Base Of Petals Research Articles

PRIMARY AND SECONDARY SOMATIC EMBRYOGENESIS OF CACAO: THE EFFECT OF EXPLANT TYPES AND PLANT GROWTH REGULATORS

<p class="abstrakinggris">The success of cacao somatic embryogenesis is affected by many factors, including the basal salt medium, the genotype, the explant type, and the concentration and composition of plant growth regulators (PGRs). The study aimed to evaluate the effects of PGRs composition on the primary somatic embryo (PSE) response and the effect of explant type and PGRs composition used in inducing PSE on the secondary somatic embryogenesis (SSE) response. PSEs were induced from basal petal and staminoid explants of MCC 01 and MCC 02 clones on DKW medium containing 2,4-D 2 mg l<sup>-1 </sup>+ kinetin 0.5 mg l<sup>-1</sup> or 2,4-D 2 mg l<sup>-1</sup> + kinetin 0.125 – 0.250 mg l<sup>-1</sup> + thidiazuron (TDZ) 2.5 – 5 µg l<sup>-1</sup> or 2,4-D 2 mg l<sup>-1</sup> + TDZ 10 µg l<sup>-1</sup>. Genotype, explant type, and PGR composition dependently affected PSE response. The best PSE response was obtained from staminoid explant of MCC 02 clone on medium containing 2,4-D 2 mg l<sup>-1</sup> + kinetin 0.5 mg l<sup>-1</sup> (20%, 9 embryos). The explant type and PGR composition used in inducing PSEs affect the SSE response. The highest SSE response of MCC 01 clone was obtained from petal explant with medium containing 2,4-D 2 mg l<sup>-1</sup> + kinetin 0.5 mg l<sup>-1</sup>. The formation of SSEs could increase the multiplication rate of MCC 01 clone by 7 times.</p>

<p><strong><em>Bredia</em></strong><strong> <em>malipoensis</em> (Melastomataceae), a new species from Yunnan, China</strong></p>

A new species, Bredia malipoensis D. H. Peng, S. Jin Zeng & Z. Y. Wen, from China, is described and illustrated here. Bredia malipoensis is morphologically similar to B. longiradiosa C. Chen in having cordate leaf blades, umbellate inflorescence and undulate petals with unguiculate bases and retuse apices. It is characterized by its terete stem and petioles, green calyx lobes, purple anthers, yellow connective appendages and white filaments. It is also morphologically similar to B. velutina Diels in having a woody stem, unequal and cordate leaf blades, but it is differentiated by having no reddish trichomes, larger and semiorbicular calyx lobes, and unguiculate petal bases. Bredia malipoensis differs markedly from the former relatives by its densely tomentose indumentum (with uniseriate non-glandular and sparse glandular trichomes) both on vegetative and floral parts, basal leaf venation and purplish-red petals. Our phylogenetic analyses using nuclear ribosomal ITS and chloroplast trnV-trnM regions strongly support the generic placement of B. malipoensis and its relatives B. longiradiosa and B. velutina within Bredia.

Reestablishment of Cabomba schwartzii (Cabombaceae), an aquatic plant species endemic to the Brazilian Amazon

Cabomba schwartzii was described by Rataj in 1977. The species discovered in the Brazilian Amazon was said to differ from other Cabomba species in having two sepals, two petals and a lobate petal base. According to the 1991 study of Ørgaard, C. schwartzii is similar to C. aquatica in other morphological characters (C. aquatica has flowers with three sepals and three petals) and since variation in number of floral parts is common in the genus, Ørgaard synonymized both species. After an analysis of C. schwartzii type material, other herbarium collections and location of four populations (two with C. schwartzii characteristics and two with C. aquatica characteristics), we conducted an integrated morphological and genetic study to evaluate whether or not C. schwartzii is a distinct species from C. aquatica. The results reveal the species to be distinct from each other and therefore C. schwartzii should be reestablished. The floral formula for C. schwartzii is K2 C2 A2+2 G1, versus K3 C3 A3+3 G2 for C. aquatica. A detailed species description and the geographical distribution of C. schwartzii are presented with a dichotomous key to distinguish both species, together with illustrations.

