Influence ďune alimentation continue avec une solution glucosée sur ľévolution des glucides et des protéines dans les divers organes de la rose coupée (Rosa hybrida cv. Carina)

Influence of continuous supply with a solution of glucose on the changes in the content of soluble sugars and proteins in various organs of the cut rose (Rosa hybrida cv. Carina). Exogenous glucose continuously supplied to the cut rose is immediately converted into saccharose in the stem tissues. This saccharose migrates to the flower, where it is immediately hyd-rolysed, and to the leaves where its hydrolysis occurs more slowly. The reducing sugars resulting from the hydrolysis of saccharose in the flower and, therefore, possibly from the hydrolysis of saccharose in leaves, induce a large accumulation of hexoses (glucose and fructose) in the flower. The protein content does not depend on the level of reducing sugars in the flower.     

Conversion of leaves into petals in Arabidopsis

More than 200 years ago, Goethe proposed that each of the distinct flower organs represents a modified leaf [1]. Support for this hypothesis has come from genetic studies, which have identified genes required for flower organ identity. These genes have been incorporated into the widely accepted ABC model of flower organ identity, a model that appears generally applicable to distantly related eudicots as well as monocot plants. Strikingly, triple mutants lacking the ABC activities produce leaves in place of flower organs, and this finding demonstrates that these genes are required for floral organ identity [2]. However, the ABC genes are not sufficient for floral organ identity since ectopic expression of these genes failed to convert vegetative leaves into flower organs. This finding suggests that one or more additional factors are required [3, 4]. We have recently shown that SEPALLATA (SEP) represents a new class of floral organ identity genes since the loss of SEP activity results in all flower organs developing as sepals [5]. Here we show that the combined action of the SEP genes, together with the A and B genes, is sufficient to convert leaves into petals.     

FLORAL STRUCTURE AND ORGANOGENESIS IN PODOPHYLLUM PELTATUM (BERBERIDACEAE)

The life cycle of Podophyllum can be divided into two phases, a subterranean phase during which a conspicuous winter mixed terminal bud forms at the end of a rhizome, and an aerial phase, during which the primordia of the structures within the winter bud give rise the next spring to an aerial shoot composed of a stem, 2 leaves, and a single flower. The transition from a vegetative to a floral apex occurs at the end of July, when the apical meristem becomes a globoid structure. During the first and second weeks of August, the floral organs are laid down along the sides of an elongated floral apex. The order of initiation of the floral organs is sepals, petals, stamens, gynoecium, and stamens. Petal primordia are initiated in early August, but growth ceases after they attain a height of about 2 mm. This inhibition persists until the middle of May in the next growing season, when the petals grow to 12 mm within 2 weeks. At anthesis the petals have enlarged to a length of 2 cm or more. The gynoecium is usually composed of a single terminal carpel. The ovules are chiefly supplied by branches from a ventral bundle complex, but that is supplemented by medullary bundles that are formed in the base of the gynoecium, below the loculus. It could be argued that these medullary bundles are surviving remnants of the vascular supply to a second carpel, no longer extant. A transmitting tract extends from the stigma about half the distance to the loculus. The tract is lined with unicellular glandular cells and is open from the stigma to the loculus.     

Translocation of 14C-sucrose in Relation to Changes in Carbohydrate Content in Rose Corollas Cut at Different Stages of Development

The dry matter and carbohydrate contents of intact growing ‘Sonia’rose corollas were measured from an immature bud to full expansionof the petals. Reducing sugars and starch, but not sucrose,accumulated throughout most of the corolla development. Thesefindings were compared with the carbohydrate changes in thecorollas of flowers cut at different stages and allowed to agewith their stems either in water or in a sucrose-containingsolution. For a few days after cutting the carbohydrate metabolismof the cut flower roughly paralleled that of the intact floweruntil starch hydrolysed to maintain the soluble carbohydratepool. Feeding with the sucrose solution maintained the solublecarbohydrate levels and retarded the hydrolysis of starch. The cut flowers were fed with ¹⁴C-sucrose and the labelled metabolitesin the leaves and flowers were analysed. Active incorporationof ¹⁴C into ethanol-soluble carbohydrates, starch and ethanol-insolublematerial was found indicating that an active anabolic phaseprecedes the catabolic phase during the senescence of the cutflower. The findings are discussed in relation to the source-sinkhypothesis of flower development, with regard to the senescenceand growth of the corollas of cut and intact flowers respectively.     

