Progress 10/01/99 to 09/30/05
In order to better understand the relationships between various components of yield, a path analysis study was carried out in two diallels of land races of tropical pumpkin. Average fruit weight and number of fruit per plant were the two variables having the most important impact on yield, with average fruit weight showing a greater effect. New tropical pumpkin cultivars developed during the first 4 years of this project were tested in a variety of environments (locations and planting seasons). Two cultivars, PRShortvine1 and PRLongvineSLR showed a performance superior to that of other materials, and were similar in yield to that of the standard cultivar `Soler.' The final field trials of these two cultivars are being analyzed, and formal release of these cultivars is expected during 2006. Inheritance of resistance to silverleaf, a whitefly-induced physiological disease, was studied. We propose the symbol Sl (Silverleaf) for the single incompletely dominant gene that
results in susceptibility to silverleaf. Plants homozygous recessive for the gene sl are resistant to silvering. The cultivar PRLongvine SLR carries resistance to silverleaf. During this project we carried out a series of studies to better understand genetic relationships between tropical pumpkin (Cucurbita moschata) and its closely related species, particularly C. argyrosperma and C. sororia. We observed a high level of compatibility between sororia and argyrosperma, no matter the direction of the cross. There was a high degree of compatibility between either argyrosperma or sororia with moschata when the former species were used as the female parent. Incompatibility was observed in the reciprocal cross where moschata was used as the maternal parent. Plants, fruits and seeds of F2 and backcross populations appeared to be normal. Monogenic morphological traits had expected segregations in interspecific backcrosses, thus suggesting a high degree of homology between these two species.
The high level of compatibility observed should make it easy to move traits of interest from one species to another. Sweet potato varieties accepted by the local market are primarily those within the tropical-type. Tropical-type describes varieties intermediate in sweetness that exhibit white, cream or light yellow-fleshed roots. Regarding varietal choices, major local producers are limited to the landrace Dominicana, which dominates the market. Genotypes tested as entries PR-98-022 to be named Camuy and PR-98-40 to be named Pujols were selected. Both genotypes yielded better than Dominicana in both experimental and in semi-commercial plots and had similar sweetness and starch content and have demonstrated tolerance to over-the-top use of herbicides. A polycross was established and total count of open pollinated seeds collected was estimated at 12,000. Obtained progeny will continue under evaluation within another project.
Two new tropical pumpkin cultivars were developed with fruit quality superior in color and texture to that of the most commonly grown cultivar in Puerto Rico. Both cultivars have improved flesh color that provides the consumer with additional health benefits since darker orange color is associated with higher levels of beta-carotene, an important anti-oxidant. For the grower, the new cultivar with a semi bush growth habit can be more easily managed than the to traditional vine types. The other new cultivar is a more traditional long-vine variety that has improved insect resistance compared to that of the commonly grown cultivar. These traits will benefit the grower by reducing costs of pest control. We also studied the ability of different species of tropical pumpkins to cross-pollinate. There is a high level of compatibility between the species we studied (they are like first cousins). This compatibility will allow breeders to move traits of interest (such as better
resistance) from one species to another. However, it also means that undesirable genes from one species (including genetically engineered genes) are able to move to another species with relative ease. This knowledge can be useful when growing various tropical pumpkin species in the same area. It should be noted that some varieties of these species also grow in temperate climates. Newly selected sweet potato genotypes have been accepted among farmers within the small farm system. About 30 requests of propagation material of new varieties have been processed.
- Rivera-Hernandez, M., L. Wessel-Beaver and J. X. Chaparro. 2005. Molecular phylogenetic analysis of genes of the carotenoid pathway in Cucurbita. HortScience 40(4):1039. (abstract)
- Wessel-Beaver, L., O. Roman-Hernandez and L. Flores-Lopez. 2006. Performance of New Tropical Pumpkin Genotypes for Puerto Rico under Varying Cultural Practices. J. Agric. Univ. P. R. (submitted).
- Espitia-Camacho, M., F.A. Vallejo-Cabrera, D. Baena-Garcia, and L. Wessel-Beaver. 2005. Path Analysis of Yield Components in Tropical Pumpkin. J. Agric. Univ. P. R. (Accepted for publication).
