Releasing a sugar brake generates sweeter tomato without yield penalty

Area of Science:

• Plant Biology
• Genetics
• Agricultural Science

Background:

• Consumer preference for tomatoes is strongly linked to higher sugar content.
• Commercial tomato varieties often have low sugar due to an inverse relationship between sugar and fruit size.
• Growers typically prioritize fruit yield over flavor quality.

Purpose of the Study:

• To identify genes controlling fruit sugar content in tomatoes.
• To investigate the role of SlCDPK27 and SlCDPK26 in regulating sugar accumulation.
• To explore methods for enhancing tomato sweetness without compromising yield or size.

Main Methods:

• Identification and characterization of two tomato calcium-dependent protein kinase genes: SlCDPK27 and SlCDPK26.
• Gene editing (knockout) of SlCDPK27 and SlCDPK26 in tomato plants.
• Analysis of sugar content (glucose and fructose) in gene-edited and wild-type tomatoes.
• Evaluation of fruit weight, yield, seed characteristics, and germination in mutant lines.

Main Results:

• SlCDPK27 and SlCDPK26 were identified as key regulators of tomato fruit sugar content.
• These genes function as 'sugar brakes' by phosphorylating and promoting the degradation of sucrose synthase.
• Gene-edited knockouts of SlCDPK27 and SlCDPK26 resulted in up to a 30% increase in glucose and fructose.
• Enhanced sweetness was achieved without any negative impact on fruit weight or overall yield.
• Mutant lines showed reduced seed count and lighter seeds but maintained normal germination.

Conclusions:

• SlCDPK27 and SlCDPK26 play a crucial role in the regulatory mechanisms of fruit sugar accumulation in tomatoes.
• Targeting these genes offers a viable strategy to increase sugar content in large-fruited tomato cultivars.
• This research provides a pathway to improve tomato flavor quality without sacrificing commercially important traits like size and yield.