The Ft hybrids obtained by crossing Brassica napus cv. Oro and Raphallus sativus var.
oleifera, were cultured in the medium (Ms 'l; 0.2 mgllitre NAA + 3 mgllitre SA + 1 gllitre
colchicine + 30 gllitre sugar + 8 gIlitre agar) for 5 days. Many buds obtained carried 56
chromosomes. With the above technique, it is possible to obtain stable amphidiploids by
the routine'hybridization between Brassica and related species. 28 bivalents were formed
in the PMC of the amphidiploids. Sometimes 26 bivalents and 1 quadrivalent were found.
There are homologous or homoeologous chromosome in one genome or between two
genomes of the amphidiploids. Another type of meiosis was discovered in the
amphidiploids in which 56 chromosomes did not form bivalents and the chromatids could
be detected in MI, several chromosome masses formed at anaphase and the pollen was
sterile. This is the first cytological evidence of sterility in the amphidiploids of rapeseed.
Unbalanced division was observed in the R. sativus var. oleifera at anaphase I of meiosis
which formed two types of pollen, one with 8 chromosomes, and another with 10
chromosomes. This could be the starting point where two basic chromosome numbers
contributed to the genome evolution.
Keywords: Amphidiploids, Brassica, Raphanus, colchicine, meiosis, genomic number.
Article DOI: NA
Print ISSN: 0019-5200
Online ISSN: 0975-6906
XU LIYUAN, XUAN PU, YAN JIXOU, Luo PENG AND LAN ZEQU info_circle