Arabidopsis thaliana loss-of-function chloroplast tata mutants display an albino phenotype indicating a chloroplast-only function

Abstract

A functional mitochondrial Tat (mtTat) pathway has been confirmed in plants, but the existence or need for a TatA subunit remains unanswered.

Two competing hypotheses have suggested that either plant mitochondria contain an unusual Tat pathway with no TatA contribution, or the chloroplast TatA (cpTatA) is dually targeted to chloroplasts and mitochondria.

Arabidopsis thaliana cptata loss-of-function mutants display an albino phenotype consistent with a dysfunctional chloroplast Tat pathway with no quantitative impact on mitochondrial complex III biogenesis, reiterating a chloroplast-specific role of cpTatA.

While these findings reject the dual-targeting hypothesis, the roles and components of the plant mitochondrial Tat pathway are yet to be fully elucidated.