Linking breadfruit cultivar names across the globe connects histories after 230 years of separation.

Every crop has a story. The story of breadfruit (Artocarpus altilis), an increasingly valued staple crop in tropical agroforestry systems, is filled with intrigue, oppression, and remains incomplete. The Caribbean is a major producer and consumer of breadfruit, yet most breadfruit there came from a single 1793 introduction aimed at providing a cheap food source for slaves forced to work on British plantations. St. Vincent was the first significant point of Caribbean introduction and played a vital role in subsequent breadfruit distribution throughout the region. Hundreds of cultivars are documented in breadfruit's native Oceania. It remains a mystery, however, which ones were introduced to the Caribbean 230 years ago-still comprising the vast diversity found there today. Integrating local knowledge, historical documents and specimens, morphological data, and DNA, we identify eight major global breadfruit lineages-five of which are found in the Caribbean and likely represent the original 1793 introduction. Genetic data were able to match two Caribbean cultivar names confidently to their Oceania counterparts. Genetics and morphology together enabled additional possible matches. Many other named cultivars within lineages are too genetically similar to differentiate, highlighting difficulties of defining and identifying variation among clonally propagated triploid crops. Breadfruit is important in resilient agroforestry in tropical islands predicted to be especially affected by climate change. Findings reveal global links, building upon collective knowledge that can be used to inform breadfruit management. Results are also summarized in a brochure about breadfruit history and diversity in St. Vincent, and the Caribbean more broadly.

Breadfruit flour is a healthy option for modern foods and food security.

Breadfruit is a traditional staple crop from Pacific islands with the potential to improve worldwide food security and mitigate diabetes. Flour produced from breadfruit is a gluten-free, low glycemic index, nutrient dense and complete protein option for modern foods but basic scientific knowledge of health impacts of a breadfruit-based diet in animals and humans was lacking. We designed a series of studies to provide basic and fundamental data on impacts of a breadfruit-based diet through an in vitro and in vivo model. Cooked breadfruit flour was digested through a multi-stage enzyme digestion model to estimate protein digestibility in comparison to wheat flour. Breadfruit protein was found to be easier to digest than wheat protein in the enzyme digestion model. The flour digestions were applied to Caco-2 cells to test the cytotoxicity and to measure the immunogenicity through cytokine expression. No significant differences were observed for immune factors and cytokines (IL-4, IL-10, IL-8, TNF-α, IFN-γ) on Caco-2 cells between the breadfruit and wheat groups. A breadfruit-based rodent chow was formulated by substitution of all of the wheat in the standard formulation with breadfruit. The diets were isocaloric, nutrient equivalent and used to feed male and female C57BL/6 mice for 21 days. No sign of malnutrition, discomfort, illness or death was observed among the mice because of the diet. The histology and the cytokine expression of the mice ileum from both groups were analyzed and showed similar results. The expression of major bacteria was measured in the colon and showed similar results. Mice fed the breadfruit diet had a significantly higher growth rate and body weight than standard diet fed mice. No negative health outcomes were observed in studies with in vitro or in vivo models and breadfruit flour is a healthy alternative to other starches for modern foods.

Development of a Breadfruit Flour Pasta Product.

Breadfruit (Artocarpus altilis) is grown throughout the tropics. Processing the perishable starchy fruit into flour provides a means to expand the use of the fruit. The flour can be used to develop new value-added products for local use and potential export. The purpose of this investigation was to develop a pasta product using breadfruit flour, test the sensory qualities of the breadfruit pasta product by sensory evaluation, and evaluate the nutritional composition. 'Ma'afala', a popular and widely distributed Polynesian cultivar was used for the study. Nutritional labeling shows that the breadfruit pasta product is high in carbohydrates (73.3%/100 g) and low in fat (8.33/100 g). Sensory evaluation indicates that 80.3% of the panelists (n = 71) found the pasta acceptable while 18.3% disliked the pasta. The breadfruit pasta product can provide a nutritious, appealing and inexpensive gluten-free food source based on locally available breadfruit in areas of the world where it can be easily grown.

A transcriptome screen for positive selection in domesticated breadfruit and its wild relatives (Artocarpus spp.).

PREMISE OF THE STUDY: Underutilized crops, such as breadfruit (Artocarpus altilis, Moraceae) have the potential to improve global food security. Humans have artificially selected many cultivars of breadfruit since its domestication began approximately 3500 years ago. The goal of this research was to identify transcriptomic signals of positive selection and to develop genomic resources that may facilitate the development of improved breadfruit cultivars in the future. METHODS: A reference transcriptome of breadfruit was assembled de novo and annotated. Twenty-four transcriptomes of breadfruit and its wild relatives were generated and analyzed to reveal signals of positive selection that may have resulted from local adaptation or natural selection. Emphasis was placed on MADS-box genes, which are important because they often regulate fruiting timing and structures, and on carotenoid biosynthesis genes, which can impact the nutritional quality of the fruit. KEY RESULTS: Over 1000 genes showed signals of positive selection, and these genes were enriched for localization to plastids. Nucleotide sites and individuals under positive selection were discovered in MADS-box genes and carotenoid biosynthesis genes, with several sites located in cofactor or DNA-binding domains. A McDonald-Kreitman test comparing wild to cultivated samples revealed selection in one of the carotenoid biosynthesis genes, abscisic acid 8'-hydroxylase 3. CONCLUSIONS: This research highlights some of the many genes that may have been intentionally or unintentionally selected for during the human-mediated dispersal of breadfruit and stresses the importance of conserving a varied germplasm collection. It has revealed candidate genes for further study and produced new genomic resources for breadfruit.

