Silencing of mitochondrial uncoupling protein gene aggravates chilling stress by altering mitochondrial respiration and electron transport in tomato

Mitochondrial uncoupling proteins (UCPs) play crucial role in the regulation of metabolic thermogenesis, photosynthesis, redox poise, and response to stress situations. However, the involvements UCPs and its regulatory mechanisms in plant mitochondrial respiration and electron transport have not yet been fully substantiated. In this article, we show that UCP is essential for effective respiratory balance and mitochondrial electron transport poise under chilling stress in tomato. Compared with pTRV (non-silenced) plants, suppression of LeUCP the expression by virus-induced gene silencing significantly decreased the total, SHAM-resistant, and CN-resistant respiratory rates, but increased cytosolic glycolysis pathway-related gene expression and enzymes’ activities under chilling stress. The transcripts’ abundances of UCRH, COX1, COX2, AOX1a, AOX2, and NDC1 genes involved in main and bypass miETC components were decreased, while those of NDUO and SDH4 were slightly increased in the leaves of LeUCP-silenced plants. In addition, silencing of LeUCP aggravated H2O2 and O2 − accumulation levels in leaves under chilling stress. Our results provide strong evidence that LeUCP is critical for respiratory homeostasis and mitochondrial electron transport signaling under chilling stress in tomato.