivars with vivid yellow flowers.

Heterologous expression of xanthophyll esterase genes affects carotenoid accumulation in petunia corollas

The majority of carotenoids in petals are xanthophylls and most of these xanthophylls are esterified with fatty acids. Although petunia (Petunia x hybrida) is an important ornamental plant, it cannot accumulate enough carotenoids to have deep-yellow flowers. Our previous study suggested that low esterification activity causes low carotenoid accumulation in petunia corollas. Here, we introduced xanthophyll esterase (XES) from the petals of Ipomoea obscura, tomato (Solanum lycopersicum), and marigold (Tagetes erecta) into a pale-yellow-flowered cultivar of petunia to see whether these affect carotenoid accumulation in petunia corollas. Carotenoid contents and the proportions of esterified xanthophylls were elevated in the corollas of XES-overexpressing (XES-OX) transformants. Expression analysis showed that the transcript levels of endogenous carotenoid biosynthetic genes, which included geranylgeranyl diphosphate synthase 2, ζ-carotene desaturase, and lycopene β-ring cyclase in corolla tubes were upregulated in XES-OX plants. In addition, we discovered a difference in the composition of esterified xanthophylls among XES-OX plants, which may be caused by differences in the substrate specificity of their respective XESs. We conclude that esterification is an important process for carotenoid accumulation and XES is a useful tool for the quantitative and qualitative control of carotenoid accumulation in petals.

Metabolome-based discrimination of chrysanthemum cultivars for the efficient generation of flower color variations in mutation breeding

INTRODUCTION

The color variations of ornamental flowers are often generated by ion-beam and gamma irradiation mutagenesis. However, mutation rates differ significantly even among cultivars of the same species, resulting in high cost and intensive labor for flower color breeding.

OBJECTIVES

We aimed to establish a metabolome-based strategy to identify biomarkers and select promising parental lines with high mutation rates using Chrysanthemum as the case study.

METHODS

The mutation rates associated with flower color were measured in 10 chrysanthemum cultivars with pink, yellow, or white flowers after soft X-ray irradiation at the floret-formation stage. The metabolic profiles of the petals of these cultivars were clarified by widely targeted metabolomics and targeted carotenoid analysis using liquid chromatography-tandem quadrupole mass spectrometry. Metabolome and carotenoid data were subjected to an un-supervised principal component analysis (PCA) and a supervised logistic regression with least absolute shrinkage and selection operator (LASSO).

RESULTS

The PCA of the metabolic profile data separated chrysanthemum cultivars according to flower color rather than mutation rates. By contrast, logistic regression with LASSO generated a discrimination model to separate cultivars into two groups with high or low mutation rates, and selected 11 metabolites associated with mutation rates that can be biomarkers candidates for selecting parental lines for mutagenesis.

CONCLUSION

This metabolome-based strategy to identify metabolite markers for mutation rates associated with flower color might be applied to other ornamental flowers to accelerate mutation breeding for generating new cultivars with a wider range of flower colors.

Comparison of petunia and calibrachoa in carotenoid pigmentation of corollas

Petunia (Petunia hybrida) is an important ornamental plant with a wide range of corolla colors. Although pale-yellow-flowered cultivars, with a low amount of carotenoids in their corollas, are now available, no deep-yellow-flowered cultivars exist. To find why petunia cannot accumulate enough carotenoids to have deep-yellow flowers, we compared carotenoid profiles and expression of carotenoid metabolic genes between pale-yellow-flowered petunia and deep-yellow-flowered calibrachoa (Calibrachoa hybrida), a close relative. The carotenoid contents and the ratios of esterified xanthophylls to total xanthophylls in petunia corollas were significantly lower than those in calibrachoa, despite similar carotenoid components. A lower esterification rate of trans-xanthophylls than of cis-xanthophylls in petunia suggests that petunia xanthophyll esterase (XES) has low substrate specificity for trans-xanthophylls, which are more abundant than cis-xanthophylls in petunia corolla. The expression of genes encoding key enzymes of carotenoid biosynthesis was lower and that of a carotenoid catabolic gene was higher in petunia. XES expression was significantly lower in petunia. The results suggest that low biosynthetic activity, high cleavage activity, and low esterification activity cause low carotenoid accumulation in petunia corollas.

