Burpee Hybrid Research Articles

The effect of a microgravity (space) environment on the expression of expansins from the peg and root tissues of Cucumis sativus.

In young cucumber seedlings, the peg is a polar outgrowth of tissue that functions by snagging the seed coat, thereby freeing the cotyledons. The development of the peg is thought to be gravity-dependent and has become a model system for plant-gravity response. Peg development requires rapid cell expansion, a process thought to be catalyzed by alpha-expansins, and thus was a good system to identify expansins that were regulated by gravity. This study identified 7 new alpha-expansin cDNAs from cucumber seedlings (Cucumis sativus L. cv Burpee Hybrid II) and examined their expression patterns. Two alpha-expansins (CsExp3 and CsExp4) were more highly expressed in the peg and the root. Earlier reports stated that pegs tend not to form in the absence of gravity, so the expression levels were compared in the pegs of seedlings grown in space (STS-95), on a clinostat, and on earth (1 g). Pegs were observed to form at high frequency on clinostat and space-grown seedlings, yet on clinostats there was more than a 4-fold reduction in the expression of CsExp3 in the pegs of seedlings grown on clinostats vs. those grown at 1 g, while the CsExp4 gene appeared to be turned off (below detection limits). There were no detectable differences in expansin gene expression levels for the pegs of seedlings grown in space or in the orbiter environmental simulator (OES) (1 g) at NASA. The microgravity environment did not affect the expression of CsExp3 or CsExp4, and the clinostat did not simulate the microgravity environment well.

Somatic Embryogenesis versus Organogenesis in Cucumber: Developing a Laboratory Exercise

Fourteen commercial cucumber (Cucumis sativus L.) cultivars were screened on media designed to induce somatic embryogenesis and shoot organogenesis. Cotyledon explants from mature dry seeds and 7-day-old seedlings also were compared for responses. Seven cultivars (Burpless F1Hybrid, Burpee Hybrid II, Cross Country, Picklebush. Sweet Delight, Tasty Green, and Yard Long) responded best for individual regeneration ability. Within the somatic embryogeneais regeneration protocol, `Picklebush' responded better than most other cultivars, while `Burpless F1 Hybrid' responded best in shoot organogenesis. Also, within each type of regeneration, the developmental stage of the cotyledon explants appeared to influence regeneration ability.

COTYLEDON AGE VERSUS IN VlTRO REGENERATION POTENTIAL IN CUCUMBER (CUCUMIS SATIVUS L.)

Seed and seedling cotyledon explants from 14 cultivars were placed on 2 media types to induce organogenesis and somatic embryogenesis. Shoots or somatic embryos were counted to determine effects of cultivar, explant and regeneration type on overall regeneration success. Opposite explant preferences were observed for each regeneration type. In somatic embryogenesis, greater numbers of seedling cotyledons were able to respond, while in organogenesis, seed cotyledons responded in greatest numbers. However, within each cultivar, no explant preferences were observed (except in `Picklebush'). Four cultivars displayed a preference for the somatic embryogenesis regeneration protocol over organogenesis: `Burpee Hybrid II' and `Burpless F1 Hybrid' (fresh market types), and `Cross Country' and `Picklebush' (pickling types). The best individual regeneration rates were obtained with `Cross Country' and `Picklebush' - both for somatic embryogenesis.

Gravity-regulated formation of the peg in developing cucumber seedlings

It has been proposed that peg formation in the vascular transition region (TR zone) between the hypocotyl and the root in Cucurbitaceae seedlings is a gravimorphogenetic phenomenon. Initiation of the peg became visible 36 h after imbibition when cucumber (Cucumis sativus L. cv. Burpee Hybrid II) seeds were germinated in a horizontal position at 24 degrees C in the dark. Simultaneously, sedimented amyloplasts (putative statoliths) were apparent in the sheath cells surrounding the vascular strands, and in the cortical cells immediately adjacent to them, in the TR zone. In contrast, the other cortical cells, some of which were destined to develop into the peg, contained amyloplasts which were not sedimented. These results suggest that the graviperception mechanism for peg formation may be like that of statoliths in shoot gravitropism. By 48 h following imbibition, the cells of the TR zone still had sedimented amyloplasts but had lost their sensitivity to gravity, possibly because of their maturation.

