背景回顾：The flowering plant family Annonaceae includes important commercially grown tropical crops, but development of promising species is hindered by a lack of genomic resources to build breeding programs. Annonaceae are part of the magnoliids, an ancient lineage of angiosperms for which evolutionary relationships with other major clades remain unclear. 

主要研究：To provide resources to breeders and evolutionary researchers, we report a chromosome‐level genome assembly of the soursop (Annona muricata). 

结果1-组装：We assembled the genome using 444.32 Gb of DNA sequences (676× sequencing depth) from PacBio and Illumina short‐ eads, in combination with 10× Genomics and Bionano data (v1). A total of 949 scaffolds were assembled to a final size of 656.77 Mb, with a scaffold N50 of 3.43 Mb (v1), and then further improved to seven pseudo‐chromosomes using Hi‐C sequencing data (v2; scaffold N50: 93.2 Mb, total size in chromosomes: 639.6 Mb).

结果2-注释：Heterozygosity was very low (0.06%), while repeat sequences accounted for 54.87% of the genome, and 23,375 protein‐coding genes with an average of 4.79 exons per gene were annotated using de novo, RNA‐seq and homology‐ased approaches. 

结果3-历史有效群体大小估计：Reconstruction of the historical population size showed a slow continuous contraction, probably related to Cenozoic climate changes.

结论：The soursop is the first genome assembled in Annonaceae, supporting further studies of floral evolution in magnoliids, providing an essential resource for delineating relationships of ancient angiosperm lineages. Both genome‐assisted improvement and conservation efforts will be strengthened by the availability of the soursop genome. As a community resource, this assembly will further strengthen the role of Annonaceae as model species for research on the ecology, evolution and domestication potential of tropical species in pomology and agroforestry.

 摘 要 

有花植物番荔枝科（Annonaceae）包括很多商业化种植的热带作物，但由于缺乏基因组资源以建立育种项目，有关该植物的进一步研究和利用受到严重阻碍。番荔枝科是木兰类植物中的一支，而木兰类植物是被子植物最早分化的支系之一，与其它被子植物主要类群之间的系统发育关系仍然存在争议。为了给育种工作者和植物演化研究者提供遗传资源，本文作者报道了刺果番荔枝（Annona muricata）的染色体级别基因组组装。作者通过676×的Pacbio和Illumina数据，结合10× Genomics和Bionano数据，组装了刺果番荔枝的基因组。作者共获得了949个scaffolds，大小约656.77 Mb，scaffold N50长3.43 Mb。作者进一步基于Hi-C数据，获得了刺果番荔枝的7个拟染色体组装，总大小639.6 Mb。作者发现刺果番荔枝的杂合度很低，仅为0.06%，重复序列占整个基因组的54.87%；另外，通过从头预测、RNA-seq以及同源预测，作者共注释了23375个蛋白编码基因，每个平均有4.79个外显子。通过重建历史有效群体大小，作者发现刺果番荔枝的历史群体在缓慢持续性收缩，这可能与新生代气候变化有关。刺果番荔枝是番荔枝科第一个报道基因组的物种，支持木兰类植物花演化的进一步研究，为揭示古代被子植物谱系的关系提供了必要的资源。刺果番荔枝的基因组将有助于加强刺果番荔枝的基因组辅助改良和保护工作。本文所报道的刺果番荔枝基因组将会进一步加强番荔枝科作为模式物种，在果树学和农林业中研究热带物种生态、演化及驯化潜力的作用。