California Wonder Research Articles

Black Root Rot Caused by Thielaviopsis basicola on Lettuce in California.

In 2005 and 2006, field-grown iceberg lettuce (Lactuca sativa) in California's coastal Salinas Valley (Monterey County) was affected by a previously unreported disease. Symptoms were observed on iceberg lettuce at the post-thin rosette stage (8 to 12 leaves). Plants were stunted and slightly chlorotic. Fine feeder roots had numerous, small (4 to 8 mm long), elongated, dark brown-to-black lesions. Larger secondary roots and taproots lacked lesions. No vascular discoloration was present. Isolations from root lesions consistently resulted in gray fungal colonies that formed catenulate, cylindrical, thin-walled, hyaline endoconidia and catenulate, subrectangular, thick-walled, dark aleuriospores. The fungus was identified as Thielaviopsis basicola (2). Conidial suspensions (5.0 × 105) of eight isolates from iceberg lettuce were used for pathogenicity tests. Iceberg cv. Ponderosa and romaine cv. Winchester were grown for 3 weeks in soilless peat moss rooting mix. Roots of 20 plants per cultivar were washed free of the rooting mix and soaked in conidial suspensions for 5 min. Plants were repotted and grown in a greenhouse. Control plant roots were soaked in sterile distilled water (SDW). After 3 weeks, inoculated iceberg exhibited slight chlorosis in comparison with control plants. Feeder roots of all iceberg plants inoculated with the eight isolates exhibited numerous black lesions and T. basicola was reisolated from these roots. Romaine lettuce, however, did not show any foliar symptoms. Small segments of roots had tan-to-light brown discoloration and T. basicola was occasionally reisolated (approximately 40% recovery). Roots of control iceberg and romaine showed no symptoms. Results were similar when this experiment was repeated. To explore the host range of T. basicola recovered from lettuce, two isolates were prepared and inoculated as described above onto 12 plants each of the following: iceberg lettuce (cv. Ponderosa), bean (cv. Blue Lake), broccoli (cv. Patriot), carrot (cv. Long Imperator #58), celery (cv. Conquistador), cotton (cv. Phy-72 Acala), cucumber (cv. Marketmore 76), green bunching onion (cv. Evergreen Bunching), parsley (cv. Moss Curled), pepper (cv. California Wonder 300 TMR), radish (cv. Champion), spinach (cvs. Bolero and Bossanova), and tomato (cv. Beefsteak). Control plant roots of all cultivars were soaked in SDW. After 4 weeks, only lettuce and bean roots had extensive brown-to-black lesions, from which the pathogen was consistently resiolated. Roots of cotton, pepper, spinach, and tomato had sections of light brown-to-orange discoloration; the pathogen was not consistently recovered from these sections. All other species and the control plants were symptomless. This experiment was repeated with similar results except that inoculated peppers were distinctly stunted compared with control plants. To my knowledge, this is the first report of black root rot caused by T. basicola on lettuce in California. Disease was limited to patches along edges of iceberg lettuce fields; disease incidence in these discrete patches reached as high as 35%. Affected plants continued to grow but remained stunted in relation to unaffected plants and were not harvested. Black root rot of lettuce has been reported in Australia (1); that report also showed that lettuce cultivars vary in susceptibility to T. basicola and isolates from lettuce were highly aggressive on bean but not on many other reported hosts of this pathogen.

DERİM SONRASI SICAK SU UYGULAMALARININ CALIFORNIA WONDER TİPİ BİBER MUHAFAZASI ÜZERİNE ETKİLERİ

In this study, the effects of hot water dip treatments on the storage of California Wonder type peppers grown in greenhouse in Antalya, were investigated. In the experiment, California Wonder type peppers were dipped into hot water at 48 and 53°C for 3 minutes. After hot water dip treatments all peppers were stored at 8°C with 90-92 % relative humidity for 32 days. During the storage period, various chemical and physical analyses, weight loss, soluble solids, titretable acidity and fruit color changes were performed on the fruit by taking from cold storage at 8 days intervals. The results showed that dipping of peppers into hot water at 48 °C for 3 minutes were positively effected on controlling decays.

