AtNDB2 Is the Main External NADH Dehydrogenase in Mitochondria and Is Important for Tolerance to Environmental Stress

Abstract

In addition to the classical electron transport pathway coupled to ATP synthesis, plant mitochondria have an alternative pathway that involves type II NAD(P)H dehydrogenases (NDs) and alternative oxidase (AOX). This alternative pathway participates in thermogenesis in select organs of some species and is thought to help prevent cellular damage during exposure to environmental stress. Here, we investigated the function and role of one alternative path component, AtNDB2, using a transgenic approach in Arabidopsis (Arabidopsis thaliana). Disruption of AtNDB2 expression via T-DNA insertion led to a 90% decrease of external NADH oxidation in isolated mitochondria. Overexpression of AtNDB2 led to increased AtNDB2 protein abundance in mitochondria but did not enhance external NADH oxidation significantly unless AtAOX1A was concomitantly overexpressed and activated, demonstrating a functional link between these enzymes. Plants lacking either AtAOX1A or AtNDB2 were more sensitive to combined drought and elevated light treatments, whereas plants overexpressing these components showed increased tolerance and capacity for poststress recovery. We conclude that AtNDB2 is the predominant external NADH dehydrogenase in mitochondria and together with AtAOX1A forms a complete, functional, nonphosphorylating pathway of electron transport, whose operation enhances tolerance to environmental stress. This study demonstrates that at least one of the alternative NDs, as well as AOX, are important for the stress response.

Phylogenomic proof of Recurrent Demipolyploidization and Evolutionary Stalling of the “Triploid Bridge” in Arundo (Poaceae)

“…macrophylla branches have a potentially adaptive value. One of those, OG0018204 is predicted to encode the nuclear core subunit of NADH dehydrogenase (ubiquinone) flavoprotein 1, a protein of the mitochondrial respiratory chain reducing ubiquinone by NADH [ 39 ], suggesting that adaptive variations in oxidative phosphorylation efficiency could have taken place during the evolution of A. donaciformis following demipolyploidization. The strongest evidence of selection intensification in A. donaciformis was, however, found in OG0018069, a homolog of BIP2, an Arabidopsis heat shock 70 kDa protein localized in the ER lumen [ 40 ].…”

Alternative Respiratory Pathway Component Genes (AOX and ND) in Rice and Barley and Their Response to Stress

“…The sequences were aligned using the Clustal program. Substrate specificity is given on the right for each enzyme that has been experimentally determined [ 10 , 39 , 42 ]. Residues are Δ, basic or hydrophilic; □, hydrophobic; ө, acidic; and G, Glycine.…”

Genomics Armed With Diversity Leads the Way in Brassica Improvement in a Changing Global Environment

“…Induced mt modifications restored fertility without causing noticeable phenotypic changes and were found to be stable and maternally inherited. The successful modifications of the mt genome pose the prospect of “mitochondrial breeding” in plants (Kazama et al, 2019 ), which can play an important role in the study and future conditioning of plant responses toward climate change (Budar and Roux, 2011 ; Sweetman et al, 2019 ; Florez-Sarasa et al, 2020 ). TALENs similar to ZFNs are time-consuming genome manipulation techniques (Razzaq et al, 2019 ) and require the extensive screening of large numbers of manipulated individuals.…”