Stages Of Flower Bud Development Research Articles

Restoring full pollen fertility in transgenic male-sterile tobacco (Nicotiana tabacum L.) by Cre-mediated site-specific recombination

Producing hybrid seed requires an efficient pollination control system to prevent unwanted self-pollination. For further breeding, it would be advantageous to restore pollen fertility in the hybrids. In this work we demonstrate the use of tapetum-specific expression of a stilbene synthase (sts) transgene to induce pollen sterility in tobacco as has been shown previously. The sts-coding region was flanked by loxP recognition sites for Cre-recombinase. From 10 T0-plants obtained, five proved to be male-sterile. They had smaller flowers with shorter stamina, but the vegetative phenotype was just as in the wild-type. Crossing male-sterile sts-plants with tobacco lines expressing the cre recombinase transgene resulted in site-specific recombination in the hybrids. GUS activity caused by fusion of the tap1-promoter with a promoterless gusA coding region indicated recombination events already in early stages of flower bud development. In all plants which had contained single or double sts-copies before crossing, these were excised, and pollen fertility was fully restored. The phenotype of these restored plants was as in wild-type controls. Contrary, from male sterile plants containing multiple copies of the sts-gene, not all copies were removed, and pollen sterility was maintained.

Seasonal Effects of a Late Application of Hydrogen Cyanamide on ‘Climax’ Rabbiteye Blueberry

Abstract A field study was conducted to evaluate the effects of hydrogen cyanamide (H2CN2) on flower and leaf buds, foliage, and fruit of ‘Climax’ rabbiteye blueberry (Vaccinium ashei, Reade), a cultivar exhibiting erratic spring foliation following mild winters. Stems of ‘Climax’ in several stages of flower bud development were sprayed with H2CN2(0, 1.0, 1.5 and 2.0% v/v), and effects on leaf development, injury to flower buds, and fruit development were studied. H2CN2 increased rate of vegetative bud opening, terminal leaf area, and overall leaf canopy. Flower bud injury was excessive when H2CN2 was applied at rates > 1.5% v/v or when flower buds were at stages 4-5 of development; 1.5% H2CN2 significantly reduced yield and rendered berries more susceptible to late spring frost injury. H2CN2 dramatically increased total number of vegetative buds developed for the next season's foliage, delaying bud break in the Spring of 2001. Results of this study agreed with similar controlled environment studies in that when H2CN2 was applied at rates not exceeding 1.0% v/v and before a majority of flower buds exceed development stage 2, vegetative bud development was enhanced and damage to flower buds was minimal.

A simple model to interpret the effects of sunflower crop management on the occurrence and severity of a major fungal disease: Phomopsis stem canker

Phomopsis stem canker ( Diaporthe helianthi Munt.-Cvet. et al.) causes drastic reductions in yield and oil content in the sunflower ( Helianthus annuus L.) crop. The use of disease-tolerant genotypes and fungicides is the basis of current disease control. Both for economic and environmental reasons, control by means of cultural practices should be promoted more. From 1992 to 2002, INRA and Cetiom collaborated to study the effects of sunflower crop management on the frequency and severity of Phomopsis attacks. As plant density and nitrogen rate significantly affect the development of sunflower leaf area, use of the fraction of photosynthetically active radiation intercepted by the canopy (fPARi) was suggested as a synthetic indicator of canopy management. In 1994, an exponential relation was observed between the proportion of sunflower stems bearing a Phomopsis lesion in mid-August and the fPARi by the canopy at anthesis in early July. This relation was successfully tested for a range of unprotected situations (1994–2000) corresponding to moderate infection pressure and various combinations of plant density and N fertilization. Such a reference curve was used to analyse the response of sunflower to stem canker infection in a range of cultural conditions: (1) high inoculum; (2) drought during head development or soon after leaf infection; (3) application of a fungicide at the early stages of flower bud development; (4) late sowing (May); (5) use of very susceptible or resistant genotypes. This simple model could help to interpret the origin of genotypic susceptibility to stem canker (crop architecture and/or physiology) and also to predict the potential risk of disease development for a given management scenario.

