A High-quality Genome Assembly of Annona squamosa (Custard Apple) Provides Functional Insights into an Emerging Fruit Crop

Abstract

Annona squamosa, also known as custard apple, is an emerging fruit crop with medicinal significance. We constructed a high-quality genome of A. squamosa along with transcriptome data to gain insights into its phylogeny, evolution and demographic history. The genome has an N50 value of 93.2 Mb assembled into seven pseudochromosomes. The demographic history showed a continuous decline in the effective population size of A. squamosa. Phylogenetic analysis revealed that magnoliids were sister to eudicots, whereas ASTRAL gene trees showed discordance due to incomplete lineage sorting (ILS). Genome syntenic and Ks distribution analyses confirmed the absence of a recent whole genome duplication event in the A. squamosa. Gene families related to photosynthesis, oxidative phosphorylation and plant thermogenesis were found to be highly expanded in the genome. Comparative analysis with other magnoliids revealed the adaptative evolution in the genes of flavonoid biosynthesis pathway, amino sugar, nucleotide sugar and sucrose metabolism, conferring medicinal value and enhanced hexose sugar accumulation. In addition, we performed genome-wide identification of SWEET genes. Our high-quality genome and evolutionary insights of this emerging fruit crop, thus, serve as a valuable resource for advancing studies in functional genomics, evolutionary biology, and crop improvement.