Flower Age Research Articles

Efficiency of Buzzing Bees in Fruit Set and Seed Set ofSolanum violaceumin Sri Lanka

Plant-pollinator interactions are often considered as tightly coevolved, mutualistic relationships. The present study aimed at determining the flower visiting bees of the vegetable crop,Solanum violaceum, and the efficiency of buzz pollination by bees on fruit and seed production in Sri Lanka. Seven bee species:Hoplonomia westwoodi,Amegilla comberi,Patellapis kaluterae,Xylocopa tenuiscapa,Apis dorsata,Trigona iridipennis, andCeratina hieroglyphicavisited the flowers ofS. violaceum, and the first four species were buzzing bees. Buzzing bees were the first to visitSolanumflowers and were followed by nonbuzzing bees. Handling time ofH. westwoodiandP. kaluteraevaried with the availability of pollen in anthers that deplete with the age of flower and stayed longer at new flowers than at old flowers. Handling time of the larger buzzing bee,H. westwoodi, was higher than that of the smallerP. kaluterae. The fruit set, seed set, and seed germinability in flowers visited by buzzing bees were significantly higher than those of the flowers bagged to exclude pollinators.

Floral traits affecting fire blight infection and management

Erwinia amylovora, the causative agent of fire blight, colonizes primarily the flowers of the sub-family Maloideae. Commercially important fruit tree species such as apple (Malus domestica) and pear (Pyrus communis) are also affected by the disease. Epiphytic bacterial populations develop on the stigma, from where the pathogen colonizes the hypanthium, aided by moisture. Under favorable conditions, nectar provides a rich medium for growth, which allows bacterial invasion of tissues through the stomata of the nectary. The paper reviews various floral traits that may play a role in the onset and progression of the infection. Flower age, stigma morphology and longevity, the size of epiphytic bacterial population, morphology of the hypanthium, anatomy of the nectary, dynamics of nectar secretion, as well as the volume, concentration and composition of the nectar are discussed in detail, comparing traits of susceptible versus tolerant apple and pear cultivars. Management programs, aiming at the suppression of E. amylovora on floral parts by antibiotics, chemical compounds, natural substances or biological control agents, are also discussed.

Transient gene expression assays in rose tissues using a Bio-Rad Helios® hand-held gene gun

Rose tissues of different varieties were transformed using a Bio-Rad Helios® hand-held biolistic gun. Parameters for optimum transient expression were optimized and included rose variety, flower age, tissue, gold particle size and DNA Loading ratio. Smooth flowers without thick waxy layers and young unopened actively growing flowers were found to be better suited for the transient expression assays. The DNA amounts, gold particle amounts and size etc. were not found to influence the efficiency of the transient transformation in these tissues. These studies indicate that biolistic transformation using hand-held guns can be used for successful transient expression assays in rose flower tissues. This is especially useful for a quick and easy analysis of genes and their expression before attempting stable transformation.

Nicotinic acid and nicotinamide on pear and apple flowers are not limiting factors for Erwinia amylovora growth when these chemicals are considered in relation to cultivar and flower age

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Evaluation and Selection of Mutative Artemisia (Artemisia annua L.) According to the Altitude Variants

Induction of genetic variant of Artemisia annua L. was conducted through the application of gamma ray irradiation in 2007-2008. The aim was to obtain a plant with high artemisine content > 0.5% and late flowering period of about > 7 month after planting. Tweleve selected genotypes were subsequently examined to gain genetic stability on altitude of 1500, 950, and 540 m asl. The results showed that the plants had shorter flowering age in Cicurug (540 m asl) than that of in Pacet (950 m asl) and Gunung Putri (1540 m asl). Genotype 8 had the latest age of flowering in the three locations than the other genotypes, however, the growth and biomass were the lowest. Vegetative growth of Artemisia in Pacet and Gunung Putri was better than those in Cicurug. Genotype of 15 in Cicurug and 5A genotype in Gunung Putri and Pacet had higher wet and dry weight than that of two other associates. Based on plant biomass, 5 genotypes from Gunung Putri and Pacet i.e. 1D, 3, 5A, 14, and 15 genotypes were selected, as well as 5 genotypes i.e. 1D, 3, 4, 5A, and 15 genotypes from Cicurug. Analisys on artemisin content successfully obtained 5 selected somaclone lines i.e. 1B, 2, 4, 14, and 3 somaclones.

