Coordination of plant mitochondrial biogenesis: keeping pace with cellular requirements

Plant mitochondria are complex organelles that carry out numerous metabolic processes related with the generation of energy for cellular functions and the synthesis and degradation of several compounds. Mitochondria are semiautonomous and dynamic organelles changing in shape, number, and composition depending on tissue or developmental stage. The biogenesis of functional mitochondria requires the coordination of genes present both in the nucleus and the organelle. In addition, due to their central role, all processes held inside mitochondria must be finely coordinated with those in other organelles according to cellular demands. Coordination is achieved by transcriptional control of nuclear genes encoding mitochondrial proteins by specific transcription factors that recognize conserved elements in their promoter regions. In turn, the expression of most of these transcription factors is linked to developmental and environmental cues, according to the availability of nutrients, light?dark cycles, and warning signals generated in response to stress conditions. Among the signals impacting in the expression of nuclear genes, retrograde signals that originate inside mitochondria help to adjust mitochondrial biogenesis to organelle demands. Adding more complexity, several nuclear encoded proteins are dual localized to mitochondria and either chloroplasts or the nucleus. Dual targeting might establish a crosstalk between the nucleus and cell organelles to ensure a fine coordination of cellular activities. In this article, we discuss how the different levels of coordination of mitochondrial biogenesis interconnect to optimize the function of the organelle according to both internal and external demands.Fil: Welchen, Elina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Agrobiotecnologia del Litoral; Argentina. Universidad Nacional del Litoral. Facultad de Bioquimica y Ciencias Biologicas. Departamento de Ciencias Biologicas. Catedra de Biologia Celular y Molecular; ArgentinaFil: García, Lucila. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Agrobiotecnologia del Litoral; Argentina. Universidad Nacional del Litoral. Facultad de Bioquimica y Ciencias Biologicas. Departamento de Ciencias Biologicas. Catedra de Biologia Celular y Molecular; ArgentinaFil: Mansilla, Natanael. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Agrobiotecnologia del Litoral; Argentina. Universidad Nacional del Litoral. Facultad de Bioquimica y Ciencias Biologicas. Departamento de Ciencias Biologicas. Catedra de Biologia Celular y Molecular; ArgentinaFil: Gonzalez, Daniel Hector. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Agrobiotecnologia del Litoral; Argentina. Universidad Nacional del Litoral. Facultad de Bioquimica y Ciencias Biologicas. Departamento de Ciencias Biologicas. Catedra de Biologia Celular y Molecular; Argentin

Differential chromatin binding preference is the result of the neo-functionalization of the TB1 clade of TCP transcription factors in grasses

The understanding of neo-functionalization of plant transcription factors (TFs) after gene duplication has been extensively focused on changes in protein–protein interactions, the expression pattern of TFs, or the variation of cis-elements bound by TFs. Yet, the main molecular role of a TF, that is, its specific chromatin binding for the direct regulation of target gene expression, continues to be mostly overlooked. Here, we studied the TB1 clade of the TEOSINTE BRANCHED 1, CYCLOIDEA, PROLIFERATING CELL FACTORS (TCP) TF family within the grasses (Poaceae). We identified an Asp/Gly amino acid replacement within the TCP domain, originated within a paralog TIG1 clade exclusive for grasses. The heterologous expression of Zea mays TB1 and its two paralogs BAD1 and TIG1 in Arabidopsis mutant plants lacking the TB1 ortholog BRC1 revealed distinct functions in plant development. Notably, the Gly acquired in the TIG1 clade does not impair TF homodimerization and heterodimerization, while it modulates chromatin binding preferences. We found that in vivo TF recognition of target promoters depends on this Asp/Gly mutation and directly impacts downstream gene expression and subsequent plant development. These results provided new insights into how natural selection fine-tunes gene expression regulation after duplication of TFs to define plant architecture.Fil: Mansilla, Natanael. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; ArgentinaFil: Fonouni-farde, Camille Audrey. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; ArgentinaFil: Ariel, Federico Damian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; ArgentinaFil: Lucero, Leandro Exequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentin

The lncRNA APOLO and the transcription factor WRKY42 target common cell wall EXTENSIN encoding genes to trigger root hair cell elongation