Overexpression of CONSTANS-like 16 enhances chlorophyll accumulation in petunia corollas

We have previously found that a gene closely related to Arabidopsis CONSTANS-like 16 (COL16) was coordinately expressed with chlorophyll content in chrysanthemum petals and leaves. Here, to elucidate whether COL16 is involved in the regulation of chlorophyll biosynthesis and accumulation, we analyzed the function of COL16 in petunia (Petunia hybrida). We identified three petunia COL16 homologs: PhCOL16a, PhCOL16b, and PhCOL16c. Expression patterns of all three homologs were associated with chlorophyll content, with lower levels in white corollas than in pale green corollas, and relatively high levels in leaves. The result suggests that PhCOL16 homologs are involved in chlorophyll accumulation. We introduced a PhCOL16a overexpression construct into petunia. The transgenic plants had pale green corollas with a higher chlorophyll content than wild-type plants. Expression of genes encoding key enzymes of chlorophyll biosynthesis was significantly higher in the transgenic plants than in the wild-type plants. The results indicate that PhCOL16 positively regulates chlorophyll biosynthesis.

Molecular mechanisms underlying the diverse array of petal colors in chrysanthemum flowers

Chrysanthemum (Chrysanthemum morifolium Ramat.) is one of the most important floricultural crops in the world. Although the origin of modern chrysanthemum cultivars is uncertain, several species belonging to the family Asteraceae are considered to have been integrated during the long history of breeding. The flower color of ancestral species is limited to yellow, pink, and white, and is derived from carotenoids, anthocyanins, and the absence of both pigments, respectively. A wide range of flower colors, including purplish-red, orange, red, and dark red, has been developed by increasing the range of pigment content or the combination of both pigments. Recently, green-flowered cultivars containing chlorophylls in their ray petals have been produced, and have gained popularity. In addition, blue/violet flowers have been developed using a transgenic approach. Flower color is an important trait that influences the commercial value of chrysanthemum cultivars. Understanding the molecular mechanisms that regulate flower pigmentation may provide important implications for the rationale manipulation of flower color. This review describes the pigment composition, genetics, and molecular basis of ray petal color formation in chrysanthemum cultivars.

Alteration of flower colour in Ipomoea nil through CRISPR/Cas9-mediated mutagenesis of carotenoid cleavage dioxygenase 4

Japanese morning glory, Ipomoea nil, exhibits a variety of flower colours, except yellow, reflecting the accumulation of only trace amounts of carotenoids in the petals. In a previous study, we attributed this effect to the low expression levels of carotenogenic genes in the petals, but there may be other contributing factors. In the present study, we investigated the possible involvement of carotenoid cleavage dioxygenase (CCD), which cleaves specific double bonds of the polyene chains of carotenoids, in the regulation of carotenoid accumulation in the petals of I. nil. Using bioinformatics analysis, seven InCCD genes were identified in the I. nil genome. Sequencing and expression analyses indicated potential involvement of InCCD4 in carotenoid degradation in the petals. Successful knockout of InCCD4 using the CRISPR/Cas9 system in the white-flowered cultivar I. nil cv. AK77 caused the white petals to turn pale yellow. The total amount of carotenoids in the petals of ccd4 plants was increased 20-fold relative to non-transgenic plants. This result indicates that in the petals of I. nil, not only low carotenogenic gene expression but also carotenoid degradation leads to extremely low levels of carotenoids.

Overexpression of carotenogenic genes in the Japanese morning glory Ipomoea (Pharbitis) nil

Japanese morning glory, Ipomoea nil, has several coloured flowers except yellow, because it can accumulate only trace amounts of carotenoids in the petal. To make the petal yellow with carotenoids, we introduced five carotenogenic genes (geranylgeranyl pyrophosphate synthase, phytoene synthase, lycopene β-cyclase and β-ring hydroxylase from Ipomoea obscura var. lutea and bacterial phytoene desaturase from Pantoea ananatis) to white-flowered I. nil cv. AK77 with a petal-specific promoter by Rhizobium (Agrobacterium)-mediated transformation method. We succeeded to produce transgenic plants overexpressing carotenogenic genes. In the petal of the transgenic plants, mRNA levels of the carotenogenic genes were 10 to 1,000 times higher than those of non-transgenic control. The petal colour did not change visually; however, carotenoid concentration in the petal was increased up to about ten-fold relative to non-transgenic control. Moreover, the components of carotenoids in the petal were diversified, in particular, several β-carotene derivatives, such as zeaxanthin and neoxanthin, were newly synthesized. This is the first report, to our knowledge, of changing the component and increasing the amount of carotenoid in petals that lack ability to biosynthesize carotenoids.

Transcriptome analysis in petals and leaves of chrysanthemums with different chlorophyll levels

BACKGROUND

Chlorophylls (Chls) are magnesium-containing tetrapyrrole macromolecules responsible for the green color in plants. The Chl metabolic pathway has been intensively studied and nearly all the enzymes involved in the pathway have been identified and characterized. Synthesis and activity of these enzymes are tightly regulated in tissue- and developmental stage-specific manners. Leaves contain substantial amounts of Chls because Chls are indispensable for photosynthesis. In contrast, petals generally contain only trace amounts of Chls, which if present would mask the bright petal color. Limited information is available about the mechanisms that control such tissue-specific accumulation of Chls.

