Priming Melon Defenses with Acibenzolar-S-methyl Attenuates Infections by Phylogenetically Distinct Viruses and Diminishes Vector Preferences for Infected Hosts

Abstract

Plant virus management is mostly achieved through control of insect vectors using insecticides. However, insecticides are only marginally effective for preventing virus transmission. Furthermore, it is well established that symptoms of virus infections often encourage vector visitation to infected hosts, which exacerbates secondary spread. Plant defense elicitors, phytohormone analogs that prime the plant immune system against attack, may be a viable approach for virus control that complements insecticide use by disrupting pathologies that attract vectors. To explore this, we tested the effect of a commercial plant elicitor, acibenzolar-S-methyl (ASM), on infection rates, virus titers, and symptom development in melon plants inoculated with one of two virus species, Cucumber mosaic virus (CMV) and Cucurbit yellow stunting disorder virus (CYSDV). We also conducted behavioral assays to assess the effect of ASM treatment and virus inoculation on vector behavior. For both pathogens, ASM treatment reduced symptom severity and delayed disease progression. For CYSDV, this resulted in the attenuation of symptoms that encourage vector visitation and virion uptake. We did observe slight trade-offs in growth vs. defense following ASM treatment, but these effects did not translate into reduced yields or plant performance in the field. Our results suggest that immunity priming may be a valuable tool for improving management of insect-transmitted plant viruses.

Defence priming in tomato by the green leaf volatile (Z)‐3‐hexenol reduces whitefly transmission of a plant virus

“…Similar results were also reported for tobacco and melon plants that were primed by acibenzolar-S-methyl, a commercially available mimic of the phytohormone SA, before being challenged with Tomato spotted wilt virus, Cucumber mosaic virus or Cucurbit yellow stunting disorder virus (Kenney, Grandmont, & Mauck, 2020;Mandal et al, 2008). Our results also indicated that Z-3-HOL pre-exposure significantly reduced whitefly vector visitation time (1 hr) and settling time (2-24 hr) (Figure 1d).…”

Combining Cultural Tactics and Insecticides for the Management of the Sweetpotato Whitefly, Bemisia tabaci MEAM1, and Viruses in Yellow Squash

“…The insecticides cyantraniliprole and terpene constituents of Chenopodium ambrosioides near ambrosioides extract also reduced the number of whitefly adults on seedlings, although cyantraniliprole alone reduced virus incidence. Acibenzolar-S-methyl, a salicylic acid analog, does not have insecticidal properties but is known to induce plant defenses against viruses by activating the salicylic acid pathway [58][59][60]. While fewer adult whiteflies were observed in the acibenzolar-Smethyl treatment compared with the non-treated control in our study, the former did not reduce virus incidence in squash seedlings.…”

“…While fewer adult whiteflies were observed in the acibenzolar-Smethyl treatment compared with the non-treated control in our study, the former did not reduce virus incidence in squash seedlings. It is possible that the timing of our acibenzolar-S-methyl application could be optimized to improve virus protection [59], or that multiple applications may be necessary for suppressing CuLCrV-induced symptoms on squash seedlings [60]. The greenhouse experiment in this study demonstrated that seedling infection in open greenhouses could be minimized with the use of IEN in conjunction with insecticides.…”

Study of barley yellow dwarf virus: dynamics of aphid-plant interaction

“…So controlling this preference by some chemical signal would be very helpful to improve crop yield. For example, in [19], they take advantage of knowledge about elicitors that prime the plant immune system against attack to test the effect of a commercial elicitor on infection rates, finding that artificially boosting immunity delayed disease and decreased symptoms. 1.…”