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Chromosomal Differentiation among the Annual Helianthus Species

John M. Chandler, Chao-Chien Jan and Benjamin H. Beard
Systematic Botany
Vol. 11, No. 2 (Apr. - Jun., 1986), pp. 354-371
DOI: 10.2307/2419126
Stable URL: http://www.jstor.org/stable/2419126
Page Count: 18
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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.
Chromosomal Differentiation among the Annual Helianthus Species
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Abstract

The chromosomal relationships of the 11 annual diploid species in Helianthus sect. Helianthus were investigated by analyzing meiotic abnormalities in the interspecific hybrids. Hybrids were secured from 40 of the 55 interspecific cross combinations via embryo culture or conventional hybridization techniques. Species differed from each other by 0-6 translocations and 0-8 paracentric inversions. Intraspecific variation in chromosome structure was found in some species but was not as complex as the interspecific variation. Pollen stainability for the different hybrids was 1% to over 75%, mainly reflecting the meiotic abnormalities of the hybrids. Chromosome end arrangements consistent with the observed hybrid multivalent configurations are presented for all but two of the species. A phylogenetic diagram based on translocation differences is presented. The chromosome end arrangement of H. debilis is considered ancestral, while those of H. neglectus and H. annuus are the most differentiated from the ancestral arrangement.

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