Genetic Diversity of Bangladeshi Jackfruit (Artocarpus heterophyllus) over Time and Across Seedling Sources

Crop genetic diversity is important, but may be lost due to intentional or non-intentional selection processes. Jackfruit ( Artocarpus heterophyllus ) is the national fruit of Bangladesh, where it displays great morphological diversity, but recent work suggests diversity may be declining. This study tests whether genetic diversity is changing over time and investigates a possible cause—a shift from direct seed planting by tree owners to purchasing seed-propagated saplings from nurseries, a method that has increased in popularity since the 1980s. We measure genetic diversity over time (across both reported tree age and tree size classes) using 13 microsatellite loci for 361 jackfruit individuals collected throughout Bangladesh. We find downward trends in diversity over time (regardless of seedling source), and no change in diversity between owner seed-propagated and nursery seed-propagated sapling trees that were planted since the early 1980s. Jackfruit, long an important crop in South and Southeast Asia, is gaining global popularity. Because it is a long-lived, out-crossing crop, changes in genetic diversity may occur gradually, and locally adapted alleles could be lost in transitioning to commercialized uniform cultivars. It is important to measure and conserve diversity baselines before selection bottlenecks occur in underutilized crops, like jackfruit, on the verge of increased industrialization.