Factors affecting flower infection and disease severity of lowbush blueberry by Botrytis cinerea

Infection of lowbush blueberry (Vaccinium angustifolium Ait. and V. myrtilloides Michx.) flowers by Botrytis cinerea Pers.:Fr. and subsequent disease was determined for differing stages of flower bud development, temperature, and duration of postinoculation wet periods. Conidium germination of B. cinerea at 20°C was poor on immature flower buds when the corolla was beginning to protrude from the calyx (floral stage F4) and when the corolla was half developed (F5), but better when flowers were at the pink bud prebloom stage (F6) or fully open (F7). Infection incidence followed a similar trend; there was none on the F4 flowers, slightly more on F5 flowers, and an increase to over 45 and 98% on F6 and F7 flowers, respectively. Immature green berries were resistant to infection, but nonpollinated ovaries from which corollas had abscised were susceptible to infection. At 4, 8, 12, 16, and 20°C, low levels of infection occurred on F7 flowers after 24, 13, 10, 8, or 6 h of postinoculation wetness, respectively. The infection incidence increased progressively with temperature and wetness duration. Lesions spread from the corolla to the peduncle of flower clusters over a 96-h wet period at 16, 20, and 24°C, but the disease failed to spread beyond the corolla at 4, 8, and 12°C. When flower clusters were inoculated with 105 or 106 conidia/mL at 20°C and incubated over a 96-h wet period, lesions spread from the corolla to the peduncle, but when the inoculum concentration was 103 or 104 conidia/mL, they did not extend beyond the corolla. These results could help to reduce fungicide applications when disease management programs are based on monitored weather conditions.

フリージアの促成栽培における低温処理後の高温遭遇が花芽の形態的変化と開花時の障害発生に及ぼす影響

Corms of the freesia 'Blue Heaven' were chilled wet at 10°C for 5 or 6 weeks and the resulting sprouting young plants were immediately exposed to 24°C for 1, 2, or 3 weeks and then to 10°C until they were planted in a plastic house maintained at 5°C or above on 13 Nov. Flower buds, exposed to the high temperature, were prepared and photographed on a scanning electron microscope (SEM). Based on their morphology, the types at flowering were classified into 6 categories. When flower buds were exposed to high temperature during the differentiation of floral primordia, the which formed, varied depending on the developmental stages of flower buds at the start of the high temperature treatment and its duration. These inflorescences were classified as gladiolus bloom or abnormal inflorescence according to the degree of heat injury. The angle between the horizontal and the crossing lines from the base of the first to that of the last floret in an is a practical indicator to measure the degree of gladiolus bloom. Visually normal inflorescence, appeared in plants which received the most severe high temperature treatment. These plants initiated leaves and flower buds after abortion of the pre-differentiated flower buds. Normal and pseudo-normal inflorescences are easily distinguished by the difference in the number of leaves or days from chilling to flowering. Heat injury was less severe if the plants were exposed to high temperatures at a more advanced stage of flower bud development.

Tobacco floral homeotic geneNfbp6 is specifically expressed during pollen and ovule development

Nfbp6 was a floral homeotic gene isolated from tobacco. It showed high homology with other class C genes. Usingin situ hybridization technique, the expression ofNfbp6 was investigated in various stages of flower development. The results showed thatNfbp6 was expressed at low level during the initiation period of stamen and carpel primordia. In the later stage of flower bud development, the transcription level ofNfbp6 gene increased especially during the formation of pollen and ovule. TheNfbp6 gene expression was also observed in the transmitting tissue of style, stomium and circular cell clusters of the anther.

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.

A moderately repetitive DNA sequence in alfalfa is transcribed in a floral-specific manner.

Based on DNA sequence analysis of 5 clones of repetitive DNA from alfalfa (Medicago sativa), we propose the existence of a dispersed middle repetitive element about 3400 bp long with a copy number in the range of 2-3 x 10(3) per haploid genome. The average A+T content of the sequences was 54.6%, compared with 61.4% for the alfalfa genome. Sequence homologies between overlapping regions of the clones ranged from 85 to 89.5% with an average of 86.6%; sequence divergence was due largely to single base pair changes, with deletions or insertions occurring randomly across sequences. An open reading frame (ORF) in one clone, RPE15, contained homologies to cereal prolamin genes and a legumin box was located upstream of the coding region. A Northern blot of RNA from various alfalfa tissues, probed with the above clone containing this ORF, showed an extensive heterodispersed pattern of hybridization in the late stages of flower bud development but in no other tissues.