Effect of organic manures and integrated nutrient management on yield potential of bell pepper (Capsicum annuum) varieties and on soil properties

A field experiment was conducted during the summer season of 2005 and 2006 at Almora (Indian Himalayas) to evaluate the comparative performance of five varieties of bell pepper (Capsicum annuum L.) and changes in soil properties under organic and integrated nutrient management (INM) systems. The number of fruits plant−1 and fruit yield was significantly higher under INM compared with organic nutrient supply. The yield reduction in the latter was 22.1% in 2005 and 21.7% in 2006 compared with INM. Among the bell pepper varieties, ‘US Agri 181’ produced significantly higher fruit yield (25.42 mg ha−1 in 2005 and 28.82 mg ha−1 in 2006) compared with other varieties. The soil pH, organic carbon, and microbial activities in terms of urease, dehydrogenase and alkaline phosphatase were higher in the plots treated with organic manures alone compared to INM. The latter, however, recorded higher N, P, and K contents in soil. The gross margin and benefit:cost (B:C) ratio were higher under INM compared with organic nutrient supply. ‘US Agri 181’ gave the highest net returns followed by ‘Aishwarya’ and ‘California Wonder’. However, the latter recorded the highest B:C ratio (9.2) compared with other varieties. We conclude that at least 25–50% price premium for organic bell pepper may be required to offset the higher cost of cultivation and low yields under organic production system. Among the bell pepper varieties, ‘US Agri 181’ was the best variety as it yielded highest followed by ‘Aishwarya’.

Osmotic versus toxic effects of NaCl on pepper plants

Water relations, mineral composition, growth and root morphology were studied in pepper plants (Capsicum annuum L. cv California Wonder). Two NaCl concentrations (30 and 60 mM) and two nutrient solutions in which the concentrations of macronutrients were increased were used to assess the ionic and osmotic effects of NaCl in these plants. The hydraulic conductivity (Lo), stomatal conductance (gs), percentage of open stomata and pressure potential (Ψp) decreased with all treatments, in a similar way for 30 mM NaCl and for its iso-osmotic solution of macronutrients, however, the decrease was higher for 60 mM NaCl than for its iso-osmotic solution. Ion analyses also revealed that nutrient concentrations were altered greatly at 60 mM NaCl. Also, changes in morphology, such as increases in cortex cell size and in intercellular spaces, were detected. Therefore, at low salinity, the effect of NaCl was mainly osmotic, however, under higher salinity also the toxicity of Na+ and Cl− participate.

Differentiation in two populations of Meloidogyne incognita from Greece in relation to reproduction on resistant tomato and pepper

The reproduction of two Meloidogyne incognita populations from Crete, Greece was assessed on ten pepper cultivars in pots in controlled conditions. One was virulent on the Mi gene of resistant tomato and was unable to reproduce on pepper while the other was avirulent on the Mi gene and produced galls and egg masses in all pepper cultivars. It has been previously reported by other researchers that various isolates of M. incognita virulent on the Mi gene (selected or natural) have a zero or decreased reproduction on the nematode susceptible peppers California Wonder and Doux Longdes Landes. This observation is confirmed in our study with a population of M. incognita from Crete on commercially grown pepper cultivars.

Three-Year Comparison of the Content of Antioxidant Microconstituents and Several Quality Characteristics in Organic and Conventionally Managed Tomatoes and Bell Peppers

Understanding how the environment and production and cultivation practices influence the composition and quality of food crops is fundamental to the production of high-quality nutritious foods. In this 3-year study, total phenolics, percent soluble solids, ascorbic acid, and the flavonoid aglycones quercetin, kaempferol, and luteolin were measured in two varieties of tomato (Lycopersicon esculentum L. cv. Ropreco and Burbank) and two varieties of bell peppers (Capsicum annuum L. cv. California Wonder and Excalibur) grown by certified organic and conventional practices in a model system. Significantly higher levels of percent soluble solids (17%), quercetin (30%), kaempferol (17%), and ascorbic acid (26%) were found in Burbank tomatoes (fresh weight basis; FWB), whereas only levels of percent soluble solids (10%) and kaempferol (20%) were significantly higher in organic Ropreco tomatoes (FWB). Year-to-year variability was significant, and high values from 2003 influenced the 3-year average value of quercetin reported for organic Burbank tomatoes. Burbank tomatoes generally had higher levels of quercetin, kaempferol, total phenolics, and ascorbic acid as compared to Ropreco tomatoes. Bell peppers were influenced less by environment and did not display cropping system differences.

