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Mitochondria are essential organelles in cells not only because they supply over 90% of the cell's energy but also because their dysfunction is associated with disease. Owing to the importance of mitochondria, there are many questions about mitochondria that must be answered. Cytoplasmic male sterility (CMS) is a mysterious natural phenomenon, and the mechanism of the origin of CMS is unknown. Despite successful utilization of CMS and restoration of fertility (Rf) in practice, the underlying mechanisms of these processes remain elusive. This review summarizes the genes involved in CMS and Rf, with a special focus on recent studies reporting the mechanisms of the CMS and Rf pathways, and concludes with potential working models., (Copyright © 2014 Elsevier B.V. and Mitochondria Research Society. All rights reserved.)

Summary: The pentatricopeptide repeat (PPR) protein family is a large family characterized by tandem arrays of a degenerate 35‐amino‐acid motif whose members function as important regulators of organelle gene expression at the post‐transcriptional level. Despite the roles of PPRs in RNA editing in organelles, their editing activities and the underlying mechanism remain obscure.Here, we show that a novel DYW motif‐containing PPR protein, PPS1, is associated with five conserved RNA‐editing sites of nad3 located in close proximity to each other in mitochondria, all of which involve conversion from proline to leucine in rice. Both pps1 RNAi and heterozygous plants are characterized by delayed development and partial pollen sterility at vegetative stages and reproductive stage.RNA electrophoresis mobility shift assays (REMSAs) and reciprocal competition assays using different versions of nad3 probes confirm that PPS1 can bind to cis‐elements near the five affected sites, which is distinct from the existing mode of PPR‐RNA binding because of the continuity of the editing sites. Loss of editing at nad3 in pps1 reduces the activity of several complexes in the mitochondrial electron transport chain and affects mitochondrial morphology.Taken together, our results indicate that PPS1 is required for specific editing sites in nad3 in rice. [ABSTRACT FROM AUTHOR]

Katanin, a microtubule-severing enzyme, consists of two subunits: the catalytic subunit P60, and the regulatory subunit P80. In several species, P80 functions in meiotic spindle organization, the flagella biogenesis, the neuronal development, and the male gamete production. However, the P80 function in higher plants remains elusive. In this study, we found that there are three katanin P80 orthologs ( OsKTN80a, OsKTN80b, and OsKTN80c) in Oryza sativa L. Overexpression of OsKTN80a caused the retarded root growth of rice seedlings. Further investigation indicates that the retained root growth was caused by the repressed cell elongation in the elongation zone and the stalled cytokinesis in the division zone in the root tip. The in vivo examination suggests that OsKTN80a acts as a microtubule stabilizer. We prove that OsKTN80a, possibly associated with OsKTN60, is involved in root growth via regulating the cell elongation and division. [ABSTRACT FROM AUTHOR]

Cytoplasmic male sterility ( CMS) has attracted great interest because of its application in crop breeding. Despite increasing knowledge of CMS, not much is understood about its molecular mechanisms. Previously, orf H79 was cloned and identified as the CMS gene in Honglian rice, but how the ORFH79 protein causes pollen abortion is still unknown., Through bacterial two-hybrid library screening, P61, a subunit of the mitochondrial electron transport chain ( ETC) complex III, was selected as a candidate that interacts with ORFH79. Bimolecular fluorescence complementation ( Bi FC) and coimmunoprecipitation (co IP) assays verified their interaction inside mitochondria. Blue native polyacrylamide gel electrophoresis ( BN- PAGE) and western blotting showed ORF79 and P61 colocalized in mitochondrial ETC complex III of CMS lines., Compared with the maintainer line, Yuetai B ( YB), a significant decrease of enzyme activity was detected in mitochondrial complex III of the CMS line, Yuetai A ( YA), which resulted in decreased ATP concentrations and an increase in the reactive oxygen species ( ROS) content., We propose that the CMS protein, ORFH79, can bind to complex III and decrease its enzyme activity through interaction with P61. This defect results in energy production dysfunction and oxidative stress in mitochondria, which may work as retrograde signals that lead to abnormal pollen development. [ABSTRACT FROM AUTHOR]

Rice is one of the most important model crop plants whose heterosis has been well exploited in commercial hybrid seed production via a variety of types of male sterile lines. Hybrid rice cultivation area is steadily expanding around the world, especially in Southern Asia. Characterization of genes and proteins related to male sterility aims to understand how and why the male sterility occurs, and which proteins are the key players for microspores abortion. Recently, a series of genes and proteins related to cytoplasmic male sterility, photoperiod sensitive male sterility, self-incompatibility and other types of microspores deterioration have been characterized through genetics or proteomics. Especially the latter, offers us a powerful and high throughput approach to discern the novel proteins involving in male-sterile pathways which may help us to breed artificial male-sterile system. This represents an alternative tool to meet the critical challenge of further development of hybrid rice. In this paper, we reviewed the recent developments in our understanding of male sterility in rice hybrid production across gene, protein and integrated network levels, and also, present a perspective on the engineering of male sterile lines for hybrid rice production. [ABSTRACT FROM AUTHOR]

Abstract: Cytoplasmic male sterility (CMS) is a phenomenon widely observed in various plant species characterized with disrupted anther development caused by mitochondrial mutation. CMS is becoming a model system for the investigations of nucleus–cytoplasmic interaction. To reveal the possible effects of CMS genes on plant growth in adverse environment, plant development and biochemical characters of mitochondria from Honglian (HL)-CMS line Yuetai A and maintainer Yuetai B treated with H2O2 were analyzed. Results showed that 40–60mM H2O2 significantly inhibits rice seedling development and growth. When treated with H2O2, ATP content and mitochondrial membrane potential in Yuetai A decreased significantly faster than those of Yuetai B. These biochemical changes were accompanied by the severe nuclear DNA fragmentation and the release of mitochondrial cytochrome c in the leaf cells of Yuetai A. In addition, the antioxidative enzyme activities and mitochondrial electron transfer chain complexes were significantly down-regulated. Disturbance of the biochemical indexes indicate that HL-CMS line is more susceptible to H2O2 stress than the maintainer line, the deleterious effects caused by the CMS-related ORFH79 peptide compromises the adaptability of HL-CMS line to the adverse environment. [Copyright &y& Elsevier]