Continued studies on the chromosomes of maize from China

During last year F1 hybrids of nine crosses between Wilbur's Flint and maize from China were grown. Microsporocytes of these hybrids were examined with light microscope by the same technique as what was previously reported (MGCNL 54:106). At pachytene stage, it was consistently observed that all the chromosomes synapsed regularly except the short arm of chromosome 10 of maize variety Peking-2. Asynaptic configuration was frequently found in this chromosome. The number of knobs varied from one to six (Table 1). For example, maize Peking-4 had only one terminal knob on the short arm of chromosome 9, while Peking-8 had six knobs. None of these had any knobs on chromosomes 2, 3 and 10.

Table 1. Numbers and positions of chromosome knobs in maize from China (K indicates homozygous knob, k heterozygous knob).
 
 
Chromosomes
  1 2 3 4 5 6 7 8 9 10
Varieties L S L S L S L S L S L S L S L S L S L S
Ying-64 - - - - - - K - - -  K - K - - - - K - -
Tich-133 - - - - - - - - - - K - K - - - - K - -
Henan-8 - - - - - - KK - - - - - - - - - - - - -
Henan-9 - - - - - - K - - - - - K - - - - - - -
Peking-2 - - - - - - K - - - K - K - K - - K - -
Peking-4 - - - - - - - - - - - - - - - - - K - -
Peking-6 - - - - - - - k - - KK - K - K - - K - -
Peking-7 - - - - - - - - K - - - K - - - - K - -
Peking-8 - K - - - - K -  - - K - K - K - - K - -

At diakinesis, 10 bivalents were regularly formed in most of the hybrids. However, hybrids involving maize variety Henan-8 had about five percent of the cells showing 20 univalents. The implication of this is under investigation.

Y. C. Ting and Margaret Yu

Please Note: Notes submitted to the Maize Genetics Cooperation Newsletter may be cited only with consent of the authors.

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