A tomato ethylene-insensitive mutant displays altered growth and higher β-carotene levels in fruit

Abstract

AbstractThe mutants insensitive to ethylene are helpful in deciphering the role of ethylene in plant development. We isolated an ethylene-insensitive tomato (Solanum lycopersicum) mutant by screening for acetylene-resistant (atr-1) seedlings. Theatr-1mutant displayed resistance to kinetin, suggesting attenuation of the ethylene sensing response.atr-1also exhibited resistance to ABA- and glucose-mediated inhibition of seed germination. Unlike theNever- ripe(Nr) mutant,atr-1seedlings were resistant to glucose, indicating ethylene sensing inatr-1is located in a component distinct fromNr. Metabolically,atr-1seedlings had lower levels of amino acids but higher levels of several phytohormones, including ABA.atr-1plants grew faster and produced more flowers, leading to a higher fruit set. However, theatr- 1fruits took a longer duration to reach the red-ripe (RR) stage. The ripenedatr-1fruits had higher β-carotene levels, retained high β-carotene and lycopene levels post-RR stage. The metabolome profiles of post-RR stageatr-1fruits revealed increased levels of sugars. Theatr-1had a P279L mutation in the GAF domain of theETR4, a key ethylene receptor regulating tomato ripening. Our study highlights that novel alleles in ethylene receptors may aid in enhancing the nutritional quality of tomato.