This provided evidence of 2 n 3 x egg formation in the triploid female parents. However, crosses between certain chromosome species and Tbr repeatedly fail due to strong sexual isolating mechanisms. The triploid F 1 hybrids we produced flowered profusely and had a high pollen stainability, but they did not produce 2 n pollen They also possess many valuable traits, including resistances to biotic and abiotic stresses and superior tuber quality 2. Waara S, Glimelius K. The somatic chromosome number varied greatly among the resulting BC 2 progenies, which included hyperaneuploids, but also a number 4.
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This second approach is preferable to reduce the number of wild genomes present in the tetraploid progeny. Resulting seeds were treated with gibberellic acid 1, ppm for 24 hr to break dormancy and sown in Styrofoam trays, and the seedlings obtained were transplanted to pots.
Genetics of Potato Solanum tuberosum. Rapid progress in obtaining a large number of 15 genotypes is expected after one or two further backcross generations, and the ebh of Cmm-specific RAPDs could speed up the selection hm tetraploid Cmm-Tbr hybrids. In terms of berry and seed set they performed better as female than as male parents, presumably ebbn chromosome imbalance is better tolerated in female than male gametophyte.
However, crosses between certain chromosome species and Tbr repeatedly fail due to strong sexual isolating mechanisms. Novy and Hanneman 22 reported the production of triploids between Cmm and Tbr to direct transfer Cmm germplasm to Tbr, but due to the lack of fertile gametes, they never could be used in crosses with tetraploid varieties. In addition, the breeding program followed is longer and more time consuming due to the number of bridge crosses and backcrosses involved.
Lower somatic chromosome numbers were predominant, manifesting a trend toward tetraploidy. The in vivo direct method we used also could be applied to exploit sexually isolated relatives of other species where an EBN system is operating.
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This provided evidence of 2 n 3 x egg formation in the triploid female parents. Plant Mol Biol Rep. To introgress genes from diploid species into the cultivated potato, Tbr-4 x can be crossed directly with 2 n gamete-producing species to synthesize a tetraploid progeny.
Indeed, 44 analyzed plants To achieve the latter goal, both in vitro and in vivo approaches have been suggested. All derived plants were vigorous and tuberized under long day conditions. The most common underlying barrier to interspecific hybridization in Solanum spp. The introgression of S. Breeding scheme followed to introgress S. For 19 primers Murashige T, Skoog F.
As a result, their EBN is four, indicating no endosperm barriers to the introgression of genes from Cmm. Cross combination Genotypes analyzed, no.
The number of chromosomes observed among BC 2 plants was highly varied, ranging from 48 to According to the endosperm balance number EBN hypothesis ebnneach Solanum species has a specific EBN, determined experimentally from crosses with tester species 5and all successful crosses require a 2: Indirect transfer is less effective when compared with direct transfer, in that it has limited genetic efficiency due to the higher percentage of unadapted germplasm transmitted.
A combination of rescue pollinations and embryo rescue has been used to exploit the diploid 1EBN species S. The somatic chromosome number varied greatly among the resulting BC 2 progenies, which included hyperaneuploids, but also a number 4. The production of near-pentaploid hybrids probably is due to ebnn loss of chromosomes during megasporogenesis in the 3 x female parent, perhaps by occasional omission from a restitution nucleus.
Mitotic analysis of root tip chromosomes indicated that most plants were pentaploid, rather than aneuploids. National Center for Biotechnology InformationU.
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M, molecular weight marker kb. Root tips were collected for mitotic analysis to check the ploidy level. Ortiz R, Ehlenfeldt M K.
10 The use of colchicine on meristems is less preferable due to drug toxicity and chimera formation. The triploid F 1 hybrids we produced flowered profusely and had a high pollen stainability, but they did not produce 2 n pollen Despite the prevalence of Cmm markers, hybrids closely resembled Tbr in growth habit and tuber characteristics.