Cold Injury of Southern Blueberries as a Function of Germplasm and Season of Flower Bud Development

The relative tolerance of flower buds and flowers of southern highbush blueberry (Vaccinium spp.) to cold damage was compared to rabbiteye (Vaccinium ashei Reade) and highbush blueberry (Vaccinium corymbosum L.). For similar stages of floral bud development, southern highbush and highbush cultivars had less winter freeze and spring frost damage than rabbiteye cultivars. Cold damage increased linearly with stage of flower bud development. Small fruit were more sensitive to frost damage than open flowers. Rabbiteye blueberry flower buds formed during the fall growth flush were more hardy than buds formed during the spring growth flush, regardless of cultivar or stage of development.

Translocation of 14C, carbohydrate content and activity of the enzymes of sucrose metabolism in rose petals temperatures

Both export of 14C from the source leaves of roses (Rosa×hybrida cv. Golden Times) and import of 14C to the petals were reduced by plant exposure to low night temperature. However, the import was affected to a greater extent than the export. During all stages of flower bud development the concentration of reducing sugars in petals of roses grown at reduced night temperature was lower than in petals of plants grown at higher night temperature. There was no significant difference in starch content in response to the night temperature, and the content of starch decreased toward complete flower bud opening. The concentration of sucrose in flowers at the low night temperature remained low during all stages of flower bud development, while at the high night temperature the concentration of sucrose increased during flower bud development, reaching a peak at the stage when petals start to unfold. At both temperatures the concentration of sucrose declined at complete flower opening. The activity of sucrose synthase (EC 2.4.1.14) was inhibited by low temperature in young rose shoots more than in the petals, while the activity of acid invertase (EC 3.2.1.26) was affected similarly in both tissues by the temperature treatments.

Uptake and metabolism of benzyladenine in the early stage of flower bud development in vitro in tobacco

Benzyladenine (BA) was found to regulate the number of flower buds regenerated in vitro from pedicel tissue of tobacco. Flower bud induction was particularly sensitive to BA levels in the range of 0.45 to 1.0 μM, where a two‐fold increase in concentration caused a threefold rise in the number of buds. When tissues were fed radioactive BA for 24h, only 9–12% of the counts were recovered in the original compound. The rest was present in metabolites, tentatively identified as the mono‐, di‐ and triribotides, 7‐ and 9‐glucosides and 9‐riboside of BA. The amount of growth regulator taken up and the quantities of BA and its metabolites in the explants were all linearly related to the concentration of the medium. The internal BA concentration was ca 60% of the level in the medium after 24 h. When the concentration in the medium was raised, relatively more BA remained in the non‐conjugated form. However, this change in the equilibrium between BA and the conjugates is too small to account for the steep rise in the curve representing concentration vs effect between 0.45 and 1.0 μM.

Comparison of Flower Bud Initiation in Peach Cultivars in Northern and Southern Hemispheres

Abstract Buds of three peach clones (‘Diamante’, ‘Capdeboscq’, and Conserva 334) were sampled weekly during the summer in Clarksville, Ark. and Pelotas, RS, Brazil and classified according to their developmental stage. The percentage of buds at stage 3 (apex showing broadening and assuming a roundish shape) was calculated, and flower bud initiation was considered to be the date when at least 50% of the examined buds were at stage 3 or beyond. In Arkansas, flower bud initiation occurred in ‘Capdeboscq’ on 18 July and in ‘Diamante’ and Conserva 334 on 25 July. In Brazil, ‘Capdeboscq’ initiated flower buds on 30 Jan. and ‘Diamante’ and Conserva 334 on 23 Jan. By transforming dates to number of days from beginning of summer, a comparison was made between the two locations for three stages of flower bud development (broadening of the apex, onset of sepal formation, and sepal differentiation). No statistically significant difference was found between locations for time of occurrence of any of the developmental stages. The largest differences obtained were no greater than differences between years at the same location. Buds of ‘Diamante’ were notably variable in stage of development at the same collection date, with some in stages 3 and 4 and others in stage 6. The possible relationship between differential rate of flower bud development and avoidance of winter cold injury is discussed.

