Morphological variation and genetic diversity of breadfruit [Artocarpus altilis (Parkinson) Fosberg] in Vanuatu

Abstract

Breadfruit, Artocarpus altilis (Parkinson) Fosberg, is a versatile tree crop widely distributed in Oceania and tropical regions. It produces starchy fruits that contribute to food security in Pacific Island countries. In Vanuatu, where it is considered as a secondary food crop, a better understanding of the diversity of this species is a prerequisite for setting up a genetic improvement strategy. A diversity study of 123 accessions collected in 27 villages on eleven islands across Vanuatu and conserved in an ex-situ field gene bank was conducted in 2023–24. Eighteen morphological descriptors of fruits and leaves were utilized and genotyping was performed using 15 single sequence repeat (SSR) markers. The results showed that Vanuatu cultivars exhibit important morphological variation. Most of them (except two) are diploid and seeded. Analysis of SSR profiles revealed four genetic groups and 99 unique multilocus genotypes. Cultivars collected in the northern and north-central regions of Vanuatu appeared to be more genetically diverse than those collected further south. A total of 152 alleles were detected across the 15 loci, with an average number of 10.13 alleles per locus. For comparison, SSR analysis of triploid seedless cultivars from Eastern Polynesia and the Indian Ocean showed that these cultivars, although morphologically different, share a very narrow genetic base and are hardly distinguishable with the set of markers used in this study. These results confirm that Vanuatu is an important centre of breadfruit diversity and that this diversity is dynamic due to the diploid nature of cultivars with a high percentage of seed propagated trees