Род Trollius L. (Ranunculaceae) во флоре Алтайской горной страны

Information on new characters, that were not previously used for the Trollius species identification is presented: consistence and degree of dissection of blade, type of margin, shape of teeth, number of petal veins, shape of nectarostigma, and morphological characters of fruits - type of the pericarp surface. The quantitative and qualitative morphological characters of the species are indicated: number of sepals and petals, distance from the petal base to the nectarostigma, length of the follicle and persistent style, as well as its shape and location. An identification key is proposed, which has been developed taking into account the suggested characters. A sinopsis of the genus Trollius (Ranunculaceae) of the Altai Mountain Country, including 3 species belonging to 2 sections is given. The synopsis includes nomenclature quotations, information on type specimens, distribution in the region, and general distribution for each species.

Organography of greenhouse and field accessions of wild Arachisspecies (section Arachis)

ABSTRACT Peanut or groundnut (Arachis hypogaea L.) is a globally important oilseed crop, with important nutritional qualities, and a rich source of amino acids and protein. Another 80 species have been described in the genus Arachis, 64 of which are found in Brazil, and even though their morphology and agronomic traits remain largely unknown, they have been cultivated for forage and for landscaping and have great potential for breeding with cultivated peanut. Thus, the morphological characterization of wild Arachis species is essential for their conservation and use. In this study, we present a morphological and agronomic characterization of 29 diploid accessions of eleven wild Arachis species and one of the tetraploid A. monticola (section Arachis) with A and B genomes and determine their intra- and interspecific variability in greenhouse and field conditions. In total, 35 morphological descriptors were developed a priori from greenhouse accessions in the first crop year and used in field accessions in the second crop year. Significant differences in descriptors compiled in the greenhouse and the field support the use of different descriptors for different experimental conditions. PCA analysis showed that the distribution of accessions accorded with the taxonomy of species. The ten morphological descriptors that were important in differentiating section Arachis accessions were seed length, lateral branch length, right apical leaflet length, right apical leaflet width, height and diameter of main stem, branch color, standard petal base color, number of flowers, and presence of bristles on rachis.

EFFECTIVE CACAO SOMATIC EMBRYO REGENERATION ON KINETIN SUPPLEMENTED DKW MEDIUM AND SOMACLONAL VARIATION ASSESSMENT USING SSRs MARKERS

This study aimed to develop the cacao ( Theobroma cacao L.) in vitro regeneration system through somatic embryogenesis on kinetin supplemented DKW medium and somaclonal variation assessment using SSR markers. Callus were initiated from basal petal and staminoid explants cultured on callus induction (CI) medium contained DKW basalt salts and kinetin:2,4-D ratios of 1:15.5, 1:7.8 or 1:3.9 and then transferred onto secondary callus growth (SCG) medium contained WPM basalt salts and kinetin:2,4-D ratios of 1:7.8 or 1:3.9. The calli were then subsequently transferred onto embryo development medium contained DKW basal salts with or without the addition of amino acids, adenine or activated charcoal for the formation of somatic embryos. Nine cacao genotypes were tested for their ability to develop somatic embryos. Results of this study indicated DKW medium supplemented with Kinetin in combination with 2,4-D effectively induced cacao somatic embryogenesis. The highest somatic embryos formation was abtained from kinetin:2,4-D ratio of 1:3.9 and 1:7.8 in CI and SCG medium respectively. Cacao genotype responses were highly explant type dependent. The developed method resulted in a high percentage of somatic embryo formation (5.6-66.7%), germination (50%) and plantlet conversion (65%) and a medium percentage of somaclonal variations based on SSRs marker analysis.

Habenaria pseudorostellifera, a New Orchid Species from China

Habenaria pseudorostellifera Kolan., Szlach. & Kras, a new orchid species from China is described and illustrated. It is distinguishable from the fairly similar H. rostellifera by details of gynostemium, shape of petals, different lateral sepals, and by presence of a dentate appendage at the petal base.

Transcriptome sequencing of purple petal spot region in tree peony reveals differentially expressed anthocyanin structural genes.

