Knocking out a negative regulator of photosynthesis 1 (NRP1) increases rice leaf photosynthesis and biomass production in the field

Improving photosynthesis is a major approach to increase crop yield potential. Here we report a negative transcription factor of photosynthesis, which can be manipulated to increase rice photosynthesis and plant biomass in the field. This transcription factor named negative regulator of photosynthesis 1 (NRP1) (Os07g0471900) which was identified through a co-expression analysis using rice leaf RNA sequencing (RNA-seq) data. The NRP1 showed significantly negative correlation with the expression of many genes involved in photosynthesis. Knocking out NPR1 led to greater photosynthesis and increased biomass in the field, while overexpression of NRP1 decreased photosynthesis and biomass. Transcriptomic data analysis shows that NRP1 can negatively regulate the expression of photosynthetic genes. Protein transactivation experiments show that NRP1 is a transcription activator, implying that NRP1 may indirectly regulate photosynthesis gene expression through an unknown regulator. This study shows that combination of bioinformatics analysis with transgenic testing can be used to identify new regulators to improve photosynthetic efficiency in crops. Overall design: For gene expression profiling, we took the leaf samples at the early heading stage. 3 replications of the top second leaves for WT, the OE lines (OE-2, OE-3, OE-4) and the CRISPR lines (C-13, C-14, C-16) were harvested in the field at about 9:00 a.m.