Identified trans-splicing of YELLOW-FRUITED TOMATO 2 encoding the PHYTOENE SYNTHASE 1 protein alters fruit color by...

Area of Science:

• Plant genetics
• Molecular biology
• Fruit development

Background:

• Fruit color is a critical trait in tomato (Solanum lycopersicum), influencing quality and economic value.
• The genetic basis of fruit color variation, particularly in cherry tomato, is complex and not fully understood.
• PHYTOENE SYNTHASE 1 (PSY1) is a key enzyme in carotenoid biosynthesis, essential for fruit pigmentation.

Purpose of the Study:

• To elucidate the genetic mechanism underlying the yellow fruit color in a cherry tomato mutant (yft2).
• To identify the specific gene responsible for altered fruit color and understand its mode of action.
• To provide new insights into the molecular regulation of carotenoid biosynthesis and fruit color development in tomato.

Main Methods:

• Map-based cloning to identify the YFT2 gene locus.
• Functional complementation assays to validate gene function.
• RNA sequencing and RACE (Rapid Amplification of cDNA Ends) to analyze gene expression and transcript structure.
• Analysis of carotenoid accumulation and gene expression in wild-type and mutant lines.

Main Results:

• The yellow fruit color in yft2 was controlled by a single recessive gene, YFT2, mapped to chromosome 3.
• The candidate gene PHYTOENE SYNTHASE 1 (PSY1) was identified, but no mutation was found in its coding region in yft2.
• A novel trans-splicing event in the YFT2 gene of yft2 resulted in a longer transcript (LT-YFT2) and significantly reduced YFT2 expression.
• This trans-splicing event led to down-regulated carotenoid biosynthesis and altered fruit color, with YFT2 exhibiting feed-forward regulation.

Conclusions:

• Trans-splicing of the YFT2 gene is the primary cause of altered tomato fruit color in the yft2 mutant.
• This post-transcriptional modification impacts carotenoid accumulation and fruit pigmentation.
• The findings reveal a novel mechanism in fruit color development and highlight the role of alternative splicing in gene regulation.