Collection, Establishment, and Evaluation of aGermplasm Collection of Pacific Island Breadfruit

Ragone, Carol Diane
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Approximately 400 accessions of breadfruit {Artocarpus altilis (Parkin.) Fosberg, A. mariannensis Trecul, and A. camansi Blanco) were collected from 17 Pacific Island groups (Fiji, Rotuma, Solomon Islands, Vanuatu, Belau, Kiribati, Mariana Islands, Marshall Islands, Pohnpei, Truk, Yap, Cook Islands, Marquesas, Samoa, Society Islands, Tokelau, and Tonga) for a germplasm collection. Micronesian accessions included interspecific hybrids between A. mariannenis and A. altilis. A total of 145 accessions were propagated and 185 trees of 135 accessions were added to a germplasm collection on Maui, Hawaii, at the Kahanu Gardens of the National Tropical Botanical Garden. The collection now consists of 226 trees of more than 100 cultivars from 17 island groups. The collection was evaluated using gel electrophoresis. Six enzyme systems (AGO, ADH, IDH, LAP, MDH, and PGM) were polymorphic, and 204 accessions were reduced to 90 unique zymotypes using cluster analysis. Only 12 zymotypes occurred in more than one island group, and one, a Polynesian triploid cultivar (A. altilis) was found in 11 island groups in Polynesia and Micronesia. Seventy-four accessions were observed to have this zymotype. The greatest isozyme variation occurred in Melanesia with 71% of the accessions uniquely characterized. Micronesia and Western Polynesia had relatively high rates of zymotypic variation with 59% and 51% variation, respectively. Only two zymotypes were found in Eastern Polynesia. Chromosome numbers for A. camansi and A. mariannensis are reported here for the first time as 2n = 56. Counts of 2n = 56 and 2n = 84 were observed for A. altilis. Most seeded cultivars of A. altilis had counts of 2n = 56, but seedless diploid cultivars were also observed. The majority of interspecific hybrids were seedless with counts of 2n = 56. Triploid interspecific hybrids were also observed.
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