Performance of Bell Pepper Cultivars in a Commercial Field Infested with Phytophthora capsici

Phytophthora blight, caused by Phytophthora capsici, is a widespread problem of many vegetables including bell peppers. Four bell pepper cultivars marketed as resistant/tolerant to P. capsici include `Paladin' (resistant), `Alliance' (tolerant), `Aristotle X3R' (tolerant), and `Revolution' (tolerant). These cultivars, along with four other widely grown cultivars (`Commandant', `King Arthur', `Legionnaire', and `Red Knight X3R') and a susceptible control (`California Wonder'), were evaluated for their performance in a commercial field highly infested with P. capsici. `Paladin' had the lowest incidence of Phytophthora blight and the greatest yield compared to all other cultivars. `Alliance', `Aristotle X3R', and `Revolution' (the tolerant cultivars) also had lower Phytophthora blight incidence and greater yields compared to the other five cultivars evaluated. Results indicated that in fields that historically have high incidence of Phytophthora blight, `Paladin' could be a reliable choice for commercial production.

Boron Nutrition of Four Sweet Pepper Cultivars Grown in Boron-Deficient Soil

ABSTRACT In a greenhouse study, boron (B) application significantly increased dry-matter yield of sweet pepper (Capsicum annum L.) cultivars (‘California Wonder,’ ‘Anahein,’ ‘Narwala,’ and ‘2573’) grown in a B-deficient (hot-water extractable, 0.28 B mg kg−1), calcareous soil of the Shujabad series (Typic Ustochrepts). Five rates of B, ranging from 0 to 8 mg B kg−1 soil, were applied as H3BO3 along with adequate basal fertilization of nitrogen (N), phosphorus (P), potassium (K), and zinc (Zn). Four plants of sweet pepper were transplanted in each pot, two of which were harvested after three weeks of transplanting and the other two after six weeks. Maximum crop biomass was produced with ∼1 mg B kg−1, but application of higher rates proved toxic, resulting in dry-matter yield reductions. The four cultivars significantly differed in relative growth rate (RGR) and relative accumulation rate of B (RARB). Cultivar ‘2573’ showed the highest RGR while ‘Anahein’ showed the highest RARB. Relative accumulation rate was positively correlated (R2 = 0.83) with dry-matter yield of four cultivars. Critical B concentration in sweet pepper whole shoots was 69 mg B kg−1 for three-week-old plants and 49 mg B kg−1 for six-week-old plants.

Potential for utilization of pepper germplasm with a variable reaction to Sclerotium rolfsii Sacc. to develop southern blight-resistant pepper (Capsicum annuum L.) cultivars

The bell-type pepper cultivar Golden California Wonder, a source of resistance to southern blight, was crossed with the susceptible cultivar Sweet Banana. The F1, F2 and backcross progenies of this cross and the parental lines were evaluated in an inoculated field study for their reactions to Sclerotium rolfsii Sacc. A categorical rating system was used to rate plants for severity of wilting and severity of stem-lesion development. The plants within all three non-segregating populations (the resistant parent, the susceptible parent and the F1) displayed a range of reactions to S. rolfsii. Variable reactions to S. rolfsii among homogeneous pepper populations were expected because this phenomenon is well documented in the literature and we had observed similar responses in field trials conducted over multiple years. The high level of variation for reactions to S. rolfsii exhibited by the parental and F1 hybrid populations and the categorical system of rating individual plants placed severe limitations on the effective use of any quantitative type of analysis. Accordingly, a weighting procedure was used to correct the F2 and backcross populations based on frequencies of apparent mis-classifications in the parental and F1 populations. Examination of the comparative frequency distributions of the parental and progeny populations and examination of the weighted segregation data suggest that the southern blight resistance in ‘Golden California Wonder’ is conditioned by a single recessive gene. The level of resistance conditioned by this reputed recessive gene appears high enough to recommend it for use in pepper breeding programmes.

