[Peculiarities of meiotic chromosomal behavior in tomato parthenocarpic forms]
1994
Nastas, L.A. | Bocharnikova, N.I. (Institute of Genetics, Kishinev (Republic of Moldova))
Sterile plants of "Severyanin" parthenocarpic species with seedless fruits whose sterility is conditioned by the presence of pat-2 gene are characterized by a lower mean chiasma frequency per meiocyte in comparison with fertile plants. The analysis of a number of various bivalent types and of chiasma distribution in a bivalent established that homozygous plants had a lower ring bivalents frequency and a greater one of open bivalents. As for bivalents having one-three chiasmas, a distinhuishing feature of which is the presence of an interstinal chiasma, parthenocarpia in sterile plants leads to significant decrease of a bivalent portion with multiply exchanges of eight type and does not influence significantly the frequency of X-bivalent and of semieight types. In fertile parthenocarpic plants recombination is maintained at a higher level by a greater frequency of bivalents with multiple exchanges. This fact contributes to the increase of the probability of additional (in relation to obligate ones) exchanges and to the decrease of the frequency of destruction of chromosomal associations with single exchanges.
显示更多 [+] 显示较少 [-]