RESULTS

To identify the regulatory steps that control Chl accumulation, we compared gene expression in petals and leaves of chrysanthemum cultivars with different Chl levels. Microarray and quantitative real-time PCR analyses showed that the expression levels of Chl biosynthesis genes encoding glutamyl-tRNA reductase, Mg-protoporphyrin IX chelatase, Mg-protoporphyrin IX monomethylester cyclase, and protochlorophyllide oxidoreductase were well associated with Chl content: their expression levels were lower in white petals than in green petals, and were highest in leaves. Among Chl catabolic genes, expression of STAY-GREEN, encoding Mg-dechelatase, which is a key enzyme controlling Chl degradation, was considerably higher in white and green petals than in leaves. We searched for transcription factor genes whose expression was well related to Chl level in petals and leaves and found three such genes encoding MYB113, CONSTANS-like 16, and DREB and EAR motif protein.

CONCLUSIONS

From our transcriptome analysis, we assume that a low rate of Chl biosynthesis and a high rate of Chl degradation lead to the absence of Chls in white chrysanthemum petals. We identified several candidate transcription factors that might affect Chl accumulation in chrysanthemum petals. Functional analysis of these transcription factors will provide a basis for future molecular studies of tissue-specific Chl accumulation.

Generation of expressed sequence tags for discovery of genes responsible for floral traits of Chrysanthemum morifolium by next-generation sequencing technology

Background

Chrysanthemum morifolium is one of the most economically valuable ornamental plants worldwide. Chrysanthemum is an allohexaploid plant with a large genome that is commercially propagated by vegetative reproduction. New cultivars with different floral traits, such as color, morphology, and scent, have been generated mainly by classical cross-breeding and mutation breeding. However, only limited genetic resources and their genome information are available for the generation of new floral traits.

Results

To obtain useful information about molecular bases for floral traits of chrysanthemums, we read expressed sequence tags (ESTs) of chrysanthemums by high-throughput sequencing using the 454 pyrosequencing technology. We constructed normalized cDNA libraries, consisting of full-length, 3′-UTR, and 5′-UTR cDNAs derived from various tissues of chrysanthemums. These libraries produced a total number of 3,772,677 high-quality reads, which were assembled into 213,204 contigs. By comparing the data obtained with those of full genome-sequenced species, we confirmed that our chrysanthemum contig set contained the majority of all expressed genes, which was sufficient for further molecular analysis in chrysanthemums.

Conclusion

We confirmed that our chrysanthemum EST set (contigs) contained a number of contigs that encoded transcription factors and enzymes involved in pigment and aroma compound metabolism that was comparable to that of other species. This information can serve as an informative resource for identifying genes involved in various biological processes in chrysanthemums. Moreover, the findings of our study will contribute to a better understanding of the floral characteristics of chrysanthemums including the myriad cultivars at the molecular level.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-017-4061-3) contains supplementary material, which is available to authorized users.

The NAC transcription factor ANAC046 is a positive regulator of chlorophyll degradation and senescence in Arabidopsis leaves

Chlorophyll (Chl) degradation occurs during leaf senescence, embryo degreening, bud breaking, and fruit ripening. The Chl catabolic pathway has been intensively studied and nearly all the enzymes involved are identified and characterized; however, the molecular regulatory mechanisms of this pathway are largely unknown. In this study, we performed yeast one-hybrid screening using a transcription factor cDNA library to search for factors controlling the expression of Chl catabolic genes. We identified ANAC046 as a common regulator that directly binds to the promoter regions of NON-YELLOW COLORING1, STAY-GREEN1 (SGR1), SGR2, and PHEOPHORBIDE a OXYGENASE. Transgenic plants overexpressing ANAC046 exhibited an early-senescence phenotype and a lower Chl content in comparison with the wild-type plants, whereas loss-of-function mutants exhibited a delayed-senescence phenotype and a higher Chl content. Microarray analysis of ANAC046 transgenic plants showed that not only Chl catabolic genes but also senescence-associated genes were positively regulated by ANAC046. We conclude that ANAC046 is a positive regulator of Arabidopsis leaf senescence and exerts its effect by controlling the expression of Chl catabolic genes and senescence-associated genes.