The pigmented cells in defined region of a petal constitute the petal spots. Petal spots attract pollinators and are found in many angiosperm families. Several cultivars of tree peony contain a single red or purple spot at the base of petal that makes the flower more attractive for the ornamental market. So far, the understanding of the molecular mechanism of spot formation is inadequate. In this study, we sequenced the transcriptome of the purple spot and the white non-spot of tree peony flower. We assembled and annotated 67,892 unigenes. Comparative analyses of the two transcriptomes showed 1,573 differentially expressed genes, among which 933 were up-regulated, and 640 were down-regulated in the purple spot. Subsequently, we examined four anthocyanin structural genes, including PsCHS, PsF3′H, PsDFR, and PsANS, which expressed at a significantly higher level in the purple spot than in the white non-spot. We further validated the digital expression data using quantitative real-time PCR. Our result uncovered transcriptome variance between the spot and non-spot of tree peony flower, and revealed that the co-expression of four anthocyanin structural genes was responsible for spot pigment in tree peony. The data will further help to unravel the genetic mechanism of peony flower spot formation.

Anatomy of Petal Drop in Sunflowers

The petals of some sunflower (Helianthus annuus) cultivars used as cut flowers are easily knocked off the flower; this ruins its appearance and destroys its market value. The objectives of this study were to characterize an abscission zone, if present, at the base of petals of sunflower florets in cultivars that differ with respect to petal drop and to determine if differences in the nature and/or development of the abscission zone among cultivars were correlated with differences in timing with respect to petal drop. In the first experiment, we measured the force required to pull petals from the flower head; in the second we investigated changes in the anatomy of the petal–achene juncture. Anatomical analysis revealed a differentiated region (the abscission zone) at the junction of the petal and achene consisting of cells with a different morphology from those above and below it. Cell division at the abscission zone of the short-lived cultivar occurred earlier than in the long-lived cultivar. These differences indicate that whereas the anatomical nature of the abscission zone is similar in the two cultivars, Procut Yellow Lite (PYL) and Procut Bicolor (PBC), the tempo of development differed. Specifically, the abscission layer reached full differentiation, or maturity, sooner in PBC, hence its earlier petal drop, than in PYL.

Dissecting pollinator responses to a ubiquitous ultraviolet floral pattern in the wild

Summary Colour patterns on flowers can increase pollinator visitation and enhance foraging behaviour. Flowers uniform in colour to humans, however, can appear patterned to insects due to spatial variation in UV reflectance on petals. A UV ‘bullseye’ pattern that is common among angiosperms – UV‐absorbing petal bases and UV‐reflective apices – purportedly functions as a nectar guide, enhancing pollinator orientation and experimental evidence suggests that UV reflectance increases floral apparency to pollinators. We test the pollinator‐attracting and pollinator‐orienting functions of floral UV pattern and UV reflectance under natural conditions. Specifically, we address whether UV reflection alone, or UV pattern influences small bee and syrphid fly attraction rates (approaching, landing and foraging visits), foraging rates, and likelihood of foraging and orienting to the centre of flowers, using Argentina anserina, a species whose flowers exhibit variability in the size of the UV bullseye. We manipulated UV properties while maintaining uniformly yellow petals to create three phenotypes – uniformly UV‐absorptive, uniformly UV‐reflective, and inversed bullseye (reflective bases and absorptive apices) and compared insect visitation and behaviour to control flowers with the common UV bullseye phenotype. The presence of UV pattern increased attraction rates by both bees and syrphid flies relative to either fully UV reflective or absorptive flowers. However, only in the inverse array did the bullseye phenotype elicit higher foraging rates than the test flower. Neither the presence of pattern, nor the reversal of the common pattern influenced the likelihood of pollinator foraging or orientating to the flowers' centre during a visit. We provide some of the first evidence to suggest that flowers with spatial variation in UV reflectance may be more conspicuous to insects than those with petals that uniformly absorb or reflect UV, all of which are naturally occurring phenotypes. Further, we verify that the most common UV pattern in nature increases insect attraction and foraging rate relative to the inverse pattern. Results confirm a distance apparency function of the UV bullseye, but we argue for reconsideration of the notion that pollinators benefit from this ubiquitous floral motif through enhanced foraging efficiency.

Quantitative Variation, Heritability, and Trait Correlations for Ultraviolet Floral Traits inArgentina anserina(Rosaceae): Implications for Floral Evolution

Premise of research. Variation in flower color in the human-visible spectrum is well studied but less understood for ultraviolet (UV) floral traits despite their ubiquity and importance in mediating plant-insect interactions. Describing the extent of quantitative phenotypic variation and determining the heritability of UV pattern are crucial for understanding the evolution of flower color. Finally, selection on vegetative biochemical properties can indirectly influence flower color evolution, and thus, establishing correlation between biochemistry and color pattern will inform whether indirect selection could act on flower color patterns.Methodology. We characterize phenotypic variation for the proportion of petal area that absorbs UV (UV proportion) in 13 populations representing two taxa in the Argentina anserina aggregate. We estimate broad-sense heritability and genetic correlations for UV proportion, floral spectral qualities measured at the base and apex of petals (UV reflectance, UV chroma, brightn...

