Abstract
The mutants resistant to ethylene are helpful in deciphering the role of ethylene in plant development. We isolated an ethylene-resistant tomato (Solanum lycopersicum) mutant by screening for acetylene-resistant (atr-1) seedlings. The atr-1 mutant displayed resistance to kinetin, suggesting attenuation of the ethylene sensing response. atr-1 also exhibited resistance to ABA- and glucose-mediated inhibition of seed germination. Unlike the Never-ripe (Nr) mutant seedlings that were hypersensitive to glucose, atr-1 seedlings were resistant to glucose, indicating ethylene sensing in atr-1 is compromised in a manner distinct from Nr. Metabolically, atr-1 seedlings had lower levels of amino acids but higher levels of several phytohormones, including ABA. atr-1 plants grew faster and produced more flowers, leading to a higher fruit set. However, the atr-1 fruits took a longer duration to reach the red-ripe (RR) stage. The ripened atr-1 fruits retained high β-carotene and lycopene levels post-RR stage and had longer on-vine longevity. The metabolome profiles of post-RR stage atr-1 fruits revealed increased levels of sugars. The atr-1 had a P279L mutation in the GAF domain of the ETR4, a key ethylene receptor regulating tomato ripening. The atr-1 exhibits phenotypic traits distinct from the Sletr4-1 (G154S) mutant, thus represents a new ETR4 allele named Sletr4-2. Our study highlights that novel alleles in ethylene receptors may aid in enhancing the nutritional quality of tomato.
Published Version
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