Heterogeneity of the internal transcribed spacer 1 (ITS1) in Tulipa (Liliaceae)

• Published in: Plant systematics and evolution Vol. 225; no. 1-4; pp. 29 - 41
• Main Authors: Booy, G, Schoot, J. van der, Vosman, B
• Format: Journal Article
• Language: English
• Published: Springer 2000
• Subjects: Biological taxonomies; Chromosomes; DNA; Genetic heterogeneity; Genetic loci; Hybridity; Internal transcribed spacers; Polymerase chain reaction; PRI Biodiversiteit en Veredeling; PRI Biodiversity and Breeding; RESTRICTION FRAGMENT LENGTH POLYMORPHISM; RIBOSOMAL DNA; Sequencing; TULIPA GESNERIANA
• ISSN: 0378-2697; 1615-6110
• DOI: 10.1007/BF00985457

Heterogeneity of the internal transcribed spacer ITS1 of the rDNA within individuals of Tulipa gesneriana L., T. kaufmanniana Regel, and their interspecific hybrids was analyzed by PCR-RFLP, using the polymorphic restriction enzymes RsaI and HinfI, and by nucleotide sequence analysis. In most cases, the sum of the sizes of the restriction fragments was higher than the entire length of the undigested ITS fragment, indicating heterogeneity at the restriction sites within an individual. Differences in band intensities within the restriction patterns indicate the occurrence of variation in copy number of these different ITS1 variants within individuals. Automated sequencing without a visual inspection often failed to detect existing heterogeneity within sequences, resulting in a discrepancy between the sequencing and restriction analysis results. By visual interpretation of the sequences, the restriction patterns could mostly be predicted well. Fluorescence in situ hybridization (FISH) experiments in four Tulipa species revealed the occurrence of several rDNA spots. The number of rDNA loci varied from seven in T. gesneriana 'Christmas Marvel' to ten in T. australis Link. This might explain the occurrence of heterogeneity in ITS sequences in Tulipa, as homogenization of variants has to take palce over different loci.