B‐ and C‐class gene expression during corona development of the blue passionflower (Passiflora caerulea, Passifloraceae)

The origin of the passionflower corona, a complex series of structures between the petals and stamens, has intrigued botanists for centuries, but has proven intractable using traditional approaches. Supplementing developmental data with expression analyses of three floral identity genes, we test whether the corona in Passiflora caerulea (blue passionflower) is homologous to petals or stamens or whether an alternative hypothesis of the corona as a novel structure is supported. Corona development was investigated using scanning electron microscopy. Expression of the P. caerulea B-class genes PISTILLATA (PcPI) and TOMATO MADS6 (PcTM6), and C-class gene AGAMOUS (PcAG) was investigated using a combination of RT-PCR and mRNA in situ hybridization analyses. Corona development starts as a ring of tissue at the base of petals. The outer radii and operculum initiate first at the periphery, followed by the inner radii and pali toward the center, and finally an annulus beneath the operculum. Late in development, a limen, the innermost component of the corona, develops from the side of the androgynophore. RT-PCR analyses indicate that the B-class genes PcPI and PcTM6 and C-class gene PcAG were all expressed in mature coronas. However, mRNA in situ hybridization analyses revealed complex temporal patterns of gene expression in the different corona elements. Our data support the hypothesis that the corona is a composite structure, with the radii, pali, and operculum homologous to stamens, and the limen, which only expresses PcTM6, considered to be a novel structure distinct from the androgynophore.

Clinical effect of phacoemulsification combined with trabeculectomy in glancoma patients

Objective To observe the clinical effects of phacomulsification. IOL implantation combined with trabeculectomy, MMC and transcornea adjustable suture in glaucoma. Methods 69 patients (72 eyes) were treated,mading conjunctive petal base in fornix madng scleral flap 5 mm × 4 mm, base in limbus corneae, setting 0.2 ～ 0.4 mg/ml MMC cotton disk under conjunctive petal and sclera petal, stopping 3 ～ 5 min,washing with normal saline then phacoemulsification. IOL trabeculectomy implantation trabeculectomy and transcornea adiustale suture. Results The mean followup time was 7.36±4.64 months. Best corrected visual acuity improved in 46 eyes(63.89%) of the patients,fixed in 9 eyes(26.39%),dropped in 7 eyes (9.72%).Preoperative IOP was 28.67±10.69 mm Hg. Final IOP of 66 eyes(91.67%) were controlled (＜21 mm Hg).The rate of functional fitering bled was 91.67%. unfunctional bleb was 8.33%, complication included correal edema shallow anterior chamber, effusion in anterior chamber in early postoperative days. Conclusion Phacoemulsification combined with trabeculectomy and adjustable suture in glaucoma patients was effective method to treat patients of glaucoma and cataract. Key words: Phacoemulsification; Trabeculectomy; Adjustable suture; MMC

Floral nectary structure, nectar production, and carbohydrate composition in theLiliumAsiatic hybrid ‘Trésor’

Floral nectary structure, nectar production, and carbohydrate composition were compared from petals (“inner tepals”) and sepals (“outer tepals”) of Lilium Asiatic hybrid ‘Trésor’ (Liliaceae). The six nectaries each occupied a narrow furrow bordered by two convergent ridges extending adaxially from the petal and sepal base. Each sepal nectary furrow was shorter and more concealed. In both nectary types, many vascular bundles comprising xylem and phloem supplied 5.5–8 layers of nectariferous parenchyma cells below the epidermis, which lacked stomata. Transmission electron microscopy of sepal nectaries demonstrated that parts of the outer epidermal wall adhered to an intact but uplifted cuticle in nectar-secreting flowers. Both apoplastic and symplastic routes were continuous from the vascular bundles to the nectary epidermis. Starch breakdown from amyloplasts throughout the nectary likely augmented nectar production. Nectar solute concentration from another Asiatic hybrid, ‘Orange Pixie’, was also significantly higher in petals. In ‘Trésor’, significantly more nectar was available from sepals, possibly reflecting reduced evaporation from multiple nectar droplets within the covered nectary furrow. However, for both hybrids, the same quantity of nectar sugar was produced by petals and sepals. Nectar composition from petals and sepals also was alike, in ‘Orange Pixie’ averaging 67/19/14 (= sucrose/fructose/glucose) and 59/25/17, respectively, and in ‘Trésor’ averaging 68/23/10 and 62/27/12, respectively.

