BGN 19: Cytology and morphology of various trisomics involving chromosome 7 of barley.

Cytology and morphology of various trisomics involving chromosome 7 of barley.*

R. Riley and T. Tsuchiya
Department of Agronomy
Colorado State University
Fort Collins, Colorado 80523 U.S.A.
*Supported by USDA-CSU Cooperative Research Project No. 58-82HW-6-8 and CSU Hatch Project.


Available related trisomics for chromosome 7 (acro 7S7L , monotelo 7S, and triplo 7 in barley were studied to compare cytology and morphology of these aneuploid stocks with their diploid siblings.

Morphologically, acro 7S7L (2n=14+1 acrosomic 7S7L) was nearly indistinguishable from the diploid sibs (2n=2x=14), but was quite different from both triplo 7 (2n=2x+1=15) and monotelo 7S (2n=14+1 telosomic 7S). Table 1 shows measurements of various plant parts among the related trisomics and the diploid sibs. Ten plants of each type were measured.

Meiosis was studied at diakinesis and metaphase I in each of the related trisomics for chromosome 7. Triplo 7 had the highest frequency of the 6 II + 1 III configuration in both diakinesis and metaphase I and acro 7S7L had the highest occurrence of univalent formation. Triplo 7 and monotelo 7S were very similar for meiotic configuration at both diakinesis and metaphase I (Table 2).

It is hypothesized that greater occurrence of univalent formation in acro 7S7L is due to the small proximal fragment of the long arm of chromosome 7 present on the extra acrosomic chromosome.

Table 1. Morphological measurements of various plant parts of acro 7S7L, monotelo 7S, triplo 7, and diploid sibs in barley.

Table 2.Meiotic configurations of related trisomics for chromosome 7 in barley (in percent).

References:

Furst, E., and T. Tsuchiya. 1983.BGN 13:47-48.

Tsuchiya, T., A. Shahla, and A. Hang. 1987. Barley Genetics V:389-395

Riley, R., and T. Tsuchiya. 1988.BGN 18:14-15.


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