Attraction of Hesperopsis gracielae (Lepidoptera: Hesperiidae) Skippers to Heliotropium curassavicum Inflorescence Models

Abstract Heliotropium curassavicum L. (Boraginaceae) is a small desert perennial producing inflorescences visited by Hesperopsis gracielae (MacNeill) (Lepidoptera: Hesperiidae), a skipper found along the lower Colorado River in Nevada, Arizona, and California. Flowers on H. curassavicum are white, with yellow centers that turn purple as flowers age, and absorb ultraviolet light. I found cymes supporting fewer yellow-centered flowers which contained greater masses of sugar. I compared attractions of H. gracielae adults to inflorescence models displaying the plant's floral colors. Skippers more-frequently approached or landed-on purple models compared with yellow models, and white models elicited fewer approaches than yellow or purple models. Attraction of sootywings to purple and yellow corresponded with numbers of purple- and yellow-centered flowers on inflorescences but not with masses of sugar in individual flowers. Models displaying yellow and purple together, or both colors plus white, elicited fewer ...

Impact of neonicotinoid insecticides on natural enemies in greenhouse and interiorscape environments

The neonicotinoid insecticides imidacloprid, acetamiprid, dinotefuran, thiamethoxam and clothianidin are commonly used in greenhouses and/or interiorscapes (plant interiorscapes and conservatories) to manage a wide range of plant-feeding insects such as aphids, mealybugs and whiteflies. However, these systemic insecticides may also be harmful to natural enemies, including predators and parasitoids. Predatory insects and mites may be adversely affected by neonicotinoid systemic insecticides when they: (1) feed on pollen, nectar or plant tissue contaminated with the active ingredient; (2) consume the active ingredient of neonicotinoid insecticides while ingesting plant fluids; (3) feed on hosts (prey) that have consumed leaves contaminated with the active ingredient. Parasitoids may be affected negatively by neonicotinoid insecticides because foliar, drench or granular applications may decrease host population levels so that there are not enough hosts to attack and thus sustain parasitoid populations. Furthermore, host quality may be unacceptable for egg laying by parasitoid females. In addition, female parasitoids that host feed may inadvertently ingest a lethal concentration of the active ingredient or a sublethal dose that inhibits foraging or egg laying. There are, however, issues that require further consideration, such as: the types of plant and flower that accumulate active ingredients, and the concentrations in which they are accumulated; the influence of flower age on the level of exposure of natural enemies to the active ingredient; the effect of neonicotinoid metabolites produced within the plant. As such, the application of neonicotinoid insecticides in conjunction with natural enemies in protected culture and interiorscape environments needs further investigation.

Delayed Selfing in an Alpine BiennialGentianopsis paludosa(Gentianaceae) in the Qinghai‐Tibetan Plateau

Delayed selfing could provide ovules with an opportunity to be fertilized as a means of "pollination assurance" before the flowers wilt. It could, thus, be regarded as an adaptation to unpredictable pollinator environments. Within the alpine biennial Gentianopsis paludosa, the showy flowers and herkogamy at the early stage of a flower's life cycle may favor outcrossing. As the flower ages, anthers contact the central stigma due to the elongation of all filaments, resulting in autonomous selfing. Flower visitors are extremely rare in a high altitude population; and examination of the mating system indicates that G. paludosa is self-pollinated under natural conditions in this population. While at the lower altitude, the bumblebee visitation rate is relatively high but possibly unreliable. Stigma receptivity is the highest on the third day of anthesis, and decreases thereafter. Pollen viability is the highest when flowers open, and gradually decreases later. Self-pollination of G. paludosa occurs at the late stage of a flower's lifecycle when stigma receptivity and pollen viability have both decreased, suggesting delayed selfing and assurance of seed production. This delayed selfing could assure seed production under the constraints of pollinator scarcity, but ensure outcrossing when pollinators were available. Such a flexible pollination mechanism is highly adaptive in the alpine environment of the Qinghai-Tibetan Plateau.