Comparative analysis of floral pigmentation between wild-type and white-flowered varieties of Cyclamen graecum

SummaryThe flower colour of Cyclamen graecum gra6 (wild-type) is pink-purple in the main part of the petal, referred to as the ‘slip’, and deep purple at the petal base, referred to as the ‘eye’. On the other hand, flowers of C. graecum gra50 (a white-flowered variant) exhibit a white colour in both the ‘slip’ and ‘eye’ regions. In this study, the relationship between floral pigmentation and the expression of several anthocyanin biosynthesis genes was investigated in C. graecum gra6 and gra50. The pigments in the ‘slip’ and ‘eye’ regions consist mainly of malvidin 3,5-diglucoside in gra6, suggesting that the difference between the colour of the ‘slip’ and ‘eye’ regions is related to the amount of anthocyanin present. White-flowered C. graecum gra50 possessed lower amounts of anthocyanins, but higher amounts of flavonols compared to gra6, suggesting a change in metabolism caused by a disruption of anthocyanin biosynthesis. Gene expression analysis demonstrated that expression of the dihydroflavonol 4-reductase gene 2 (CgraDFR2) was lower in gra50 compared with gra6, whereas expression of the three other key genes (dihydroflavonol 4-reductase gene 1, flavonoid 3’,5’-hydroxylase, and anthocyanidin synthase) did not differ greatly. These results suggest that the white-flowered variant (gra50) may result from a defect in expression of the CgraDFR2 gene.

Comparison of anthocyanins in non-blotches and blotches of the petals of Xibei tree peony

A comparison in non-blotches and blotches of 35 cultivars of Xibei tree peony was investigated to explore flower coloration of Xibei tree peony (the second cultivar group in Chinese tree peony). With high performance liquid chromatography (HPLC) analysis, six anthocyanins including peonidin 3,5-di- O-glucoside (Pn3G5G), peonidin 3- O-glucoside (Pn3G), cyanidin 3,5-di- O-glucoside (Cy3G5G), cyanidin 3- O-glucoside (Cy3G), pelargonidin 3,5-di- O-glucoside (Pg3G5G), and pelargonidin 3- O-glucoside (Pg3G) were detected in non-blotches and blotches of petals. Total anthocyanins (TA), total flavones and flavonols (TF), and the copigmentation index (CI) were also analyzed. Cyanidin-based glycosides, which accumulated abundantly at the basal petal, resulted in blotch formation. Some peculiar cultivars with only one kind of anthocyanins or without anthocyanins in non-blotches were found in this study. For example, ‘Feng Zi Xiu Se’, ‘Ou Duan Si Lian’, and ‘Xi Wang’ contained only Pn3G5G; ‘Bing Shan Cang Yu’ and ‘Jin Bo Dang Yang’ contained only Cy3G; while no anthocyanins were found in ‘Bing Shan Xue Lian’. Several cultivars were rich in Pg-based glycosides, such as ‘Ni Hong Huan Cai’, and ‘Ju Yuan Shao Nv’. These cultivars would be excellent parents for creating new cultivars with novel flower color in the future.

Plastid ontogeny during petal development in Arabidopsis.

Imaging of chlorophyll autofluorescence by confocal microscopy in intact whole petals of Arabidopsis thaliana has been used to analyze chloroplast development and redifferentiation during petal development. Young petals dissected from unopened buds contained green chloroplasts throughout their structure, but as the upper part of the petal lamina developed and expanded, plastids lost their chlorophyll and redifferentiated into leukoplasts, resulting in a white petal blade. Normal green chloroplasts remained in the stalk of the mature petal. In epidermal cells the chloroplasts were normal and green, in stark contrast with leaf epidermal cell plastids. In addition, the majority of these chloroplasts had dumbbell shapes, typical of dividing chloroplasts, and we suggest that the rapid expansion of petal epidermal cells may be a trigger for the initiation of chloroplast division. In petals of the Arabidopsis plastid division mutant arc6, the conversion of chloroplasts into leukoplasts was unaffected in spite of the greatly enlarged size and reduced number of arc6 chloroplasts in cells in the petal base, resulting in few enlarged leukoplasts in cells from the white lamina of arc6 petals.

