A telomere-to-telomere genome of Manilkara zapota (Chiku) reveals the repeat-mediated genome evolution

Abstract

Manilkara zapota (Chiku) is a tropical fruit tree in the Sapotaceae family. In this study, we assembled the first Telomere-to-telomere (T2T) genome assembly of M. zapota, spanning 1.6 Gb with high contiguity (N50 = 134 Mb). Comparative analysis revealed a very recent divergence and a shared WGD among Sapotaceae members. A newly constructed Ancestral Sapotaceae Karyotype (ASK) suggests a fusion-dominated chromosome structure in the family. The genome exhibits lineage-specific proliferation of transposable elements (TEs) accompanied by a recent burst of LTR-Gypsy elements (∼0.09 mya). Genome-wide methylation profiling revealed elevated CpG and CHG methylation levels and age-dependent reinforcement of TE silencing, suggesting strong epigenetic regulation that stabilises the repeat-rich genome while maintaining gene expression. Collectively, these findings advance our understanding of repeat-rich genome evolution in plants and provide a valuable framework for genomic-assisted breeding in M. zapota.