Effects of postharvest pretreatments and preservative solutions on vase life longevity and flower quality of sweet pea (Lathyrus odoratus L.)

The effects of postharvest pretreatments on vase life, keeping quality and carbohydrate concentrations in cut sweet pea (Lathyrus odoratus L.) flowers were investigated. Compared to the control, all treatments promoted floret quality and extended longevity. The cut flowers held in the solution containing sucrose + 8-hydroxyquinoline (Suc+HQS) was more effective in promoting absorption rate, achieved greater maximum fresh mass, had better water balance for a longer period, extended the vase life (up to 17 d), and delayed degradation of chlorophylls. The same treatment also enhanced the concentration of soluble carbohydrates in the petals and stems and leaf chlorophyll (Chl) content, whereas it was lowest in silver thiosulphate (STS) treatment. However, concentrations of anthocyanin in the petals were higher for treatment with sucrose or STS plus sucrose than in control or STS alone treatments. Our results suggest that pulse treatment with HQS plus sucrose for 12 h is the most effective for improving pigmentation and use as a commercial cut flower preservative solution to delay flower senescence, enhance quality, and prolong the vase life of sweet pea. The results also showed that soluble carbohydrate concentration in petals and stems is an important factor in determining the vase life of sweet pea flowers.     

Invertase and sucrose synthase in flowers

Sucrose and reducing sugar concentrations in petals of cut carnation flowers, whose life was prolonged up to 7 days by bathing stalks in sucrose solutions, were respectively 3-fold and 2-fold higher than those bathed in water. Reducing sugar concentrations were about 7-fold higher than sucrose concentrations. A study of invertase and sucrose synthase activities in flower petals of carnation and four other species of flowers revealed that both enzymes may be involved in hydrolysis of translocated sucrose. Invertase activity, while being up to 20-fold higher than sucrose synthase activity in some species was approximately comparable in others. More detailed studies on invertase from petals of 3 flower species demonstrated the presence of only the acid form of the enzyme with a K_m value for sucrose of about 2.5 mM.     

表油菜素内酯对月季切花保鲜作用的研究

本文初步探讨了表油菜素内酯（epiBR）对瓶插月季切花的保鲜作用。与对照（蒸馏水）和基本液（2％蔗糖＋500mgL-1柠檬酸＋250mgL-8-羟基喹啉＋25mgAgNO3）相比,经epiBR处理（基本液＋0．1mgL-1epiBR）的月季切花花枝坚挺,蓝变延迟,瓶插寿命延长1-1.5倍。测定有关生理指标表明,epiBR处理对月季切花瓶插花枝前期鲜重的增加及后期的保持有明显作用。并显著延缓花瓣和叶片质膜相对透性的增加,还能使瓶插前期花瓣还原糖含量增加。epiBR处理对花瓣蛋白质和叶片叶绿素含量变化无明显影响,而对花瓣花青素水平下降有轻微的促进作用。     

Possible Roles of Methyl Glucoside andMyo-inositol in the Opening of Cut Rose Flowers

Methyl glucoside andmyo-inositol are present in all organs ofrose (Rosa hybridaL.). To investigate the possible role of thesecarbohydrates in the opening of cut roses, flowers with a 10,20 or 40-cm-long stem and a single flower bud (about 1.5 cmin diameter) were placed in water and flower opening and changesin sugar content in flowers and stems examined for 7 d. Thelonger the stem of the cut flower, the larger was the flowerdiameter. In stems, the concentration of carbohydrates, includingmethyl glucoside andmyo-inositol markedly decreased before floweropening. In petals, contents of glucose, methyl glucoside andmyo-inositolalso decreased before flower opening, but those of fructose,sucrose and xylose did not. When glucose and methyl glucosidewere added to the vase water (4%) flower opening was clearlypromoted; this was accompanied by an increase in methyl glucosideand fructose concentrations in petals. On the contrary,myo-inositolinhibited flower opening, and this was accompanied by an increaseinmyo-inositol and xylose concentrations in petals. These resultssuggest that methyl glucoside and/or its metabolites are transportedinto the petal cells, thereby lowering the osmotic water potentialand promoting flower opening.Myo-inositol is not readily metabolized,and exogenousmyo-inositol given at a high concentration mayact as an extracellular osmolyte, which inhibits water uptakeand flower opening.Copyright 1999 Annals of Botany Company Cut flowers, methyl glucoside,myo-inositol,Rosa hybrida,soluble carbohydrate.     

Sucrose‐cleaving enzymes and carbohydrate pools in Lilium longiflorum floral organs

The activities of soluble invertase (EC 3.2.1.26), cell wall invertase (EC 3.2.1.26) and sucrose synthase (EC 2.4.1.13) were determined in Easter lily ( Lilium longiflorum Thunb. cv. Nellie White) floral organs during flower development. These enzyme activities were correlated with dry weight gains and carbohydrate pools to investigate the importance of their expression in maintaining sink strength of floral organs. In the early stages of flower bud development, anthers exhibited the highest rates of dry weight gain and activity of sucrolytic enzymes. Once anther growth was completed, the dry weight gain of tepal, filament, stigma and style increased with a concomitant increase in hexose concentrations and invertase activity. Although all three enzymes capable of catalyzing sucrose cleavage were present in every flower organ of L. longiflorum , soluble invertase was the predominant enzyme in all flower organs except stigma where cell wall invertase dominated. Soluble invertase activity was highly correlated with dry weight gain in most of the flower organs.     

Effects of Ethylene and Sucrose on Translocation of Dry Matter and 14C-Sucrose in the Cut Flower of the Glasshouse Carnation (Dianthus caryophyllus) During Senescence

The translocation and distribution of dry matter were studiedin the floral and vegetative parts of the cut carnation duringsenescence. The change in dry weights of the tissues and theamount of radioactivity recovered from them after feeding with¹⁴C-sucrose were measured. Treatments with ethylene and sucrosewere used to alter the rate of senescence of the flowers. Sucrosemoved through the stem relatively unchanged but was rapidlyinverted and metabolized in the petals. During natural ageing,¹⁴C moved from the stem to the flower and the movement was enhancedby exogenous sucrose, which also reduced the loss of dry matterin the petals and promoted their growth. Treatment with ethylenecaused petals to wilt and lose dry weight, and ovaries to enlargeand increase in dry weight. The distribution of radioactivityin flowers fed with 14C-sucrose before and after ethylene treatmentsupported the observation that dry matter was translocated betweenthe flower parts. The results indicate that a change in thesource-ink relationships of the flower parts contributes tothe factors that determine the rate of flower senescence.     

Eucalyptus has a functional equivalent of the Arabidopsis floral meristem identity gene LEAFY

Two genes cloned from Eucalyptus globulus, Eucalyptus LeaFy (ELF1 and ELF2), have sequence homology to the floral meristem identity genes LEAFY from Arabidopsis and FLORICAULA from Antirrhinum. ELF1 is expressed in the developing eucalypt floral organs in a pattern similar to LEAFY while ELF2 appears to be a pseudo gene. ELF1 is expressed strongly in the early floral primordium and then successively in the primordia of sepals, petals, stamens and carpels. It is also expressed in the leaf primordia and young leaves and adult and juvenile trees.The ELF1 promoter coupled to a GUS reporter gene directs expression in transgenic Arabidopsis in a temporal and tissue-specific pattern similar to an equivalent Arabidopsis LEAFY promoter construct. Strong expression is seen in young flower buds and then later in sepals and petals. No expression was seen in rosette leaves or roots of flowering plants or in any non-flowering plants grown under long days. Furthermore, ectopic expression of the ELF1 gene in transgenic Arabidopsis causes the premature conversion of shoots into flowers, as does an equivalent 35S-LFY construct. These data suggest that ELF1 plays a similar role to LFY in flower development and that the basic mechanisms involved in flower initiation and development in Eucalyptus are similar to those in Arabidopsis.     

Structure and development of ‘witches' broom’ galls in reproductive organs of Byrsonima sericea (Malpighiaceae) and their effects on host plants

Galls are anomalies in plant development of parasitic origin that affect the cellular differentiation or growth and represent a remarkable plant–parasite interaction. Byrsonima sericea DC. (Malpighiaceae) is a super host of several different types of gall in both vegetative and reproductive organs. The existence of galls in reproductive organs and their effects on the host plant are seldom described in the literature. In this paper, we present a novel study of galls in plants of the Neotropical region: the ‘witches' broom’ galls developed in floral structures of B. sericea. The unaffected inflorescences are characterised by a single indeterminate main axis with spirally arranged flower buds. The flower buds developed five unaffected brownish hairy sepals and five pairs of elliptical yellow elaiophores, five yellow fringed petals, 10 stamens and a pistil with superior tricarpellar and trilocular ovary. The affected inflorescences showed changes in architecture, with branches arising from the main axis and flower buds. The flower buds exhibited several morphological and anatomical changes. The sepals, petals and carpels converted into leaf‐like structures after differentiation. Stamens exhibited degeneration of the sporogenous tissue and structures containing hyphae and spores. The gynoecium did not develop, forming a central meristematic region, from which emerges the new inflorescence. In this work, we discuss the several changes in development of reproductive structures caused by witches' broom galls and their effects on reproductive success of the host plants.     

Isolation of the tomato AGAMOUS gene TAG1 and analysis of its homeotic role in transgenic plants.

To understand the details of the homeotic systems that govern flower development in tomato and to establish the ground rules for the judicious manipulation of this floral system, we have isolated the tomato AGAMOUS gene, designated TAG1, and examined its developmental role in antisense and sense transgenic plants. The AGAMOUS gene of Arabidopsis is necessary for the proper development of stamens and carpels and the prevention of indeterminate growth of the floral meristem. Early in flower development, TAG1 RNA accumulates uniformly in the cells fated to differentiate into stamens and carpels and later becomes restricted to specific cell types within these organs. Transgenic plants that express TAG1 antisense RNA display homeotic conversion of third whorl stamens into petaloid organs and the replacement of fourth whorl carpels with pseudocarpels bearing indeterminate floral meristems with nested perianth flowers. A complementary phenotype was observed in transgenic plants expressing the TAG1 sense RNA in that first whorl sepals were converted into mature pericarpic leaves and sterile stamens replaced the second whorl petals.     

Wrinkled petals and stamens 1, is required for the morphogenesis of petals and stamens in Lotus japonicus

Although much progress has been made in understanding how floral organ identity is determined during the floral development, less is known about how floral organ is elaborated in the late floral developmental stages. Here we describe a novel floral mutant, wrinkled petals and stamens1 （wps1）, which shows defects in the development of petals and stamens. Genetic analysis indicates that wpsl mutant is corresponding to a single recessive locus at the long arm of chromosome 3. The early development of floral organs in wpsl mutant is similar to that in wild type, and the malfunction of the mutant commences in late developmental stages, displaying a defect on the appearance of petals and stamens. In the mature flower, petals and stamen filaments in the mutant are wrinkled or folded, and the cellular morphology under L1 layer of petals and stamen filaments is abnormal. It is found that the expression patterns of floral organ identity genes are not affected in wpsl mutants compared with that of wild type, consistent with the unaltered development of all floral organs. Furthermore, the identities of epidermal cells in different type of petals are maintained. The histological analysis shows that in wpsl flowers all petals are irregularly folded, and there are knotted structures in the petals, while the shape and arrangement of inner cells are malformed and unorganized. Based on these results, we propose that Wpsl acts downstream to the class B floral organ identity genes, and functions to modulate the cellular differentiation during the late flower developmental stages.     

Ethylene biosynthetic genes are differentially expressed during carnation (Dianthus caryophyllus L.) flower senescence

Ethylene production and expression patterns of an 1-aminocyclopropane-1-carboxylic acid (ACC) oxidase (CARAO1) and of two ACC synthase (EC 4.4.1.14) genes (CARACC3 and CARAS1) were studied in floral organs of cut carnation flowers (Dianthus caryophyllus L.) cv. White Sim. During the vase life and after treatment of fresh flowers with ethylene, production of ethylene and expression of ethylene biosynthetic genes first started in the ovary followed by the styles and the petals. ACC oxidase was expressed in all the floral organs whereas, during the vase life, tissue-specific expression of the two ACC synthase genes was observed. After treatment with a high ethylene concentration, tissue specificity of the two ACC synthase genes was lost and only a temporal difference in expression remained. In styles, poor correlation between ethylene production and ACC synthase (CARAS1) gene expression was observed suggesting that either activity is regulated at the translational level or that the CARAS1 gene product requires an additional factor for activity.Isolated petals showed no increase in ethylene production and expression of ethylene biosynthetic genes when excised from the flower before the increase in petal ethylene production (before day 7); showed rapid cessation of ethylene production and gene expression when excised during the early phase of petal ethylene production (day 7) and showed a pattern of ethylene production and gene expression similar to the pattern observed in the attached petals when isolated at day 8. The interorgan regulation of gene expression and ethylene as a signal molecule in flower senescence are discussed.     

