Hales Best Research Articles

Powdery mildew of chayote (Sechium edule) caused by Podosphaera xanthii race 2 in Brazil

AbstractThe causal agent of chayote (Sechium edule) powdery mildew (PM) was identified in Brazil. Microscopic examinations revealed hyaline and ovoid conidia, borne in chains and displaying distinctive extra‐vacuolar fibrosin bodies. Morphology agreed to the standard description of the anamorph of Podosphaera xanthii. To confirm this identification, genomic DNA was extracted from field isolates and used in PCR assays with ITS primers. Amplicons were Sanger‐sequenced and the nucleotide alignments of all isolates displayed identity levels above 97% with P. xanthii isolates in GenBank database. Phylogenetic analyses indicated only P. xanthii isolates as the PM‐inducing pathogens in chayote. Inoculation assays were performed using chayote, zucchini and a set of muskmelon differential cultigens for determination of the physiological races of P. xanthii. All chayote isolates were pathogenic to chayote and zucchini seedlings. Five isolates were also pathogenic to the muskmelon cultigens ‘Hale's Best Jumbo’, ‘Védrantais’, ‘PMR‐45’ and ‘Edisto 47’, whereas ‘PMR‐5’ was asymptomatic during the experimental period. The virulence profile of chayote‐infecting isolates allowed their classification as P. xanthii race 2. To the best of our knowledge, this is the first worldwide report of P. xanthii race 2 in chayote. This report has relevant epidemiological and disease management implications, allowing more sustainable chayote cultivation under tropical and subtropical conditions.

Melon Seedlings Phytomass under Poultry Litter Biochar Doses

The use of organic waste for the preparation of seedling substrates is an important environmental and economic option. In this perspective, substrates using biochar emerges as an alternative for seedling production due to their favorable physical and chemical characteristics. The present study aimed to evaluate the efficiency of doses of poultry litter biochar as a substrate constituent for the production and quality of the seedlings. The work was conducted in a semi protected environment, belonging to the Federal University of Campina Grande—UFCG. The statistical design used was completely randomized in a 6 × 2 factorial scheme, consisting of 6 doses of biochar (0, 4, 8, 12, 16 and 20 t∙ha−1) and two varieties of melon (Yellow and Hales Best Jumbo) with 4 repetitions totaling 48 experimental units. The fresh and dry plant phytomass mass (aerial, roots and total), root length and the quality of seedlings were evaluated. It was concluded that the addition of poultry litter biochar to the substrate was beneficial, promoting an increase in the analyzed seedling variables, being the ideal dose for good development of melon seedlings 12 t∙ha−1. The Yellow variety presented a better response than the Hales Best Jumbo to the charcoal application. Considering the advantages of the use of poultry litter biochar on the substrate composition, found in the present study, its utilization constitutes a viable alternative for the development of melon seedlings and for the environmental disposal of the poultry litter.

Yield and Characteristics of Melon Fruits under Different Fertilization Management and Soil Cover

Aims: To evaluate the 'Canary' and 'Hale's Best Jumbo' melon yield and fruit characteristics as a function of fertilization management and soil cover with mulch.
 Study Design: The design was a randomized complete block design in a 2x3x2 factorial scheme, with three replications and seven plants per plot.
 Place and Duration of Study: The experiment was conducted from June to September 2015, at the Center of Agrarian and Biodiversity Sciences of the Federal University of Cariri, located in the city of Crato, Cariri region, Brazil.
 Methodology: Two varieties of melon ('Canary' and 'Hale's Best Jumbo') were studied under three fertilization managements (mineral fertilization via soil, mineral fertilization via soil + organic fertilization and mineral fertilization via soil + foliar fertilization) with the presence or absence of soil cover with polyethylene mulch.
 Results: The use of mineral + organic fertilization and mineral + leaf fertilization promoted an increase in fruit mass and yield of approximately 3.93 t ha-1 (25.50%) and 4.64 t ha-1 (30%), respectively. Both melon cultivars presented the best responses grown on plastic mulch, with yield increases of 79.66% and 26.16% for 'Canary' and 'Hale's Best Jumbo', respectively. Moreover, the 'Hale's Best Jumbo' cultivar presented higher soluble solids contents than the 'Canary' melon, with an increase of 11.26% (0.76 ° Brix).
 Conclusion: The use of soil cover and additional fertilization (organic or foliar) in the cultivation of melon provides an increase in size, mass and productivity, while soil cover increases the soluble solids content in fruits.

