A single locus confers tolerance to continuous light and allows substantial yield increase in tomato

An important constraint for plant biomass production is the natural day length. Artificial light allows for longer photoperiods, but tomato plants develop a detrimental leaf injury when grown under continuous light—a still poorly understood phenomenon discovered in the 1920s. Here, we report a dominant locus on chromosome 7 of wild tomato species that confers continuous light tolerance. Genetic evidence, RNAseq data, silencing experiments and sequence analysis all point to the type III light harvesting chlorophyll a/b binding protein 13 ( CAB-13 ) gene as a major factor responsible for the tolerance. In Arabidopsis thaliana , this protein is thought to have a regulatory role balancing light harvesting by photosystems I and II. Introgressing the tolerance into modern tomato hybrid lines, results in up to 20% yield increase, showing that limitations for crop productivity, caused by the adaptation of plants to the terrestrial 24-h day/night cycle, can be overcome. Domesticated tomato plants are damaged by continuous light exposure, limiting the usefulness of artificial light to boost yields. Velez-Ramirez et al . identify a locus conferring continuous light tolerance in wild tomatoes, and show that its introgression into modern tomato lines enhances yield by 20%.