Work

Low red:far-red light ratios reduce the content of major sesquiterpenes in type VI trichomes of Solanum habrochaites and increase plant attractiveness to Tuta absoluta females

Year: 2025

Type: article

Abstract: BACKGROUND AND AIMS: A low ratio of red to far-red radiation (R:FR ratio) is a signal of competition for light in plant canopies. Plants exposed to low R:FR ratios typically display reduced accumulation of chemical defences against herbivorous insects. In Arabidopsis and other model plants, this effect of low R:FR ratios has been explained on the basis of changes in jasmonate metabolism and signalling. In the genus Solanum, volatile organic compounds, mainly terpenoids produced in trichome glands and released to the environment, are very important signalling molecules involved in plant interactions with insect herbivores. Our aim was to investigate the effect of low R:FR ratios on the terpenes produced and released by plants of the wild tomato species Solanum habrochaites and its consequences for the behaviour of the specialist herbivore Tuta absoluta. METHODS: Plants of S. habrochaites (accession LA2167) were exposed to white light (WL) or WL supplemented with FR and used to evaluate morphological responses, production and emissions of volatile organic compounds, and herbivore attractiveness. KEY RESULTS: Solanum habrochaites plants responded to low R:FR ratios with the typical shade avoidance syndrome, characterized by elongated shoots and hyponastic leaves. This morphological response to low R:FR ratios was accompanied by a reduction in the content and emission of 7-epizingiberene, which was correlated with reduced expression of two biosynthetic genes (zFPS and ShZIS) in type VI trichome glands. Finally, choice bioassays demonstrated that T. absoluta moths preferred plants from the FR treatment over control (WL) plants, a result consistent with the reduced production of 7-epizingiberene, which is known for its insect-repellent properties. CONCLUSIONS: Collectively, our results suggest that terpene accumulation in glandular trichomes in S. habrochaites is regulated by light at the transcriptional level and that this regulation could have important consequences for plant resistance to herbivory in plant stands.

Source: Annals of Botany

DOI: 10.1093/aob/mcaf292