Identification of genes associated with chlorophyll accumulation in flower petals

Plants have an ability to prevent chlorophyll accumulation, which would mask the bright flower color, in their petals. In contrast, leaves contain substantial amounts of chlorophyll, as it is essential for photosynthesis. The mechanisms of organ-specific chlorophyll accumulation are unknown. To identify factors that determine the chlorophyll content in petals, we compared the expression of genes related to chlorophyll metabolism in different stages of non-green (red and white) petals (very low chlorophyll content), pale-green petals (low chlorophyll content), and leaves (high chlorophyll content) of carnation (Dianthus caryophyllus L.). The expression of many genes encoding chlorophyll biosynthesis enzymes, in particular Mg-chelatase, was lower in non-green petals than in leaves. Non-green petals also showed higher expression of genes involved in chlorophyll degradation, including STAY-GREEN gene and pheophytinase. These data suggest that the absence of chlorophylls in carnation petals may be caused by the low rate of chlorophyll biosynthesis and high rate of degradation. Similar results were obtained by the analysis of Arabidopsis microarray data. In carnation, most genes related to chlorophyll biosynthesis were expressed at similar levels in pale-green petals and leaves, whereas the expression of chlorophyll catabolic genes was higher in pale-green petals than in leaves. Therefore, we hypothesize that the difference in chlorophyll content between non-green and pale-green petals is due to different levels of chlorophyll biosynthesis. Our study provides a basis for future molecular and genetic studies on organ-specific chlorophyll accumulation.

Identification of the carotenoid modifying gene PALE YELLOW PETAL 1 as an essential factor in xanthophyll esterification and yellow flower pigmentation in tomato (Solanum lycopersicum)

Xanthophylls, the pigments responsible for yellow to red coloration, are naturally occurring carotenoid compounds in many colored tissues of plants. These pigments are esterified within the chromoplast; however, little is known about the mechanisms underlying their accumulation in flower organs. In this study, we characterized two allelic tomato (Solanum lycopersicum L.) mutants, pale yellow petal (pyp) 1-1 and pyp1-2, that have reduced yellow color intensity in the petals and anthers due to loss-of-function mutations. Carotenoid analyses showed that the yellow flower organs of wild-type tomato contained high levels of xanthophylls that largely consisted of neoxanthin and violaxanthin esterified with myristic and/or palmitic acids. Functional disruption of PYP1 resulted in loss of xanthophyll esters, which was associated with a reduction in the total carotenoid content and disruption of normal chromoplast development. These findings suggest that xanthophyll esterification promotes the sequestration of carotenoids in the chromoplast and that accumulation of these esters is important for normal chromoplast development. Next-generation sequencing coupled with map-based positional cloning identified the mutant alleles responsible for the pyp1 phenotype. PYP1 most likely encodes a carotenoid modifying protein that plays a vital role in the production of xanthophyll esters in tomato anthers and petals. Our results provide insight into the molecular mechanism underlying the production of xanthophyll esters in higher plants, thereby shedding light on a longstanding mystery.

Sequence analysis of the genome of carnation (Dianthus caryophyllus L.)

The whole-genome sequence of carnation (Dianthus caryophyllus L.) cv. ‘Francesco’ was determined using a combination of different new-generation multiplex sequencing platforms. The total length of the non-redundant sequences was 568 887 315 bp, consisting of 45 088 scaffolds, which covered 91% of the 622 Mb carnation genome estimated by k-mer analysis. The N50 values of contigs and scaffolds were 16 644 bp and 60 737 bp, respectively, and the longest scaffold was 1 287 144 bp. The average GC content of the contig sequences was 36%. A total of 1050, 13, 92 and 143 genes for tRNAs, rRNAs, snoRNA and miRNA, respectively, were identified in the assembled genomic sequences. For protein-encoding genes, 43 266 complete and partial gene structures excluding those in transposable elements were deduced. Gene coverage was ∼98%, as deduced from the coverage of the core eukaryotic genes. Intensive characterization of the assigned carnation genes and comparison with those of other plant species revealed characteristic features of the carnation genome. The results of this study will serve as a valuable resource for fundamental and applied research of carnation, especially for breeding new carnation varieties. Further information on the genomic sequences is available at http://carnation.kazusa.or.jp.

Transcriptome analysis of carnation (Dianthus caryophyllus L.) based on next-generation sequencing technology

Background

Carnation (Dianthus caryophyllus L.), in the family Caryophyllaceae, can be found in a wide range of colors and is a model system for studies of flower senescence. In addition, it is one of the most important flowers in the global floriculture industry. However, few genomics resources, such as sequences and markers are available for carnation or other members of the Caryophyllaceae. To increase our understanding of the genetic control of important characters in carnation, we generated an expressed sequence tag (EST) database for a carnation cultivar important in horticulture by high-throughput sequencing using 454 pyrosequencing technology.