Apple Pandemis Control, Half-Inch Green Application, 1984

Abstract Insecticides were evaluated for control of overwintered apple pandemis larvae. Five-year-old trees on a semi-dwarf rootstock were used in this test. Treatments were applied with a handgun sprayer at 400 psi to the point of drip simulating a dilute application of approximately 400 gal per acre. Four single-tree replicates, each separated by an unsprayed tree, were used per treatment in a randomized complete block design. Treatments were applied on 6 Apr at the one-half inch green stage of flower bud development. Temperature at application was 50°F with a light wind (<5 mph). Pre-treatment counts of 5 fruit buds per tree provided an indication of relative infestation level in the orchard. Post-treatment evaluation was made on 17 Apr at "pink" stage of flower bud development. All flower buds on each tree were examined. The total number of buds, buds with feeding injury, and buds with live larvae were recorded. A moderate population of apple pandemis was present in the test orchard with about 5% of fruiting buds infested or showing signs of injury. Twenty five-leaf samples were collected from each tree on 12 Jul and 16 Aug, returned to the laboratory, brushed, and the number of mites recorded. Data are presented as average mites per leaf for the 2 sample periods.

Apple, Pre-Bloom Control of Pandemis Leafroller, 1985

Abstract Ten-year-old apple trees were sprayed with insecticides to evaluate their efficacy in controlling overwintering larvae of apple pandemis. Insecticides were applied as a dilute spray to the point of drip (approximately 400 gal per acre) using a handgun sprayer at 400-500 psi. All materials were combined with 1 gal of oil/A. The test experimental design was a randomized complete block with 5 single-tree replicates per treatment. Pre-treatment counts were made on Apr 10. Ten fruit buds from each tree were removed and returned to the laboratory for examination under a dissecting microscope. Numbers of larvae found were recorded. Treatments were applied on 10 Apr at half-inch green stage of flower bud development. Post-treatment counts were made on 18 Apr. Each tree was examined and the number of leafroller feeding sites and live larvae recorded.

Apple Pandemis Control, Pink Application, 1984

Abstract Insecticide treatments were evaluated for control of overwintered apple pandemis larvae in a 5-year-old orchard on a semi-dwarf rootstock located at the Tree Fruit Research Center. Treatments were applied with a handgun sprayer at 400 psi to the point of drip simulating a dilute spray of approximately 400 gal per acre. The experimental design was a randomized complete block with 4 single-tree replicates per treatment. Treatments were applied at pink stage of flower bud development on 17 Apr. Temperature at time of application was 50°F with a light breeze (<2 mph). No pretreatment counts were taken through a general inspection indicated that a high leafroller population was present (about 10% fruit buds infested). Posttreatment evaluation was made on 26 Apr when most king bloom had opened. All flower clusters on each tree were examined. The total number of flower clusters, clusters with feeding injury and clusters with live larvae were recorded. Mites were sampled on 11 Jul and 16 Aug. A 25-leaf sample was collected from each tree, returned to the laboratory, brushed, and number of mites counted. Data are presented as mean mites per leaf for the season.

冷蔵期間が促成ボタンの生育及び切花品質に及ぼす影響

The present study was undertaken to establish forcing system for tree paeony. First, the flower bud differentiation and development in tree paeony (Paeonia suffruticosa Ardr. cv.′Hanakisoi′) was observed, and secondly the effects of the duration of cold storage on the flowering time and quality of cut flowers of forced tree paeony were investigated.1. The differentiation of leaves had already finished and the differentiation of petals had begun on Aug. 27. Stamens in a few sample plants and pistils in the majority of sample plants were going to form on Sept 27 and Oct. 18 respectively.2. As the storage at 0°C was prolonged, the sprouting and flowering became earlier. However, the number of days and cumulative temperature from sprouting to flowering differed little with the duration of 3 cold storage within 5 to 7 weeks.3. The flowering percentage was highest after 5 week storage and lowest after 7-week storage.4. The weight of cut flower and the number of petals did not differ significantly with the storage duration. However, the flower diameter was increased and the leaf area decreased with shortening the duration of cold storage. And especially, the development of lower leaves tended to be suppressed.5. Cut flowers looked well-balanced and were superior in figure after the trees were chilled during 6 to 7 weeks.These results show that the stage of flower bud development before cold storage and the temperature and duration of cold storage have a great influence on the flowering time, flowering percentage and the quality of cut flowers of forced tree paeony.

