Preharvest UV-C radiation triggers accumulation of volatile organic compounds in strawberry leaves.
Yanqun Xu, Zisheng Luo , Marie Thérèse Charles, Daniel Rolland. Preharvest UV-C radiation triggers accumulation of volatile organic compounds in strawberry leaves. Joint Annual Conference for the Canadian Society of Agronomy and the Canadian Society for Horticultural Science, La Plaza, Montreal, QC, Canada, 24-26 July, 2016 (Oral presentation)
Plain language summary
The effectiveness of short wave ultraviolet for the disinfection of water, air and surface is well established. Recent studies have demonstrated that very low level of short wave ultraviolet, also called UV-C, can help plants defend themselves against pests. The present study was designed to understand how UV-C can have such beneficial effect. The results have shown that treatment of strawberry plants with a specific low dose of UV-C cause a change in the volatile compounds of the leaves. Several of the volatile compounds increased by UV-C are described in the scientific literature as being effective deterrents of plants natural enemies. These observations suggest that changes in the volatile profile of leaves treated with UV-C can explain the lower disease incidence that occurs in the treated plants. UV-C treatment of growing plants can be considered as interesting alternative when developing integrated pest management programs with the objective to reduce dependence on chemical pesticides in agriculture.
The role of plant volatiles as semiochemicals in both biotic and abiotic interactions is well characterized. Plant volatiles act as pollinator attractants, are deterrents to natural enemies (herbivores, pathogens, and pests), and are involved in intra- and inter-plant signaling and direct defense. Recent studies have highlighted that preharvest UV C can be an environmentally friendly approach to limit disease development in growing plants. In an attempt to understand the mode of action of preharvest UV C, a preliminary study was conducted to evaluate the potential impact of that treatment on strawberry semiochemicals. Growth-chamber-grown strawberry plants were exposed to UV C radiation at 3 different dosages from flower set until fruit ripening, for a period of 7 weeks. Fully expanded leaves were collected at the end of the survey period. A total of 41 volatile compounds were identified by gas chromatography–mass spectrometry. Of that total, 29 were significantly influenced by preharvest UV C treatment in a dose-dependent manner. Partial least square discriminant analysis revealed that 26 volatiles, 18 of which were fatty-acid-derived volatiles, were significantly affected by preharvest UV C radiation. Among the identified volatiles, a subset of 9 fatty-acid-derived volatiles and 3 isoprene-derived volatiles (acetone, hexanal, (E) 2-hexenal, 2-hexenal, (Z) 3-hexen-1 ol, 1 hexanol, heptanal, 1 octen-3 ol, nonanal, cis-linalool oxide, linalool, and β pinene) have been described in the literature for their role in plant–microbe interactions. Based on these observations, it is worth suggesting that changes in the volatile profile may be an integrated part of the lower disease incidence that occurs in strawberry plants treated with preharvest UV C radiation.