- Wessel-Beaver, L. 2005. Release of `Soler' Tropical Pumpkin. J. Agric. Univ. P.R. (Accepted for publication). Sanjur, O., D.R. Piperno, T.C. Andres, and L.Wessel-Beaver. 2005. Using molecular markers to study plant domestication: The case of Cucurbita. In: D.M. Reed (ed.), Biomolecular archaeology: Genetic approaches to the past. Center for Archaeological Investigation, Occasional Paper No. 32, Southern Illinois University, Carbondale.
Progress 01/01/04 to 12/31/04
Six new tropical pumpkin (Cucurbita moschata) genotypes (two open pollinated populations and five lines) were evaluated on the basis of yield, quality and pest resistance of the standard cultivar `Soler.' Two genotypes (PRShortvine-1 and PRLongvineSLR) were tested at two within row planting distances (0.9 m and 1.9 m). Soler was planted at 0.9 m. Lines E0305-1, E0305-2 E0305-3 and E0305-4 were planted at 1.9 m. Lines E0305-1 and E0305-2 were highly susceptible to the melonworm, Diaphania hyalinata. Those same lines, as well as PRShortvine-1, were also susceptible to downy mildew, Pseudoperonospora cubensis. Flesh color of the new genotypes tended to be more orange than that of Soler. All genotypes produced similar yields. Within-row planting distance had no effect on yield and no effect on fruit size of PRShortvine-1. PRLongvineSLR produced a greater number of smaller fruits at the 1.9-m planting distance. Seed production in fruits of PRShortvine-1 and PRLongvineSLR
was similar to that of Soler. Despite some shortcomings, PRShortvine-1 and PRLongvineSLR are two advanced open-pollinated populations that merit consideration for formal release on the basis of their field performance, good fruit quality and ability to produce economical amounts of seed in a seed production program. Two elite sweet potato clones were compared in southern Puerto Rico on the basis of yield, sugar content and alcohol insoluble solids to the recommended cultivars Miguela and Dominicana. Yield of elite clones was better than that of the standards. On average, percentage of alcohol insoluble solids for new clones 98-22 and 98-40 were 73 and 78% both higher than that of the standards, and indicative new clones are starchier. Percentages of maltose and sucrose after baking of clone 98-22 were 3.6 and 9.9, respectively higher than that of Miguela but lower than that of Dominicana. Among clones, 98-40 had the least maltose and sucrose content. As the standards, new clones are
susceptible to the sweet potato weevil. We are considering formal release based on their ability to produce commercial sweet potato of good appearance and appropriate sweetness for the fresh market.
If the tropical pumpkin variety PRShortvine-1 is released, it has the potential to be planted on 1,000 to 1,500 acres of land in Puerto Rico and to generate from $2 to $5 million dollars per year in income at the farm gate level. This variety would also likely be adapted to production areas in the southern U.S.
- Wessel-Beaver, L., Cuevas, H.E., Andres, T.C. and Piperno, D.R. 2004. Genetic compatibility between Cucurbita moschata and C. argyrosperma. In: A. Lebeda and H. S. Paris (eds.) Progress in Cucurbit Genetics and Breeding Research, Proc. of Cucurbitaceae 2004, the 8 th EUCARPIA Meeting on Cucurbit Genetics and Breeding, Palacky University, Olomouc, Czech Republic, pp 393-400.
- Wessel-Beaver, L., Sud-Gonzalez, J. and Cuevas-Marrero H. 2004. Morphological traits of possible use as species markers in Cucurbita moschata and C. argyrosperma. Cucurbit Genetics Coop. Rpt. 27 (in press).
Progress 01/01/03 to 12/31/03
Three cycles of selection have been completed in PRShortvine, a population with semi-bush growth habit and superior fruit quality (flesh thickness, texture and color). Emphasis has been placed on selecting for appropriate fruit size and shape (fruit size and shape is still somewhat variable in the population). A second population, PRLongvineSLR, has undergone two cycles of selection. This long vine population derives from lines selfed out of the OP cultivar Soler, and is resistant to whitefly-induced silverleaf resistance (Soler is susceptible). These two populations, along with several inbred lines, selected from the PRShortvine population, are now ready for more extensive testing against the check variety Soler. A trial with large (20 m x 7 m) plots is in progress at the Isabela substation and two other similar trials are planned at two other locations. A protocol for DNA extraction in pumpkin, and for some initial molecular marker work, was begun. A field and
molecular study of genetic compatibility between C. moschata and a sister species, C. argyrosperma, demonstrated a high degree of compatibility between these species when the latter is used as the female parent, but incompatibility in the reciprocal cross where C. moschata is used as the maternal parent. Plants, fruits and seeds of F2 and backcross populations appeared to be normal. Monogenic morphological traits had expected segregations in interspecific backcrosses, suggesting a high degree of homology between these two species. Finally, over the past year we have made a total of 10 plantings of 5 genotypes at each of two locations (planting approximately every 4 to 6 weeks) in order to study the effect of day length and temperature on growth and flowering. No general pattern relating to day length, nor average temperature, could be discerned. Genotype differences were due to internode length, not total number of leaves or nodes.