Muskmelon Cultivar Attractiveness to Striped Cucumber Beetle and Susceptibility to Bacterial Wilt

Bacterial wilt of cucurbits, incited by Erwinia tracheiphila (E. F. Smith) and vectored by the striped cucumber beetle [Acalymma vittatum (F.)] (SCB), is a serious disease of muskmelon (Cucumis melo L.). Cultivars differ in attractiveness to SCB and susceptibility to bacterial wilt, but no cultivar resistant to bacterial wilt has been introduced. In 2015 and 2016, replicated field plots of eight cultivars were grown at Lafayette, Wanatah, and Vincennes, IN, to identify differences in attractiveness to SCB and susceptibility to bacterial wilt. ‘Savor’ had significantly more beetle activity than ‘Hales Best’, ‘Superstar’, and ‘Aphrodite’ in three of six site-years, and more than ‘Diplomat’, ‘Dream Dew’, ‘Athena’, and ‘Wrangler’ in two site-years. Beetle activity for ‘Athena’, ‘Superstar’, and ‘Wrangler’ did not differ significantly from ‘Aphrodite’ for any site-year. Bacterial wilt severity was significantly greater for ‘Diplomat’ and ‘Dream Dew’ than for other cultivars in four site-years. ‘Superstar’ had the least disease in five site-years, but significantly less than ‘Aphrodite’, ‘Athena’, and ‘Hales Best’ in only one site-year. At one site, additional plots of each cultivar were populated with five SCBs per plant, and rowcovers were applied to keep the SCBs near the plants for 3 weeks. This resulted in similar beetle activity on all cultivars, but most disease in ‘Dream Dew’ and least in ‘Superstar’ and ‘Athena’. Marketable yield was generally highest for ‘Aphrodite’, ‘Superstar’, and ‘Athena’ when plants were exposed to natural beetle populations. Overall, ‘Savor’ and ‘Diplomat’ were the most attractive to beetles, and ‘Diplomat’ and ‘Dream Dew’ were the most susceptible to bacterial wilt. ‘Aphrodite’, ‘Athena’, and ‘Superstar’ were less attractive to beetles and showed more tolerance to bacterial wilt in both 2015 and 2016.

Cetylpyridinium chloride direct spray treatments reduce Salmonella on cantaloupe rough surfaces.

Cetylpyridinium chloride (CPC) solutions (0, 0.5, or 1.0%) were applied to cantaloupe (“Athena” and “Hale's Best Jumbo” cultivars) rind plugs, either before or after inoculation with a broth culture of Salmonella Michigan (109 CFU/mL) and held at 37°C for 1 or 24 hr. Rind plugs were diluted, shaken, and sonicated, and solutions were enumerated. Texture quality and color were evaluated over 14 days storage at 4°C after 0 and 1% CPC spray applications. A 0.5 or 1.0% (vol/vol) application of CPC after Salmonella reduced the pathogen levels between 2.34 log CFU/mL and 5.16 log CFU/mL in comparison to the control (p < .01). No differences were observed in the firmness and color of 1% CPC treated cantaloupes. Salmonella concentrations on cantaloupes, treated with 1.0% CPC, were lower after 1 hr storage as compared to 24 hr. And, Salmonella on “Athena” surfaces were more susceptible to CPC spray treatments than on “Hale's Best Jumbo.”Practical applicationsCetylpyridinium chloride (CPC) is the active ingredient of some antiseptic oral mouth rinses, and has a broad antimicrobial spectrum with a rapid bactericidal effect on gram‐positive pathogens. The spray application of CPC solutions to cantaloupe may reduce the level of Salmonella surface contamination during production from irrigation water and manure fertilizers and, during food processing by contaminated equipment and food handlers. Since the surfaces of cantaloupes are highly rough or irregular, bacteria can easily attach to these surfaces and become difficult to remove. Appropriate postharvest washing and sanitizing procedures are needed that can help control Salmonella and other pathogens on melons, especially on cantaloupes with nested surfaces. A direct surface spray application of CPC may be an alternative antimicrobial postharvest treatment to reduce pathogen contamination of cantaloupe melons, while providing an alternative to chlorine‐based solutions.