Transferring Cucumber Mosaic Virus-White Leaf Strain Coat Protein Gene into Cucumis melo L. and Evaluating Transgenic Plants for Protection against Infections

A single regeneration procedure using cotyledon explants effectively regenerated five commercially grown muskmelon cultivars. This regeneration scheme was used to facilitate gene transfers using either Agrobacterium tumefaciens (using `Burpee Hybrid' and `Hales Best Jumbo') or microprojectile bombardment (using `Topmark') methods. In both cases, the transferred genes were from the T-DNA region of the binary vector plasmid pGA482GG/cp cucumber mosaic virus-white leaf strain (CMV-WL), which contains genes that encode neomycin phosphotransferase II (NPT II), β-glucuronidase (GUS), and the CMV-WL coat protein (CP). Explants treated with pGA482GG/cpCMV-WL regenerated shoots on Murashige and Skoog medium containing 4.4 μm 6-benzylaminopurine (BA), kanamycin (Km) at 150 mg·liter-1 and carbenicillin (Cb) at 500 mg·liter-1. Our comparison of A. tumefaciens- and microprojectile-mediated gene transfer procedures shows that both methods effectively produce nearly the same percentage of transgenic plants. R0 plants were first tested for GUS or NPT II expression, then the polymerase chain reaction (PCR) and other tests were used to verify the transfer of the NPT II, GUS, and CMV-WL CP genes. This analysis showed that plants transformed by A. tumefaciens contained all three genes, although co-transferring the genes into bombarded plants was not always successful. R1 plants were challenge inoculated with CMV-FNY, a destructive strain of CMV found in New York. Resistance levels varied according to the different transformed genotypes. Somaclonal variation was observed in a significant number of R0 transgenic plants. Flow cytometry analysis of leaf tissue revealed that a significant number of transgenic plants were tetraploid or mixoploid, whereas the commercial nontransformed cultivars were diploid. In a study of young, germinated cotyledons, however, a mixture of diploid, tetraploid, and octoploid cells were found at the shoot regeneration sites.

Purification and Characterization of Galactinol Synthase from Mature Zucchini Squash Leaves

Galactinol synthase catalyzes the first committed step in the biosynthesis of raffinose sugars. Previous attempts to purify the enzyme have proven difficult and have resulted in low quantities of unpurified enzyme. Galactinol synthase was purified 752-fold from mature zucchini (Cucurbita pepo L. cv Burpee Hybrid) leaves using sequential liquid chromatography on DE 52, Octyl-Sepharose CL-4B, and Sephacryl S-200. This isolation scheme resulted in an 18.6% recovery of the initial activity. The purified enzyme had a specific activity of 23.3 micromoles per minute per milligram protein, a pH optimum of 7.5, and the activity was enhanced by dithiothreitol and MnCl(2). The enzyme was only half as active with MgCl(2) as with MnCl(2). Na(+), K(+), and Ca(2+) cations had little effect on the enzyme activity, while Co(2+), Zn(2+), Cu(2+), and Fe(3+) cations were strongly inhibitory at 10 millimolar concentrations. Purified galactinol synthase bound specifically to the substrates myo-inositol and UDP-galactose (K(m) = 6.5 and 1.8 millimolar, respectively), while exhibiting little affinity for an alternative glycosyl donor (UDP-glucose) or inositol epimers (epi- and scyllo-). Ten millimolar concentrations of UMP, UDP, UTP, AMP, ADP, ATP, NAD(+), NADH, NADP(+), UDP-xylose, and UDP-mannose, or 20 millimolar sucrose, talose, galactose, glucose, xylose, and melibiose exhibited various degrees of inhibitory effects. Twenty millimolar stachyose, raffinose, fructose, and mannose, and 10 millimolar UDP-glucuronic acid and UDP-galacturonic acid had little or no effect on the enzyme activity. The purified galactinal synthase is a monomer of M(r) 42,000 with an isoelectric point of 4.1.

