The physiological role of mitochondrial ADNT1 carrier during senescence in Arabidopsis

Abstract

The Adenine Nucleotide Transporter 1 (ADNT1) carrier resides in the mitochondrial inner membrane of plants. Unlike other ADP/ATP carriers, ADNT1 mediates preferably an exchange of mitochondrial matrix ATP by cytosolic AMP, and, to a lesser extent, cytosolic ADP. Because we have previously demonstrated that ADNT1 expression is stronger in senescing tissues, we investigated here the role of ADNT1 carrier during natural and dark-induced senescence in Arabidopsis thaliana. ADNT1 deficient lines displayed an early onset of developmental senescence during both natural and dark-induced senescence. In agreement, moderate loss of chlorophyll content and a reduced PSII photochemical efficiency (Fv/Fm) was observed in the ADNT1 deficient lines at the end of an extended period of darkness. Despite these changes, minor alterations in the levels of sucrose and protein were observed in the ADNT1 deficient lines during dark treatment. However, the levels of a few amino acids as well as the tricarboxylic acid cycle intermediates correlated with ADNT1 expression mainly at the end of dark treatment. Altogether, these results demonstrate that the physiological influence of the AMP/ATP transporter ADNT1 increases during the natural aging and in the later stages of extended darkness treatment. Our data suggest that proper expression of the ADNT1 is important in plant senescence.