| Citrus is rich in vitamin C,which has high nutritional value and economic value,and its cultivation area and production rank first all over the world.In recent years,the whole genome sequencing of citrus has been completed,but gene functional research is relatively backward,especially biotic or abiotic stress.Therefore,the study of citrus ankyrin repeat and cytophilic protein gene family can not only predict the function of gene family members,but also provide theoretical basis for the functional identification and species evolution researchIn the paper,we performed the genome-wide analysis of the ankyrin repeat and cyclophilin gene families in C.Clementina and C.sinensis.Based on the composition and arrangement of domains,we divided the ankyrin and cyclophilin gene family members into different subfamilies.Then,we identified the distribution of ANK genes in the chr omosomes of Citrus,reconstructed orthologous genes and gene clusters,and predicted the potential function of citrus ankyrin and cyclophilin genes by differential expression in Citrus tissues The research results as follow(1)We identified 192 and 205 ANK genes in Citrus clementina and Citrus sinensis,respectively.Based on the pattern of protein domains in ANK genes,we classified citrus ANK genes into 11 subfamilies.We found that subfamilies ANK-M,ANK-TM and ANK-BTB have significantly expanded in citrus genomes.The phylogenetic analysis of these ANK genes showed that there are five evolutionary groups of ANK genes.We partitioned ANK genes into clades and found most clades include ANK genes from both Citrus genomes.This suggests that two Citrus genomes have similar numbers and types of ANK genes.Meanwhile,although we found 26 and 28 ANK gene clusters in C.clementina and C.sinensis,respectively,only gene cluster is completely conserved.This result implied the expansion of ANK genes may be resulted from independent evolutionary events in C.clementina and C.sinensis.Furthermore,we compared the gene expressions of ANK genes in C.clementina and C.sinensis,and found that about one third of orthologous ANK genes differentially expressed between fruit and flower of C.clementina and C.sinensis;and most of them were highly expressed in the fruit and flower of C.clementina.These ANKs showed different gene expression patterns in different tissues and the ANK genes with the highest expression in different tissues of C.Clementina and C.sinensis were related to embryo development,germination,leaf morphology,plant height,flowering time,cold sensitivity,injury response,salt tolerance and disease resistance.These ANK genes may play an important role in biotic or abiotic stress response in Citrus.(2)We identified 30 and 32 cyclophilin genes(CYPs)in Citrus clementina and C.sinensis,respectively.Based on the pattern of the protein domains,we could classify these 62 CYPs into 7 subfamilies.The results of phylogenetic analysis of these CYPs showed that CYPs originally containing only cyclophilin domain,and gradually differentiated into multidomain genes.All branches in the phylogenetic tree containing the C.clementina cyclophilin gene(CcCYP)and the C.sinensis cyclophilin gene(CsCYP),indicating that they may have been separated before species differentiation.A total of 27 cis-regulatory element are expressed in the promoter analysis,it indicates that the CYP gene may play an important regulatory role in jasmonic acid,abscisic acid and light response.CYPs in Citrus tend to be distributed in clusters and we could identify 2 and 2 CYP clusters in C.clementina and C.sinensis,respectively.Among cyclophilin genes,26 orthologous pairs were conserved in C.clementina and C.sinensis.These CYPs showed different gene expression patterns in different tissues and the CYP genes with the highest expression in different tissues of C.clementina and C.sinensis were related to immunosuppression,protein transport,root growth and light regulation.These CYPs may play an important role in biological process in Citrus. |
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