Genomic structure and expression of alternative oxidase genes in legumes

• Published in: Plant, cell and environment Vol. 42; no. 1; pp. 71 - 84
• Main Authors: Sweetman, Crystal, Soole, Kathleen L., Jenkins, Colin L.D., Day, David A.
• Format: Journal Article
• Language: English
• Published: United States Wiley Subscription Services, Inc 01.01.2019
• Subjects: Alternative oxidase; Biological evolution; Chickpeas; Cicer - enzymology; Cicer - genetics; Cicer - metabolism; Electrophoresis, Polyacrylamide Gel; Environmental stress; Gene expression; Gene Expression Regulation, Plant; Genes; Genes, Plant - genetics; Genomes; Immunoblotting; Isoforms; Legumes; Mitochondria; Mitochondria - enzymology; Mitochondria - metabolism; Mitochondrial Proteins - genetics; Mitochondrial Proteins - metabolism; Organs; Oxidase; oxidative stress; Oxidoreductases - genetics; Oxidoreductases - metabolism; Oxygen Consumption; Photosynthesis; Plant Proteins - genetics; Plant Proteins - metabolism; Plant tissues; Proteins; respiration; Reverse Transcriptase Polymerase Chain Reaction; Soybeans; legumes; respiration; mitochondria; alternative oxidase; oxidative stress
• DOI: 10.1111/pce.13161
• ISSN: 0140-7791

Mitochondria isolated from chickpea (Cicer arietinum) possess substantial alternative oxidase (AOX) activity, even in non‐stressed plants, and one or two AOX protein bands were detected immunologically, depending on the organ. Four different AOX isoforms were identified in the chickpea genome: CaAOX1 and CaAOX2A, B and D. CaAOX2A was the most highly expressed form and was strongly expressed in photosynthetic tissues, whereas CaAOX2D was found in all organs examined. These results are very similar to those of previous studies with soybean and siratro. Searches of available databases showed that this pattern of AOX genes and their expression was common to at least 16 different legume species. The evolution of the legume AOX gene family is discussed, as is the in vivo impact of an inherently high AOX capacity in legumes on growth and responses to environmental stresses. Many legumes have a distinct pattern of AOX gene composition and expression, with multiple isoforms of AOX2, at least one of which is strongly expressed constitutively and another strongly expressed in photosynthetic tissues. This is in contrast to most other species where AOX1 isoforms are predominantly expressed, usually in a stress‐induced manner, and raises questions about the role of AOX in legumes and its impact on plant growth and performance.