Results

We constructed a normalized cDNA library and a 3’-UTR library of carnation, obtaining a total of 1,162,126 high-quality reads. These reads were assembled into 300,740 unigenes consisting of 37,844 contigs and 262,896 singlets. The contigs were searched against an Arabidopsis sequence database, and 61.8% (23,380) of them had at least one BLASTX hit. These contigs were also annotated with Gene Ontology (GO) and were found to cover a broad range of GO categories. Furthermore, we identified 17,362 potential simple sequence repeats (SSRs) in 14,291 of the unigenes. We focused on gene discovery in the areas of flower color and ethylene biosynthesis. Transcripts were identified for almost every gene involved in flower chlorophyll and carotenoid metabolism and in anthocyanin biosynthesis. Transcripts were also identified for every step in the ethylene biosynthesis pathway.

Conclusions

We present the first large-scale sequence data set for carnation, generated using next-generation sequencing technology. The large EST database generated from these sequences is an informative resource for identifying genes involved in various biological processes in carnation and provides an EST resource for understanding the genetic diversity of this plant.

Carotenoid isomerase is key determinant of petal color of Calendula officinalis

Orange petals of calendula (Calendula officinalis) accumulate red carotenoids with the cis-configuration at the C-5 or C-5' position (5-cis-carotenoids). We speculated that the orange-flowered calendula is a carotenoid isomerase (crtiso) loss-of-function mutant that impairs the cis-to-trans conversion of 5-cis-carotenoids. We compared the sequences and enzyme activities of CRTISO from orange- and yellow-flowered calendulas. Four types of CRTISO were expressed in calendula petals. The deduced amino acid sequence of one of these genes (CoCRTISO1) was different between orange- and yellow-flowered calendulas, whereas the sequences of the other three CRTISOs were identical between these plants. Analysis of the enzymatic activities of the CoCRTISO homologs showed that CoCRTISO1-Y, which was expressed in yellow petals, converted carotenoids from the cis-to-trans-configuration, whereas both CoCRTISO1-ORa and 1-ORb, which were expressed in orange petals, showed no activity with any of the cis-carotenoids we tested. Moreover, the CoCRTISO1 genotypes of the F2 progeny obtained by crossing orange and yellow lines linked closely to petal color. These data indicate that CoCRTISO1 is a key regulator of the accumulation of 5-cis-carotenoids in calendula petals. Site-directed mutagenesis showed that the deletion of Cys-His-His at positions 462-464 in CoCRTISO1-ORa and a Gly-to-Glu amino acid substitution at position 450 in CoCRTISO1-ORb abolished enzyme activity completely, indicating that these amino acid residues are important for the enzymatic activity of CRTISO.

Carotenoid composition and carotenogenic gene expression during Ipomoea petal development

Japanese morning glory (Ipomoea nil) is a representative plant lacking a yellow-flowered cultivar, although a few wild Ipomoea species contain carotenoids in their petals such as Ipomoea sp. (yellow petals) and I. obscura (pale-yellow petals). In the present study, carotenoid composition and the expression patterns of carotenogenic genes during petal development were compared among I. nil, I. obscura, and Ipomoea sp. to identify the factors regulating carotenoid accumulation in Ipomoea plant petals. In the early stage, the carotenoid composition in petals of all the Ipomoea plants tested was the same as in the leaves mainly showing lutein, violaxanthin, and beta-carotene (chloroplast-type carotenoids). However, in fully opened flowers, chloroplast-type carotenoids were entirely absent in I. nil, whereas they were present in trace amounts in the free form in I. obscura. At the late stage of petal development in Ipomoea sp., the majority of carotenoids were beta-cryptoxanthin, zeaxanthin, and beta-carotene (chromoplast-type carotenoids). In addition, most of them were present in the esterified form. Carotenogenic gene expression was notably lower in I. nil than in Ipomoea sp. In particular, beta-ring hydroxylase (CHYB) was considerably suppressed in petals of both I. nil and I. obscura. The CHYB expression was found to be significantly high in the petals of Ipomoea sp. during the synthesis of chromoplast-type carotenoids. The expression levels of carotenoid cleavage genes (CCD1 and CCD4) were not correlated with the amount of carotenoids in petals. These results suggest that both I. obscura and I. nil lack the ability to synthesize chromoplast-type carotenoids because of the transcriptional down-regulation of carotenogenic genes. CHYB, an enzyme that catalyses the addition of a hydroxyl residue required for esterification, was found to be a key enzyme for the accumulation of chromoplast-type carotenoids in petals.

