Linkage relationships are reported for 34 markers in celery (Opium grave lens L. vary ‘dulcet’) including 21 RFLP, 11 isozyme, and 2 morphological traits. The mapping was carried out in a cross between celery and an annual accession from Thailand, A143, and based on F 2 segregation of 136 plants. A total of 318 centiMorgans (cM) are covered by the markers distributed in 8 linkage groups. Probes for the identification of RFLPs were isolated from a celery cDNA library and were also obtained from heterogonous sources. Eco RV, Eco RI, and Hind III were the most useful restriction enzymes in uncovering polymorphism. In our cross, 18% of the cDNA probes were found to be polymorphic for at least one of the enzymes used. Six of the markers showed significant deviations from expected F 2 ratios.
Genetically marked tissues of celery (Opium grave lens) were employed to contrast genetic and chromosomal stability in serially bulk-transferred callus and regenerated plants. After six months in culture, 84% of the callus cells were karologically indistinguishable from normal, while the remainder exhibited chromosome loss and/or fusion. All of 50 clones derived from this tissue expressed the control phenotype with respect to heterozygous isozyme markers. Of 95 plants regenerated from the same tissue, 94 were phenotypic ally indistinguishable from the original explants donor, and cytogenetic analyses revealed the presence in 4.3% of an accessory chromosome, while the remainder were normal diploids. Analysis of the shelfed progeny of these regenerated plants revealed the presence of a new recessive mutation causing abnormal leaf morphology at a frequency of 1.8%. Only one of 40 cells in 12-month-old callus tissue was karyologically indistinguishable from normal, the remainder consisting primarily of hypo diploids. The observation that all 50 clones were phenotypic ally heterozygous was statistically inconsistent with the hypothesis that hypodiploidy was associated with random complete chromosome loss. The culture had, at this point, lost the ability to regenerate. It is speculated that embryogenic cloning of celery may be suitable under certain circumstances for direct field establishment, but that levels of new genetic variation are sufficiently high to preclude its use for seed production.
Sources:
http://deepblue.lib.umich.edu/handle/2027.42/46011
http://www.springerlink.com/conten
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http://alternativeremedies.wordpress.com/
Aida Emami (41715923)
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