A Database for Triticeae and Avena
Two ditelotetrasomic plants with normal 14 chromosomes plus two extra
telocentric chromosomes for short arm of chromosome 5 (ditelotetra 5S)
were found in the progenies of monotelotrisomics for 5S (Wang and
Tsuchiya, 1988). Five ditelotetra 5S plants developed from the progenies
of one of the ditelotetra 5S were grown in the greenhouse in late April
1988. In mid-May, these plants were moved to growth chamber (14-17 °C)
for increasing tillers since the temperature in greenhouse was too high
(23-30 °C). One month later these plants were moved back to the
greenhouse. When some young spikes were studied for meiosis, the
chromosome configurations at Diakinesis and Metaphase I showed different
chromosome numbers among spikes of the same plant. Chromosome
configurations varied from cell to cell with 7II, 71I+lI, 7II+2I, and so
on. This indicated that chromosome elimination occurred on some tillers.
Further investigation was conducted and many root tips for each plant were
studied. The results are shown below in Table 1.
The data in Table 1 showed that all these five plants were chimera
for their chromosome numbers, with 2n=14, 2n=14+1 telo and 2n=14+2 telos.
These suggested that the extra telocentric chromosome(s) were eliminated
in some roots and maybe in tillers.
What caused the elimination of telocentric chromosome is unknown.
A possible explanation is that the warm-cool-warm temperature fluctuation
during early growing stages might have induced chromosome elimination.
Further study is necessary to find causes for elimination of the
telosome 5S in the ditelotetrasomics for 5S.
Wang, S., and T. Tsuchiya. 1988. Ditelotetrasomics for the short arm of
chromosome 5 (ditelo 5S) in barley. BGN 18:21-23.