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The Cyto-Geography of the Bothriochloa ischaemum Complex. II. Chromosome Behavior

Robert P. Celarier
American Journal of Botany
Vol. 44, No. 9 (Nov., 1957), pp. 729-738
Stable URL: http://www.jstor.org/stable/2438393
Page Count: 10
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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.
The Cyto-Geography of the Bothriochloa ischaemum Complex. II. Chromosome Behavior
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Abstract

A detailed cytological study of Bothriochloa ischaemum was made from samples of most of its geographical range of distribution. In this report 57 entries were analyzed. Assuming 10 to be the basic number, tetraploids, pentaploids and hexaploids were found. There were 42 tetraploids from Europe and the Near East and two from the Far East, four hexaploids from the Far East and two from Turkey, and seven pentaploids, apparently all from one entry from South China. The chromosome behavior was more or less irregular for all entries. The tetraploids had frequent quadrivalents, occasional univalents and lagging chromosomes, and a low frequency of bridge + fragment. The hexaploids were of two types; one had minor irregularities, only slightly more than the tetraploids, and the other was extremely irregular with a high frequency of univalents and lagging chromosomes, and a low frequency of quadrivalents, bridges and fragments. The pentaploids were similar to the irregular hexaploids in all respects. The evidence strongly suggests that B. ischaemum is a polyploid complex in which apomixis has become important. Possible origins and genomic constitution of the species are discussed and it is postulated that B. ischaemum var. songaricas contains a genome C which is foreign to B. ischaemum var. ischaemum.

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