Delmopinol hydrochloride reduces Salmonella on cantaloupe surfaces.

Since the surfaces of cantaloupes are highly rough or irregular, bacteria can easily attach and become difficult to remove. Appropriate postharvest washing and sanitizing procedures can help control Salmonella and other pathogens on cantaloupe or other melons during postharvest operations. Delmopinol hydrochloride (delmopinol) is a cationic surfactant that is effective for treating and preventing gingivitis and periodontitis. The application of delmopinol to two cantaloupe cultivars was evaluated for reducing the level of inoculated Salmonella. Athena and Hale's Best Jumbo (HBJ) cantaloupe rind plugs (2.5 cm. dia.) were inoculated with nalidixic acid‐resistant Salmonella Michigan (approx. 1.0 × 109 CFU/ml). After 15 min, rind plugs were sprayed with 10 ml of a delmopinol spray solution (0% or 1.0% vol/vol) and held at 35°C for 1 hr or 24 hr. Rind plugs were diluted with Butterfield's phosphate buffer, shaken and sonicated, and solutions were enumerated on 50 ppm nalidixic acid‐tryptic soy agar. The texture quality and color of additional cantaloupes were evaluated, after 1% delmopinol spray treatment, over 14‐day storage at 4°C. A 1.0% application of delmopinol after 1 hr reduced Salmonella concentration by ~3.1 log CFU/ml for both “HBJ” skin rind plugs and “Athena” stem scar rind plugs in comparison to the control (p < .05). No differences were observed in the texture and color (L*, a*, b* values) of 1% delmopinol‐treated cantaloupes as compared to control. Storage of cantaloupes treated with 1.0% delmopinol solution for 1 hr had a greater effect on reducing concentration of Salmonella compared to 24‐hr treatment. A surface spray application of 1% delmopinol on cantaloupes could be an alternative antimicrobial postharvest treatment that could make surface bacteria more susceptible to sanitizers or physical removal.

Caracterização morfológica qualitativa de progênies de meios irmãos de meloeiro

The melon is a vegetable much appreciated in the feeding of Brazilians, and this culture has two main botanical groups, Inodorus and Reticulatus, which have different characteristics that complement each other. The objective of this work was to carry out the qualitative morphological characterization of the progenies of half brothers of meloeiro. Were evaluated 100 progenies of half-brothers of melon, by crossing the varieties Amarelo Ouro x Hale's Best, belonging to the groups Valenciano (Inodorus) and American (Reticulatus), respectively. The data of the scales of notes were distributed in classes of relative frequency for each trait considered and the selection of the fruits with the desirable characteristics (fruit grid, grid distribution, ribs of the fruit, the fruit peduncle separation, pulp color, shape of the fruit, and the mature fruit color). The progenies of half brothers studied showed high variability of the characters, with 8.58% of fruits with the desirable characteristics.

Mathematical models to estimate leaf area of melon plant cultivar Hale’s Best Jumbo at different phenological stages using linear measurements

Melon plants cv. Hale's Best Jumbo Cantaloupe were cultivated under field conditions in Sinop - MT in order to develop mathematical models based on linear measurements which allow the estimation of leaves area. Were collected four times leaves, first collection at 20 days after sowing (DAS) with 45 leaves, second collection at 30 DAS with 40 leaves, third collection was performed 40 DAS with 40 leaves was performed 50 days with 33 sheets. 45 leaves in the first test at 30 days after sowing (DAS), 40 sheets in the 2nd collection at 40 DAS, 40 leaves on the 3rd collection at 50 DAS and 33 leaves on the 4th collection at 60 DAS. Linear measurements were taken along the length of leaf central vein (C) and the largest width (W) perpendicular to the central vein. At each time was determined leaf area (LA) using a LI-COR LI-3100 area integrator. The data length and width and and product of C by L were considered the independent variable (x) and real leaf area (AF) as dependent variable (y). Were performed linear regression analyzes for each of the seasons and the length and width of the sheet and the product CL. From the results it is concluded that: a) the length of the central rib does not allow to accurately estimate the leaf area of melon, b) the greatest width of the sheet provides a better estimative of leaf area, c) the phenological stage 3 provides the best estimate of the foliar area and d) the model that best estimates leaf area of melon is Y = 10.284 x - 16.404 value of r = 0.8627.