Semi-bush types have been developed with fruit quality superior in color and texture to that of the most commonly grown variety in Puerto Rico. These traits are highly desirable to consumers. For the grower, semi bush tropical pumpkin can be more easily managed than traditional vine types. Traditional long-vine varieties are also being developed with an emphasis on incorporating insect, disease and virus resistance. These traits will benefit the grower by reducing costs of pest and disease control. We also studied the ability of different species of tropical pumpkins to be cross-pollinated. There is a high level of compatibility between the species we studied (they are like first cousins). This compatibility will allow breeders to move traits of interest (such as better resistance) from one species to another. However, it also means that undesirable genes from one species (including genetically engineered genes) are able to move to another species with relative ease.
This knowledge can be useful when growing various tropical pumpkin species in the same area. It should be noted that some varieties of these species also grow in temperate climates.
- Cuevas, H.E. and L. Wessel Beaver. 2003. Genetic compatibility between two species of tropical pumpkin. HortScience 38:735 (abstract)
- Chesney, P., L. Wessel Beaver and D.N. Maynard. 2004. Tropical pumpkin intercropped with beans and cowpeas. HortScience (accepted for publication)
- Wessel Beaver, L., J. Perez Arocho and O. Roman Hernandez. 2003. A comparison of the vegetative and reproductive performance of pumpkins of varying growth habit. Annual Meeting of the Sociedad Puertorriquena de Ciencias Agricolas, November 21, 2003, Guanyanilla, Puerto Rico. p. 11. (abstract)
- Cuevas Marrero, H.E. 2003. Compatibilidad genetica y flujo de genes entre Cucurbita moschata y C. argyrosperma. M.S. Thesis. University of Puerto Rico, Mayaguez Campus, Mayaguez, Puerto Rico. 81 pp.
Progress 01/01/02 to 12/31/02
Half sib recurrent selection in two breeding populations (a semi-bush and a long vine population) continues. The semi-bush population has gone through two and a half, and the long-vine population one and a half, cycles of selection. In addition to continued recurrent selection, inbred lines are also being selfed out of these populations. Studies on the inheritance of resistance to whitefly-induced silverleaf disorder, leaf mottling, and the relationship between these two traits are nearly complete. Genetic leaf mottling appears to be controlled by two genes and linked to silvering in the presence of silverleaf whitefly. Inheritance follows a model of recessive epistasis. In this model, a dominant gene results in mottle leaf (yellow or grey) while the recessive is greenleaf. The M gene expresses grey mottle only in the presence of the previously mentioned dominant gene. Silverleaf resistance appears to be closely or completely linked to the recessive m alele. A study
on the effect of daylength and temperature on flowering and development in both long vine and semi-bush tropical pumpkin has been initiated but no data has been analyzed. Genetic compatibility and phylogenetic studies between Cucurbita moschata and the closely related species C. argyrosperma continue. It is clear that gene flow from C. moschata to C. argyrosperma populations (including the wild species C. sororia) can occurr easily. Progeny from crosses between these species are fertile in the F1 generation and beyond. Backcross (interspecific F1 x C. moschata) progeny segregated in the expected ratios (1:1 or 1:0) for the monogenic traits hard rind, bitterness and bush growth habit. This indicates a close homology between the two species. However, gene flow in the opposite directions, from C. argyrosperma to C. moschata is probably very limited. Work has begun to test the hypothesis that the two species are separated by a complementary nuclear-cytoplasmic incompatibility system. When
comparing reciprocal backcrosses of the F1 interspecific hybrid with C. moschata all progeny are viable when C. moschata is used as the female parent, while only half of the progeny are viable when the reciprocal cross is made. These data suggest that if introgression of C. argyrosperma genes into C. moschata occurs, it occurs only indirectly via an interspecific genetic bridge. Finally, in collaborative work with the Smithsonian Tropical Research Institute we studied the relationship between rind phytoliths (silica bodies important in diagnosing the presence of Cucurbita species in archeological sites) and rind lignification. Both traits are controlled by a single dominant allele.
