title: Importance of ascorbate peroxidases OsAPX1 and OsAPX2 in the rice pathogen response pathways and growth and reproduction revealed by their transcriptional profiling.
abstract: We have identified and characterized two rice ascorbate peroxidase (OsAPX1 and OsAPX2) genes against diverse signals known to involve in defense/stress responses, using "2-week-old rice seedling in vitro model system". Oryza sativa ascorbate peroxidase 1 and 2 (OsAPX1/2) share 83% similarity to each other at amino acid level and belong to a small gene family in the rice genome. OsAPX1/2 show a weak constitutive expression in leaves. Their transcripts were up-regulated upon wounding (by cut), and diverse signals such as salicylic acid (SA), ethylene (using the ethylene generator, ethephon), abscisic acid (ABA), hydrogen peroxide, copper sulfate, protein phosphatase (PP) inhibitors, cantharidin (CN), endothall (EN) and okadaic acid (OA), and blast pathogen (Magnaporthe grisea) attack, but surprisingly not by jasmonic acid (JA). Interestingly, the OsAPX2 inductions were more potent and rapid than OsAPX1, whose expression increased gradually with time. These inductions were influenced by light signal(s), and showed requirement for certain de novo synthesized protein factor(s). Intriguingly, OsAPX1/2 mRNAs expression manifested a clear rhythmicity under light/dark cycle. Differential regulation of the OsAPX1/2 expressions by diverse environmental cues, including pathogen, and their developmental regulation in both young and reproductive stages strongly suggests their role in stress-signaling pathways and development in rice.
authors.affiliation: Research Laboratory for Agricultural Biotechnology and Biochemistry, GPO Box 8207, Kathmandu, Nepal. gkagrawal@onebox.com
authors.forename: Ganesh Kumar
authors.initials: GK
authors.lastname: Agrawal
authors.forename: Nam Soo
authors.initials: NS
authors.lastname: Jwa
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Iwahashi
authors.forename: Randeep
authors.initials: R
authors.lastname: Rakwal
mesh_terms: D000595:Amino Acid Sequence; D060387:Ascorbate Peroxidases; D002940:Circadian Rhythm; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D007527:Isoenzymes / Q000235:genetics* / Q000378:metabolism; D020082:Magnaporthe / Q000254:growth & development; D008969:Molecular Sequence Data; D012275:Oryza / Q000235:genetics* / Q000254:growth & development / Q000382:microbiology; D010544:Peroxidases / Q000235:genetics* / Q000378:metabolism; D010802:Phylogeny; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012098:Reproduction / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction / Q000235:genetics; D014158:Transcription, Genetic
chemical_list: D007527:Isoenzymes; D012333:RNA, Messenger; D010544:Peroxidases; D060387:Ascorbate Peroxidases