Two haplotype-resolved genome assemblies for AAB allotriploid bananas provide insights into banana subgenome asymmetric evolution and Fusarium wilt control

Bananas(Musa spp.)are one of the world’s most important fruit crops and play a vital role in food security for many developing countries.Most banana cultivars are triploids derived from inter-and intraspecific hybrid-izations between the wild diploid ancestor species Musa acuminate(AA)and M.balbisiana(BB).We report two haplotype-resolved genome assemblies of the representative AAB-cultivated types,Plantain and Silk,and precisely characterize ancestral contributions by examining ancestry mosaics across the genome.Widespread asymmetric evolution is observed in their subgenomes,which can be linked to frequent homol-ogous exchange events.We reveal the genetic makeup of triploid banana cultivars and verify that subge-nome B is a rich source of disease resistance genes.Only 58.5%and 59.4%of Plantain and Silk genes,respectively,are present in all three haplotypes,with>50%of genes being differentially expressed alleles in different subgenomes.We observed that the number of upregulated genes in Plantain is significantly higher than that in Silk at one-week post-inoculation with Fusarium wilt tropical race 4(Foc TR4),which con-firms that Plantain can initiate defense responses faster than Silk.Additionally,we compared genomic and transcriptomic differences among the genes related to carotenoid synthesis and starch metabolism between Plantain and Silk.Our study provides resources for better understanding the genomic architecture of culti-vated bananas and has important implications for Musa genetics and breeding.

Two gap-free reference genomes and a global view of the centromere architecture in rice

Rice(Oryza sativa),a major staple throughout the world and a model system for plant genomics and breeding,was the first crop genome sequenced almost two decades ago.However,reference genomes for all higher organisms to date contain gaps and missing sequences.Here,we report the assembly and analysis of gap-free reference genome sequences for two elite O.sativa xian/indica rice varieties,Zhenshan 97 and Minghui 63,which are being used as a model system for studying heterosis and yield.Gap-free reference genomes provide the opportunity for a global view of the structure and function of centromeres.We show that all rice centromeric regions share conserved centromere-specific satellite motifs with different copy numbers and structures.In addition,the similarity of CentO repeats in the same chromosome is higher than across chromosomes,supporting a model of local expansion and homogenization.Both genomes have over 395 non-TE genes located in centromere regions,of which∼41%are actively transcribed.Two large structural variants at the end of chromosome 11 affect the copy number of resistance genes between the two genomes.The availability of the two gap-free genomes lays a solid foundation for further understanding genome structure and function in plants and breeding climate-resilient varieties.

GenomeSyn:a bioinformatics tool for visualizing genome synteny and structural variations

Advances in the next-generation and long-read sequencing technologies have promoted the development of genome-wide comparative genomics analysis,and constructing pangenomes and identifying structural variations(SVs)are becoming the frontier of genomics.Comparative genomics is of critical importance for determining the gene function and the evolutionary basis of traits.

Citrus Pan-Genome to Breeding Database(CPBD):A comprehensive genome database for citrus breeding

Dear Editor,The genus Citrus comprises more than 30 species worldwide(Swingle,1943).However,citrus genetics and traditional breeding are hindered due to asexual reproduction,long generation time,and empirical utilization of the germplasm.The whole-genome information of different citrus species accelerates the genetic studies and improves the breeding efficiency by high-density markers.