STUDIES ON THE ANTIOXIDANT COMPONENTS AND ACTIVITIES OF THE METHANOL EXTRACTS OF COMMERCIALLY GROWN HEMEROCALLIS FULVA L. (DAYLILY) IN TAIWAN

ABSTRACT We explored the antioxidant components and activities of daylily Hemerocallis fulva L. flowers among two growth areas, three flower ages and two processing methods. The results showed that the growth area, flower age and processing method all significantly influenced the functional components and antioxidant activities grown in mountainous areas of Taiwan. The total phenols, flavonoids and total chlorophylls of the methanol extracts of D3DF were 59.51, 70.76 and 5.67% of the respective values of F3DF. The total phenols and anthocyanins of the methanol extracts of F1DF were 2.64 mg GAE/100 g·dried basis (db) and 0.102 µmole/100 g·db, which were significantly higher than the others. The total flavonoid contents of F1DF, F2DF, F3DF and D3DF were 20.83, 29.67, 31.65 and 22.30 mg QE/100 g·db, respectively, with the F1DF level as the lowest. The reducing power showed that both the fresh and dried flowers were very weak. The amounts of most flavonoids in the flowers from Hualien were greater than those from Taidong. PRACTICAL APPLICATIONS The aim of this research was to discuss the antioxidant activities and the main components of Hemerocallis fulva L. (day lily); for example, the content of total phenols, flavonoids and total chlorophylls. In particular, the study examines the content of 10 common types of flavonoids. The research used different solvents to extract H. fulva L. grown at different time and origins. The findings provide consumers with a better understanding of the functions of H. fulva L. It increases the H. fulva L. uptake and improves consumers' health. Consequently, it increases farmers' income.

Transient gene expression in rose petals via Agrobacterium infiltration

The study of gene function in roses is hampered by the low efficiency of transformation systems and the long time span needed for the generation of transgenic plants. For some functional analyses, the transient expression of genes would be an efficient alternative. Based on current protocols for the transient expression of genes via the infiltration of Agrobacterium into plant tissues, we developed a transient expression system for rose petals. We used β-glucuronidase (GUS) as a marker gene to optimize several parameters with effects on GUS expression. The efficiency of expression was found to be dependent on the rose genotype, flower age, position of petals within a flower, Agrobacterium strain and temperature of co-cultivation. The highest GUS expression was recorded in petals of the middle whirls of half-bloomed flowers from cultivars of ‘Pariser Charme’ and ‘Marvel’.

Populus CEN/TFL1 regulates first onset of flowering, axillary meristem identity and dormancy release in Populus

Members of the CENTRORADIALIS (CEN)/TERMINAL FLOWER 1 (TFL1) subfamily control shoot meristem identity, and loss-of-function mutations in both monopodial and sympodial herbaceous plants result in dramatic changes in plant architecture. We studied the degree of conservation between herbaceous and woody perennial plants in shoot system regulation by overexpression and RNA interference (RNAi)-mediated suppression of poplar orthologs of CEN, and the related gene MOTHER OF FT AND TFL 1 (MFT). Field study of transgenic poplars (Populus spp.) for over 6 years showed that downregulation of PopCEN1 and its close paralog, PopCEN2, accelerated the onset of mature tree characteristics, including age of first flowering, number of inflorescences and proportion of short shoots. Surprisingly, terminal vegetative meristems remained indeterminate in PopCEN1-RNAi trees, suggesting the possibility that florigen signals are transported to axillary mersitems rather than the shoot apex. However, the axillary inflorescences (catkins) of PopCEN1-RNAi trees contained fewer flowers than did wild-type catkins, suggesting a possible role in maintaining the indeterminacy of the inflorescence apex. Expression of PopCEN1 was significantly correlated with delayed spring bud flush in multiple years, and in controlled environment experiments, 35S::PopCEN1 and RNAi transgenics required different chilling times to release dormancy. Considered together, these results indicate that PopCEN1/PopCEN2 help to integrate shoot developmental transitions that recur during each seasonal cycle with the age-related changes that occur over years of growth.

