Somaclonal variation in micropropagated tulips as a source of novel genotypes - field and molecular characteristic.

Somaclonal variation (SV) was evaluated in tissue-culture (TC) derived plants of the tulip cultivar 'Giewont' and genotype "Bs6", the mutant selected from among the micropropagated plants of the cultivar 'Blue Parrot' in 2004. The plant material of both genotypes derived from the long-term cultures maintained in vitro for a period of 2, 4 or 6 years. The plants were planted outdoors in an insect-proof tunnel in 1999-2004. Phenotypic evaluation was done during the subsequent years of cultivation, in 2006 and 2007. The plants of the mutant "Bs6" have parrot flowers which are 1.5-2 cm longer with stems which are 7-10 cm longer than the original 'Blue Parrot' plants. Further the flower colour changed from purple-violet to red-purple. In 2008, selected "Bs6" true-to-type plants have given start new cultivar 'Agalia'. SV frequency in 'Giewont' and "Bs6" ranged from 5.9 to 15.3%, including 1.5-6.8% SV frequency resulted from instable variants, characterized with a flower fasciation or a partly green tepal, accreted with a last leaf. Some off-type plants of genotype "Bs6" had minor changes, i.e. the flower shape was altered to non-parrot type. Variants with major changes, having highly malformed flowers, occurred regularly in both genotypes. They had always leaves with thicken, vitreous venation. Such leaf malformation was also found within juvenile plants. Similar variants were previously observed in TC-derived plants of tulip 'Prominence'. DNA analysis of 'Giewont', "Bs6" and 'Prominence' variants (both the flowering and juvenile plants) with ISSR (inter simple sequence repeats) technique confirmed that the leaf malformation resulted from genetic changes. The results indicate that the trait of leaf thicken, vitreous venation can be considered as a morphological marker for early detecting the major genetic changes within juvenile plant material.