Developmental stage-dependent differential gene expression of superoxide dismutase isoenzymes and their localization and physical interaction network in rice (Oryza sativa L.)

Superoxide dismutase (SOD) isoenzymes are essential for scavenging excess reactive oxygen species in living organisms. So far, expression pattern of SOD isoenzymes genes along leaf development plus their sub-cellular localization and physical interaction network have not yet been clearly elucidated. Using multiple bioinformatics tools, we predicted the sub-cellular localizations of SOD isoforms and described their physical interactions in rice. Using in silico approaches, we obtained several evidences for existence of seven SOD genes and a SOD copper chaperone gene. Their transcripts were differentially expressed along with different developmental stage of rice leaf. Finally, we performed quantitative real time-polymerase chain reaction (qRT-PCR) to validate in silico differential expression pattern of SOD genes experimentally. Expression of two cytosolic cCuZn-SODs was high during the whole vegetative stage. Two plastidic Fe-SODs were found and their expression levels were very low and started to increase from the late vegetative stage. Their expression patterns were very similar to each other, indicating the formation of heterodimer. However, their expression patterns are different from those for ArabidopsisFe-SODs. The expression of pCuZn-SOD was very high in the early developmental stage, but qRT-PCR results were different, which remains for further study. From the results on the differential expression of SOD genes, we can understand the role of each SOD gene and even predict their role under certain circumstances based on in silico analysis.