Low-coverage, whole-genome sequencing of Artocarpus camansi (Moraceae) for phylogenetic marker development and gene discovery.

PREMISE OF THE STUDY: We used moderately low-coverage (17×) whole-genome sequencing of Artocarpus camansi (Moraceae) to develop genomic resources for Artocarpus and Moraceae. METHODS AND RESULTS: A de novo assembly of Illumina short reads (251,378,536 pairs, 2 × 100 bp) accounted for 93% of the predicted genome size. Predicted coding regions were used in a three-way orthology search with published genomes of Morus notabilis and Cannabis sativa. Phylogenetic markers for Moraceae were developed from 333 inferred single-copy exons. Ninety-eight putative MADS-box genes were identified. Analysis of all predicted coding regions resulted in preliminary annotation of 49,089 genes. An analysis of synonymous substitutions for pairs of orthologs (Ks analysis) in M. notabilis and A. camansi strongly suggested a lineage-specific whole-genome duplication in Artocarpus. CONCLUSIONS: This study substantially increases the genomic resources available for Artocarpus and Moraceae and demonstrates the value of low-coverage de novo assemblies for nonmodel organisms with moderately large genomes.

Preparation of a Breadfruit Flour Bar.

Breadfruit is a nutritious, high energy food with a low quantity of protein but excellent protein quality. It has the potential to be developed into desired products which will help increase its utilization and add value to the crop. The overall purposes of this investigation were to develop a portable, nutritious, ready-to-eat breadfruit product (bar), test the sensory qualities of the product, and evaluate the nutritional properties of the product. Flour made from the Micronesian variety, Meinpadahk (Artocarpus altilis × Artocarpus mariannensis), was utilized for the development of the breadfruit bar. Breadfruit is a rich source of fiber, vitamins such as vitamin C, minerals such as potassium, and phytochemicals such as flavonoids. Nutritional labeling indicates that the breadfruit bar is high in carbohydrates and low in fat, and sensory evaluation indicates that 81% of the panelists found the bar acceptable while 19% disliked the bar. The breadfruit bar can provide an appealing and inexpensive gluten-free food source based on locally available breadfruit.

Chloroplast microsatellite markers for Artocarpus (Moraceae) developed from transcriptome sequences.

PREMISE OF THE STUDY: Chloroplast microsatellite loci were characterized from transcriptomes of Artocarpus altilis (breadfruit) and A. camansi (breadnut). They were tested in A. odoratissimus (terap) and A. altilis and evaluated in silico for two congeners. METHODS AND RESULTS: Fifteen simple sequence repeats (SSRs) were identified in chloroplast sequences from four Artocarpus transcriptome assemblies. The markers were evaluated using capillary electrophoresis in A. odoratissimus (105 accessions) and A. altilis (73). They were also evaluated in silico in A. altilis (10), A. camansi (6), and A. altilis × A. mariannensis (7) transcriptomes. All loci were polymorphic in at least one species, with all 15 polymorphic in A. camansi. Per species, average alleles per locus ranged between 2.2 and 2.5. Three loci had evidence of fragment-length homoplasy. CONCLUSIONS: These markers will complement existing nuclear markers by enabling confident identification of maternal and clone lines, which are often important in vegetatively propagated crops such as breadfruit.

Breadfruit (Artocarpus altilis): a source of high-quality protein for food security and novel food products.

Protein deficiency has been observed as a leading cause of malnutrition and child death in the tropics. The current study evaluated the protein quality of 49 important breadfruit cultivars (41 Artocarpus altilis and 8 hybrids of A. altilis × A. mariannensis). While significant differences were found between cultivars, all varieties contained a full spectrum of the essential amino acids and are especially rich in phenylalanine, leucine, isoleucine, and valine. The cultivar Ma'afala contained significantly higher total essential amino acid content than other varieties and higher-quality protein than staples such as corn, wheat, rice, soybean, potato, and pea.

Development of microsatellite loci in Artocarpus altilis (Moraceae) and cross-amplification in congeneric species.

PREMISE OF THE STUDY: Microsatellite loci were isolated and characterized from enriched genomic libraries of Artocarpus altilis (breadfruit) and tested in four Artocarpus species and one hybrid. The microsatellite markers provide new tools for further studies in Artocarpus. • METHODS AND RESULTS: A total of 25 microsatellite loci were evaluated across four Artocarpus species and one hybrid. Twenty-one microsatellite loci were evaluated on A. altilis (241), A. camansi (34), A. mariannensis (15), and A. altilis × mariannensis (64) samples. Nine of those loci plus four additional loci were evaluated on A. heterophyllus (jackfruit, 426) samples. All loci are polymorphic for at least one species. The average number of alleles ranges from two to nine within taxa. • CONCLUSIONS: These microsatellite primers will facilitate further studies on the genetic structure and evolutionary and domestication history of Artocarpus species. They will aid in cultivar identification and establishing germplasm conservation strategies for breadfruit and jackfruit.

