Genome-Wide Analysis of Multiple Organellar RNA Editing Factor (MORF) Family in Kiwifruit (Actinidia chinensis) Reveals Its Roles in Chloroplast RNA Editing and Pathogens Stress

Abstract

Kiwifruit (Actinidia chinensis) 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. Multiple organellar RNA editing factor (MORF) 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 MORF genes in kiwifruit at the genome-wide level, especially those involved in the response to pathogens stress. In this study, we identified ten MORF genes in the kiwifruit genome. The genomic structures and chromosomal locations analysis indicated that all the MORF 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 MORF gene family members were classified into six groups (Groups A–F). A synteny analysis indicated that two pairs of MORF genes were tandemly duplicated and five pairs of MORF genes were segmentally duplicated. Moreover, based on analysis of RNA-seq data from five tissues of kiwifruit, we found that both expressions of MORF genes and chloroplast RNA editing exhibited tissue-specific patterns. MORF2 and MORF9 were highly expressed in leaf and shoot, and may be responsible for chloroplast RNA editing, especially the ndhB genes. We also observed different MORF expression and chloroplast RNA editing profiles between resistant and susceptible kiwifruits after pathogen infection, indicating the roles of MORF 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 MORF genes, in particular, for clarifying the resistance mechanisms in kiwifruits and breeding new cultivars with high resistance.

Decoding RNA Editing Sites Through Transcriptome Analysis in Rice Under Alkaline Stress

“…Latest research reported that MORF involved in plant growth, development, stress response such as survival of seedling rice, drought resistance in poplar, and pathogen resistance in tobacco ( Wang et al, 2019 ; Zhang et al, 2019 ; Yang et al, 2020 ). Our results showed the downregulation of MORF genes under alkaline stress and agreement with the findings of Zhang et al (2019) and Xiong et al (2022) . Similarly, NbMORF8 which is present in the mitochondria and negatively enhance the immunity to Phytophthora pathogens in tobacco ( Yang et al, 2020 ).…”

“…More and more members of PPR proteins are reported but the exact number of involved PPR is still missing ( Schmitz-Linneweber and Small, 2008 ). Similarly, in kiwifruit, MORF2 and MORF9 are well documented; they interact with NADH4 and are very important for RNA editing of chloroplast genome ( Xiong et al, 2022 ) while MORF8 interact with MORF1 and MORF2 ( Zehrmann et al, 2015 ; Huang et al, 2019 ).…”

Genome-wide identification and expression analysis of peach multiple organellar RNA editing factors reveals the roles of RNA editing in plant immunity

“…Many mutants with impaired editing of specific sites exhibited strong deleterious phenotypes, even lethality [ 9 – 12 ]. In our previous studies, we found that the RNA editing events in grapes were reduced in response to heat stress [ 11 ], the RNA editing events in kiwifruits were reduced in response to pathogens infection [ 13 ].…”

Comprehensive Analysis of StSRO Gene Family and Its Expression in Response to Different Abiotic Stresses in Potato

“…When plants are subjected to the stress of abiotic and biotic environments, they can usually adapt to changing and complex environments by inducing the expression of stress genes [ 1 , 2 , 3 ]. Many members of the plants’ gene families were involved in plant-specific development and a series of stresses [ 4 , 5 ]. For example, multiple organellar RNA editing factor ( MORF) genes regulate the plant–pathogen interaction by controlling the extent of RNA editing; growth regulatory factors ( GRF) genes show different expression patterns in different tissues or under drought and salt stress; MaGRAS plays an important role in response to abscisic acid (ABA) and abiotic stress [ 5 , 6 , 7 ].…”

“…Many members of the plants’ gene families were involved in plant-specific development and a series of stresses [ 4 , 5 ]. For example, multiple organellar RNA editing factor ( MORF) genes regulate the plant–pathogen interaction by controlling the extent of RNA editing; growth regulatory factors ( GRF) genes show different expression patterns in different tissues or under drought and salt stress; MaGRAS plays an important role in response to abscisic acid (ABA) and abiotic stress [ 5 , 6 , 7 ]. The SIMILAR-TO-RCD-ONE ( SRO ) plays a vital role in plants coping with abiotic and biotic stresses and participating in growth and development [ 4 , 8 , 9 ].…”