Jasmonate-dependent plant defenses mediate soybean thrips and soybean aphid performance on soybean

Abstract

Insect herbivores from different feeding guilds induce different signaling pathways in plants. In this study, we examined the effects of salicylic acid (SA)-and jasmonic acid (JA)-mediated defenses on performance of insect herbivores from two different feeding guilds: cellcontent feeders, soybean thrips and phloem feeders, soybean aphids. We used a combination of RT-qPCR analysis and elicitor-induced plant resistance to determine induction of SA and JA signaling pathways and the impact on herbivore performance. In the early interaction between the host plant and the two herbivores, SA and JA signaling seems to occur simultaneously. But overall, soybean thrips induced JA-related marker genes, whereas soybean aphids increased SA and ABA-related marker genes over a 24-h period. Populations of both soybean thrips and soybean aphids were reduced (47 and 25 %, respectively) in methyl jasmonate (MeJA)-pretreated soybean plants. SA treatment has no effect on either herbivore performance. A combination pretreatment of SA and MeJA did not impact soybean thrips population but reduced soybean aphid numbers which was comparable with MeJA treatment. Our data suggest that SA-JA antagonism could be responsible for the effect of hormone pretreatment on thrips performance, but not on aphid performance. By linking plant defense gene expression and elicitor-induced resistance, we were able to pinpoint the role for JA signaling pathway in resistance to two herbivores from different feeding guilds.

Sipha maydissensitivity to defences ofLolium multiflorumand its endophytic fungusEpichloëoccultans

“…In the present study, the aphid S. maydis was not affected by the induction of the SA pathway (triggered by the plant exposure to the hormone). This insect insensitivity to plant SA-dependent defences has been reported for other aphids species (Bastías et al, 2018a;Bastías et al, 2018b;Onkokesung et al, 2016;Selig et al, 2016). The S. maydis insensitivity to SA-dependent defences could be explained by the potential capability of this insect species in detoxify L. multiflorum anti-herbivore metabolites.…”

Location, location, location: Feeding site affects aphid performance by altering access and quality of nutrients

“…Aphid population on adaxial, abaxial, and stem surfaces was evaluated by confining adult apterous aphids on the specific plant part using foam clip cages (36.5 x 25.4 x 9.5 mm) with no-thrips screen (BioQuip, Rancho Dominguez, CA). Ten adult apterous aphids were placed on either the adaxial, abaxial or stem surfaces and the total number of nymphs, apterous and alate adult aphids were recorded daily for four days, which is the time taken by soybean aphids to complete one generation under our laboratory conditions [25].…”

Resistance Components and Interactions of Aphis glycines (Hemiptera: Aphididae) and Heterodera glycines (Tylenchida: Heteroderidae) in Soybean

“…Several studies have described the differential changes in phytohormones that occur during aphid-feeding in resistant, tolerant, and susceptible cultivars [93,94,95,96,97]. The cyclical expression patterns of the different markers and responsive genes for salicylic acid (SA) observed in aphid-infested plants suggests the role of SA in soybean resistance to aphid feeding [94].…”

“…MeJA may be the elicitor to induce plant defenses [94]. Thus, the JA signaling pathway that assists the induction of other enzymes, including polyphenol oxidase (PPO), lipoxygenases, peroxidases, and proteinase inhibitors, appears to play a crucial role in aphid-resistance against susceptible soybean cultivar [94,98]. a permanent feeding site called a syncytium [14,109].…”