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Studies on the Genome Constitution of Triticum timopheevi Zhuk. II. The T. timopheevi Complex and Its Origin

E. B. Wagenaar
Evolution
Vol. 20, No. 2 (Jun., 1966), pp. 150-164
DOI: 10.2307/2406569
Stable URL: http://www.jstor.org/stable/2406569
Page Count: 15
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Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Studies on the Genome Constitution of Triticum timopheevi Zhuk. II. The T. timopheevi Complex and Its Origin
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Abstract

Introductions belonging to the wild-growing tetraploid Timopheevi group of wheat and collected in the Transcaucasian states of the USSR, northern Iraq, and eastern Turkey were intercrossed and the subsequent F1 hybrids studied cytologically. Chromosome pairing was complete in these hybrids; mostly 14 bivalents were present. However, associations of from three to 16 chromosomes were observed in a number of hybrids indicating that some differentiation has taken place in three accessions from Transcaucasia. Other accessions from the southern USSR, and from the rest of the distributional area seem to be cytogenetically homogeneous. These results indicate that members of this complex should be considered as one species, T. timopheevi. On the basic of previously obtained data and the present results the origin of T. timopheevi was discussed. The species probably arose from T. dicoccoides in northern Iraq through a series of double mutations which occurred simultaneously or in quick succession and induced a strong sterility barrier with its close relatives. Other subsequent factors, such as geographical isolation, gene and chromosome differentiation led to the present T. timopheevi complex, which is unique in the wheat genus.

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