Conditioning Cucumbers for Quarantine Heat Treatments

Abstract Cucumber fruit (Cucumis sativus L. cv. Burpee Hybrid II) were more tolerant of hot water immersions (30 to 60 min at 45C or 30 to 50 min at 46C) after being conditioned at 32.5 ± 0.5C in air for 24 hr. This increased tolerance was associated with a significant decrease in surface pitting. Hot water-treated cucumbers held for 3 days at 24C after storage at 10C for 7 days were yellower than untreated fruit. Degreening was greatest for the 30-min immersion and decreased with increasing immersion times.

Conditioning Cucumbers to Increase Heat Resistance in the EFE System

ABSTRACTThe ethyiene‐forming enzyme system (EFE) in cucumber fruit (Cucumis sativus L. cv. Burpee Hybrid II) developed an increased tolerance to hot water immersions of 30 to 60 min at 45°C and 30 to 50 min at 46°C when conditioned at 32.5 ± 0.5°C in air for 24 hr. Thermodynamic analysis of the heat inactivation of the ethyiene‐forming enzyme (EFE) system in conditioned and unconditioned cucumbers showed: Increased D‐value in the heat resistant EFE of conditioned cucumbers; larger energies of activations and Q10 for conditioned cucumbers; larger entropy and enthalpy changes in conditioned cucumbers. The EFE system in conditioned cucumbers was in a more ordered state than in control cucumbers which was speculated to be due to the formation of hydrophobic bonds during conditioning thereby increasing the thermostability of the EFE system.

Yield and Yield Quality in Precocious Yellow Zucchini Cultivars

Abstract Two precocious yellow-fruited zucchinis (Cucurbita pepo L. cvs. Goldy and Gold Rush) and a green-fruited control, ‘Burpee Hybrid Zucchini9, were compared for yield and yield quality in a series of 6 trials conducted in Israel. Overall, ‘Goldy’ and ‘Burpee Hybrid Zucchini’ produced a similar number of fruits and yield of “Grade A’’ fruits, but ‘Gold Rush’ produced significantly less. Yield quality, expressed as the percentage of “Grade A” fruits, was higher in ‘Goldy’ and ‘Burpee Hybrid Zucchini’ than in ‘Gold Rush’. Off-color fruit production was the most important parameter which reduced yield quality in ‘Gold Rush’.

Influence of Mycorrhizal Fungi on the Mineral Nutrition and Yield of Onion in Saline Soil1

AbstractIn a number of studies, salt‐affected plants have been found to contain lower P concentrations than non‐salinized control plants. This study was performed to evaluate the ability of two vesicular‐arbuscular mycorrhizal fungi (VAM) to improve the yield and salt tolerance of onion (Allium cepa L. var. Burpee hybrid 5276) by facilitating P uptake from a saline soil. Onion was grown in a Delhi loamy sand soil (mixed, thermic Typic Xeropsamment) in the glasshouse under ambient light conditions. Plants infected with Glomus fasciculatus and G. monosporus VAM had higher bulb and total onion dry weights than nonmycorrhizal plants in P deficient soil at low (−0.06 MPa bars) irrigation water solute potential (Ψ3), intermediate (−0.20 MPa Ψ3), and high (−0.41 MPa). Plants infected with G. fasciculatus yielded significantly more than G. monosporus plants at low (Ψ3 = −0.06 MPa) and high (Ψ3 = −0.41 MPa) salinity; at Ψ3 = −0.20 MPa bars, yields were not significantly different for mycorrhizal plants. Mycorrhizal infection with both fungi tended to decrease linearly with increasing salinity, although it remained high (58 to 46%) even at high salinity. As salinity increased, nonmycorrhizal plants developed lower concentrations of P, Mg, and K in shoot tissues, K in bulb tissues, with lower total uptake (mg plant−1) of Ca, Mg, K, Zn, and Mn. Mycorrhizal onion had greater concentrations of P and K in shoot tissues, P in bulb tissues, and greater P, Ca, Mg, Na, K, Zn, and Fe total uptake than nonmycorrhizal plants at intermediate soil salinity. Tissues of mycorrhizal plants contained only 70 % as much Mn as nonmycorrhizal plants; high Zn and Fe concentrations were reduced in plant tissues at high salinity compared with intermediate and low salinity. Improved nutritional status of onion plants due to mycorrhizal fungi is at least partially responsible for increased plant growth under saline conditions, although other mechanisms may be involved.