Semi-bush types have been developed with fruit quality superior in color and texture to that of most commonly grown cultivars in Puerto Rico, traits desirable to consumers. For the grower, short vined tropical pumpkin can be more easily managed than traditional types. Traditional types are being developed with an emphasis on incorporating insect, disease and virus resistance.
- Serrano, E. 2001. Heterosis y perdida de vigor por cansanguinidad en cruces de lineas de calabaza Cucurbita moschata Duchense de zonas templadas y tropicales. M.S. Thesis. University of Puerto Rico, Mayaguez, Puerto Rico. 32 pages.
- Flores-Lopez, L. and L. Wessel-Beaver. 2001. Performance of tropical pumpkins with compact growth habit under varying planting distances. HortScience 36(3):521. (Abstract)
- Wessel-Beaver, L. and T. C. Andres. 2001. Potential gene flow between two tropical pumpkins: Cucurbita moschata and C. argyrosperma. Annual meeting of the Sociedad Puertorriquena de Ciencias Agricolas, Nov. 16, Centro de Bellas Artes, Caguas, Puerto Rico. p. 18. (Abstract)
- Gonzalez-Roman, M. 2002. Herencia de plateado y su relacion con la expresion de moteado genetico en la calabaza (Cucurbita moschata Duchense). M.S. Thesis. University of Puerto Rico, Mayaguez, Puerto Rico. 49 pages.
- Flores, L. E. 2002. Comportamiento de lineas e hibridos de tipo compacto de calabaza (Cucurbita moschata) a diferentes distancias de siembra. M.S. Thesis. Universisty of Puerto Rico, Mayaguez, Puerto Rico.
- Piperno, D. R., I Holst, L. Wessel-Beaver, and T. Andres. 2002. Evidence for the control of phytolith formation in Cucurbita fruit by the hard rind (Hr) genetic locus: Archaeological and ecological implications. Proc. Nat. Academy Sci. 99:10923-10928.
- Wessel-Beaver, L., S. Crooke, and L. Lepe. 2002. Fruit age, fruit storage, and seed storage period affect management of seed in a tropical pumpkin breeding program. 26th International Horticultural Congress Program. p. 435. (abstract)
- Gonzalez-Roman, M. and L. Wessel-Beaver. 2002. Resistance to silverleaf disorder is controlled by a single recessive gene in Cucurbita moschata Duchense. Cucurbit Gen. Coop. Rpts. (accepted).
- Nienhuis, J. and L. Beaver. 2002. Comparison of genetic diversity between Cucurbita moschata accessions from the Pairmani Bolivia and USDA germplasm banks. 26th International Horticultural Congress Program. p. 537. (abstract)
- L. Flores and L. Beaver. 2002. Comportamiento de lineas e hibridos de calabaza (Cucurbita moschata) de tipo compacto a diferentes distancias de siembra. Annual Meeting of the Puerto Rican Society of Agricultural Sciences, November 15, 2002, Isabela, Puerto Rico. p. 19. (abstract)
- H. E. Cuevas and L. Wessel Beaver. 2002. Compatibilidad genetica y flujo de genes entre Cucurbita moschata y Cucurbita argyrosperma. Annual Meeting of the Puerto Rican Society for Agricultural Sciences, November 15, 2002, Isabela, Puerto Rico. p. 20. (abstract)
Progress 01/01/01 to 12/31/01
Two tropical pumpkin populations are being improved via half-sib recurrent selection. One and a half cycles of selection have been completed in the short-vine population. The short-vine (bushy) trait has been maintained. Fruit quality is superior to that of traditional long-vine cultivar `Soler'. Yield is less than that of `Soler', but very acceptable, considering a once-over harvest is carried out at about 90 days. The long-vine population was developed from silverleaf resistant progenies and is in the first cycle of selection. Some susceptible plants appeared in June 2001 under conditions of heavy whitefly populations. These plants were removed before anthesis. Fruits are smaller than Soler, but with thick, yellow flesh. Inheritance studies of silverleaf and leaf mottling confirm that mottle leaf is dominant to green leaf . Contrary to some previous work, this data shows silvering resistant x susceptible F2 progeny segregating 3:1, suggesting that silvering
resistance is controlled by a single recessive gene. Interpretation of the data becomes more difficult when the data is combined. In these studies we also observed an additional phenotypic class, yellow mottle leaf. We have previously observed this phenotype, but its relationship to silvering and mottle leaf is not known nor has the trait been reported in any other literature. In this study, it was always associated with silverleaf resistance. Studies of phylogenetic relationships using mtDNA and other data suggest a very close relationship between C. moschata and C. argyrosperma. A compact plant type of sweetpotato has been selected among local landraces collected throught Puerto Rico. This clone have showns 20 percent more yield compare to that of traditional cultivars.