Comparison of mild extraction procedures for determination of plant-available arsenic compounds in soil

In this work three mild extraction agents for determination of plant-available fractions of elements in soil were evaluated for arsenic speciation in soil samples. Pepper (Capsicum annum, L.) var. California Wonder was cultivated in pots, and aqueous solutions of arsenite, arsenate, methylarsonic acid, and dimethylarsinic acid, at a concentration of 15 mg As kg(-1) soil, were added at the beginning of the experiment. Control pots (untreated) were also included. Deionized water, 0.01 mol L(-1) CaCl2, and 0.05 mol L(-1) (NH4)2SO4 were used to extract the plant-available fraction of the arsenic compounds in soil samples collected during the vegetation period of the plants. Whereas in control samples the extractable arsenic fraction did not exceed 1% of total arsenic content, soil amendment by arsenic compounds resulted in extraction of larger amounts, which varied between 1.4 and 8.1% of total arsenic content, depending on soil treatment and on the extracting agent applied. Among arsenic compounds determined by HPLC-ICPMS arsenate was predominant, followed by small amounts of arsenite, methylarsonic acid, and dimethylarsinic acid, depending on the individual soil treatment. In all the experiments in which methylarsonic acid was added to the soil methylarsonous acid was detected in the extracts, suggesting that the soil bacteria are capable of reducing methylarsonic acid before a further methylation occurs. No significant differences were observed between analytical data obtained by using different extraction procedures.

Impact of drip and surface irrigation on growth, yield and WUE of capsicum ( Capsicum annum L.)

A study was conducted to understand the effect of different irrigation methods and schedules on morphological, biophysical, yield and water use efficiency (WUE) of capsicum ( Capsicum annum L.) var. California Wonder. The plants grown under drip irrigation had more number of branches and plant heights compared to that of surface irrigated plants. The total yield was less at lower levels of irrigation. Above ground matter that included stem and leaf dry weight had positive correlation with yield under drip (0.992 ∗∗) and surface irrigation (0.926 ∗∗). The carbon dioxide exchange rates varied considerably under different methods of irrigation due to difference in irrigation timings and quantity of water applied. A shift in photosynthetic mechanism was observed in plants under IW/CPE 1.0 treatment. The relationship of WUE and net photosynthesis was also studied. The yield was found to have significant positive correlation with total dry matter (TDM, 0.865 ∗∗) and net photosynthesis (0.840 ∗∗). Any factor that could bring in a change in net photosynthesis and TDM may cause variation in yield in capsicum. Root mass was more in surface irrigated crop where as total root length was more in drip irrigated crop. As the quantity of water applied increased the root finesses decreased. Thus drip irrigation at 100% CPE is beneficial for capsicum plant in terms of yield, better plant morphological characters, viz. plant height number of branches, root finesses and root length, etc.

A New Begomovirus Species Causing Tomato Leaf Curl Disease in Varanasi, India.

