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Wheat Information Service
Number 77: 19 - 22 (1993)


Detection of Quadrivalents in the Brazilian wheat 'Frondoso'

William A. Berzonsky

Agronomy Dept., Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, OH 44691, USA


Translocations have been detected in many wheat (Triticum aestivum L.) cultivars in comparison to the chromosome standard, 'Chinese Spring' (Baier et al. 1974; Vega and Lacadena 1982; Lange et al.1987). Heterozygous reciprocal translocations might persist in wheat cultivars, even after generations of self-pollination, due to the compensation for deficient genes by genes on homoeologous chromosomes.

Primard et al. (1991) identified quadrivalents in the wheat cultivar 'Atlas 66' due to a heterozygous reciprocal translocation involving chromosome arms 2AL and 2DL. They indicated that the translocation had persisted through seven generations of self-pollination and that its origin was unknown.

Atlas 66 was developed in North Carolina, USA from the cross'Frondoso'//'Redhart 3'/'Noll 28'(Heyne 1958). Frondoso originated from Brazil (USDA, ARS, Germplasm Resources Information Network, Beltsville, Maryland, USA). Love (1951) examined 19 Brazilian wheat cultivars for meiotic instabilities. One of these cultivars, 'Frontana', a cultivar with the same pedigree as Frondoso, had an abnormal meiosis characterized by failure of pairing and lagging of bivalents at disjunction.

The purpose of this study was to examine the meiosis of Frondoso for quadrivalents. The existence of quadrivalents was hypothesized based on Frondoso's Brazilian origin, its use as a parent in the development of Atlas 66, and the prior identification of quadrivalents in Atlas 66.


Materials and methods

Seed of Frondoso was obtained from the USDA National Small Grains Collection. Frondoso is a red spring wheat cultivar developed from the cross 'Fronteira'/'Mentana' (USDA, ARS, Germplasm Resources Information Network, Beltsville, Maryland, USA).

Anthers, with pollen mother cells (PMCs) at metaphase I, were identified in temporary acetocarmine smears (Darlington and Lacour 1950) and fixed in a 3:1, 95% alcohol:glacial acetic acid mixture. Anthers, collected from 10 different plants grown in a glasshouse, were hydrolyzed in 1N HCI for 12 min, stained with Feulgen (Darlington and LaCour 1950), and smeared in propionic orcein. Slides were made permanent by mounting a coverslip with Canada Balsam after passing them through a 50:50, 100% tertiary butyl alcohol (TBA):glacial acetic acid mixture and two changes of 100% TBA.

Meiotic observations were made for 20 well-spread, complete cells from each plant sampled and configurations were recorded following the nomenclature of Kimber and Sears (1968).

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