A gene regulatory network controlled by the NAC transcription factor ANAC092/AtNAC2/ORE1 during salt-promoted senescence

The onset and progression of senescence are under genetic and environmental control. The Arabidopsis thaliana NAC transcription factor ANAC092 (also called AtNAC2 and ORE1) has recently been shown to control age-dependent senescence, but its mode of action has not been analysed yet. To explore the regulatory network administered by ANAC092 we performed microarray-based expression profiling using estradiol-inducible ANAC092 overexpression lines. Approximately 46% of the 170 genes up-regulated upon ANAC092 induction are known senescence-associated genes, suggesting that the NAC factor exerts its role in senescence through a regulatory network that includes many of the genes previously reported to be senescence regulated. We selected 39 candidate genes and confirmed their time-dependent response to enhanced ANAC092 expression by quantitative RT-PCR. We also found that the majority of them (24 genes) are up-regulated by salt stress, a major promoter of plant senescence, in a manner similar to that of ANAC092, which itself is salt responsive. Furthermore, 24 genes like ANAC092 turned out to be stage-dependently expressed during seed growth with low expression at early and elevated expression at late stages of seed development. Disruption of ANAC092 increased the rate of seed germination under saline conditions, whereas the opposite occurred in respective overexpression plants. We also detected a delay of salinity-induced chlorophyll loss in detached anac092-1 mutant leaves. Promoter-reporter (GUS) studies revealed transcriptional control of ANAC092 expression during leaf and flower ageing and in response to salt stress. We conclude that ANAC092 exerts its functions during senescence and seed germination through partly overlapping target gene sets.

NICOTIANA MUTABILIS – A NOVEL SYSTEM FOR STUDYING ETHYLENE-MEDIATED FLORAL SENESCENCE

Nicotiana mutabilis, a tobacco species recently discovered in southern Brazil, has flowers that change color during their display life. Opening buds are white, and as the flower ages, the color changes, at first gradually, and then rapidly through light pink to dark pink and even red. The onset of the pigment change is associated with a marked increase in ethylene production, and the change is delayed by treating the flowers with 1-methylcyclopropene (1-MCP), an inhibitor of ethylene action. Expression of the gene encoding chalcone synthase increased slightly in association with a substantial rise in concentrations of anthocyanins in the petals. Likewise, expression of a homolog of SAG12, a leaf senescence-associated gene first isolated from Arabidopsis, increased as the color change advanced and ethylene production increased. The numerous genetic and experimental tools available for N. tabacum can readily be applied to this close relative to provide an interesting new model for studying flower senescence.

The impact of plant and flower age on mating patterns.

Over a season, plant condition, amount of ongoing reproduction and biotic and abiotic environmental factors vary. As flowers age, flower condition and amount of pollen donated and received also vary. These internal and external changes are significant for fitness if they result in changes in reproduction and mating. Literature from several fields was reviewed to provide a picture of the changes that occur in plants and flowers that can affect mating over a season. As flowers age, both the entire flower and individual floral whorls show changes in appearance and function. Over a season, changes in mating often appear as alteration in seed production vs. pollen donation. In several species, older, unpollinated flowers are more likely to self. If flowers are receiving pollen, staying open longer may increase the number of mates. In wild radish, for which there is considerable information on seed paternity, older flowers produce fewer seeds and appear to discriminate less among pollen donors. Pollen donor performance can also be linked to maternal plant age. Different pollinators and mates are available across the season. Also in wild radish, maternal plants appear to exert the most control over paternity when they are of intermediate age. Although much is known about the characters of plants and flowers that can change over a season, there is less information on the effects of age on mating. Several studies document changes in self-pollination over time, but very few, other than those on wild radish, consider more subtle aspects of differential success of pollen donors over time.

