Manipulation of alternative oxidase can influence salt tolerance in Arabidopsis thaliana.
The growth and development of plants can be limited by environmental stresses such as salinity. It has been suggested that the non-phosphorylating alternative respiratory pathway in plants, mediated by the NAD(P)H dehydrogenase [NAD(P)H DH] and alternative oxidase (AOX), is important during environmental stresses. The involvement of this alternative pathway in a stress response may be linked to its capacity to uncouple carbon metabolism from adenylate control and/or the minimization of the formation of destructive reactive oxygen species (ROS). Salinity stress is a widespread, adverse environmental stress, which leads to an ionic imbalance, hyperosmotic stress and oxidative stress, the latter being the result of ROS formation. In this study, we show that salinity stress of Arabidopsis thaliana plants resulted in the formation of ROS, increased levels of Na+ in both the shoot and the root and an increase in transcription of Ataox1a, Atndb2 and Atndb4 genes, indicating the formation of an abridged non-phosphorylating electron transport chain in response to salinity stress. Furthermore, plants constitutively over-expressing Ataox1a, with increased AOX capacity, showed lower ROS formation, 30-40% improved growth rates and lower shoot Na+ content compared with controls, when grown under salinity stress conditions. Thus, more active AOX in roots and shoots can improve the salt tolerance of Arabidopsis as defined by its ability to grow more effectively in the presence of NaCl, and maintain lower shoot Na+ content. AOX does have an important role in stress adaptation in plants, and these results provide some validation of the hypothesis that AOX can play a critical role in cell re-programming under salinity stress.
Smith
Chevaun Anne
CA
School of Biological Sciences, Flinders University, GPO Box 2100, Adelaide 5001, South Australia, Australia.
Melino
Vanessa Jane
VJ
Sweetman
Crystal
C
Soole
Kathleen Lydia
KL
D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D004579:Electron Transport / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D024101:Mitochondrial Proteins; D009252:NADPH Dehydrogenase / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D010940:Plant Proteins; D018517:Plant Roots / Q000187:drug effects / Q000378:metabolism; D018520:Plant Shoots / Q000187:drug effects / Q000378:metabolism; D011188:Potassium / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D055049:Salt Tolerance / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D012964:Sodium / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology; D013312:Stress, Physiological / Q000187:drug effects / Q000235:genetics; D014158:Transcription, Genetic / Q000187:drug effects; D000099188:Alternative Oxidase
D024101:Mitochondrial Proteins; D009252:NADPH Dehydrogenase; D010088:Oxidoreductases; D010940:Plant Proteins; D011188:Potassium; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D012964:Sodium; D012965:Sodium Chloride; D000099188:Alternative Oxidase