Biosynthesis of plant pigments: anthocyanins, betalains and carotenoids

Plant compounds that are perceived by humans to have color are generally referred to as 'pigments'. Their varied structures and colors have long fascinated chemists and biologists, who have examined their chemical and physical properties, their mode of synthesis, and their physiological and ecological roles. Plant pigments also have a long history of use by humans. The major classes of plant pigments, with the exception of the chlorophylls, are reviewed here. Anthocyanins, a class of flavonoids derived ultimately from phenylalanine, are water-soluble, synthesized in the cytosol, and localized in vacuoles. They provide a wide range of colors ranging from orange/red to violet/blue. In addition to various modifications to their structures, their specific color also depends on co-pigments, metal ions and pH. They are widely distributed in the plant kingdom. The lipid-soluble, yellow-to-red carotenoids, a subclass of terpenoids, are also distributed ubiquitously in plants. They are synthesized in chloroplasts and are essential to the integrity of the photosynthetic apparatus. Betalains, also conferring yellow-to-red colors, are nitrogen-containing water-soluble compounds derived from tyrosine that are found only in a limited number of plant lineages. In contrast to anthocyanins and carotenoids, the biosynthetic pathway of betalains is only partially understood. All three classes of pigments act as visible signals to attract insects, birds and animals for pollination and seed dispersal. They also protect plants from damage caused by UV and visible light.

[Coagulation and fibrinolysis system in pediatric cardiopulmonary bypass]

Coagulation and fibrinolysis system was evaluated during and after pediatric cardiopulmonary bypass (CPB. Twenty-two atrial septal defect (ASD) patients were surgically repaired under CPB and aortic cross-clamp through right thoracotomy. Drainage was established by gravity, CPB flow was kept 2.4 l/min/m2 and ACT was controlled over 400 seconds. HCT, PLT, fibrinogen, AT-III, D-dimer, thrombin-antithrombin complex (TAT), alpha2 plasmin inhibitor-plasmin complex (PIC), and plasminogen activator inhibitor (PAI-1) were measured at 6 points [after induction of anesthesia, 10 minutes after initiating CPB, end of CPB, on the entrance of intensive care unit (ICU), postoperative day (POD) 1, and at outpatient division]. Both fibrinogen and AT-III showed low values during CPB (121.9 +/- 22.0 mg/dl, 57.6 +/- 10.6%). D-dimer increased at 1 week postoperatively in all patients (5.57 +/- 3.45 microg/ml). There were significantly positive correlations between CPB duration and TAT value at the end of CPB (r = 0.88, p < 0.01), on the entrance of ICU (r = 0.71, p < 0.01). There was also a positive correlation between CPB duration and PIC value on the entrance of ICU (r = 0.53, p < 0.01). Five patients showed high PAI-1 value on the entrance of ICU, which remained high in 2 of them on POD 1. The outcomes from the current study suggest that there is a potential of coagulation-dominant disseminated intravascular coagulation (DIC) during pediatric CPB even in ASD patients who do not need long CPB. Longer CPB and severe hemodilution might become risk factors.

Carotenoid cleavage dioxygenase (CmCCD4a) contributes to white color formation in chrysanthemum petals

The white petals of chrysanthemum (Chrysanthemum morifolium Ramat.) are believed to contain a factor that inhibits the accumulation of carotenoids. To find this factor, we performed polymerase chain reaction-Select subtraction screening and obtained a clone expressed differentially in white and yellow petals. The deduced amino acid sequence of the protein (designated CmCCD4a) encoded by the clone was highly homologous to the sequence of carotenoid cleavage dioxygenase. All the white-flowered chrysanthemum cultivars tested showed high levels of CmCCD4a transcript in their petals, whereas most of the yellow-flowered cultivars showed extremely low levels. Expression of CmCCD4a was strictly limited to flower petals and was not detected in other organs, such as the root, stem, or leaf. White petals turned yellow after the RNAi construct of CmCCD4a was introduced. These results indicate that in white petals of chrysanthemums, carotenoids are synthesized but are subsequently degraded into colorless compounds, which results in the white color.

Analysis of carotenoid composition in petals of calendula (Calendula officinalis L.)

Nineteen carotenoids were identified in extracts of petals of orange- and yellow-flowered cultivars of calendula (Calendula officinalis L.). Ten carotenoids were unique to orange-flowered cultivars. The UV-vis absorption maxima of these ten carotenoids were at longer wavelengths than that of flavoxanthin, the main carotenoid of calendula petals, and it is clear that these carotenoids are responsible for the orange color of the petals. Six carotenoids had a cis structure at C-5 (C-5'), and it is conceivable that these (5Z)-carotenoids are enzymatically isomerized at C-5 in a pathway that diverges from the main carotenoid biosynthesis pathway. Among them, (5Z,9Z)-lycopene (1), (5Z,9Z,5'Z,9'Z)-lycopene (3), (5'Z)-gamma-carotene (4), and (5'Z,9'Z)-rubixanthin (5) has never before been identified. Additionally, (5Z,9Z,5'Z)-lycopene (2) has been reported only as a synthesized compound.

