Two 24-mer primers, MUSKFOM I and MUSKFOM II, were developed that amplify a 1.5-kb DNA fragment in race 1 Fusarium wilt resistant muskmelon (Cucumis melo L.), but not in race 1 susceptible germplasm tested. Three race 1 resistant cultivars and two race 1 resistant breeding lines as well as eight race 1 susceptible lines were analyzed using the two sequence-specific primers in the polymerase chain reaction. These primers should prove valuable for nondestructive determination of Fom 2 gene introgression in breeding programs.
W. Patrick Wechter, Ralph A. Dean, and Claude E. Thomas
Konstantinos Anagnostou, Molly Kyle, and Rafael Perl-Treves
We have studied the relationship of resistance to watermelon mosaic virus (WMV), zucchini yellow mosaic virus (ZYMV), papaya ringspot virus (PRSV), and powdery mildew (PM) in melon (Cucumis melo). We have confirmed monogenic dominant inheritance of these four resistances and report that PI414723-4S3, which was initially selected as a source of ZYMR, is also a source of dominant monogenic resistance to PRSV. Further, we observed departure from independent assortment for resistance to WMV and ZYMV in a study of 73 (UC Top Mark × PI414723-4S3) F3 families (χ2 = 39.87 significant at both 0.01 and 0.05 levels), indicating linkage between Wmv and Zym. The map distance between these resistance genes calculated from the number of recombinant families (RF% = 9.58) was 10.5 cM. Compari-sons among WMV, PM, ZYMV-PM, PRSV-PM, ZYMV-PRSV, and WMV-PRSV of 48 (TM × PI414723-4S3) F3 families, which were screened with all four pathogens, showed no consistent cosegregation.
Joseph N. Wolukau, Xiaohui Zhou, and JinFeng Chen
designed to identify AFLP markers linked to GSB resistance in PI 420145. Materials and Methods Plant and fungal material. PI 420145 ( Cucumis melo subsp. melo ) was originally collected from Japan and has resistance to D. bryoniae under field
Methods Plant materials. Earl's Knight Natsukei No.2 ( Cucumis melo L.) melon seeds were planted in a seedbed on 20 Mar. 2004 with nursery plants spaced at 40-cm intervals in a plastic film greenhouse on 20 Apr. 2004. The flowers that opened on
S.M. Lutfor Rahman*, Jeffrey T. Baker, Raul I. Cabrera, Dennis J. Timlin, and Bruno Quebedeaux
We collected growth and yield data on eight cantaloupe cultivars and constructed a simple phenology model that uses local weather data to allow growers to quantify phenological growth and development to project harvest dates. Main vine plastochron interval (PI), time to harvest, and final yield were determined. PI was calculated for each cultivar × transplanting date combination as the reciprocal of the slope of main vine node number vs. growing degree days. Among the tested cultivars,`Ovation' and `Primo' produced significantly higher yields of marketable melons (51.3 Mg/ha, 49.5 Mg/ha, respectively), whereas `Santa Fe' produced the lowest (28.6 Mg/ha). The rest of the tested cultivars produced on average 34.4 Mg/ha. Fruit weight was significantly higher in `Morning Ice' (2.7 kg/fruit) and lowest in `Mission' (1.4 kg/fruit). There were also significant differences among cultivars in the number of marketable melons/ha, which ranged from 11500 melons/ha for `Morning Ice' to 32300 melons/ha for `Ovation'. Plant dry matter production was higher in `Ovation' and `Mission' than all the other cultivars. The relative days to maturity were significantly higher in `Morning Ice' and `Honey Brew' (115 days) and lower in `Gold Rush' (72 days). There were no differences found in days to maturity for `Mission', and `Ovation'(82 days). The average % of soluble solids content ranged from 9.5 for `Ovation' to 14.5 for `Mission' and `Honey Brew'. The variety cantaloupensis types are earlier in maturity than inodorus types. PI was significantly different for all cultivars. Main vine node number was a useful descriptor of vegetative development for cantaloupes. Procedures for calibrating and fitting the model for these cultivars will be discussed and outlined
Within the Cucurbitaceae are two genera, Cucumis and Citrullus (muskmelons and watermelon, respectively), with sweet-tasting fruits. Per-capita consumption of these two genera rank melons (11.6 kg) second only to bananas (12.6 kg) as the most-consumed fruit in the United States. Consumption of melons, especially muskmelon and honey dew fruits, is significant from the standpoint of their nutritional benefits to humans. Orange-fleshed melons provide a person with 100% of their daily requirement of vitamins A and C. Melons also are a significant source of nutrients: sugars, dietary fiber, calcium, iron, potassium, and “phytochemicals.” Phytochemicals are compounds not presently recognized as having nutrient value. Thirty-eight known phytochemicals are in melons and have preventive properties in addition to anti-cancer attributes. Use of beta-carotene-rich melons is important in chemopreventive trials. Melon production and genetic factors may affect human health-beneficial nutrient and phytochemical quality attributes.
