B chromosomes and structural hybridity in Petunia hybrida Vilm

R. N. Gohil, Ranjana Kaul
Petunia hybrida Vilm. is a common ornamental grown for its beautiful flowers which range in colour from white to deep red and purple (Bailey 1958) . In Kashmir this species exists as a diploid with 2n=14. In continuation with our studies on the Kashmir plants (Koul and Gohil 1973) we came across a population of P. hybrida in which some of the plants had multivalents during male meiosis along with a single B chromosome. The present paper puts on record the karyotype and meiotic details of the
more » ... mal plants as well as the structural hybrids having one B chromosome. Material and methods Karyotypic studies were made from the root tips procured by germinating the seeds set by the two types of plants. Root tips were pretreated in 0.3% aqueous colchicine solution for three hours at room temperature, thoroughly washed in tap water, fixed in 1:3 acetic alcohol for 24 hours, and subsequently stained by Feulgen's procedure. Squashes were made in 1% acetocarmine. For meiotic details young flower buds were fixed in 1:1:1 (absolute ethanol, chloroform and acetic acid). Anthers were squashed in 1% acetocarmine. All the studies were made from tem porary mounts. Observations During the course of present investigation 11 populations of Petunia hybrida cultivated in various gardens of the Kashmir valley were studied for cytological de tails. In all these, plants were found to be diploid with 2n=2x=14 and in ten of them the pollen mother cells were found to undergo normal meiosis. One of the populations, however, was found to be of mixed type. In this population majority of the plants underwent normal meiosis. A few plants (4) were having 14+1B chromosome and their meiosis was characteristic of translocation heterozygotes. In morphological details these plants could not be differentiated from the rest. This population was of mixed phenotype with plants bearing white, red, purple, mauve and deep purple flowers. Somatic chromosomes Somatic complement of P. hybrida comprises of four median and ten submedian chromosomes. The salient features of the karyotype of plants with and without B
doi:10.1508/cytologia.45.763 fatcat:rp6llo7ufreybehkpochospniy