Transcriptome and Metabolite Profiling of Tomato SGR-Knockout Null Lines Using the CRISPR/Cas9 System

Area of Science:

• Plant Biology
• Molecular Genetics
• Biochemistry

Background:

• The Stay-green 1 (SGR1) protein regulates chlorophyll degradation and leaf senescence in plants.
• The specific role of SGR1 in tomato (Solanum lycopersicum) remains unclear.
• Understanding SGR1 function is crucial for managing fruit ripening and plant longevity.

Purpose of the Study:

• To investigate the function of tomato SGR1 by creating a knockout (KO) line.
• To identify molecular pathways affected by SGR1 disruption using transcriptomic and metabolomic analyses.
• To elucidate the role of SGR1 in pigment biosynthesis and plant metabolism.

Main Methods:

• Generated a SGR1-knockout (KO) null tomato line using CRISPR/Cas9 gene editing.
• Performed RNA sequencing to identify differentially expressed genes (DEGs).
• Conducted gas chromatography-tandem mass spectrometry to analyze metabolite changes.

Main Results:

• The SGR1-KO null line exhibited a turbid brown fruit color with elevated chlorophyll and carotenoid levels compared to wild-type (WT).
• Identified 728 DEGs between WT and SGR1-KO lines, with significant alterations in photosynthesis, chloroplast, and carotenoid biosynthesis genes.
• Observed accumulation of primary metabolites like sucrose, fructose, glucose, and malate in SGR1-KO leaves and fruit.

Conclusions:

• The SGR1-KO null lines provide critical insights into the mechanisms of SGR1 action.
• Demonstrated SGR1's role in regulating pigment content and its impact on plant metabolic pathways.
• Established the involvement of SGR1 in photosynthesis, chloroplast function, and carotenoid biosynthesis in tomatoes.