Resistance of melon cultivars to Bemisia tabaci biotype B

The silverleaf whitefly, Bemisia tabaci biotype B, is currently one of the most important pests of melon, causing direct and indirect damage to plants, and significantly reducing production in the field. Due to the need for alternative methods of chemical control in melon crops, the melon cultivars AF-646, AF-682, Don Luis, Frevo, Jangada, Nilo, Vereda, Amarelo Ouro and Hales Best were assessed at field, greenhouse, and laboratory trials for resistance to whitefly B. tabaci biotype B. In general, 'Hales Best' and 'Amarelo Ouro' were the most resistant, showing oviposition non-preference against whitefly. The trichome density is associated with the variation in oviposition on the cultivars and should be further investigated in future work. These results may be helpful in melon breeding programs, focusing on plant resistance to B. tabaci biotype B.

Phloem‐Mobile Aux/IAA Transcripts Target to the Root Tip and Modify Root ArchitectureF

In plants, the phloem is the component of the vascular system that delivers nutrients and transmits signals from mature leaves to developing sink tissues. Recent studies have identified proteins, mRNA, and small RNA within the phloem sap of several plant species. It is now of considerable interest to elucidate the biological functions of these potential long-distance signal agents, to further our understanding of how plants coordinate their developmental programs at the whole-plant level. In this study, we developed a strategy for the functional analysis of phloem-mobile mRNA by focusing on IAA transcripts, whose mobility has previously been reported in melon (Cucumis melo cv. Hale's Best Jumbo). Indoleacetic acid (IAA) proteins are key transcriptional regulators of auxin signaling, and are involved in a broad range of developmental processes including root development. We used a combination of vasculature-enriched sampling and hetero-grafting techniques to identify IAA18 and IAA28 as phloem-mobile transcripts in the model plant Arabidopsis thaliana. Micro-grafting experiments were used to confirm that these IAA transcripts, which are generated in vascular tissues of mature leaves, are then transported into the root system where they negatively regulate lateral root formation. Based on these findings, we present a model in which auxin distribution, in combination with phloem-mobile Aux/IAA transcripts, can determine the sites of auxin action.

Influence of genotype and explant source on thein vitroregeneration ability of different melon varieties

Nine genotypes of melon (Cucumis melo L.) were selected for the investigation of regeneration. Most of the tested varieties showed regeneration ability on medium containing 0.5 mg l⁻¹ or 1 mg l⁻¹ BA, but following the appearance of shoot buds, only six varieties produced leafy shoots. The effect of combinations of BA with different auxins (IAA, NA, 2,4-D) and ABA in the culture medium on shoot regeneration was tested on cotyledon explants of 'Hógolyó' and 'Hale's Best'. To establish optimal conditions for the adventitious shoot induction six types of seedling-derived explants were prepared from seedlings of four different ages. The best results for shoot forming capacity were achieved with cotyledons followed by decapitated seedlings and hypocotyls derived from 4-day-old seedlings. Cotyledon segments of 'Hógolyó' and 'Hale's Best' were also cultivated on media with different concentrations of IAA and BA supplemented with 0.26 mg l⁻¹ ABA. The highest number of well-formed plantlets was counted for 'Hógolyó' on the medium supplemented with 0.9 mg l⁻¹ BA+ 0.6 mg l⁻¹ IAA+ 0.26 mg l⁻¹ ABA. This is the first report on the in vitro regeneration of 'Hógolyó' from decapitated seedling and hypocotyl explants and of 'JavÍtott Zentai', 'Muskotály', 'Hógolyó', 'Tétényi csereshéjú' and 'Magyar Kincs' from cotyledon explants.