EFFECT OF FLOWER BUD DEVELOPMENT IN CHRYSANTHEMUM ON VESICULAR‐ARBUSCULAR MYCORRHIZA FORMATION

SummaryRoots of single stem Chrysanthemum morifolium plants were inoculated with the vesicular‐arbuscular mycorrhizal (VAM) fungus, Glomus fasciculatus, at several stages of flower bud development. Compared to vegetative control plants, VAM formation was reduced during early stages of flower bud development, but not during later bud expansion. A decrease of reducing sugars and amino acids in root extracts during early bud development coincided with a decrease in root exudation of these compounds. These results suggest that reduction of VAM formation during early flower bud development resulted from a decrease in the availability and net leakage of metabolites necessary to sustain the mycorrhizal fungus during pre‐ and post‐infection.

Visual Monitoring Trap for Tarnished Plant Bug Adults on Apple1

Sticky-coated, non-ultraviolet-reflecting white rectangle traps (15 by 20 cm) hung from apple tree branches at ca. 70 cm above ground proved significantly more effective 10 detecting adult tarnished plant bugs(TPB), Lygus lineolaris (Palisot de Beauvois), than three other sampling methods: visual counts of adults on trees, limb jarring of adults onto a drop cloth, and net sweeps of ground cover vegetation. For 12 orchard situations in which no prebloom. insecticide treatments were applied, there were significant positive linear relationships between levels of TPB-injured fruit at harvest and cumulative trap capture levels through the tight-cluster (r2 = 0.736) and late-pink (r2 = 0.526) stages of flower bud development. If the economic injury level for TPB is considered to be 2.0% fruit damage, then our findings suggest a tentative action threshold of cumulative capture of 3.0 adults per trap through tight cluster or 4.4 adults per trap through late pink.

Effect of a Dormant Application of Surfactants on Bud Development and Disease Control in Selected Deciduous Fruit Plants1

Abstract Spray treatment a single dormant application of high concentrations of anionic (Triton CS7) and nonionic (Triton N57 and Triton X100) surfactants caused up to 5 days delay in bud break in apple (Malus domestica Borkh.), but had less effect on grape (Vitis spp.) and peach (Prunus persica (L.) Batsch) and none on pear (Pyrus spp.). Surfactants tended to extend the bud break period but were frequently lethal to buds, particularly at concentrations of 3% and 5% active ingredient. In field studies, surfactants delayed the early stages of flower bud development but not bloom of apple or peach and did not control apple scab caused by Venturia inaequalis (Cke.) wint. or powdery mildew caused by Podosphaera leucotricha (Ell & Ev.) Salm.

Soil Temperature Effects on Cyclamen Flowering1

Abstract Six-week treatment at a 13°C soil temperature initiated at the 4- and 6-leaf stages most effectively advanced flowering of Cyclamen persicum Mill. cvs. Mayer Reinweiss and Rosa von Zehlendorf-Tas. Stage of flower bud development immediately after treatment of 13°, 18.5, 24.0 and 29.5°C soil temperatures was more advanced, and mean flower bud number increased with each decrease of 5.5°C in soil temperature. At age 9 months, mean days to flower was lower and mean number of flowers per plant was higher with each decrease of 5.5°C in soil temperature. Plants treated at the 6-leaf stage flowered earlier and produced more flowers than those treated at the 4-leaf stage. The 9-month-old plants which had been treated at the 6-leaf stage were generally more advanced vegetatively than those treated at the 4-leaf stage, but the effect of soil temperature treatment on vegetative growth was negligible.