Isolation and identification of mosquito (Aedes aegypti ) biting deterrent fatty acids from male inflorescences of breadfruit (Artocarpus altilis (Parkinson) Fosberg).

Dried male inflorescences of breadfruit ( Artocarpus altilis , Moraceae) are burned in communities throughout Oceania to repel flying insects, including mosquitoes. This study was conducted to identify chemicals responsible for mosquito deterrence. Various crude extracts were evaluated, and the most active, the hydrodistillate, was used for bioassay-guided fractionation. The hydrodistillate and all fractions displayed significant deterrent activity. Exploratory GC-MS analysis revealed more than 100 distinctive peaks, and more than 30 compounds were putatively identified, including a mixture of terpenes, aldehydes, fatty acids, and aromatics. A systematic bioassay-directed study using adult Aedes aegypti females identified capric, undecanoic, and lauric acid as primary deterrent constituents. A synthetic mixture of fatty acids present in the most active fraction and individual fatty acids were all significantly more active than N,N-diethyl-m-toluamide (DEET). These results provide support for this traditional practice and indicate the potential of male breadfruit flowers and fatty acids as mosquito repellents.

Mutualism breakdown in breadfruit domestication.

During the process of plant domestication, below-ground communities are rarely considered. Some studies have attempted to understand the changes in root symbionts owing to domestication, but little is known about how it influences mycorrhizal response in domesticated crops. We hypothesized that selection for above-ground traits may also result in decreased mycorrhizal abundance in roots. Breadfruit (Artocarpus sp.) has a long domestication history, with a strong geographical movement of cultivars from west to east across the Melanesian and Polynesian islands. Our results clearly show a decrease in arbuscular mycorrhizas (AMs) along a domestication gradient from wild to recently derived cultivars. We showed that the vesicular and arbuscular colonization rate decreased significantly in more recently derived breadfruit cultivars. In addition, molecular analyses of breadfruit roots indicated that AM fungal species richness also responded along the domestication gradient. These results suggest that human-driven selection for plant cultivars can have unintended effects on below-ground mutualists, with potential impacts on the stress tolerance of crops and long-term food security.

In vitro conservation and sustained production of breadfruit (Artocarpus altilis, Moraceae): modern technologies for a traditional tropical crop.

Breadfruit (Artocarpus altilis, Moraceae) is a traditionally cultivated, high-energy, high-yield crop, but widespread use of the plant for food is limited by poor quality and poor storage properties of the fruit. A unique field genebank of breadfruit species and cultivars exists at the National Tropical Botanical Garden in the Hawaiian Islands and is an important global resource for conservation and sustainable use of breadfruit. However, this plant collection could be damaged by a random natural disaster such as a hurricane. We have developed a highly efficient in vitro plant propagation system to maintain, conserve, mass propagate, and distribute elite varieties of this important tree species. Mature axillary shoot buds were collected from three different cultivars of breadfruit and proliferated using a cytokinin-supplemented medium. The multiple shoots were maintained as stock cultures and repeatedly used to develop whole plants after root differentiation on a basal or an auxin-containing medium. The plantlets were successfully grown under greenhouse conditions and were reused to initiate additional shoot cultures for sustained production of plants. Flow cytometry was used to determine the nuclear deoxyribonucleic acid content and the ploidy status of the in vitro grown population. The efficacy of the micropropagation protocols developed in this study represents a significant advancement in the conservation and sustained mass propagation of breadfruit germplasm in a controlled environment free from contamination.

Complex origins of breadfruit (Artocarpus altilis, Moraceae): implications for human migrations in Oceania.

Breadfruit (Artocarpus altilis, Moraceae), a traditional starch crop in Oceania, has enjoyed legendary status ever since its role in the infamous mutiny aboard the H.M.S. Bounty in 1789, yet its origins remain unclear. Breadfruit's closest relatives are A. camansi and A. mariannensis. DNA fingerprinting data (AFLP, amplified fragment length polymorphisms) from over 200 breadfruit cultivars, 30 A. camansi, and 24 A. mariannensis individuals were used to investigate the relationships among these species. Multivariate analyses and the identification of species-specific AFLP markers indicate at least two origins of breadfruit. Most Melanesian and Polynesian cultivars appear to have arisen over generations of vegetative propagation and selection from A. camansi. In contrast, most Micronesian breadfruit cultivars appear to be the result of hybridization between A. camansi-derived breadfruit and A. mariannensis. Because breadfruit depends on humans for dispersal, the data were compared to theories on the human colonization of Oceania. The results agree with the well-supported theory that humans settled Polynesia via Melanesia. Additionally, a long-distance migration from eastern Melanesia into Micronesia is supported.