Journal of Heredity Advance Access originally published online on December 23, 2004
Journal of Heredity 2005 96(2):124-131; doi:10.1093/jhered/esi012
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Cytogenetics of Semi-Fertile Triploid and Aneuploid Intergeneric Vine Cacti Hybrids
From the Department of Life Sciences and The Institutes for Applied Research, Ben-Gurion University of the Negev, PO Box 653, Beer-Sheva 84105, Israel (Tel-Zur, Mizrahi); and Levi Eshkol School of Agriculture, The Hebrew University of Jerusalem, PO Box 12, Rehovot 76100, Israel (Abbo)
Address correspondence to Y. Mizrahi at the address above, or e-mail: mizrahi{at}bgu.ac.il
Crosses between the diploid Hylocereus polyrhizus, as the female parent, and the tetraploid Selenicereus megalanthus, as the male parent, yielded triploid and aneuploid hybrids. The fruits of these hybrids combined the attractive appearance of Hylocereus fruits with the delicious taste of S. megalanthus fruits. The aim of this work was to assess the fertility and breeding potential of the triploid and aneuploid hybrids with a view to developing an improved vine cactus crop. Pollen mother cells at metaphase I revealed univalents, bivalents, trivalents, and occasionally quadrivalents. Chromosome distribution at anaphase I revealed different classes of chromosome segregation as well as lagging chromosomes. At metaphase II, parallel and tripolar spindles were observed. The occurrence of triads was frequent, whereas dyads were rarely observed. Pollen stainability varied among the clones studied ranging from 9.8% to 18.6%. The diameters of the stained pollen grains varied widely, probably as a result of the number of chromosomes. Despite the allotriploid origin of our hybrids, functional female and male gametes were produced in considerable proportions, most likely as a result of balanced chromosome segregation. The triploid and aneuploid clones studied yielded viable seeds whose number per fruit was strongly dependent on the pollen donor.