Detection of QTL for yield-related traits using recombinant inbred lines derived from exotic and elite US Western Shipping melon germplasm

The inheritance of yield-related traits in melon (Cucumis melo L.; 2n = 2x = 24) is poorly understood, and the mapping of quantitative trait loci (QTL) for such traits has not been reported. Therefore, a set of 81 recombinant inbred lines (RIL) was developed from a cross between the monoecious, highly branched line USDA 846-1 and a standard vining, andromonoecious cultivar, 'Top Mark'. The RIL, parental lines, and three control cultivars ('Esteem', 'Sol Dorado', and 'Hales Best Jumbo') were grown at Hancock, WI and El Centro, CA in 2002, and evaluated for primary branch number (PB), fruit number per plant (FN), fruit weight per plant (FW), average weight per fruit (AWF), and percentage of mature fruit per plot (PMF). A 190-point genetic map was constructed using 114 RAPD, 43 SSR, 32 AFLP markers, and one phenotypic trait. Fifteen linkage groups spanned 1,116 cM with a mean marker interval of 5.9 cM. A total of 37 QTL were detected in both locations (PB = 6, FN = 9, FW = 12, AWF = 5, and PMF = 5). QTL analyses revealed four location-independent factors for PB (pb1.1, pb1.2, pb2.3, and pb10.5), five for FN (fn1.1, fn1.2, fn1.3, fn2.4, and fn8.8), four for FW (fw5.8, fw6.10, fw8.11, and fw8.12), two for AWF (awf1.3 and awf8.5), and one for PMF (pmf10.4). The significant (P </= 0.05) positive phenotypic correlations observed among PB, FN, and FW, and negative phenotypic correlations between PB and AWF and between FN and AWF were consistent with the genomic locations and effects (negative vs. positive) of the QTL detected. Results indicate that genes resident in highly branched melon types have potential for increasing yield in US Western Shipping type germplasm via marker-assisted selection.

AGROBACTERIUM TUMEFACIENS-MEDIATED TRANSFORMATION AND REGENERATION OF MUSKMELON (CUCUMIS MELO L.)

Agrobacterium-based plasmid vectors allow the transformation of a wide range of plant species by capitalizing on anatural bacterial system to introduce DNA into the nucleargenome of plants. A regeneration protocol for muskmelon(Cucumis melo cv. Hales Best Jumbo) was established usingsegments of cotyledon as explants, and combined this protocolwith A. tumefaciens-mediated transformation to producetransgenic muskmelon plants. Cotyledon explants excised from 4-day-old seedlings of muskmelon and cut into four segments afterremoved the edges of the cotyledons, co-cultivated with A.tumefaciens strain LBA4404 harboring binary pRGG bar plasmid.The plasmid contained phosphinothricin acetyl transferase gene(bar) as selectable marker for herbicide resistance (glufosinatammonium, lindan) and β-glucuronidase gene (gusA) as reporterfor 20 min. Then, transferred to regeneration medium, MSmedium supplemented with different combinations of plantgrowth regulators (pH 5.0), and incubated in a growth room at25°C with a photoperiod of 16h light/8h dark for 3 days. Anovernight bacterial culture and low pH medium (5.0) used duringco-cultivation, to improve the transformation efficiency. For shootinduction, explants were transferred onto MS medium containeddifferent combinations of plant growth regulators with pH 5.8,and 500 mg/l claforan (cefotaximum) was added to the medium,to prevent the growth of Agrobacterium. The elimination of theAgrobacterium was the key of successful regeneration andtransformation after co-cultivation. After co-cultivation on MSmedium with a low pH, explants were transferred to selectivemedium, with higher pH 5.8, containing 500 mg/l claforan andglufosinat ammonium in concentrations ranged from 0 to10 mg/l(0, 1, 2, 3, 4, 5, 8 and 10 mg/l) to know the optimum selectiveconcentration during shoot formations. The results indicated that,MS medium supplemented with 1.05 mg/l indole-3-acetic acid(IAA)+0.6 mg/l 6-benzyladenine (BA)+0.24 mg/l abscisic acid(ABA) ranked the best in shoot formations. Shoots formed fromco-cultivated cotyledons with Agrobacterium died under theconditions of high concentration more than 3 mg/l glufosinatammonium. The medium was changed every two weeks till shootswere induced. All shoots rooted on MS medium supplementedwith 0.3 mg/l indole-3-butyric acid (IBA). The expression of theintroduced gene construct was confirmed by GUS staining ofcallus and shoot segments. Finally, transgenic muskmelon plantswere produced efficiently by inoculating pieces of cotyledons asexplants with A. tumefaciens strain LBA4404 harboring pRGG bar plasmid. The methods have been used to develop a moreefficient transformation and regeneration procedures by usefulgenes, such as herbicide-resistance, that can be introduced intomuskmelon by indirect insertion of such genes using the geneticengineering approach.