Carotenoid composition in petals of chrysanthemum (Dendranthema grandiflorum (Ramat.) Kitamura)

Sixteen xanthophylls were isolated from the petals of chrysanthemum (Dendranthema grandiflorum (Ramat.) Kitamura). Among them, (3S,5S,6R,3'R,6'R)-5,6-dihydro-5,6-dihydroxylutein (1) and five di-Z geometrical isomers of lutein-5,6-epoxide, i.e., 9Z,13'Z (2), 13Z,9'Z (3), 9'Z,13'Z (4), 9Z,13Z (5), and 9Z,9'Z (7), had never before been identified as natural products. All of the carotenoids isolated from chrysanthemum, except for (9Z)-violaxanthin, are beta,epsilon-carotene (alpha-carotene) derivatives. The analyses indicate that carotenoids from the petals of chrysanthemum have a very characteristic composition.

Isolation and characterization of a 60 kDa 2,4-D-binding protein from the shoot apices of peach trees (Prunus persica L.); it is a homologue of protein disulfide isomerase

To obtain a candidate auxin-binding protein (ABP), a soluble 60 kDa protein was isolated from an extract of shoot apices of peach trees (Prunus persica L.) by affinity chromatography on a 2,4-dichlorophenoxyacetic acid (2,4-D)-linked Sepharose4B column. The 60 kDa polypeptide, designated Pp60, was purified as a single band on SDS-PAGE by column chromatography. Its dissociation constant (Kd) for [14C]-2,4-D was calculated to be 3.5 x 10(-5) M. The binding of Pp60 for [14C]-2,4-D was inhibited by naphthalene-1-acetic acid (NAA) and p-chlorophenoxyisobutyric acid (PCIB) as well as 2,4-D. Indole-3-acetic acid (IAA) had little effect on the binding. These results suggested that Pp60 is a protein that has an affinity for 2,4-D, NAA, and PCIB in vitro. The partial amino acid sequences of Pp60 showed high homology to those of protein disulfide isomerase (EC 5.3.4.1). Immunoblot analysis demonstrated that Pp60 exists ubiquitously in shoots and leaves. In fruit, expression of Pp60 is restricted at an early stage of development.

Cloning of genes encoding auxin-binding proteins (ABP19/20) from peach: significant peptide sequence similarity with germin-like proteins

An auxin-binding protein (ABP) was previously isolated from shoot apices of peach trees to homogenity on standard SDS-PAGE. Analysis of low-bis SDS-PAGE and direct peptide sequencing of purified peach ABP demonstrated that the ABP was composed of two types of polypeptides (designated ABP19 and ABP20). Several cDNA and genomic clones which encode peach ABPs were obtained and analysed. We found that there are at least three classes of ABPs in the peach genome. Open reading frames of these ABPs were 627 bp, predicting a 209 amino acid polypeptide of 22 kDa. An N-terminal hydrophobic signal sequence of 18 amino acids and a putative N-glycosylation site at N60-T-T/S were deduced. Homology search analysis revealed that ABP19 is highly homologous to proteins related to the germin family. The deduced amino acid sequence of ABP19 showed very low overall sequence homology with ABP1, an ABP isolated from maize coleoptile, but it contained a small region which shared 40% homology with a putative auxin binding site in ABP1 (BoxA). In addition, the sequence surrounding the region is highly conserved among peach ABPs and the germin family.

The soybean GH2/4 gene that encodes a glutathione S-transferase has a promoter that is activated by a wide range of chemical agents

Transcriptional activation of the soybean (Glycine max) GH2/4 gene (also referred to as Gmhsp26-A) and increase in abundance of the GH2/4 mRNA (also referred to as pCE54) have been previously shown to occur following treatment of soybean seedlings with auxins, nonauxin analogs, heavy metals, and a variety of other agents. To determine whether the GH2/4 promoter is responsive to an array of different agents, we have analyzed the inducibility of the GH2/4 promoter fused to the beta-glucuronidase reporter gene in transgenic tobacco (Nicotiana tabacum) plants. We have shown that a wide variety of chemical agents induce this promoter in a tissue-specific and concentration-dependent manner. In addition, we have used an affinity-purified antibody raised against recombinant GH2/4 protein to show that the GH2/4 protein increases in response to auxin application and is localized in the cytosol of soybean cells. Recombinant GH2/4 protein can be purified to homogeneity on a glutathione-agarose resin, and the purified protein has glutathione S-transferase activity when assayed with the substrate 1-chloro-2,4-dinitrobenzene.

