| Rice (Oryza sativa) is a semiaquatic plant which is able to survive submergence for a certain period of time through initiation of a number of metabolic pathways. We characterized and cloned the isocitrate lyase (ICL) and malate synthase (MS) genes, which encode two key enzymes in glyoxylate cycle. The results revealed that the expressions of Icl and Ms were both transciptionally activated under submergence. The expressions of Icl and Ms were also activated under acetaldehyde stress, indicating that glyoxylate cycle was induced by acetaldehyde other than low oxygen. In addition, we characterized and cloned two rice acetyl-coenzymeA synthetase genes, OsAcs2 and OsAcs4, and found that OsAcs4 was poorly expressed in all detected tissues, but its mRNAs accumulated at high level after treated with submergence or with acetaldehyde stress. We also identified that the expression of acetaldehyde dehydrogenase2a (ALDH2a) was increased under submergence or acetaldehyde stress, suggesting a co-regulation of ALDH, ACS and glyoxylate cycle in the reactions for coverting acetaldehyde into less toxic intermetabolites. OsAcs2 was highly expressed in all detected tissues, but not perticularly corresponding to the submergence and acetaldehyde stress. Retroposition is a shot-gun strategy of the genome to achieve evolutionary diversities by mixing and matching coding sequences with novel regulatory elements. We have identified 69 retroposons in the Arabidopsis genome by a computational approach. Most of them were derivatives of mature mRNAs, and 20 genes contained relics of the reverse transcription process, such as truncations, deletions and extra sequence additions. Of them, 22 are processed pseudogenes, and 52 genes are likely to be actively transcribed, especially in tissues from apical meristems (roots and flowers). Functional compositions of these retroposon parental genes imply that not...
|
PDF Full Text Request