Abstract Detail

Biotic and abiotic stress

Alber, Nicole [1], Sivanesan, Hampavi [1], Vanlerberghe, Greg [1].

Investigating the role of plant mitochondria in NO synthesis and signalling.

Plant mitochondria are proposed to act as signaling organelles that orchestrate acclimation responses to abiotic and biotic stress. While the primary signals being generated by mitochondria are largely unknown, reactive oxygen and nitrogen species are considered strong candidates. In this study, laser-scanning fluorescence confocal microscopy was used to detect leaf mesophyll nitric oxide (NO) amounts in wild-type and transgenic tobacco plants with varying amounts of mitochondrial alternative oxidase (AOX). AOX knockdowns showed higher amounts of NO than wild-type when treated with inhibitors of Complex III or ATP synthase, but not following treatment with an inhibitor of the TCA cycle enzyme aconitase, suggesting an influence of AOX on NO production under specific mitochondrial dysfunction scenarios. Interestingly, treatment with antimycin A, an inhibitor of the Q_i-site of Complex III, generated much higher NO amounts than treatment with myxothiazol, an inhibitor of the Q_o-site, even though both inhibitors were equally effective at inhibiting oxygen consumption. When both inhibitors were used concurrently, NO amount was similar to that with myxothiazol alone. Plants grown with ammonium instead of nitrate showed no increase in NO when treated with antimycin A or myxothiazol. The levels of NO produced by these plants mimicked those of nitrate grown plants when nitrite was supplied along with the inhibitor treatment. These results suggest that Complex III is a site of normoxic generation of NO in plant mitochondria and that this generation is regulated by AOX amount.

1 - University of Toronto, CSB, 1265 Military Trail, Toronto, Ontario, M1C 1A4, Canada

Keywords:
Nitric Oxide
Mitochondrial alternative oxidase
Antimycin A
Myxothiazol.

Presentation Type: Oral Paper:Papers for Topics
Session: 20
Location: Salon 13/14/The Shaw Conference Centre
Date: Monday, July 27th, 2015
Time: 3:45 PM
Number: 20007
Abstract ID:936
Candidate for Awards:CSPB President's Award for Best Student Presentation