Hybridization and fertility of hybrid derivatives of Solatium melongena L. and Solanum macrocarpon L.

Eleven genotypes of Solanum melongena L. and one genotype tentatively identified as Solanum macrocarpon were reciprocally intercrossed. Three patterns of the crossability were determined: a) reciprocally crossable, b) reciprocally non-crossable, and c) unidirectionally crossable. In toto 524 F1 interspecific hybrids were grown during one season under open pollination conditions in the field. A large proportion of the F1 hybrids produced seed set. The highest degree of seed set was recorded in the reciprocal F1 hybrid of S. melongena (cv. 'Burpee Hybrid') and S. macrocarpon (Acc. 21-73). In addition, a limited number of back-cross progeny have been produced. The germinating seeds produced an F2 generation of which some recombinants showed a considerably higher degree of fertility than the F1. This finding suggests the possibility of the transfer of genes for resistance to two-spotted spider mite from S. macrocarpon to S. melongena.

CALCIUM DEFICIENCY SYMPTOMS IN GREENHOUSE CUCUMBERS

In a sand culture experiment with seeded and seedless greenhouse cucumbers (Cucumis sativus L.), induced Ca deficiency over a range of nutrient Ca applications produced characteristic foliar and plant symptoms. Severe deficiency was associated with top leaf tissue levels of 0.20% Ca and less. Fruit symptoms were a proportionate stunting, center and stem-end constriction in Burpee hybrid, and a progressively darker green color in Sporu. Mild symptoms were difficult to recognize and could only be confirmed by tissue analysis, although it was not possible to determine an exact threshold value for incipient deficiency.