Occurrence of Podosphaera xanthii Race 2 on Cucumis melo in Brazil.

Powdery mildew is an important disease of melons (Cucumis melo L.) cultivated in greenhouses in Brazil. Currently, there are 5 races of Podosphaera xanthii (formerly known as Sphaerotheca fuliginea) and 2 races of Golovinomyces cichoracearum (formerly known as Erysiphe cichoracearum) described on melons worldwide, but only race 1 of P. xanthii has been reported in Brazil (1). However, typical whitish powdery fungal growth was observed on an experimental hybrid yellow melon resistant to race 1 of P. xanthii during the summer of 2000 in a greenhouse in Bragança Paulista, State of São Paulo. Conidia collected from diseased leaves were spread onto 0.5% water agar medium and maintained at 22°C for 24 h with 12 h of light and 12 h of darkness. Most of the germinated conidia displayed fibrosin inclusion bodies when observed in a solution of 3% potassium hydroxide (KOH), and approximately 1 of 50 also displayed forked germ tubes. These features allowed us to identify P. xanthii as the causal agent. Conidia raised on the susceptible yellow melon 'Amarelo CAC' were used to inoculate cotyledons of the differential melon lines (2) 'Hale's Best Jumbo' (susceptible to races 1, 2, and 3 of P. xanthii), 'PMR-45' (resistant to race 1 and susceptible to races 2 and 3), and 'PMR-6' (resistant to races 1 and 2 and susceptible to race 3). Inoculations were performed on 10 plants of each differential line and replicated four times. The presence or absence of symptoms was evaluated 18 days after inoculation. 'Hale's Best Jumbo' and 'PMR-45' were rated as susceptible while 'PMR-6' was rated as resistant, thus indicating the presence of race 2 of P. xanthii in Brazil. During field surveys from 2001 to 2003, this race was found on squash (Cucurbita moschata), summer squash (C. pepo), and melons in São Paulo.

Development of regeneration protocols for selected cucurbit cultivars

A shoot regeneration protocol was developed for five cultivars of theCucurbitaceae. The influence of the seed coat, an ethanol pre-treatment,different seed sources, NaOCl concentrations and treatment times ondecontamination were investigated. The effects of combinations of BA, kinetin,iP and TDZ with IAA in the culture medium on shoot regeneration of cotyledonaryexplants were tested. The cultivars Cucurbita maxima cv.A-line, C. maxima cv. Chicago Warted and C.pepo cv. Rolet, did not form shoots on any of the treatments.However, somatic embryos formed on C. maxima cv. ChicagoWarted explants. Cucumis melo cv. Hales Best 36 was highlyregenerable and shoots formed on all the treatments containing cytokinin. Theshoot regeneration response was significantly higher on BA-containing media thanwith the other cytokinins tested. Although Cucumis sativuscv. Ashley responded poorly, shoot development was observed on media containingBA or iP.

The Effects of Some Parameters on Agrobacterium-Mediated Transformation in Muskmelon

Some parameters involved in Agrobacterium-mediated transformation in muskmelon Hales best (HBS) were studied. Cotyledon explants excised from 3.5-day-old seedlings were co-cultivated with Agrobacterium tumefaciens harbouring binary vectors which contained GUS and BAR genes. After co-cultivation on a low pH medium, explants were transferred to selective medium, with higher pH, containing Claforan and Finale. The medium was changed every two weeks till shoots were induced. All shoots rooted on MS medium supplemented with 0.3 mg/L IBA. These parameters combined as a whole led to successful transformation. The expression of the introduced gene construct was confirmed by GUS staining of shoot segments.&#x0D;

Raffinose oligosaccharide concentrations measured in individual cell and tissue types in Cucumis melo L. leaves: implications for phloem loading.

