Variation in the flowering gene SELF PRUNING 5G promotes day-neutrality and early yield in tomato

Zachary Lippman, José Jiménez-Gómez and colleagues show that cultivated tomatoes have lost day-length-sensitive flowering, compared to their wild relatives, as a result of cis -regulatory variation affecting expression of SP5G , a paralog of the florigen gene SFT . They engineered SP5G loss-of-function mutant plants, resulting in rapid flowering and early yield. Plants evolved so that their flowering is triggered by seasonal changes in day length 1 . However, day-length sensitivity in crops limits their geographical range of cultivation, and thus modification of the photoperiod response was critical for their domestication 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 . Here we show that loss of day-length-sensitive flowering in tomato was driven by the florigen paralog and flowering repressor SELF-PRUNING 5G ( SP5G ). SP5G expression is induced to high levels during long days in wild species, but not in cultivated tomato because of cis- regulatory variation. CRISPR/Cas9-engineered mutations in SP5G cause rapid flowering and enhance the compact determinate growth habit of field tomatoes, resulting in a quick burst of flower production that translates to an early yield. Our findings suggest that pre-existing variation in SP5G facilitated the expansion of cultivated tomato beyond its origin near the equator in South America, and they provide a compelling demonstration of the power of gene editing to rapidly improve yield traits in crop breeding.