Occurrence of Gibberellin A3 in Parthenocarpic Apple Fruit

The gibberellins have been established as effective fruit setting agents (5). In 'the apple, where auxins are generadlly inactive, the giibberellins induce parthenocarpy and sustain fruit growth to maturity (2,6,10). This pronounced fruit-setting activity and the established observation -that asymmetric growth of apple fruit is related to incomplete seed development, has encouraged investigations on the relationship of endogenous seed gibberellins to fruit-set and growth. Gibiberellin-like activity ihas been demonstrated in endosperm (11) and GA4 and GA7 iden'tilfied in immature apple 'seed (8). The biosynthesis of gibberellins by 'seeds is viewed as a specific role of seeds in fruit-set of the apple (7). However, some cultivars of Malus are prone to produce seedless fruit after exposure to 'low temperature during the fruit-setting period. The presence of giibberellinlile substances in such parthenocarpic fruit is, herein, reported. Immature seedless apple fruits (Malus sylvestris Mill., selectiion New Jersey 12) developing subsequent to a severe 'frost, 4 days after full bloom, were -harvested (6-wk post-'bloom), frozen immedi;ately and stored at -30? until' used. Frozen fruits (6.9 kg) were immersed in 100 % acetone (7.6 -liters), then each fruit was halved to check for seedlessness (no seeds were found), homogenized 'in acetone and extracted twice by stirring under nitr-ogen for 24 hours at 2?. The filtrates were combined and concentrated to an aqueous solution (3.5,1iters, pH of 2.8) in vacuo. The pH of the filtrate was increased to 6.0 with 10 % KOH !(13) and centrifuged to remove proteins and other insoluble substances. The supernate was washed with n-hexane and adjusted to pH 2.0, stirred for 2 hours aifter aiddition of 70 g of activated charcoal and filtered. The charcoal was washed several times with distilled water and eluted with acetone. The eluate (acetone) was evaporated ito dryness, the residue (2.62 g) suispended in phosphate buffer (0.2 M, pH 6.2) and extracted with chloroform (9). The aqueous phase was adjusted ,to pH 2.5 with suilfuric acid and extracted with ethyl acetate. The chlorofom and ethyl aicetate extracts were dried over anhydrous sodium sulfate and evaporated to dryness yielding residues of 0.108 and 0.690 g, respectively. Tihese residues were taken ,up in ethanol and lanolin paste preparations of either fraction were found to induce parthenocarpy in tomato. The chloroform fraction was more active than the ethyl acetate fraction. Considerable quantities of inhibitors we-re present in the ethyl acetate fraction as was evidenced by injury of treated ovaries. Further puriification was aohieved by streaking the extracts on Whatman 3 MM paper (57 X 46 am) and developing with isopropanol :ammonium hydroxide:water (10:1:1 v/v). The chromatograms were cut transversely, at intervailis of 0.1 RF, and eluted with 80 % ethanod. The gi;bberellin aictivity of each eluate was assessed uising dwarf pea (9) (cv. Morse's Progress No. 9) and eticutmber seedling (4) (cv. Burpee Hybrid) assays. The chloroform fraction contained an active component(s) migrating to RF 0.4 to 0.7 and which was similar in activity and RF with authentic GA. treated tinder identical conditions (fig 1). A greater quantitative response was obtained from the chloroform than ethyl acetate fraction (approx 10-folld) in the dwarf pea assay. Little or no activity was observed for both fractions in the cucumber assay. Further purification was limited to the active component(s) of the chloroform fraction migrating to RF 0.4 to 0.7. The eluate was streaked on silica gel-G plates (E. Merck F-254, 250 p). Plates were developed with the lower phase of carbon tetrachloride :acetic acid :water (8:3 :5, v/v) plus 20 % ethyl acetate. The active component(s) did not migrate, thtus it was elluted from the origin with ethanol and rechromatographed tusing benzene: n-'butanol :acetic acid (70:25 :5 v/v) as the developing solvent. The active component(s) was identical to GA1 and/or GA3 with respect to RF (0.54) and color of filtorescence and differed in both respects 1 Michigan Agricultural Experiment Station Journal Article No. 4227.

Greenhouse cucumber nutrition a growth analysis study

The total nutrient absorption of a greenhouse cucumber plant, var. Burpee hybrid, has been determined and is equivalent to 408 kg of nitrogen, 92 kg of phosphorus, 550 kg of potassium, 237 kg of calcium and 57 kg of magnesium per hectare. These figures will form the basis for the estimation of a practical fertilizer schedule. Comparison of this crop with the greenhouse tomato shows that the cucumber is a more succulent plant and a more efficient producer of fruit. The anatomical distribution of nutrients throughout the various tissues is demonstrated and may be used as a guide in setting standards for diagnostic tissue tests.

The Effect of Potassium On the Rate of Development of the Root-Knot Nematodes Meloidogyne Incognita, M. Javanica and M. Hapla

Studies were made on the relationship between potassium nutrition of cucumber, Cucumis sativus, variety Burpee hybrid, and the development of the root-knot nematode Meloidogyne incognita (Kofoid & White), M. javanica (Treub), and M. hapla, Chitwood, in roots of this host plant. The rate of development of M. incognita was retarded at low levels of potassium and accelerated at high levels. Final populations of the nematode were increased significantly when excess potassium was available to the host plant. M. javanica and M. hapla were not influenced by potassium.

