Peculiar phenomena of rDNA locus on chromosomes of some Chinese plants in Scilla scilloides

Abstract

Two molecular cytological phenomena such as NOR and/rDNA loci in the chromosome complement of Scilla scilloides were observed by in situ hybridization using rDNA probe. Most of the plants of the species collected in Shaanxi Province, the People’s Republic of China were diploid of genome A that was characterized by a pair of satellited a₂ chromosomes carrying heavy rDNA signal at the secondary constriction comprising of constricted region and its adjacent chromosome arms at metaphase. At interphase the rDNA signals dispersed in the nucleolus with condensed signal body at terminal end. A plant of AA diploid showed that rDNA signal of one a₂ chromosome condensed through the cycle of respective division, whereas that of another a₂ chromosome showed the normal behavior. Another phenomenon occurred frequently in small B-chromosomes in S. scilloides. The diploid and tetraploid plants of the genome B collected in Jiangsu had several small B-chromosomes carrying condensed rDNA signal in addition to b₁ chromosomes with heavy rDNA signal at metaphase and interphase, suggesting rDNA of small B-chromosomes did not involve to nucleolus organization.