Influence of the Non-ripening Mutants rin and nor on the Aroma of Tomato Fruit

Abstract

Differences in aroma have been examined in headspace samples of ripe tomato (Lycopersicon esculentum Mill.) fruit of ‘Rutgers’ and of yellowing fruit of the nonripening mutants rin and nor. Volatiles were trapped and separated by gas chromatography, and the intensity of the effluent aromas was rated by sniffing. Intense aroma compounds were identified by mass spectrometry. Sixty-nine intense compounds were found in ‘Rutgers’, of which 46 were present in one or both mutant strains. Fifteen compounds with odor intensities rated medium to very strong were identified that were deficient or absent in fruit of the mutants. The latter compounds included two aldehydes, seven alcohols, two ketones, three sulfur-containing compounds, and a phenol. A few compounds were intense odors in ‘Rutgers’ and in one or both mutants; hex-2-enal, linalool, phenylacetaldehyde, methyl salicylate, 2-phenylethanol, and eugenol. Some compounds were detected that were more intense in rin and nor than in ‘Rutgers’ (e.g., guaiacol). It is proposed that the “normal background aroma” in fresh tomatoes is caused by those intense odors, which are common to both normal and mutant strains, whereas the bland flavor of mutant fruit is caused by the absence of those intense aroma compounds found only in ‘Rutgers’. The intense aroma compounds found only in ‘Rutgers’ may be crucial determinants of acceptability in fresh tomato fruit.

Mechanism of Fruit Ripening

“…Therefore, breeders have "incidentally" reduced ethylene synthesis or action by generating genotypes with extended shelf life. Because many genes of aroma biosynthesis are ethylene-regulated (El-Sharkawy et al 2005;Manriquez et al 2006), this has often resulted in a severe loss of flavor in long-keeping genotypes that have commonly been generated by breeding with non-ripening mutants (McGlasson et al 1987;Aubert and Bourger 2004). One major challenge for the future is to uncouple the down-regulation of ethylene from inhibition of aroma volatile production.…”

Double CRISPR knockout of pectin degrading enzymes improves tomato shelf‐life while ensuring fruit quality

“…Differences in VOC levels between the tomato lines could be attributed to ethylene production rates. Ethylene‐deficient mutants are known to have reduced aroma (Alexander & Grierson, 2002; McGlasson et al, 1987). Similarly, certain VOCs are triggered by exogenous ethylene (Tobaruela et al, 2021).…”

Puesta en valor de variedades tradicionales de tomate

“…En general, cada uno de estos compuestos suele aumentar su concentración durante el proceso de maduración del fruto, pudiendo estar regulados directamente por el etileno o indirectamente a través del efecto del etileno sobre la acumulación de carotenoides (Baldwin et al, 1991). Así, los mutantes rin y nor que retrasan la maduración, en algunos casos se han relacionado con una menor acumulación de volátiles (McGlasson et al, 1987). Su uso puede tener efectos negativos sobre el sabor.…”

“…Esto se debe principalmente al comportamiento anormal respecto a la degradación de la clorofila, la síntesis de carotenos y demás procesos asociados durante el proceso de maduración de los frutos (Sink Jr. et al, 1974). Los frutos de larga vida presentan una menor concentración en azúcares (Hobson, 1980;Causse et al, 2003), β-caroteno (Hobson, 1980;Kuzyomenskii, 2007), licopeno (Causse et al, 2003) y numerosos compuestos volátiles importantes en el perfil aromático del tomate (Kopeliovitch et al, 1982;McGlasson et al, 1987;Causse et al, 2003;Kovacs et al, 2009), por lo que finalmente se caracterizan por mostrar un aroma y un sabor más pobres (Garg et al, 2008).…”

“…These traditional varieties or landraces are today highly appreciated by consumers, which have expressed for a long time their increasing concern on the low organoleptic quality of modern bred tomato varieties .Several factors are involved in this lack of flavour, including early harvest (Maul et al, 1998), the use of delayed ripening genes (McGlasson et al, 1987) and an excessive focus on high yield, disease resistance and external appearance during the development of breeding programs. On the contrary, Spanish tomato landraces outstand in their organoleptic quality and have consequently found their place in niche market with selective consumers, who are willing to pay up to 4.7 times the price of modern commercial varieties in order to recover the true flavour of vegetables .…”