Reaction of Drosophila to Different Varieties of Tomatoes

Studies were conducted at Beltsville, Maryland, to determine whether varieties of tomatoes differ in attractiveness to Drosophila melanogaster Meig. adults. San Marzano and Pennheart were the least attractive and Rutgers was the most attractive. Other varieties compared were Grothen's Globe, Pritchard, Burpee Hybrid, Pan America, Greater Baltimore, Pearson, Garden State, Marglobe, Burpee Globe, Chesapeake, Stokesdale, and John Baer.

Chemical Induction of Male Sterility in Cucurbits

Male sterility in crop plants is receiving increased attention for its usefulness in the production of hybrid seed. A chemical method of inducing male sterility would have great merit in certain cucurbits where daily hand removal of staminate flowers on a large scale is economically prohibitive and the maintenance of naturally occurring sterile lines is extremely difficult. This primarily monoecious family presents a special challenge in that flower sex expression has been reportedly altered by chemical treatment (1-3). The chemical suppression of all male flowers in cucurbits would be a means of producing purely female plants. Preliminary studies were conducted in the greenhouse with cucumbers (Cucumis sativus, vars., National Pickling and Burpee Hybrid) and squash (Cucurbita pepo, var. Table Queen). By spraying young cucumber plants after 2 to 3 true leaves had formed with 100 ppm of a-naphthaleneacetic acid (NA) or 25 ppm of 2,3,5-triiodobenzoic acid, the ratios of staminate to pistillate flowers were reduced from approximately 23: 1 to 8: 1 in National Pickling and from 14: 1 to 2: 1 in Burpee Hybrid. Results were comparable to those reported by Laibach and Kribben (1), in which the decreases in ratios were accompanied by both an increase in the number of pistillate flowers and a decrease in the number of staminate flowers. NA (100 ppm) applied to Table Queen squash when the first true leaf had fully expanded resulted in an average decrease in staminate-pistillate flower ratio from 1.47: 1 to 0.4: 1, with occasional plants producing no staminate flowers. Subsequent field studies (1953) with Table Queen squash revealed that NA (100 ppm) applied as a spray when the seedlings had 1 to 2 true leaves and the treatment repeated 10 days later (4 to 5 true leaves) delayed the appearance of staminate flowers, and treated plants produced exclusively pistillate flowers for 8 days prior to the opening of any staminate flowers. During the fall, winter, and spring months (195354), additional chemicals, including maleic hydrazide (4), were evaluated. Table Queen squash (Stock No. D0421, Ferry-Morse Seed Co.) was used as the test plant (2) and was grown in the greenhouse at 68°F night temperature and a photoperiod of 16 hr. Such an environment normally favored the early production of staminate flowers followed by the presence of both staminate and pistilate types, as described by Nitsch et al. (2). A remarkable suppression of staminate flower buds was obtained with maleic hydrazide (MH); the selective inhibition was comparable to that reported by Moore (5) and Naylor (6) for maize. Several spray patterns successfully induced male sterility during the 3to 4-wk interval that each crop was allowed to flower in the greenhouse. Dipping or spraying the plants in a solution containing 250 or 350 ppm of MH when the first true leaf was expanding and followed by a second treatment when 4 to 5 true leaves had developed resulted in plants that produced the usual number (8 to 10) of pistillate flowers in normal spatial arrangement, with no staminate flowers. Characteristic flowering patterns following treatment showed only rudimentary staminate flower buds or bud initials at the nodes in which they normally occurred. In other instances nonfunctional staminate male flower buds developed in which the sepals were abnormally enlarged (Fig. 1B) and some flowers eventually opened, but the androecia failed to develop (Fig. 1D), having aborted in a manner similar to that of the male-sterile mutant in winter squash described by Scott and Riner (7). It was further found that a single application of MH (250, 350, or 500 ppm), applied when 1 to 2 true leaves had developed, resulted in a high percentage of plants that produced only pistillate flowers.