| Summary: | Kiwifruit (<i>Actinidia chinensis</i>) is well known for its high vitamin C content and good taste. Various diseases, especially bacterial canker, are a serious threat to the yield of kiwifruit. <i>Multiple organellar RNA editing factor</i> (<i>MORF</i>) genes are pivotal factors in the RNA editosome that mediates Cytosine-to-Uracil RNA editing, and they are also indispensable for the regulation of chloroplast development, plant growth, and response to stresses. Although the kiwifruit genome has been released, little is known about <i>MORF</i> genes in kiwifruit at the genome-wide level, especially those involved in the response to pathogens stress. In this study, we identified ten <i>MORF</i> genes in the kiwifruit genome. The genomic structures and chromosomal locations analysis indicated that all the <i>MORF</i> genes consisted of three conserved motifs, and they were distributed widely across the seven linkage groups and one contig of the kiwifruit genome. Based on the structural features of MORF proteins and the topology of the phylogenetic tree, the kiwifruit <i>MORF</i> gene family members were classified into six groups (Groups A–F). A synteny analysis indicated that two pairs of <i>MORF</i> genes were tandemly duplicated and five pairs of <i>MORF</i> genes were segmentally duplicated. Moreover, based on analysis of RNA-seq data from five tissues of kiwifruit, we found that both expressions of <i>MORF</i> genes and chloroplast RNA editing exhibited tissue-specific patterns. <i>MORF2</i> and <i>MORF9</i> were highly expressed in leaf and shoot, and may be responsible for chloroplast RNA editing, especially the <i>ndhB</i> genes. We also observed different <i>MORF</i> expression and chloroplast RNA editing profiles between resistant and susceptible kiwifruits after pathogen infection, indicating the roles of <i>MORF</i> genes in stress response by modulating the editing extend of mRNA. These results provide a solid foundation for further analyses of the functions and molecular evolution of <i>MORF</i> genes, in particular, for clarifying the resistance mechanisms in kiwifruits and breeding new cultivars with high resistance.
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