Abstract:

The gene encoding sorghum NADP malic enzyme, which plays a key role in C₄ photosynthetic pathway, was isolated by RT-PCR and cDNA library screening. The 2 139 bp cDNA sequence obtained includes a 1 911-bp open reading frame that encodes 636 amino acids and a terminating codon (GenBank accession number: AY274836). It was then introduced into Nongken 58, a rice variety, using an Agrobacterium-mediated system. Southern hybridization, Northern hybridization and enzyme activity determination all confirmed the effective expression of sorghum (Sorghum vulgare L.) C₄ type NADP-ME in rice, with the enzyme activity being elevated 1–7 folds. However, no appreciable change was demonstrated in carbon assimilation of the transgenic rice though increased photoinhibition was noted under high light intensity.

Key words: NADP malic enzyme (NADP-ME), sorghum, transgenic rice, physiology of photosynthesis