In November 2001, a leaf curl disease of tomato, manifested by yellowing of leaf lamina, upward leaf curling, leaf distortion, shrinking of leaf surface, and stunted plant growth was observed in tomato-growing areas in the Varanasi and Mirzapur districts of eastern Uttar Pradesh, India, which caused yield losses up to 100%. The causal agent was infective to tomato cv. Punjab Chuhara by whiteflies and grafting. Inoculated plants developed symptoms observed in naturally infected tomatoes. Viral DNA was isolated from artificially inoculated tomato plants using 1% CTAB (2) followed by a concentration of supercoiled DNA by alkaline denaturation (1). A geminivirus was confirmed by polymerase chain reaction using DNA-A degenerate primers (3), and a 550-bp amplified product was obtained from artificially and naturally infected plants. Full-length viral genomes of DNA-A and DNA-B were cloned in plasmid pUC18 at HindIII and XbaI sites, respectively. Partial tandem dimers of the viral clones were infective to Nicotiana benthamiana and tomato cv. Organ Spring through particle bombardment. Infected N. benthamiana plants exhibited downward and upward leaf curling, big veins, leaf puckering with interveinal chlorosis, and stunting. On tomato, symptoms were the same as those seen on naturally infected plants. Cloned DNA also infected Capsicum annuum cv. California Wonder (upward leaf curling and stunting) and tobacco cv. Xanthi (leaf curling and crinkling) but failed to infect Phaseolus vulgaris, okra, cotton, and N. glutinosa. The Varanasi isolate was sap transmissible (0.1 M potassium phosphate buffer, pH 7.0) from the bombarded plants to N. benthamiana and tomato cv. Organ Spring. DNA-A alone infected N. benthamiana (upward leaf curling and big veins) and tomato cv. Organ Spring (mild leaf curl), but symptoms were delayed and milder. Full-length genome sequencing revealed DNA-A (AY190290) contained 2,757 nt and DNA-B (AY190291) contained 2,688 nt. DNA-A of the Varanasi isolate shares 98.4% identity with a DNA-A sequence (AF449999) obtained from a tomato showing leaf curl symptoms from the same region and 97.1% identity with an isolate from Gujarat (900 km from Varanasi). All three sequences represent isolates of the same species, herein called Tomato leaf curl Gujarat virus, based on the priority of submission of the DNA sequence for the Gujarat region (ToLCGV; AF 413671). All isolates noted were obtained from GenBank. However, except for the DNA-A sequence, no other information is available for these ToLCGV isolates. DNA-A of the ToLCGV-Varanasi isolate shares 66.8% identity with Tomato leaf curl New Delhi virus, severe strain (ToLCNdV-Svr) (U15015), and 84.1% with Tomato leaf curl Karnataka virus (U38239). No DNA-B has been reported for these two ToLCGV isolates, and no infectious clone proving the etiology of the disease has been constructed, except for ToLCGV-Varanasi. DNA-B of ToLCGV-Varanasi shares 79.2% homology with ToLCNdV-Svr and 84.1% with ToLCNdV-Luc (X89653). These results suggest that the isolate from Varanasi belongs to ToLCGV, a previously undescribed geminivirus species causing a devastating tomato leaf curl disease in Gujarat and Uttar Pradesh.

トウガラシ果実のフェノール，フラボノイドおよびカプサイシノイド含量の品種間差異

Immature and ripe fruits of Japanese hot and sweet peppers were analyzed for total phenolic, flavonoid and capsaicinoid contents. The results showing varietal differences are summarized as follows. The amount of phenolic compounds was higher in hot and ripe pepper fruits than in sweet and immature pepper fruits. There was no difference in quercetin content between hot and sweet peppers during fruit growing. The contents were rather high in 'Hirosaki Zairai', 'Tochigi Santaka' and 'Yatsufusa' hot peppers and in 'Green 300' sweet peppers; the quercetin content of 'California Wonder' and 'Wonder Bell' was markedly low. In all varieties examined, the luteolin content was higher than that of quercetin content, more in hot peppers than in sweet peppers, except in 'Sapporo Ohnaga'. Luteolin content in immature fruits was higher than that in ripe fruits; a reverse relationship occurred in 'Wonder Bell'. Capsaicinoids, that were only detected in hot peppers was highest in immature 'Yatsufusa' and ripe 'Kagawa Hontaka' fruits. Our data reveal that the total phenolics content is a good indicator of the anti-oxidant activity of pepper fruits, and that the anti-oxidant levels in sweet peppers, especially in the ripe fruits of 'Fushimi Amanaga' and 'Wonder Bell' are higher than they are in hot peppers.

A Cultivar by Any Other Name: Genetic Variability in Heirloom Bell Pepper 'California Wonder'

Random amplified polymorphic DNA (RAPD) analysis can provide a means of evaluating and comparing genetic variability within cultivars. The purpose of this study was to evaluate the relative genetic variability between accessions of two open-pollinated bell pepper cultivars: 'California Wonder', an heirloom cultivar, and 'Jupiter', a modern cultivar. RAPD molecular markers were used to assess the genetic variability between accessions of these two cultivars. The high levels of genetic variability found among accessions of 'California Wonder' may preclude its use as a standard cultivar in research.

Factors important for somatic embryogenesis in zygotic embryo explants ofCapsicum annuum L.