Soon O. Park* and Kevin M. Crosby
Mature fruit size and shape are important traits of most melon types. Our objective was to identify RAPD markers associated with major QTL affecting fruit weight, length, diameter and shape by means of bulked segregant analysis in an F2 population from the ananas melon cross of Deltex (larger fruit size) × TGR1551 (smaller fruit size). Clear separations for fruit weight, length, diameter, and shape between Deltex and TGR1551 were observed. Continuous distributions for fruit weight, length, diameter and shape were found in the F2 population indicating quantitative inheritance for the fruit traits. Significant positive correlations were detected between fruit weight and shape traits (r = 0.73 to 0.80). A significant positive correlation was observed between fruit weight and glucose (r = 0.35) or fructose (r = 0.25), whereas no correlation was noted between fruit weight and sucrose or total soluble solids. Two small and large bulks for fruit weight and shape were developed from F2 plants. A total of 240 primers were used to simultaneously screen between the small and large bulks, and between Deltex and TGR1551. Twenty-six RAPD markers were polymorphic for the small and large bulks. Ten markers were found to be significantly and consistently associated with fruit size and shape traits on the basis of simple linear regression. Of the 10 markers associated, four displayed an amplified DNA fragment in the small bulk, while six showed an amplified DNA fragment in the large bulk. The associated marker OJ07.350 explained 15% to 27% of the phenotypic variation for the fruit traits. These markers associated with QTL for melon fruit size and shape are expected to be useful in melon breeding programs for modifying fruit size.
Hector Nunez-Palenius*, Daniel Cantliffe, Harry Klee, and Donald Huber
`Galia' is a high-quality muskmelon cultivar that is grown in green-houses or tunnels to maximize fruit yield and to help improve fruit quality. Maximum fruit quality and flavor are achieved when `Galia' are harvested at maturity. This however leads to reduced firmness and short shelf life. In vitro regeneration and transformation of `Galia' melon is a strategy that can be used to increase fruit shelf life. Melon cotyledons were transformed with the ACC oxidase gene in antisense orientation according to the protocol described by Nunez-Palenius et al. (2001, 2003). Experiments were conducted to compare fruit quality parameters between transgenic (TT) and wild type (WT) fruits from plants grown in greenhouse conditions. The melon plants were grown using commercial growing practices that included pruning and training to one vertical stem and the use of soilless media and drip fertigation. Wild type fruits were harvested at 37, 42, and 50 days after pollination (DAP), whereas transgenic fruits were harvested at 42, 50, and 56 DAP. TT fruits were harvested with that delaying period since their ripening process was slower than WT. Thirteen preharvest parameters were evaluated in transgenic and wild type fruits. Wild type and transgenic weight, lenght, width, soluble solids, tritatable acidity, pH, firmness, flesh thickness, seed cavity size and seed number parameters were not significantly different. Ethylene production and ACC oxidase from 42 DAP wild type fruits were greater than from transgenic fruits. Transgenic (ACC oxidase) galia melon fruits had a delayed fruit ripening process compared with wild type fruits.
V. V. Meglic, T. F. Horejsi, J. E. Staub, and J. D. McCreight
The genetic diversity of 400 U.S. melon germplasm plant introductions was assessed using 35 enzyme systems. Polymorphisms were observed at 24 putative loci (Ac, Acp1, Acp4, Ak2, Ak3. Ak4, Fdp1, Fdp2, Fdp4, Gpi, Idh, Mdh2, Mdh4, Mdh5, Mdhb, Mpi1, Mpi2, Pgd1, Pgd2, Pgm, Pep-g1, Pep-1a, Pep-pap, Skdh) representing 17 different enzymes. Sixteen loci demonstrated simple Mendelian inheritance. Multivariate analyses aided in reduction of data using 16 loci and linkage relationships were observed among the plant introductions. Two of 16 loci (Pgd1 and Acp1) segregated independently. Fourteen loci were assigned into three linkage groups (A-C): A Fdp1, Fdp2, Acp4, Skdh; B Mdh2, Mdh4, Mdh5, Mdh6, Pep-g1, Pgm; C Mpi2, Ac, Idh.
Samuel Mendlinger and Dov Pasternak
The increasing salinity of both irrigated lands as well as irrigation water in many parts of the world have emphasized the importance of having appropriate breeding strategies for developing salt tolerant cultivars. In a program to breed for salt tolerance (high yield and good quality at 5,000 ppm salinity) in melons, several breeding strategies were tried. The only systems that succeeded was using combining abilities in a hybrid program. We found that salinity did not effect the number of fruit or fruit quality but only fruit weight. Fruit weight of hybrids grown in fresh water was controlled by dominant genes (h2=0.09) whereas the same hybrids grown under salinity had fruit weight control by additive genes (h2=0.54) Therefore, we were capable of breeding tolerant hybrids from non-tolerant parents.