Evaluation of Physico-Chemical and Genetic Diversity of Jackfruit (Artocarpus heterophyllus) Germplasm Available in the South-Western Region of Bangladesh

Abstract

Jackfruit (Artocarpus heterophyllus Lam.), being a highly cross-pollinated crop, possesses considerable variation in fruit characteristics. The present study was undertaken to assess the natural variability in the physico-chemical and genetic characteristics of jackfruit germplasm (Gp) from the south-western region of Bangladesh. Significant variation in physico-chemical characteristics of jackfruit was observed among the 75 germplasm. In the case of physical traits, higher variability was observed for characteristics such as rachis weight (25.73%), rachis length (11.65%), skin weight (9.09%), skin thickness (11.99%), and spine length (8.13%), while other parameters showed moderate variation. Among the biochemical characteristics, a high coefficient of variation was recorded for ascorbic acid (13.86%) and carotenoid (8.54%) contents. Moderate variation was observed for carbohydrate (5.27%) and flavonoid (3.92%) contents, while other parameters showed little variation. The highest (7.7 mg/100 g) and lowest (3.21 mg/100 g) ascorbic acid contents were recorded in Gp29 and Gp16, respectively. The highest and lowest carotenoid contents were observed in Gp15 (0.787 mg/100 g) and Gp35 (0.157 mg/100 g), respectively. Genetic diversity among 60 jackfruit germplasm was evaluated using four primers, which produced 33 unambiguous, readable, and reproducible DNA bands. An average of 8.25 bands was obtained per primer, with band sizes ranging from 100 bp to 7.5 kb. Of the 33 bands, 21 (63.63%) were polymorphic, while 12 (36.36%) were monomorphic among the 60 germplasm. The distance matrix obtained through UPGMA analysis and the dendrogram showed similarity among the variants ranging from 60.4% to 98.3%, indicating their close relationships. A lower genetic distance coefficient (<2%) was found among Gp4, Gp5, Gp7, Gp20, Gp18, Gp19, Gp46, and Gp47. The dendrogram cluster analysis separated all 60 germplasm into two clusters at a distance coefficient of 0.13. The highest genetic distance coefficient (1.2%) was observed between Gp24 and the other germplasm in the multiple sub-clusters, indicating a diverse genetic relationship at a linkage distance of 1.0%. Cluster 1 contained only Gp24, while Cluster 2 contained the remaining 59 germplasm and was further separated into two sub-clusters, in which Gp53, Gp54, and Gp56 formed a clade. The lowest diversity value of 0.017 indicated high similarity between Gp7 and Gp20. The genetic distance index between Gp27 and Gp53 was the highest, with a value of 0.396. The present study revealed high to moderate physico-chemical diversity and low to moderate genetic diversity among the jackfruit germplasm. These findings provide useful information for the selection of jackfruit germplasm for crop improvement.