Gene Cloning of the Orange Carotenoid Protein from Cyanobacteria,and Its Ectopic Expression and Functional Evaluation in Escherichia coli Involvement of Singlet Oxygen in the Breakdown of Photosynthetic Pigments in the Leaves of Rice Seedling Exposed to Osmotic Stress and Light Singlet Oxygen Generated in PS¢ò Particles Promotes the Superoxide Generation