Analysis of apocarotenoid volatiles from lettuce () induced by insect herbivores and characterization of gene.

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Plant apocarotenoids have been shown to have a diverse biological role in herbivore-plant interactions. Despite their importance, little is known about herbivores' effect on apocarotenoid emissions in . In this study, we examined changes in apocarotenoid emissions in lettuce leaves after infestation by two insects, viz., larvae and aphids. We found that -ionone and -cyclocitral showed higher concentrations than the other apocarotenoids, with a significant increase as per the intensity of infestation of both herbivore species. Furthermore, we performed functional characterization of 1 () genes. Three genes were overexpressed in strains, and recombinant proteins were assayed for cleavage activity on an array of carotenoid substrates. The LsCCD1 protein cleaved carotene at the 9,10 (9',10') positions producing -ionone. The transcript analysis of genes revealed differential expression patterns under varying levels of herbivores' infestation, but the results were inconsistent with the pattern of -ionone concentrations. Our results suggest that LsCCD1 is involved in the production of -ionone, but other regulatory factors might be involved in its induction in response to herbivory. These results provide new insights into apocarotenoid production in response to insect herbivory in lettuce.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13205-023-03511-4.