Induced mutations in SIE8 and SIACO1 control tomato fruit maturation and shelf-life

Fruit maturation and softening are critical traits that control fruit shelf-life. In the climacteric tomato (Solanum lycopersicum L.) fruit, ethylene plays a key role in fruit ripening and softening. We characterized two related proteins with contrasting impact on ethylene production, ACC oxidase 1 (SIACO1) and SIE8. We found SIACO1 and SIE8 to be highly expressed during fruit ripening. To identify loss-of-function alleles, we analysed the tomato genetic diversity but we did not find any natural mutations impairing the function of these proteins. We also found the two loci evolving under purifying selection. To engineer hypomorphic alleles, we used TILLING (target-induced local lesions in genomes) to screen a tomato ethylmethane sulfonate-mutagenized population. We found 13 mutants that we phenotyped for ethylene production, shelf-life, firmness, conductivity, and soluble solid content in tomato fruits. The data demonstrated that slaco1-1 and slaco1-2 alleles could be used to improve fruit shelf-life, and that sle8-1 and sle8-2 alleles could be used to accelerate ripening. This study highlights further the importance of SIACO1 and SIE8 in ethylene production in tomato fruit and how they might be used for post-harvest fruit preservation or speeding up fruit maturation.

Automated summary

This study identified the crucial roles of SIACO1 and SIE8 in ethylene production during tomato fruit ripening, and successfully engineered multiple alleles for improving fruit shelf-life or accelerating maturation.