Mitochondrial composition, function and stress response in plants.

The primary function of mitochondria is respiration, where catabolism of substrates is coupled to ATP synthesis via oxidative phosphorylation. In plants, mitochondrial composition is relatively complex and flexible and has specific pathways to support photosynthetic processes in illuminated leaves. This review begins with outlining current models of mitochondrial composition in plant cells, with an emphasis upon the assembly of the complexes of the classical electron transport chain (ETC). Next, we focus upon the comparative analysis of mitochondrial function from different tissue types. A prominent theme in the plant mitochondrial literature involves linking mitochondrial composition to environmental stress responses, and this review then gives a detailed outline of how oxidative stress impacts upon the plant mitochondrial proteome with particular attention to the role of transition metals. This is followed by an analysis of the signaling capacity of mitochondrial reactive oxygen species, which studies the transcriptional changes of stress responsive genes as a framework to define specific signals emanating from the mitochondrion. Finally, specific mitochondrial roles during exposure to harsh environments are outlined, with attention paid to mitochondrial delivery of energy and intermediates, mitochondrial support for photosynthesis, and mitochondrial processes operating within root cells that mediate tolerance to anoxia and unfavorable soil chemistries. [Formula: see text] [ A. Harvey Millar (Corresponding author)]