Semiochemicals from ex Situ Abiotically Stressed Cactus Tissue: A Contributing Role of Fungal Spores?

Abstract

Semiochemicals play a central role in communication between plants and insects, such as signaling the location of a suitable host. Fungi on host plants can also play an influential role in communicating certain plant vulnerabilities to an insect. The spiroketal conophthorin is an important semiochemical produced by developing fungal spores. Spiroketals are also used as signals for scolytid communication. Plants and fungi are known to emit varying volatile profiles under biotic and abiotic stress. This paper reports distinctive temporal-volatile profiles from three abiotic treatments, room temperature (control), -15 °C (cold), and -15 °C to room temperature (shock), of cactus tissue plugs. Volatiles from the three treatments included monoterpenes from control plugs, compounds of varying classes and origin at later stages for cold plugs, and known semiochemicals, including spiroketals, at later stages for shock plugs. The results highlight several important findings: a unique tissue source of the spiroketals; abiotic cold-shock stress is indicated as the cause of spiroketal production; and, given previous findings of spirogenesis, fungal spore involvement is a probable biosynthetic origin of the spiroketals. These findings suggest an important role of fungal volatiles as signaling plant vulnerability to insects.

Harnessing Insect–Microbe Chemical Communications To Control Insect Pests of Agricultural Systems

“…From a chemical aspect, what compounds are specifically attractive and what microbe produces them and under what conditions? Do these microbes signal a specific vulnerability of the host plant (e.g., a natural damage point of the fruit)? Can microbes be introduced into plants and used to affect insect behavior? Finally, given the importance of microbe signaling, what effect will a change in abiotic conditions have on microbe–insect–plant systems?…”

Volatile-organic compound changes in rose twigs consequent to infection with rose powdery mildew

“…The VOC profile in a plant can change quickly and can be detected by the olfactory receptors of insects. Insect olfaction receptors are particularly good at performing quality assessments based on VOCs emitted by host plants (Beyaert et al, 2010;Beck et al, 2014). VOCs emitted by plants can indicate the health statuses of potential host plants to insects and act as semiochemicals allowing plants and insects to communicate.…”

Volatile profile of Calycanthus occidentalis achenes and evidence for a diverse range of semiochemicals for vespicochory by pestiferous Vespula pensylvanica

“…The volatile profiles of the achenes were surprisingly high in the number of compounds and chemical class diversity. A total of 102 compounds were detected consistently in the three batches of achenes analysed by SPME GC-MS. Table 2 provides the 44 authenticated compounds reported by relative abundances, and illustrates the wide diversity to published methods [24]. The vials were capped and placed in an oven at 40 °C to mimic warm weather conditions and facilitate full volatile emission from the achenes.…”

“…Achenes used for volatile collections were from the same batches as those collected for wasp observational and behavioural trials as described in Burge and Beck [7], with vouchers deposited at the University California, Davis Center for Plant Diversity. Collected achenes were transported overnight from California to the USDA-ARS Florida laboratory in sealed brown paper bags or sealed 4 or 11-mL scintillation vials with modified lids as described in Beck et al [24].…”