CMA banding pattern of chromosomes is useful for the identification of chromosome doubling in haploid citrus
2004
Yamamoto, M. (Kagoshima Univ. (Japan). Faculty of Agriculture) | Tominaga, S.
A variant plant showing long internodes arose from a hapbid plant obtained from clementine (Citrus clemenilna). Flow cytometric analysis and chromosome count reealed that It was a mixoplold with both haplold (2n=x=9) and diploid (2n=2x=18) cells. The average length of the guard cells of the variant was almost the same as that of the haploid plant. This suggested that the epidermis of the variant consisted of haploid cells and that other leaf tissues consisted of diploid cells. Since in citrus the first germ layer forms the epidermic and the second and third layers form all the leaf tissues except for the epidermis, (he variant was considered to be a ploidy periclinal chimera. When chromosomes of the young leaves were stained with chromomycin A3 (CMA), they could be classified into four types based on the number and the position of the CMA-positive bands. The chromosome configuration of the variant differed from that of the original diploid clementine. The number of chromosomes of each type in the diploid ceUs of the variant was twice the number of those In the haploid plant. These results demonstrated that the dipbid cells of the variant were doubled hapbold cells, and that CMA analysis of chromosomes is useful for the Identification of doubled haploids in citrus.
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