Karyotypic and genome size variation in Cajanus cajan (L.) Millsp.(pigeonpea) and some wild relatives

Ohri, D. and Singh, S.P. (2002) Karyotypic and genome size variation in Cajanus cajan (L.) Millsp.(pigeonpea) and some wild relatives. Genetic Resources and Crop Evolution, 49 (1). pp. 1-10.

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Detailed karyotypes and 4C DNA amounts have been studied in five cultivars of Cajanus cajan and 20 species belonging to Cajanus, Rhynchosia, Dunbaria, Flemingia and Paracalyx. C. cajan shows intraspecific variability and its karyotype is most similar to that of C. cajanifolius (sect. Cajanus) in the morphology and number of satellite chromosomes and the lack of any correlation between chromosome size within the complement and asymmetry. Karyotypes of C. lineatus and C. sericeus belonging to sect. Atylia are similar with respect to maximum rindex and the ratio of longest and shortest chromosomes in their respective complements. C. acutifolius (sect. Frutocosa) is distinct in having a very low ratio (1.44) between the longest and the shortest chromosomes, while in C. albicans, C. goensis, C. scarabaeoides (sect. Cantharospermum) there is no chromosome pair with r-index >2.0. C. mollis and C. volubilis (sect. Volubilis) show similarity with regard to ratio between the longest and the shortest chromosomes and a distinct chromosome pair with an arm ratio of 2.7 and C. platycarpus is distinct (sect. Rhynchosoides) in having the smallest ratio (1.36) between the longest and the shortest chromosomes. 4C DNA amounts in Cajanus and Rhynchosia vary between 3.28 pg to 11.69 pg and 4.92 pg to 11.13 pg respectively, while in Dunbaria, Flemingia and Paracalyx these vary between 4.70 and 7:06 pg. In the genus Cajanus karyotypic features and 4C DNA amounts agree with the sectional classification and bring out a close relationship between C. cajan and C. cajanifolius. This is supported by studies based on seed protein patterns, isozyme analysis, trypsin and chymotrypsin inhibitor patterns, RFLP and RAPD data and crossability relationships. A clear relation between DNA amount and abnormalities effecting the extent of pairing and recombination in interspecific hybrids shows the importance of this study in developing future breeding programme involving C. cajan and its wild relatives that are of potential value.

Item Type: Article
Uncontrolled Keywords: Cajanus, Rhynchosia, Dunbaria, Flemingia, Paracalyx, karyotypes, DNA content, species relationships, Leguminosae
Author Affiliation: Plant Breeding and Genetics Division, National Botanical Research Institute, Lucknow-226 001, U.P., India
Subjects: Crop Improvement > Genetics
Divisions: Pigeonpea
Depositing User: Sandhya Gir
Date Deposited: 09 Sep 2011 08:00
Last Modified: 09 Sep 2011 08:01
Official URL: http://dx.doi.org/10.1023/A:1013866611410
URI: http://eprints.icrisat.ac.in/id/eprint/2624

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