Structural changes in the plastid DNA of rice (Oryza sativa L.) during tissue culture

To investigate the rearrangement of the plastid genome during tissue culture, DNA from rice callus lines, which had been derived individually from single protoplasts isolated from seed or pollen callus (protoclones), was analyzed by Southern hybridization with rice chloroplast DNA (ctDNA) clones as probes. Among 44 long-term cultured protoclones, maintained for 4, 8 or 11 years, 28 contained plastid DNA (ptDNA) from which portions had been deleted. The ptDNA of all protoclones that had been maintained for 11 years had a deletion that covered a large region of the plastid genome. The deletions could be classified into 15 types from their respective sizes and positions. By contrast, no deletions were found in the ptDNA of 38 protoclones that had been maintained for only 1 month. These results indicate that long-term culture causes deletions in the plastid genome. Detailed hybridization experiments revealed that plastid genomes with deletions in several protoclones were organized as head-to-head or tail-to-tail structures. Furthermore, ptDNAs retained during long-term culture all had a common terminus at one end, where extensive rearrangement is known to have occurred during the speciation of rice and tobacco. Morphological analysis revealed the accumulation of starch granules in plastids and amyloplasts in protoclones in which the plastid genome had undergone deletion. Our observations indicated that novel structural changes in the plastid genome and morphological changes in the plastid had occurred in rice cells during long-term tissue culture. Moreover, the morphological changes in plastids were associated with deletions in the plastid genome.

Analysis of growth failure in children treated for acute lymphoblastic leukemia

Growth patterns were surveyed in 303 children with acute lymphoblastic leukemia who had remained in continuous first complete remission for a minimum of 1 year (median 3 years). Chemotherapy was given for 3 years, and central nervous system prophylaxis consisted of cranial irradiation at a total dose of 18 Gy or intravenous high-dose methotrexate (1.5-6 g/m2 for three to six doses). Intensive chemotherapy, including cyclophosphamide, doxorubicin, and cytosine arabinoside was given to children with high-risk features. Two of 205 children with low- or intermediate-risk features and 13 of 98 children with high-risk features showed a decrease in the growth rate of less than -2 SD. In 14 of these 15 patients, the age at onset was over 9 years and growth failure became most predominant in the prepubertal period: ten of these children showed a tendency toward delayed pubertal development, but eight showed later catch-up growth with pubertal maturation after completion of chemotherapy. Thus, chemotherapy appeared to contribute temporarily to the growth failure and gonadal impairment that occurred in the prepubertal period. No obvious correlation between the administered cranial irradiation and growth failure was found, but further study with a longer follow-up will be necessary to determine the long-term effects of irradiation on subsequent growth patterns in children.

[Experimental studies on hepatic circulation: effects of drugs on blood flows in liver tissue and portal vein of the cats]

The effects of some drugs on the hepatic circulation were examined by thermoelectrical and electromagnetic methods under pentobarbital-anesthesia in normal and CCl4-pretreated cats. The following results were obtained. 1. Both adrenergic alpha and beta receptor functions were involved in the regulation of the hepatic circulation of normal cats. 2. Three calcium blockers (nifedipine, nicardipine, diltiazem) had different potencies in increasing the hepatic blood flow of normal cats. 3. The isolated veins including portal vein showed the regional difference in the responsiveness to calcium blockers. 4. In CCl4-pretreated cats, adrenergic alpha receptor function was dominant in the control of hepatic circulation and diltiazem raised portal venous pressure.

A comparative study of immunological and cytochemical profiles between adult and childhood acute lymphoblastic leukemias (ALLs): heterogeneity in adult common ALL

To investigate the biological differences between adult and childhood acute lymphoblastic leukemia (ALL), leukemic blasts from 33 patients with ALL (22 adults and 11 children) and from 11 patients in the lymphoid crisis of chronic myeloid leukemia (CML) were studied using cytochemical and immunological markers and also by the outcome of their treatment. The cytochemical studies showed that blasts from seven of the adult ALL patients were dense-granular-positive (DG-positive) for beta-glucuronidase, whereas the blasts from the children were negative except for one (with T-ALL). In the adults with common ALL (cALL), survival of patients DG-positive for this enzyme were significantly shorter than that of eight patients with a scattered granular pattern (p less than 0.05). The mean ratio between the percentage of blasts positive for cALL antigen (cALLA) to that of blasts positive for terminal deoxynucleotidyl transferase (TdT) in the adult group with cALL (0.6 +/- 0.3) was significantly lower (p less than 0.01) than in the group of children with cALL (1.1 +/- 0.2) or in the lymphoid-crisis group (1.5 +/- 1.0). These findings indicate that adult cALL consists of two distinct subpopulations, one with less differentiated phenotype (cALL-/TdT+) and the other with more (cALL+/TdT+). In contrast, the blast cells in childhood cALL and some patients in lymphoid crisis had a relatively homogeneous population with the latter phenotypes. The results suggest that the clonotypic cells in adult ALL, particularly in cALL, appear to be more immature than those in childhood ALL. The beta-glucuronidase patterns indicate a further heterogeneity in adult ALL.