How do plants make mitochondria?

Abstract

Plant mitochondria can diVer in size, shape, number and protein content across diVerent tissue types and over development. These diVerences are a result of signaling and regulatory processes that ensure mitochondrial function is tuned in a cell-speciWc manner to support proper plant growth and development. In the last decade, the processes involved in mitochondrial biogenesis are becoming clearer, including; how dormant seeds transition from empty promitochondria to fully functional mitochondria with extensive cristae structures and various biochemical activities, the regulation of nuclear genes encoding mitochondrial proteins via regulators of the diurnal cycle in plants, the mitochondrial stress response, the targeting of proteins to mitochondria and other organelles and connections between the respiratory chain and protein import complexes. All these Wndings indicate that mitochondrial function is a part of an integrated cellular network, and communication between mitochondria and other cellular processes extends beyond the known exchange or transport of metabolites. Our current knowledge now needs to be used to gain more insight into the molecular components at various levels of this hierarchical and complex regulatory and communication network, so that mitochondrial function can be predicted and modiWed in a rational manner.

Chloroplast Signaling in Plants

“…Inhibitors that specifically block chloroplast biogenesis induced diverse expression patterns in genes that encode mitochondrial proteins (Ruckle et al 2012). A loss-of-function mutation in mitochondrial ALTERNATIVE OXI-DASE (AOX)1a downregulated the expression of PhANGs (Carrie et al 2013). These findings are consistent with complex interactions between chloroplasts and mitochondria.…”

“…ABI4 helps to downregulate the expression of Lhcb1.2 by binding CCAC elements in the promoter of Lhcb1.2 (section "Loss-of-Function Alleles of GUN1 Broadly Disrupt Plastid Signaling"). ABI4 was also found to upregulate ALTERNATIVE OXIDASE1a (AOX1a) expression that is induced by mitochondria-to-nucleus signaling by binding to CACC and CCAC elements in the AOX1a promoter (Carrie et al 2013).…”

Fission and Fusion of Plant Mitochondria, and Genome Maintenance

“…Several factors are involved in mitochondrial biogenesis, including gene expression in the nucleus and mitochondria and protein import from the cytosol to the mitochondria. These processes are covered in some excellent recent reviews (Millar et al, 2008;Carrie et al, 2013;Law et al, 2014;Czarna et al, 2016). Here, I focus on recent investigations of the fission and fusion of plant mitochondria and its relatedness to their genome maintenance.…”

Mitochondrial Proteome Studies in Seeds during Germination

“…Numerous studies on biogenesis of mitochondria in seeds support rather the maturation model of mitochondrial biogenesis during germination [10,11,12,13]. It is proposed that biogenesis of mitochondria during germination starts from the development of structurally simple and metabolically/energetically quiescent promitochondria existing in dry mature seeds into fully active and cristae-containing organelles [4,14]. This transition is accompanied by sequential and dynamic gene expression, protein turnover, and post-translational modifications.…”