Evolution towards self‐compatibility when mates are limited

Theory of plant mating system evolution predicts the spread of self-compatibility (SC) in a predominantly self-incompatible population when inbreeding depression (ID; the decline in fitness because of selfing) is small and when compatible mates are limited. I tested these two predictions by measuring the occurrence of SC in 13 natural populations of Ranunculus reptans L. that varied in ID and frequency of cross-incompatible mates. Enforced selfing experiments were conducted in 2 years. In the first year, self-pollination was applied at two flower ages to investigate the occurrence of delayed SC. I found that SC was not uncommon across all populations, but self-compatible plants usually produced few seeds. There was no evidence for delayed SC. The occurrence of SC was not associated with population-level ID, but populations with more limited availability of compatible mates had a significantly higher frequency of plants that were at least partially self-compatible. The results indicate that, in R. reptans, a shortage of available mates in small populations may cause the evolution of partial SC and mixed mating.

Regent Honeyeater Habitat Restoration Project Lurg Hills, Victoria

Summary The Regent Honeyeater Habitat Restoration Project is a landscape scale community effort to protect and restore all significant remnants of native woodland habitat in the agricultural district of the Lurg hills, Victoria. While focus is placed on the Regent Honeyeater, many other declining birds and mammals also benefit from the restoration project. Over 14 years of sustained effort, the project has involved 115 local landholders (approximately 95% of local farms) and about 17 000 volunteers. Together, they have protected relatively healthy remnants by fencing, planted or direct seeded depleted understoreys and replanted open areas that had been cleared for agriculture. Other restoration activities include ecological thinning of ‘pole forests’, mistletoe removal, environmental weeding, feral animal control, kangaroo reduction, systematic monitoring of a range of threatened and declining woodland birds, and nest box placement for hollow‐dependent mammals. The works have achieved the rapid closing of some high‐priority gaps in the local landscape, connecting the Lurg hills project area to other major regional habitats nearby. The oldest tree plantings are now 12 yrs old and 6‐m high and the first Ironbarks flowered in 2006. While the Regent Honeyeater has not yet returned in numbers (because the trees have not yet reached optimum flowering age), surveys and nest box monitoring reveal a range of threatened birds and mammals are already using this project’s regenerated and reconstructed habitats.

Patterns of variation in lipophilic and hydrophilic constituents in flower developmental stages of Echinacea purpurea (L.) Moench cultivated in Slovakia

The objective of this study was to examine and demonstrate how harvesting age (flower age) contribute to the variations in the quality of <i>Echinacea purpurea</i> (L.) Moench. The effects of different flower developmental stages on caffeic acid derivatives and isobutylamide content are described. These phytochemicals were extracted from fresh plants with 60% ethanol and quantified by the HPLC analysis. The results revealed that the quality of <i>Echinacea</i> is strongly influenced by the flower developmental stages. The highest content of both hydrophilic and lipophilic components in the anthodium of Echinacea plants were found in the third (mature) developmental stage, which is regarded as the optimum one for the harvest to obtain optimum yield levels.

Effect of Pollination on Floral Longevity and Costs of Delaying Fertilization in the Out-crossing Polygala vayredae Costa (Polygalaceae)

