AtCOX17, a copper chaperone involved in COX biogenesis, mediates stress responses in Arabidopsis

GARCÍA LUCILA; COLOMBATTTI, FRANCISCO; WELCHEN ELINA; GONZALEZ, DANIEL H.

Congreso; 8vo International Conference in Plant Mitochondrial Biology; 2013

COX17 is a protein involved in cytochrome c oxidase (COX) biogenesis providing copper ions for incorporation into the COX2 subunit in yeast. We studied the function of AtCOX17-1 and AtCOX17-2, two Arabidopsis genes that encode proteins with similarity to the yeast copper chaperone using artificial microRNAs to silence their expression in plants. Copper content is increased in these plants, which also show repression of the low copper-responsive miR398. This is mediated by SQUAMOSA PROMOTER BINDING PROTEIN-LIKE7 (SPL7), a known regulator of copper deficiency responses. AtCOX17 silenced plants show increased sensitivity to salt stress, as evidenced by higher lipid peroxidation and decreased chlorophyll content under these conditions. Silenced plants also show altered expression of stress-responsive genes involved in alternative respiratory pathways (AOX1a and NDB2) and lower transcript levels of antioxidant enzymes (CAT3, APX1, ASO). AtCOX17 expression is increased in mutants in ABSCISIC ACID INSENSITIVE4 (ABI4), a transcription factor that also regulates AOX1a expression. Moreover, Arabidopsis plants over-expressing AtCOX17 show decreased sensitivity to salt stress and increased transcript levels of AOX1a. Our findings suggest that AtCOX17 mediates the response of plants to environmental cues.