New cultivars developed from this breeding program can add value for both the grower and consumer of tropical pumpkin and tropical type sweet potato. Short vined tropical pumpkin and compact type sweet potato can be more easily managed than to traditional types. Genetic resistance to pests would reduce the need for insecticides, thus reducing costs of tropical pumpkin production in an environmentally sound manner.
- No publications reported this period
Progress 01/01/00 to 12/31/00
With tropical pumpkins emphasis was on population development, testing of short-vine materials, and germplasm evaluation. To develop a long-vine breeding population, 48 S1 families we evaluated. Attention was given to whitefly and silverleaf resistance. The best 10 families will be recombined to form a long-vine breeding population. A short-vine population was developed and 34 half sib families from that population are under evaluation. The best 7 families will be recombined for the next cycle of selection. Experimental short-vine hybrids were tested under different planting distances. The recommended planting density for the long-vined types of tropical pumpkins is 1.8 x 1.8 m. To determine the appropriate in-row planting distance, six compact tropical pumpkin experimental hybrids were planted at 0.9, 1.4 and 1.8 m. Yields averaged 30,150 kg/ha. This yield compares very favorably with that of traditional types that produce similar yields but with multiple harvests.
Yields at the 0.9 and 1.4 in-row planting distance were not different and were superior to plots planted at 1.8 m. Planting compact types at the traditional distance of 1.8 m reduced yield to 70 percent of that of more densely planted plots. An in-row planting distance of 1.4 m (with 1.8 m between rows) will likely optimize yield and fruit size in these genotypes. New materials from South America were evaluated and seed increased by selfing. Included were accessions from Colombia (11), Panama (7), Brazil (1), Bolivia (selfed progeny from 2 accessions), and Paraguay (selected progenies of a single accession with silvering resistance), as well as a series of F1 crosses among and between various accessions of Cucurbita moschata, C. argyrosperma, C. sororia, C. ecuadorensis, C. ficifolia, and C. pepo. A genetic compatibility study was carried out using C. moschata as the only source of pollen for C. argyrosperma and C. sororia. This is believed to be the first study clearly documenting
gene flow in the field from C. moschata to C. argyrosperma and C. sororia. For tropical-type sweet potatos, 130 genotypes were evaluated in Eastern Puerto Rico. A polycross was planted, but seed set was low. The evaluation of the 7 elite clones in three locations is underway.
Additional work is needed before the release of experimental lines either as improved germplasm or as horticultural varieties.
- WESSEL-BEAVER, L. 2000a. Evidence for the center of diversity of Cucurbita moschata in Colombia. Cucurbit Genetics Cooperative Report 23:54-55.
- WESSEL-BEAVER, L. 2000b. Cucurbita argyrosperma sets fruit in fields where C. moschata is the only pollen source. Cucurbit Genetics Cooperative Report 23:62-63.
Progress 01/01/99 to 12/31/99
Tropical-type sweet potato (Ipomoea batatas): One hundred twenty-three accessions have been assembled as baseline germplasm to be evaluated under field conditions for physical characteristics of the storage root and diseases. Accessions include tropical, staple and substaple types. Tropical pumpkin (Cucurbita moschata): A planting of tropical germplasm from Bolivia, Colombia, Ecuador and Panama was initiated in October 1999. A limited number of pollinations were harvested because of excessive rain. This germplasm has been replanted; evaluation is in progress.
- No publications reported this period