Differential respiratory and morphological responses of carnations pulsed or continuously treated with silver thiosulfate

The effect of pulse or continuous silver thiosulfate treatment of cut carnation flowers ( Dianthus caryophyllus L. cv. Elliott's White) on ethylene action was investigated. Flowers were treated either with a 2.0 mM silver thiosulfate 2 h pulse or continuously with 0.2 mM silver thiosulfate and exposed to 0.1–10.0 μl l −1 ethylene. Reciprocally, flowers pulsed with 0.5, 1.0, or 2.0 mM silver thiosulfate were treated with either 4.0 or 8.0 μl l −1 ethylene. Petal tissues were separated into basal and apical segments and assayed for silver ions by atomic absorption spectrophotometer. Although increased respiration occurred in flowers pulsed with 1.0 or 2.0 mM silver thiosulfate, no morphological changes symptomatic of floral senescence accompanied this increase. Flowers continuously treated with 0.2 mM silver thiosulfate exhibited no morphological or respiratory responses to any concentration of exogenous ethylene, whereas both a respiratory increase and irreversible petal wilting were observed in flowers pulsed with 0.5 mM silver thiosulfate. Best fit regression analysis of this data suggests that the interaction between silver ions and ethylene is competitive. The differential distribution of silver ions between basal and apical regions of pulsed or continuously treated petals indicates that the petal base may play an important role in regulating carnation petal senescence.

Spatial fragrance patterns within the flowers ofRanunculus acris (Ranunculaceae)

Floral scents emitted from different flower parts ofRanunculus acris were investigated by trapping headspace volatiles onto Porapak Q followed by solvent desorption and GC-MS analysis. Isoprenoids, strongly dominated bytrans-β-ocimene, constituted the principal class of volatiles in all flower parts except pollen; sesquiterpenes were especially diverse. Odors collected separately from petals, stamens, and sepals + gynoecium comprised the same volatiles, but these were present in disparate proportions among the flower parts, thereby creating subtle contrasts within the flower. The main sources of volatiles were the petals and stamens, which made equal contributions to the whole-flower fragrance. Emissions from the petals differed quantitatively between the apical and basal petal regions, thereby paralleling optical nectar-guide patterns. Pollen odor was markedly unlike that of other flower parts, with only few volatiles, a high representation of 5-methylene-2(5H)-furanone (protoanemonin), and no detectabletrans-β-ocimene. The distinctiveness of the pollen's volatile profile suggests that it may serve a signalling role to pollen-feeding insects.

Expression of Ethylene Biosynthetic Pathway mRNAs is Spatially Regulated within Carnation Flower Petals

The spatial regulation of ethylene biosynthesis within carnation (Dianthus caryophyllus L. cv. White Sim) flower petals was investigated. When detached petals separated into upper and basal portions were exposed to ethylene, autocatalytic ethylene production specifically in the basal portions resulted. Ethylene-induced ethylene production in the basal petal tissue was associated with the accumulation of mRNAs for 1-aminocyclopropane-1-carboxylate (ACC) synthase and ACC oxidase. In contrast, the upper petal portions did not accumulate ACC synthase mRNA nor exhibit an induction of ACC synthase activity in response to ethylene. Upper petal tissue exhibited a transient accumulation of ACC oxidase mRNA and increased ACC oxidase activity in response to ethylene, although the levels of both were significantly lower than that exhibited by basal tissue. Both upper and basal petal tissue responded to ethylene with the accumulation of senescence-related mRNAs represented by the cDNA clones pSR5 and pSR12, indicating that the lack of expression of ACC synthase and the limited accumulation of ACC oxidase mRNA were not a result of overall differences in ethylene responsiveness between upper and basal petal tissue. Upper portions isolated from intact senescing petals produced elevated levels of ethylene at approximately 25 % the rate of basal tissue and contained lower, but detectable levels of ACC synthase and ACC oxidase mRNAs as compared to basal petal tissue. Following dissection, the upper petal tissue exhibited a decrease in ethylene production, while the basal tissue continued to produce ethylene at elevated rates. These results indicate ethylene production in the upper tissue is largely the result of transport of ACC and ethylene from the basal tissue.