RRC ID 4049
Author Lunde C, Baumann U, Shirley NJ, Drew DP, Fincher GB.
Title Gene structure and expression pattern analysis of three monodehydroascorbate reductase (Mdhar) genes in Physcomitrella patens: implications for the evolution of the MDHAR family in plants.
Journal Plant Mol. Biol.
Abstract The ascorbate-glutathione pathway plays a major role in the detoxification of reactive oxygen species (ROS) in vascular plants. One of the key enzymes in this pathway is monodehydroascorbate reductase (MDHAR), a FAD enzyme that catalyses the reduction of the monodehydroascorbate radical. To elucidate the evolution and functional role of MDHAR we identified and characterised MDHARs from the moss Physcomitrella patens. Expressed sequence tag (EST) databases containing approximately 100.000 ESTs from Physcomitrella were searched and three isoforms of monodehydroascorbate reductase (PpMDHAR1, PpMDHAR2 and PpMDHAR3) were identified. In vascular plants MDHAR is found in the cytosol, chloroplast, mitochondria and peroxisome. Surprisingly, all three PpMDHARs resembled the cytosolic isoforms from vascular plants lacking the NH(2)-terminal or COOH-terminal extension found in organelle targeted MDHARs. The number and position of introns was also conserved between PpMDHARs and cytosolic MDHARs from vascular plants. Phylogenetic analysis revealed that cytosolic MDHARs are monophyletic in origin and the ancestral gene evolved before the divergence of bryophytes more than 400 million years ago. Transcript analyses showed that expression of PpMdhar1 and PpMdhar3 was increased up to 5-fold under salt stress, osmotic stress or upon exposure to abscisic acid. In contrast, PpMdhar transcription levels were unchanged upon chilling, UV-B exposure or oxidative stress. The conservation of cytosolic MDHAR in the land-plant lineage and the transcriptional upregulation under water deficiency suggest that the evolution of cytosolic MDHAR played an essential role in stress protection for land plants when they inhabited the dry terrestrial environment.
Volume 60(2)
Pages 259-75
Published 2006-1
DOI 10.1007/s11103-005-3881-8
PMID 16429263
MeSH Amino Acid Sequence Base Sequence Bryopsida / enzymology Bryopsida / genetics* DNA, Plant Evolution, Molecular* Gene Expression Regulation, Enzymologic* Gene Expression Regulation, Plant* Molecular Sequence Data NADH, NADPH Oxidoreductases / chemistry NADH, NADPH Oxidoreductases / genetics* Phylogeny Promoter Regions, Genetic Sequence Homology, Amino Acid Sequence Homology, Nucleic Acid
IF 3.543
Times Cited 25
Arabidopsis / Cultured plant cells, genes pdp01778 pdp04463 pdp17834 pdp21517 pdp26665 pdp33985 pdp34716 pdp37441 pdp38825 pdp40062 pdp45399