Re: [Aroid-l] Intrageneric crossing - a good reference

From: "Julius Boos" ju-bo at msn.com> on 2006.01.24 at 04:23:48(13773) Reply-To : Discussion of aroids Sent : Monday, January 23, 2006 1:13 AM To : Discussion of aroids Subject : Re: [Aroid-l] Intrageneric crossing - a good reference Dear Peter, Thanks---to put this in a nutshell, it is suspected and confirmed by the 1988 testing that the ORIGINAL collected plant was a hybrid between two COLOCASIA species, C. esculenta X C. gigantia, not between a Colocasia X Alocasia. AND--a cross between Alocasia brsibanensis X Colocasia esculenta was made by man, ONE seed developed into ONE plant. This confirms that a cross is remotely possible between these two seemingly closely related genera, in which the dividing lines between these two genera are still vague, and that it is easier for two different species within the SAME genus can and will cross. Julius +More reference H. Yoshino, T. Ochiai and M. Tahara (2000) Phylogenetic relationship between Colocasia and Alocasia based on molecular techniques. In: D. Zhu, P. B. Ezyaguirre, M. Zhou, L. Sears and G. Liu (eds) Ethnobotany and genetic diversity of Asian taro: focus on China. International Plant Genetic Resources Institute and Chinese Society for Horticultural Science, Beijing. pp. 66-73. Summary: A taro strain collected in Nepal in 1973 was considered to be an intergeneric hybrid between Alocasia and Colocasia, on the basis of chloroplast DNA analyses carried out in the 1980s (but see later work with isozymes, noted below). Subsequently, an artificial cross was attempted and numerous seeds were obtained after a cross between C. esculenta var. aquatilis (Hassk.) Kitamura (from Nepal) and Alocasia brisbanensis (F. M. Bailey) Domin (ex Kyoto Botanical Garden). Most seeds did not germinate and only a single plant developed fully. This plant was triploid and chromosome painting using genomic in situ hybridisation (GISH) showed that 14 of 42 chromosomes were derived from A. brisbanensis. It was concluded that the plant was an intergeneric hybrid, formed as an unreduced egg of C. esculenta fertilised with normal A. brisbanensis pollen. Isozyme analyses by V. X. Nguyen (1998), PhD, Okayama University, contradicted the original interpretation of the Nepalese hybrid, indicating that it was a cross between C. esculenta and C. gigantea (i.e. intra-generic, not inter-generic). ***** Comments by PJM: Among other Asian accessions (Nepal and China) Nguyen found further examples of hybridsation between C. esculenta and C. gigantea. Taxonomically, C. gigantea is possibly misplaced in Colocasia, but it is not necessarily to be regarded as closer to Alocasia. As Yoshino points out, and as Tony Avent indicates in this list, there is much to be learned about hyribidisation among these aroids. The experimental survival of a hybrid between genera was made possible by a rare polyploidisation event that allowed odd chromosomes to be carried along by a normal full complement of chromosomes. Vigorous offspring are less likely after intergeneric crosses than after interspecies (intrageneric) crosses. An intergeneric crossing has not yet been proven to occur in the wild, though it is possible in principle. PJM ***** Dear Pete and Marek: The Alocasia x Colocasia hybrid that you mentioned looks a lot like A. macrorhizos. I was fortunate to examine this hybrid several years ago growing at a Hawaii taro research station. It was found in an area of Nepal where the two genera grow together. On our expedition last year to N. Vietnam, we visited a restricted military area near the China border. We found Colocasia gigantea growing with Alocasia macrorhizos. Growing among them were several plants that superficially appeared to be bi-generic hybrids. We have not had these plants tested yet to confirm this yet, so this is just a preliminary observation. If anyone is doing work in that region, I will be glad to direct them to the population for further study. Tony Avent Plant Delights Nursery @ Juniper Level Botanic Garden 9241 Sauls Road Raleigh, North Carolina 27603 USA Minimum Winter Temps 0-5 F Maximum Summer Temps 95-105F USDA Hardiness Zone 7b email tony@plantdelights.com website http://www.plantdelights.com phone 919 772-4794 fax 919 772-4752 "I consider every plant hardy until I have killed it myself...at least three times" - Avent _______________________________________________ Aroid-l mailing list Aroid-l@gizmoworks.com http://www.gizmoworks.com/mailman/listinfo/aroid-l -- Peter Matthews (Dr) National Museum of Ethnology Senri Expo Park, Suita City Osaka 565-8511, Japan Tel. +81 6 6876-2151 (museum exchange, J. only) Tel. +81 6 6878-8357 (Peter's office) Fax +81 6 6878-7503 (museum) Websites: The Research Cooperative http://www.researchco-op.co.nz A meeting place for research writers, editors, translators and proofreaders **** Sato Project: http://www.satoproject.blogspot.com Plant genetic resources in Eurasia **** _______________________________________________ Aroid-l mailing list Aroid-l@gizmoworks.com http://www.gizmoworks.com/mailman/listinfo/aroid-l _______________________________________________ Aroid-l mailing list Aroid-l@gizmoworks.com http://www.gizmoworks.com/mailman/listinfo/aroid-l

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