The effect of pollination on flower life span has been widely studied, but so far little attention has been paid to the reproductive consequences of delayed pollination in plants with long floral life spans. In the present study, Polygala vayredae was used to answer the following questions. (1) How does male and female success affect the floral longevity of individual flowers? (2) How does delaying fertilization affect the female fitness of this species? Floral longevity was studied after experimental pollinations involving male and/or female accomplishment, bagging and open pollination. The reproductive costs of a delay in the moment of fertilization were evaluated through fruit set, seed-ovule ratio and seed weight, after pollination of flowers that had been bagged for 2-18 d. Senescence of the flowers of P. vayredae was activated by pollen reception on the stigmatic papillae, while pollen removal had no effect on floral longevity. Nonetheless, a minimum longevity of 8 d was detected, even after successful pollination and pollen dissemination. This period may be involved with the enhancement of male accrual rates, as the female accomplishment is generally achieved after the first visit. Floral life span of open-pollinated flowers was variable and negatively correlated with pollinator visitation rates. Delayed pollination had a major impact on the reproductive success of the plant, with fruit set, seed-ovule ratio and seed weight being significantly diminished with the increase of flower age at the moment of fertilization. A strong relationship between pollination and floral longevity was observed. Flowers revealed the ability to extend or reduce their longevity, within some limits, in response to the abundance of efficient pollinators (i.e. reproductive fulfilment rates). Furthermore, with scarce or unpredictable pollinators, a long floral life span could maintain the opportunity for fertilization but would also have reproductive costs on production of offspring. Reduced female fitness late in the flower's life could shift the cost-benefit balance towards a shorter life span, partially counteracting the selection for longer floral life span potentially mediated by scarce pollination services.

SUSCEPTIBILITY OF APPLE HYPANTHIUM TO ERWINIA AMYLOVORA IN RELATION TO FLOWER AGE AND COUGARBLIGHT MODEL

Fire blight risk in the northwestern United States is widely determined with the Cougarblight model, involving a 4-day temperature evaluation developed on the assumption that flower stigmas support growth of E. amylovora for only a few days. Studies relating flower age to stigma receptiveness to bacteria did not offer a satisfactory explanation for the effectiveness of the model, and thus, the relation of flower age to hypanthial infection was investigated. Direct inoculations of flower hypanthia of various ages were performed with detached crab apple flowers in the laboratory and with Gala apple flowers in the orchard in 2005 and 2006. In both environments, disease incidence decreased with flower age. Rate of declining susceptibility was dependent on temperature in the laboratory. Regression analysis of orchard data indicated an inoculum dose effect, with steepest decline of susceptibility occurring during the initial days after petal expansion. In 2005. when conditions were most favorable for disease, the pathogen level of 104 CFU (representing a maximum population due to wetting of a few hours according to laboratory tests) caused a disease incidence that decreased from 40 to 18% for flowers 0 to 4 days old and from 12 to 9% for flowers 5 to 8 days old. Cougarblight and other models now incorporating a blossom-age component (e.g., MaryblytTM) may be explained by multiple factors. Our general understanding is that high temperatures during bloom allow E. amylovora to reach maximal levels of population on stigmas within a time period when hypanthia are still highly susceptible to infection upon wetting. Further study of these interrelationships could lead to improvements in fire blight risk assessment.

Nectar secretion strategy in three Japanese species: changes in nectar volume and sugar concentration dependent on flower age and flowering order

We explored how changes in nectar volume and nectar sugar concentration depend on flower age and flowering order in Gentiana triflora Pallas var. japonica (Kusnez.) Hara, Lobelia sessilifolia Lamb., and Hemerocallis middendorffii Trautv. et Mey. var. esculenta (Koidz.) Ohwi. In G. triflora var. japonica and H. middendorffii var. esculenta, change in nectar volume was small, whereas larger changes in nectar sugar concentration occurred depending on flower age. In L. sessilifolia, both the mean nectar volume and nectar sugar concentration clearly decreased with flower age. In all species, the mean nectar volume of the early-flowering group per plant was high. In terms of the change in sex allocation, the investment in male and female organs of the early-flowering group was high in G. triflora var. japonica and L. sessilifolia. We suggest that plants of G. triflora var. japonica and H. middendorffii var. esculenta secrete floral nectar for up to several days to sustain nectar volume to keep attracting pollinators while simultaneously reducing resource usage. Greater nectar secretion in the early-flowering group, in which flowers have more pollen and ovules, may contribute to greater reproductive success and may be effective for pollinators in learning the location of the plants and flowers. In addition, learning by pollinators should result in increased reproductive success of the later blooming flowers.