Transcriptomic and physiological analysis of OsCAO1 knockout lines using the CRISPR/Cas9 system in rice

Area of Science:

• Plant genetics
• Molecular biology
• Agricultural science

Background:

• Rice chlorophyllide a oxygenase (OsCAO1) is crucial for chlorophyll b synthesis and photosynthesis.
• Understanding OsCAO1's role is key to manipulating rice plant development and senescence.

Purpose of the Study:

• To generate and characterize rice lines with altered leaf color by knocking out the OsCAO1 gene.
• To investigate the effects of OsCAO1 knockout on plant physiology, gene expression, and grain quality.

Main Methods:

• CRISPR/Cas9 gene editing technology was employed to generate OsCAO1 knockout lines.
• Phenotypic analysis, chlorophyll and carotenoid content measurement, and transcriptome analysis were performed.
• Agronomic traits including leaf morphology and grain quality were evaluated.

Main Results:

• Eighty-one edited rice lines with pale green, short, narrow leaves were successfully generated.
• Edited lines exhibited reduced chlorophyll b and carotenoid levels.
• Transcriptome analysis revealed significant changes in genes related to chlorophyll biosynthesis and metabolism.
• Grain quality traits such as gel consistency and chalkiness were improved in edited lines.

Conclusions:

• Knocking out the OsCAO1 gene significantly alters rice leaf color and affects chlorophyll degradation and ROS scavenging.
• OsCAO1 plays a vital role in regulating both natural and induced senescence in rice.
• OsCAO1 knockout influences rice growth period, leaf development, and grain quality, offering potential for crop improvement.