Effects of knockout of CO2-responsive CCT protein, a regulator of starch synthesis on physiological characteristics of rice

Abstract

ABSTRACTCO2-Responsive CCT Protein (CRCT) is suggested to be a positive regulator of starch synthesis-related genes in the vegetative organs of rice. To investigate the physiological function of CRCT, we produced CRCT knockout lines by CRISPR/Cas9 system. CRCT knockout tended to slightly reduce photosynthetic performance and had some adverse effects on growth parameters such as tiller number and straw dry weight. The starch content in the leaf sheath of CRCT knockout lines was significantly lower than that of wild-type. qRT-PCR and RNA-seq analysis showed that sucrose treatment induced the expression of CRCT, which, in turn, induced many starch synthesis-related genes in wild-type, whereas this induction did not occur in CRCT knockout lines. In conclusion, our results suggest that sugar induction of starch synthesis-related genes is almost fully dependent on CRCT, making it a necessary factor for normal photosynthesis and growth of rice.

Keywords

• CCT Protein
• growth
• photosynthesis
• Rice (oryza sativa)
• sugar response
• starch