We used four cultivars ofCapsicum annuum L.—Sweet Banana, California Wonder, Yolo Wonder, and Ace—to reexamine the critical factors influencing somatic embryogenesis from zygotic embryo explants, as reported in the literature. When we followed the protocol of Buyukalaca and Mavituna (1996), which had induced somatic embryogenesis from mature zygotic embryos of cv. Ace, only callus was formed without embryogenesis from our mature zygotic embryo expiants. Using the procedures of Harini and Lakshmi Sita (1993) and Binzel et al. (1996), with some modifications, we were able to induce somatic embryogenesis in all four cultivars. Rates of conversion were significantly reduced, from 75% and 65% to 40% and 28% in ’Sweet Banana’ and ’California Wonder’, respectively, when the immature zygotic embryo expiants were held on the induction medium for longer than two weeks. Likewise, somatic embryogenesis of ’Yolo Wonder’ was not observed if the induction medium was supplemented with 10% glucose or fructose, or without 10% sucrose. For somatic embryo induction and eventual plantlet conversion in Yolo Wonder’, maltose could adequately replace sucrose. In all four cultivars, somatic embryos were initiated from immature zygotic explants on media with or without coconut water, under both light and dark conditions.

EFFECTS OF SUPPLEMENTARY POTASSIUM AND PHOSPHORUS ON PHYSIOLOGICAL DEVELOPMENT AND MINERAL NUTRITION OF CUCUMBER AND PEPPER CULTIVARS GROWN AT HIGH SALINITY (NaCl)

Two cucumber (Cucumis sativus) cultivars, Seraset F1 and Rabina F1, and two pepper (Capsicum annuum) cultivars, California Wonder and Charliston 52, were grown hydroponically for six weeks to investigate the effectiveness of supplementary potassium (K) and phosphorus (P) applied to the root zone of plants grown at high (60 mM) NaCl concentration. Treatments used in this experiment were (i) control: nutrient solution alone, (ii) high salt: nutrient solution plus 60 mM NaCl, and (iii) high salt with supplementary P and K: nutrient solution plus 60 mM NaCl, 1 mM KH2PO4, and 2 mM K2SO4. Supplementary 1 mM KH2PO4 and 2 mM K2SO4 was added to nutrient solution for four weeks. Plants grown at high salt produced less dry matter and chlorophyll than those in normal nutrient solution for both cucumber and pepper cultivars. Reductions in both dry matter and chlorophyll concentrations were greater for pepper than cucumber. Supplementary K and P restored dry matter and chlorophyll concentrations for both species to levels similar to the control. Membrane permeability increased with high salt application and these increases were greater for pepper. Supplementary K and P restored membrane permeability in both species to levels similar to the control. Plant daily water use was decreased by high salt but it was restored with supplementary K and P to levels similar to the control. Sodium (Na) concentration in plant tissues increased for both species in the high salt treatment. Concentrations of P and K were in the deficient range in the plants grown at high salt and supplementary K and P application corrected these deficiencies.

Bacterial stem and peduncle canker of greenhouse pepper

Disease losses to Erwinia carotovora subsp. carotovora were 12 and 20% in 1996 and 1998, respectively, in greenhouse peppers (Capsicum annuum) at St. David's, Ontario. The disease was also observed on field peppers near Harrow in 1996–1997. Symptoms consisted of dark brown to black cankers on the stem nodes and fruit peduncles, dark discolouration of the internal stem tissue, and internal breakdown of the pith with stem hollowness in some cases. Extensive physiological and biochemical tests were conducted on all isolates recovered to verify identity. Reactions of greenhouse and field strains were generally similar with a few exceptions. Spraying, spraying + wounding or rubbing, and stem inoculation were conducted with selected isolates. 'Early California Wonder' pepper plants that were wounded and then sprayed with a bacterial suspension consistently showed extensive collapse of stems and death of plants 4 days later regardless of isolate used. 'Trust' tomato plants (Lycopersicon esculentum) showed a similar response or, in some cases, developed an internal brown stem discolouration and hollowness. Spraying or spraying + rubbing of leaves with isolates also caused extensive disease development but fewer plants were affected. Greenhouse and field isolates caused similar symptoms on both tomatoes and peppers. This is the first report of bacterial stem canker on greenhouse peppers in Canada.