Raffinose, stachyose, and galactinol are synthesized in intermediary cells (specialized companion cells) of the minor-vein phloem of cucurbits. To better understand the role of these carbohydrates and the regulation of their synthesis and transport, we measured the concentrations of each of the components of the raffinose oligosaccharide synthetic pathway in mesophyll and sieve element-intermediary cell complexes (SE-ICCs) in the leaves of melon (Cucumis melo L. cv. Hale's Best Jumbo). These concentrations are consistent with a polymer-trapping mechanism for phloem loading, with sucrose diffusing from mesophyll into intermediary cells and being made into raffinose and stachyose, which are too large to diffuse back to the mesophyll. To determine carbohydrate concentrations, we developed a method involving microdissected tissues. Blind endings of areoles, and mesophyll surrounding these veins, were separately removed from lyophilized leaf tissue. Carbohydrates were quantitated by high-performance liquid chromatography with pulsed amperometric detection. A small amount of mesophyll remained attached to the blind endings; the carbohydrate contribution of these cells to the vein sample was eliminated by subtraction, based on the amount of chlorophyll. Volumes of cells and subcellular compartments were calculated by morphometric analysis and were used to calculate carbohydrate concentrations. Assuming no subcellular compartmentation, the additive concentration of sugars in the SE-ICCs of minor veins is about 600 mM. Stachyose and raffinose concentrations are about 330 mM and 70 mM, respectively, in SE-ICCs; concentrations of these sugars are much lower in mesophyll (0.2 and 0.1 mM). This is consistent with the view that stachyose and raffinose are unable to pass through the plasmodesmata between intermediary cells and bundle-sheath cells. Sucrose levels appear to be higher in the SE-ICC (about 130mM) than in the mesophyll (about 10 mM), but if compartmentation is taken into account the gradient for sucrose is probably downhill from mesophyll to intermediary cells. Flux through plasmodesmata between the bundle sheath and intermediary cells was calculated and was found to be within the range of values of flux through plasmodesmata reported in the literature.

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.

Host Effects on Reproduction and Adult Longevity of Squash Bugs (Heteroptera: Coreidae)

Reproductive phases, fecundity, and adult longevity of the squash bug, Anasa tristis (De Geer), were determined under laboratory conditions at a constant temperature of 26.7°C for five cucurbit hosts. Squash bugs on muskmelon, Cucumis melo L. ‘Hales Best #36’, had the longest premating phase. The preoviposition phase was shorter and the oviposition phase was longer on two cultivars of Cucurbita pepo L., yellow straightneck ‘Hyrific’ squash and ‘Jack O'Lantern’ pumpkin, than on watermelon, Citrullus lanatus (Thunberg) Matsumura and Nakai ‘Crimson Sweet’, and muskmelon. Females had the longest postoviposition phase on watermelon. The highest fecundity was observed on pumpkin seedlings. Host type did not affect egg mass size, egg hatch, percent hatch, or egg development. Higher percentages of egg masses were oviposited on the abaxial leaf surface than other plant locations on all hosts. Male squash bugs lived longer on pumpkin, squash, and watermelon than on muskmelon and cucumber, Cucumis sativus L. ‘Poinsett’, whereas females lived longer on pumpkin than on squash, muskmelon, and cucumber. Males lived longer than females on pumpkin and squash. The different host effects on reproduction, fecundity, and longevity indicate that host type is important when developing control strategies for the squash bug.

Measuring Netted Muskmelon Maturity by Delayed Light Emission

ABSTRACTNetted muskmelon fruits of Hale's Best, Magnum 45 and Saticoy cultivars in 6 different maturity classes, from immature to mature were examined. Maturity class was based on days after anthesis. The melons were evaluated for differences in delayed light emission (DLE) measurements and physical and chemical properties that relate to maturity. DLE, firmness, and chlorophyll decreased with increasing maturity, whereas Hunter a and soluble solids increased. DLE correlated highly (r =−0.94) with a calculated maturity index, indicating that DLE could be used as a nondestructive technique for measuring the maturity of netted muskmelon.