Chromosome-Scale Cerasus humilis Genome Assembly Reveals Gene Family
Evolution and Possible Genomic Basis of Calcium Accumulation in Fruits
Abstract
Chinese dwarf cherry (Cerasus humilis), which is well known as “calcium
fruit” for its high calcium content, is widely utilized in North China
for its ecological and economical value. Understanding the evolutionary
history and genetic basis underlying the calcium accumulation in this
fruit is a fundamental goal in comparative genomics. In this study, we
obtained a chromosome-scale C. humilis genome for the cultivar
“zhisha” using PacBio and Proximo Hi-C technologies. The final
assembled genome lengths were 235.41 Mb with an N50 contig length of
3.23 Mb. The genome contained 26,800 protein-coding genes, while 41.33%
of the genome length consisted of TEs. Phylogenetic analysis revealed
that C. humilis displayed a close relationship with Prunus and
phylogenetically diverged from its common ancestor ~23.2
million years ago (MYA). Functional enrichment of expanded gene families
in C. humilis genome highlighted genes involved in signal transduction,
antiporter activity, polygalacturonase activity, auxin efflux
transmembrane transporter activity, and auxin efflux, which is related
to calcium transport and distribution. Phylogenetic analysis coupled
with tissue-specific expression patterns indicated that PSGs identified
in this study, such as WAK2 and CBL10, may also be responsible for the
high Ca2+ accumulation ability in C. humilis. These results glean
tremendous insight into the fundamental genetic basis of the high
calcium content in C. humilis fruit. In addition, the reference C.
humilis genome we present in this study will be valuable resources for
breeding of this fruit species and molecular evolution analysis with
related species.