Plant long noncoding RNAs (lncRNAs) are key chromatin dynamics regulators, directing the transcriptional programs driving a wide variety of developmental outputs. Recently, we uncovered how the lncRNA AUXIN REGULATED PROMOTER LOOP (APOLO) directly recognizes the locus encoding the root hair (RH) master regulator ROOT HAIR DEFECTIVE 6 (RHD6) modulating its transcriptional activation and leading to low temperature-induced RH elongation. We further demonstrated that APOLO interacts with the transcription factor WRKY42 in a novel ribonucleoprotein complex shaping RHD6 epigenetic environment and integrating signals governing RH growth and development. In this work, we expand this model showing that APOLO is able to bind and positively control the expression of several cell wall EXTENSIN (EXT) encoding genes, including EXT3, a key regulator for RH growth. Interestingly, EXT3 emerged as a novel common target of APOLO and WRKY42. Furthermore, we showed that the ROS homeostasis-related gene NADPH OXIDASE C (NOXC) is deregulated upon APOLO overexpression, likely through the RHD6-RSL4 pathway, and that NOXC is required for low temperature-dependent enhancement of RH growth. Collectively, our results uncover an intricate regulatory network involving the APOLO/WRKY42 hub in the control of master and effector genes during RH development.Fil: Martinez Pacheco, Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Mansilla, Natanael. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; ArgentinaFil: Moison, Michael. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; ArgentinaFil: Lucero, Leandro Exequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; ArgentinaFil: Berdion Gabarain, Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Ariel, Federico Damian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; ArgentinaFil: Estevez, Jose Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentina. Universidad Andrés Bello; Chile. Millennium Institute for Integrative Biology; Chil

Arabidopsis SCO Proteins Oppositely Influence Cytochrome c Oxidase Levels and Gene Expression during Salinity Stress

SCO proteins are involved in the insertion of copper during the assembly of cytochrome c oxidase (COX), the final enzyme of the mitochondrial respiratory chain. Two SCO proteins, named HCC1 and HCC2, are present in seed plants, but HCC2 lacks the residues involved in copper binding, leading to uncertainties about its function. In this work, we performed a transcriptomic and phenotypic analysis of Arabidopsis thaliana plants with reduced expression of HCC1 or HCC2. We observed that a deficiency in HCC1 causes a decrease in the expression of several stress-responsive genes, both under basal growth conditions and after applying a short-term high salinity treatment. In addition, HCC1 deficient plants show a faster decrease in chlorophyll content, photosystem II quantum efficiency, and COX levels after salinity stress, as well as a faster increase in alternative oxidase capacity. Notably, HCC2 deficiency causes opposite changes in most of these parameters. Bimolecular fluorescence complementation analysis indicated that both proteins are able to interact. We postulate that HCC1 is a limiting factor for COX assembly during high salinity conditions and that HCC2 probably acts as a negative modulator of HCC1 activity through protein-protein interactions. In addition, a direct or indirect role of HCC1 and HCC2 in the gene expression response to stress is proposed.Fil: Mansilla, Natanael. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; ArgentinaFil: Welchen, Elina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; ArgentinaFil: Gonzalez, Daniel Hector. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentin

Arabidopsis thaliana SURFEIT1-like genes link mitochondrial function to early plant development and hormonal growth responses

Mutations in SURFEIT1 (SURF1) genes affect cytochrome c oxidase (COX) levels in different prokaryotic and eukaryotic organisms. In this work, we report that Arabidopsis thaliana has two genes that potentially encode SURF1 proteins, as a result of a duplication that took place in Brassicaceae. Both genes encode mitochondrial proteins and mutation in AtSURF1a causes embryonic lethality. Mutation in AtSURF1b, instead, causes defects in hypocotyl elongation under growth-stimulating conditions, such as low light intensity, increased ambient temperature and incubation with glucose. Mutants in AtSURF1b show reduced expression of the auxin reporter DR5:GUS and increased levels of the gibberellin reporter GFP-RGA, suggesting that auxin and gibberellin homeostasis are affected. In agreement, growth defects caused by AtSURF1b mutation can be overcome by treatment with indole-3-acetic acid and gibberellin A3, and also by increasing expression of the auxin biosynthesis gene YUC8 or the transcription factor PIF4, which shows lower abundance in AtSURF1b-deficient plants. Mutants in AtSURF1b display lower COX levels, higher alternative oxidase and superoxide levels, and increased expression of genes that respond to mitochondrial dysfunction. Decreased hypocotyl growth and DR5:GUS expression can be reversed by treatment with reduced glutathione, suggesting that redox changes, probably related to mitochondrial dysfunction, are responsible for the effect of AtSURF1b deficiency on hormone responses. The results indicate that changes in AtSURF1b affect mitochondrial function and the production of reactive oxygen species, which, in turn, impinges on a growth regulatory circuit that involves auxin, gibberellins and the transcription factor PIF4.Fil: Gras, Diana Ester. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; ArgentinaFil: Mansilla, Natanael. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; ArgentinaFil: Rodriguez, Carina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; ArgentinaFil: Welchen, Elina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; ArgentinaFil: Gonzalez, Daniel Hector. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentin

BREVIPEDICELLUS/KNAT1 targets TCP15 to modulate filament elongation during Arabidopsis late stamen development

The Arabidopsis homeodomain protein BREVIPEDICELLUS/KNAT1 represses the expression of the gene encoding the transcription factor TCP15 to limit filament growth at late stages of stamen development.Fil: Gastaldi, Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; ArgentinaFil: Alem, Antonela Lucía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; ArgentinaFil: Mansilla, Natanael. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; ArgentinaFil: Ariel, Federico Damian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; ArgentinaFil: Viola, Ivana Lorena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; ArgentinaFil: Lucero, Leandro Exequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; ArgentinaFil: Gonzalez, Daniel Hector. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentin