1.A Chromosome-level Genome Assembly of Wild Castor Provides New Insights into Its Adaptive Evolution in Tropical Desert
Lu JIANJUN ; Pan CHENG ; Fan WEI ; Liu WANFEI ; Zhao HUAYAN ; Li DONGHAI ; Wang SEN ; Hu LIANLIAN ; He BING ; Qian KUN ; Qin RUI ; Ruan JUE ; Lin QIANG ; Lü SHIYOU ; Cui PENG
Genomics, Proteomics & Bioinformatics 2022;20(1):42-59
Wild castor grows in the high-altitude tropical desert of the African Plateau,a region known for high ultraviolet radiation,strong light,and extremely dry condition.To investigate the potential genetic basis of adaptation to both highland and tropical deserts,we generated a chromosome-level genome sequence assembly of the wild castor accession WT05,with a genome size of 316 Mb,a scaffold N50 of 31.93 Mb,and a contig N50 of 8.96 Mb,respectively.Compared with cultivated castor and other Euphorbiaceae species,the wild castor exhibits positive selection and gene family expansion for genes involved in DNA repair,photosynthesis,and abiotic stress responses.Genetic variations associated with positive selection were identified in several key genes,such as LIG1,DDB2,and RECGI,involved in nucleotide excision repair.Moreover,a study of genomic diversity among wild and cultivated accessions revealed genomic regions containing selection signatures associated with the adaptation to extreme environments.The identification of the genes and alleles with selection signatures provides insights into the genetic mechanisms under-lying the adaptation of wild castor to the high-altitude tropical desert and would facilitate direct improvement of modern castor varieties.
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