ES7 Functions in Nitrogen Metabolism and Chlorophyll Synthesis in Rice

Glutamate synthase (GOGAT) is a key enzyme for nitrogen metabolism and ammonium assimilation in plants. Recently, researchers from the China National Rice Research Institute identified and characterized an early senescence 7 (es7) rice mutant and aimed to characterize the function of the rice gene, ES7.

The leaves of the es7 mutant begin to senesce at the tillering stage, about 60 days after sowing, and become increasingly senescent as the plants develop at the heading stage. However, when es7 plants are grown under high CO₂ conditions, the senescence phenotype and chlorophyll content are rescued. Analysis showed that senescence-associated genes were significantly upregulated in the es7 mutant.

Scientists then identified the ES7 gene, which encodes a ferredoxin-dependent glutamate synthase (Fd-GOGAT). ES7 is expressed constitutively, and its protein was localized in the chloroplast. Further analysis revealed that several genes related to nitrogen metabolism were differentially expressed while chlorophyll synthesis-associated genes were significantly downregulated in the mutant rice plant.

These results demonstrate that ES7 is involved in nitrogen metabolism and affects chlorophyll synthesis. It may also be associated with photorespiration, thus, affecting leaf senescence in rice.

For more on this study, read the article in Plant Science.