rarely have direct use as improved cultivars ( Guo et al., 2004b ); and the most important application of somatic hybridization is the building of novel germplasm as a source of elite breeding parents for various types of conventional crosses, including
of the maternal parent has been the usual cross protocol in breeding programs ( Bellini, 1993 ; Fontanazza and Baldoni, 1990 ; Lavee, 1990 ; Rallo, 1995 ). Several authors have tried cloth and paper bags in previous experiments, obtaining higher
Allotetraploid somatic hybrid plants of `Nova' tangelo [a sexual hybrid of `Clementine mandarin (C. reticulata Blanco) × `Orlando' tangelo (C. reticulata × C. paradisi Macf.)] + `Succari' sweet orange (C. sinensis L. Osbeck), and `Hamlin' sweet orange (C. sinensis L. Osbeck) + `Dancy' tangerine (C. reticulata) were regenerated following protoplast fusion. `Nova' and `Hamlin' protoplasts were isolated from ovule-derived embryogenic callus and suspension cultures, respectively, and fused using a polyethylene glycol method with seedling leaf-derived protoplasts of `Succari' and `Dancy', respectively. Plants were regenerated via somatic embryogenesis, and somatic hybrids were identified on the basis of leaf morphology, root-tip cell chromosome number, and electrophoretic analysis of peroxidase and phosphoglucose mutase isozyme banding patterns. Diploid plants were regenerated from unfused protoplasts of `Hamlin', `Nova', and `Succari'. Tetraploid plants of `Hamlin' and `Succari' were also recovered, apparently resulting from homokaryotic fusions. No `Dancy' plants were recovered. The somatic hybrid and autotetraploid plants can be used for interploid hybridization with selected monoembryonic scions to generate improved seedless triploid tangor/tangelo cultivars. The lack of suitable tetraploid breeding parents has previously inhibited the development of quality seedless cultivars by this method.
conjunction with its use as a parent in the ‘Mountain Vineyard’ F 1 hybrid grape tomato ( Panthee and Gardner, 2013 ). NC 6 grape resulted from breeding to develop a late blight-resistant, compact, indeterminate, brachytic growth habit grape tomato breeding
homozygous-resistant for Sw-5 and I-3 using molecular marker-assisted selection. Fig. 1. Pedigree of ‘Mountain Vineyard’ hybrid grape tomato and its parents, NC 4 grape and NC 5 grape tomato breeding lines. The determinate ( sp gene) grape tomato line NC
Abstract
Mite resistance of strawberry, Fragaria ☓ ananassa Duch, based on the ability to support low populations of the twospotted spider mite, Tetranychus urticae Koch, was assessed in the progeny of 15 crosses at two locations. The best parents were Washington State University selections 72–83M, 75-7-5 and 75-57-3 and the poorest parents were the susceptible cultivars ‘Totem’ and ‘Rainier’. General combining ability estimates for mite resistance were higher than specific combining ability estimates. Heritability estimates, based on parent/offspring regression, were high and ranged from 0.62 to 0.92. These observations suggest that additive genetic factors play a major role in the inheritance of mite resistance.
Allotetraploid somatic hybrid plants of `Hamlin' sweet orange (Citrus sinensis L. Osbeck) + `Femminello' lemon (C. limon L. Burm. f.), and Milam lemon (purported hybrid of C. jambhiri Lush) + `Femminello' lemon were regenerated via somatic embryogenesis following protoplast fusion. `Hamlin' and Milam protoplasts were isolated from undeveloped ovule-derived embryogenic callus cultures and fused using a polyethylene glycol method with seedling leaf-derived protoplasts of `Femminello' lemon. Somatic hybrids were identified on the basis of leaf morphology, root-tip cell chromosome number, and electrophoretic analyses of phosphoglucose isomerase, phosphoglucose mutase, and 6-phosphogluconate dehydrogenase leaf isozymes. The somatic hybrids will be used in interploid crosses with lemon in an effort to generate seedless triploid lemon types with improved tolerance to mal secco disease.
Interploid hybridization was conducted using `Key' lime [Citrus aurantifolia (Cristm.) Swing.], `Lakeland' limequat hybrid [C. aurantifolia × Fortunella japonica (Thumb.) Swing.], Palestine sweet lime (C. limettioides Tan.), `Etrog' citron (C. medica L.), and seven lemon [C. limon (L.) Burm. F.] varieties as female progenitors and five allotetraploid somatic hybrids {`Hamlin' sweet orange [C. sinensis (L.) Osbeck] × `Femminello' lemon (C. limon)]; `Key' lime × `Valencia' sweet orange (C. sinensis); `Valencia' sweet orange × rough lemon (C. jambhiri Lush); Milam lemon (purported C. jambhiri hybrid) × `Femminello' lemon (C. limon); and `Valencia' sweet orange × `Femminello' lemon} and two autotetraploids [`Giant Key' lime (C. aurantifolia) and `Femminello' lemon] as pollen progenitors. A few tetraploid × diploid crosses were also performed. Thirty-five parental cross combinations were accomplished in 2000, 2001, and 2002. The breeding targets were seedlessness, cold-tolerance, and disease resistance. Triploid hybrids were recovered through embryo culture. Generation of triploid citrus hybrids was affected by several factors including sexual compatibility, cross direction, embryo developmental stage, pollen viability, as well as horticultural practices and climatic conditions. Efficiency of triploid hybrid production was higher in diploid × tetraploid crosses than the reciprocal. Many more triploid hybrids were generated from lemon seed progenitors compared to the other acid citrus fruit progenitors. `Todo el Año', `Lisbon', and `Limonero Fino 49' showed the highest sexual compatibility. Embryo germination rate and normal plant recovery were also higher in lemons as compared to the other seed progenitors. Low winter temperatures might have affected the hybrid production efficiency from tropical acid fruit progenitors. A total of 650 hybrids (mostly triploid) were transferred to soil. The novel genetic combinations of these progenies should be valuable for the genetic improvement of acid citrus fruit (lemons and limes).
their parentages as recorded in breeding records and parentages as indicated by SNP haplotype analysis. Parents or grandparents in bold typeface in the Actual parent columns were identified using SNP array markers in this study. Parentage information
, the estimation of the breeding value of the mealy parent is necessary. Narrow-sense heritability or combining ability has been estimated to improve breeding strategies and to evaluate the potential of cultivars for use as parents in fruit breeding