The role of Arabidopsis COX assembly factors in copper homeostasis and stress responses

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

Puerto Madryn

Congreso; 46 Annual Meeting Argentine Society for Biochemistry and Molecular Biology; 2010

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB)

Cytochrome c oxidase (CcO) requires copper (Cu) as a cofactor for its activity. Recent findings have proposed that mitochondrial proteins involved in CcO assembly may have additional functions in plants. In this work, we overexpressed (OE) three CcO assembly factors, COX17-1, COX17-2 and COX19, to investigate their role in Cu homeostasis and the oxidative response. The expression of miR398 and Cu transporters was increased in OECox17-2 and OECox19, suggesting the existence of a Cu-deficiency response, although Cu levels were not significantly modified. Plants showed a decrease in the number and size of rosette leaves, in cell size and in plant height, inhibition of root growth and a delayed germination time. Some of these phenotypes were reversed by the inclusion of Cu in the growth medium. Total dark respiration was similar to wild-type, but the alternative respiratory pathway activity and transcript levels of the alternative oxidase gene AOX1a were increased in OECox17-2. OECox19 and OECox17-1 showed a significant decrease in transcript levels of BCS1, encoding a mitochondrial protein responsive to oxidative stress. Altered transcriptional responses of AOX1a, BCS1 and the ferritin gene FER1 were observed under stress conditions. The results suggest that Cox17-2 and Cox19 participate in Cu homeostasis and that the three proteins influence the response of the plant to stress.