Genome-Wide Analysis of Multiple Organellar RNA Editing Factor Family in Poplar Reveals Evolution and Roles in Drought Stress

Abstract

Poplar (Populus) is one of the most important woody plants worldwide. Drought, a primary abiotic stress, seriously affects poplar growth and development. Multiple organellar RNA editing factor (MORF) genes—pivotal factors in the RNA editosome in Arabidopsis thaliana—are indispensable for the regulation of various physiological processes, including organelle C-to-U RNA editing and plasmid development, as well as in the response to stresses. Although the poplar genome sequence has been released, little is known about MORF genes in poplar, especially those involved in the response to drought stress at the genome-wide level. In this study, we identified nine MORF genes in the Populus genome. Based on the structural features of MORF proteins and the topology of the phylogenetic tree, the P. trichocarpa (Ptr) MORF family members were classified into six groups (Groups I–VI). A microsynteny analysis indicated that two (22.2%) PtrMORF genes were tandemly duplicated and seven genes (77.8%) were segmentally duplicated. Based on the dN/dS ratios, purifying selection likely played a major role in the evolution of this family and contributed to functional divergence among PtrMORF genes. Moreover, analysis of qRT-PCR data revealed that PtrMORFs exhibited tissue- and treatment-specific expression patterns. PtrMORF genes in all group were involved in the stress response. These results provide a solid foundation for further analyses of the functions and molecular evolution of MORF genes in poplar, and, in particular, for improving the drought resistance of poplar by genetics manipulation.

Characterization, Expression, and Interaction Analyses of OsMORF Gene Family in Rice

“…In A. thaliana , MORF proteins can form homodimers and heterodimers that participate in RNA editing [5,14]. Although the MORF genes were reported to respond to abiotic stress in poplar, few reports have been published on the functions of OsMORFs and their responses to abiotic stress in rice [3]. In this study, we provide further insight into the structure of the OsMORF genes family, its tissue expression patterns, and responses to cold and salt stresses, as well as the interactions between OsMORF proteins.…”

“…RNA editing is relatively conserved among flowering plants, with types of base conversion including A-to-I, U-to-C, and C-to-U [2]. Among these conversions, the predominant form in plastids and the mitochondria is C-to-U [2,3]. Previous studies showed that there are 30–40 and 400–500 C-to-U conserved RNA editing sites in chloroplasts and mitochondria, respectively, in flowering plants [1,4].…”

“…Previous studies showed that there are 30–40 and 400–500 C-to-U conserved RNA editing sites in chloroplasts and mitochondria, respectively, in flowering plants [1,4]. In plants, the RNA editing sites are recognized by trans-regulatory elements, followed by the catalysis of base conversion [1,3]. The trans-regulatory elements include organelle RNA recognition motif proteins (ORRM), organelle zinc-finger proteins (OZ), protoporphyrinogen oxidase 1 (PPO1), pentatricopeptide repeat proteins (PPR), multiple organellar RNA editing factor (MORF) family proteins also call RNA editing factor interacting protein (RIP) [1,3,5].…”

“…In plants, the RNA editing sites are recognized by trans-regulatory elements, followed by the catalysis of base conversion [1,3]. The trans-regulatory elements include organelle RNA recognition motif proteins (ORRM), organelle zinc-finger proteins (OZ), protoporphyrinogen oxidase 1 (PPO1), pentatricopeptide repeat proteins (PPR), multiple organellar RNA editing factor (MORF) family proteins also call RNA editing factor interacting protein (RIP) [1,3,5]. Studies have shown that ORRM1 is necessary for plastid RNA editing, whereas ORRM2, ORRM3, ORRM4, and ORRM5 can influence RNA editing in mitochondria [5].…”

“…Moreover, in rice, wsp1 had reduced chlorophyll accumulation in leaves and showed a phenotype of white immature panicles [18]. Furthermore, in poplar, it has been reported that the PtrMORF genes respond to drought [3].…”