Genetically marked tissues of celery (Apium graveolens) 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 phenotypically indistinguishable from the original explant donor, and cytogenetic analyses revealed the presence in 4.3% of an accessory chromosome, while the remainder were normal diploids. Analysis of the selfed 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 hypodiploids. The observation that all 50 clones were phenotypically 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.
All Science Journal Classification (ASJC) codes
- Apium graveolens
- Plant tissue culture
- chromosome instability
- somaclonal variation