Variability of Flavonol Contents during Floral Morphogenesis in the Poppy Papaver somniferum L.

We studied the contents of flavonols (kaempferol and quercetin) in the meristem of vegetative and generative apices of the main plant shoot in floral Papaver somniferum L. mutants, as well as in the normal plants at successive stages of flower development. Five stages of flower development were distinguished. Flavonols (kaempferol and quercetin) were present in all flower organs at all stages of floral morphogenesis we studied. However, their contents and distribution in different organs and at different stages of flower development markedly varied. No significant differences were found in the contents of flavonols in the meristems of vegetative and generative apices of the main shoot in the lines of floral mutants, as well as between the lines with different amounts of vegetative phytomeres. In the plants with normal flower structure, the contents of flavonols (kaempferol + quercetin) sharply increased with the beginning of differentiation of flower organs, i.e. from stage 3, to reach a maximum in the open flower, when gametogenesis is terminated and fertilization takes place. The level of flavonol contents in the petals (upper part) and stamen was at a maximum at all stages of flower development, while that in the gynaecium was at a minimum. The kaempferol : quercetin ratio was shifted towards quercetin at successive stages of flower development, most significantly in the stamens. The involvement of flavonols in the regulation of floral morphogenesis at stages of flower organs differentiation and functioning is discussed.     

Variability of flavonol contents during floral morphogenesis in Papaver somniferum L

We studied the contents of flavonols (kaempferol and quercetin) in the meristem of vegetative and generative apices of the main plant shoot in floral Papaver somniferum mutants, as well as in the normal plants at successive stages of flower development. Five stages of flower development were distinguished. Flavonols (kaempferol and quercetin) were present in all flower organs at all stages of floral morphogenesis we studied. However, their contents and distribution in different organs and at different stages of flower development markedly varied. No significant differences were found in the contents of flavonols in the meristems of vegetative and generative apices of the main shoot in the lines of floral mutants, as well as between the lines with different amounts of vegetative phytomeres. In the plants with normal flower structure, the contents of flavonols (kaempferol + quercetin) sharply increased with the beginning of differentiation of flower organs, i.e. from stage 3, to reach a maximum in the open flower, when gametogenesis is terminated and fertilization takes place. The level of flavonol contents in the petals (upper part) and stamen was at a maximum at all stages of flower development, while that in the gynaecium was at a minimum. The kaempferol: quercetin ratio shifted towards quercetin at successive stages of flower development, most significantly in the stamens. The involvement of flavonols in the regulation of floral morphogenesis at stages of flower organs differentiation and functioning is discussed.     

Enhanced formation of aromatic amino acids increases fragrance without affecting flower longevity or pigmentation in Petunia × hybrida

Purple Petunia × hybrida V26 plants accumulate fragrant benzenoid‐phenylpropanoid molecules and anthocyanin pigments in their petals. These specialized metabolites are synthesized mainly from the aromatic amino acids phenylalanine. Here, we studied the profile of secondary metabolites of petunia plants, expressing a feedback‐insensitive bacterial form of 3‐deoxy‐di‐arabino‐heptulosonate 7‐phosphate synthase enzyme (AroG*) of the shikimate pathway, as a tool to stimulate the conversion of primary to secondary metabolism via the aromatic amino acids. We focused on specialized metabolites contributing to flower showy traits. The presence of AroG* protein led to increased aromatic amino acid levels in the leaves and high phenylalanine levels in the petals. In addition, the AroG* petals accumulated significantly higher levels of fragrant benzenoid‐phenylpropanoid volatiles, without affecting the flowers' lifetime. In contrast, AroG* abundance had no effect on flavonoids and anthocyanins levels. The metabolic profile of all five AroG* lines was comparable, even though two lines produced the transgene in the leaves, but not in the petals. This implies that phenylalanine produced in leaves can be transported through the stem to the flowers and serve as a precursor for formation of fragrant metabolites. Dipping cut petunia stems in labelled phenylalanine solution resulted in production of labelled fragrant volatiles in the flowers. This study emphasizes further the potential of this metabolic engineering approach to stimulate the production of specialized metabolites and enhance the quality of various plant organs. Furthermore, transformation of vegetative tissues with AroG* is sufficient for induced production of specialized metabolites in organs such as the flowers.