DEVELOPMENT OF DNA MARKERS LINKED TO BACTERIAL LEAF SPOT RESISTANCE OF CHILLI

Bacterial leaf spot disease (Xanthomonas campestris pv. vesicatoria; Xcv) causes severe damage to chilli (Capsicum annuum L.) and has been a major yield constraint. An introduced chilli accession 3-25-27 derived from Florida XVR 3-25 has a dominant gene, Bs2, which confers resistance to Xcv races 1, 2 and 3. To identify RAPD markers linked to Bs2, bulked segregant analysis (BSA) and random amplified polymorphic DNA (RAPD) analysis were performed. Isogenic DNA pools were made from 10 resistant and 10 susceptible plants in a BC 1 F 1 population derived from crosses between 3-25-27 and Early California Wonder. Two RAPD markers, OPD05 and OPF10, were identified from a total of 460 10-basepair primers. From the linkage analysis it was found that two markers were located on either side of the Bs2 gene. OPD05 was located 5.3 cM away from Bs2 gene and OPF10 was located 4.9 cM from the Bs2 on the opposite side to OPD05. For practical use, identified RAPD markers were converted to sequence characterized amplified regions (SCARs). Primer sequences with various lengths were designed and examined for their ability to detect a resistance marker. SCF10, originating from the RAPD marker OPF10, was amplified using a 24-basepair primer set, and it showed polymorphism between resistant and susceptible individuals. The initial SCARs developed from OPD05, however, showed monomorphism between resistant and susceptible plants. After trials with various primer combinations, it was possible to develop a polymorphic SCD05 marker. These markers enable the identification of the Bs2 gene on segregating progenies for marker-assisted selection.

Viral Satellite RNAs for the Prevention of Cucumber Mosaic Virus (CMV) Disease in Field-Grown Pepper and Melon Plants.

A benign viral satellite RNA, in combination with a mild strain of cucumber mosaic virus (CMV-S), was used as a "vaccine" or "preinoculum" to demonstrate the feasibility of protecting pepper (Capsicum annuum cv. California Wonder) and melon (Cucurbita melo cv. Janus des Canaries) against two severe CMV strains, CMV-D and CMV-16, in the final 2 years of a 4-year pilot field and greenhouse experiment. In the field, healthy pepper and melon seedlings challenged with CMV-D and CMV-16 reduced yields by 33 to 60%; CMV-S caused only limited yield reduction in pepper and had no effect on the yield of melon. Different time intervals between preinoculation of pepper and melon seedlings with CMV-S and challenge inoculation with the severe CMV strains were tested. All plants challenged 3 weeks after vaccination showed nearly complete protection from subsequent infection by severe strains. The yield from preinoculated and challenged pepper plants was 80% that of untreated plants, while the yield from preinoculated and challenged melon plants was increased slightly over the untreated control plants. The use of this technology for biological control of plant viruses is discussed.

Effect of Potassium Nutrition during Bell Pepper Seed Development on Vivipary and Endogenous Levels of Abscisic Acid (ABA)

Seeds in fruit of bell pepper (Capsicum annuum `California Wonder') plants grown in nutrient solutions deficient in potassium (<3 mmol·L-1) showed a higher incidence of sprouting (i.e., vivipary) than seeds in fruit from plants grown at adequate potassium levels (6 mmol·L-1). Tissue analysis showed a progressive drop in the leaf content of potassium with increasing plant maturation for all levels of potassium nutrition. However, potassium in fruit and seeds increased at later stages of maturity. ABA was extracted, isolated and identified from bell pepper seeds obtained from fruit grown under the potassium treatments (0.0, 0.6, 1.5, 3.0, and 6.0 mmol·L-1) at five fruit maturity stages (mature-green to overripe). At early fruit maturity stages, there were no significant differences in seed ABA content in the fruit from the different potassium treatments. However, differences in ABA content and vivipary among the potassium treatments became highly significant as the fruit matured. The concentration of ABA in seeds of potassium-deficient treatments was ≈14% of the control (0.4 versus 2.8 μg·g-1 dry mass). High concentrations of ABA in bell pepper seeds were associated with low incidence of vivipary and high potassium content in the leaves, fruit and nutrient solution.