Evidence for additive effects of virus infection and water availability on phytohormone induction in a staple crop

Davis, Thomas S.; Bosque‐Pérez, Nilsa A.; Popova, Inna E.; Eigenbrode, Sanford D.

doi:10.3389/fevo.2015.00114

Cited by 18 publications

(13 citation statements)

References 31 publications

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“…Lastly, the separation differences between all compounds were optimized in MRM, achieving a detection limit of 5 nmol with excellent chromatographic peak shape and signal to noise ratio. Similar protocols have been used to quantify plant hormones, and these studies report hormone concentrations comparable to those reported here (Bastías et al., ,; Davis, Bosque‐Pérez, Popova, & Eigenbrode, ; Eberl, Hammerbacher, Gershenzon, & Unsicker, ; Ohnmeiss & Baldwin, ; Paulmann et al., ).…”

Section: Methodssupporting

confidence: 80%

Jasmonic acid regulation of the anti‐herbivory mechanism conferred by fungal endophytes in grasses

et al. 2018

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1. The most studied mechanism of protection against herbivores in grasses associated with Epichloë fungal endophytes has been the fungal production of alkaloids.However, the contribution of the plant immune response on the level of resistance to herbivores in symbiotic grasses has been poorly explored. We studied the relationship between the plant hormone, jasmonic acid (JA) and Epichloë fungal endophytes on herbivore defences in symbiotic grasses. We hypothesized that an exogenous application of methyl jasmonate (MeJA), an activator of the plant JA defence response, would increase the level of resistance of endophyte-symbiotic and non-symbiotic plants to a chewing insect. As Epichloë endophytes produce alkaloids, an enhancement of the JA defence would complement the resistance given by these alkaloids. Lolium multiflorum plants symbiotic and non-symbiotic with the endophyteEpichloë occultans were subjected to an exogenous application of MeJA followed by a challenge with the generalist chewing insect Spodoptera frugiperda. We measured the level of plant resistance to chewing insects, and the defences conferred by host plants and fungal endophytes.3. Symbiotic plants were more resistant to S. frugiperda than their non-symbiotic counterparts. However, despite the fact that the concentration of JA significantly increased in all plants exposure to MeJA, neither endophyte-symbiotic nor nonsymbiotic plants showed an enhanced resistance to insects. Unexpectedly, the exposure of endophyte-symbiotic plants to MeJA led to a reduction in the concentration of loline alkaloids (i.e. N-formyllolines and N-acetylnorlolines), consequently decreasing the level of plant resistance to the herbivore. Synthesis.Our results suggest that, rather than complementing the alkaloid-based defence, the jasmonic acid hormone weakens the anti-herbivore mechanism conferred by Epichloë endophytes. The present study highlights that the interaction between the jasmonic acid hormone and the presence of leaf fungal endophytes can be of importance for the effectiveness of the anti-herbivore defences of symbiotic plants.

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Section: Methodssupporting

confidence: 80%

Jasmonic acid regulation of the anti‐herbivory mechanism conferred by fungal endophytes in grasses

et al. 2018

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“…Both infected barley cultivars showed an increase in SA concentrations compared to healthy plants, whereas the heat stimulus did not induce a response ( Figure 5B ). Davis et al (2015) showed a similar increase in SA for BYDV infected wheat plants. SA promotes ROS production, on the one hand, and ROS scavenging, on the other, in a temporally dynamic way ( Herrera-Vasquez et al, 2015 ).…”

Section: Discussionmentioning

confidence: 53%

Barley yellow dwarf virus Infection Leads to Higher Chemical Defense Signals and Lower Electrophysiological Reactions in Susceptible Compared to Tolerant Barley Genotypes

et al. 2018

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Barley yellow dwarf virus (BYDV) is a phloem limited virus that is persistently transmitted by aphids. Due to huge yield losses in agriculture, the virus is of high economic relevance. Since the control of the virus itself is not possible, tolerant barley genotypes are considered as the most effective approach to avoid yield losses. Although several genes and quantitative trait loci are known and used in barley breeding for virus tolerance, little is known about molecular and physiological backgrounds of this trait. Therefore, we compared the anatomy and early defense responses of a virus susceptible to those of a virus-tolerant cultivar. One of the very early defense responses is the transmission of electrophysiological reactions. Electrophysiological reactions to BYDV infection might differ between susceptible and tolerant cultivars, since BYDV causes disintegration of sieve elements in susceptible cultivars. The structure of vascular bundles, xylem vessels and sieve elements was examined using microscopy. All three were significantly decreased in size in infected susceptible plants where the virus causes disintegration of sieve elements. This could be associated with an uncontrolled ion exchange between the sieve-element lumen and apoplast. Further, a reduced electrophysiological isolation would negatively affect the propagation of electrophysiological reactions. To test the influence of BYDV infection on electrophysiological reactions, electropotential waves (EPWs) induced by leaf-tip burning were recorded using aphids as bioelectrodes. EPWs in infected susceptible plants disappeared already after 10 cm in contrast to those in healthy susceptible or infected tolerant or healthy tolerant plants. Another early plant defense reaction is an increase in reactive oxygen species (ROS). Using a fluorescent dye, we found a significant increase in ROS content in infected susceptible plants but not in infected tolerant plants. Similar results were found for the phytohormones abscisic acid and three jasmonates. Salicylic acid levels were generally higher after BYDV infection compared to uninfected plants. Heat stimulation caused an increase in jasmonates. By shedding light on the plant defense mechanisms against BYDV, this study, provides further knowledge for breeding virus tolerant plants.

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“…For example, changes in proteins involved in JA synthesis and accumulation were noted in a diversity of plants exposed to water deficit (Fan et al, 2009;Harb et al, 2010;Bonhomme et al, 2012;Ahmad et al, 2016;Haider et al, 2017), while other studies have indicated lack of JA induction in drought-stressed plants (Muñoz-Espinoza et al, 2015;Nachappa et al, 2016). The exact nature of interactions among the defensive responses of plants to biotic and abiotic stresses remains understudied, however, despite their importance to plant-pathogen, plant-insect, and plant-pathogenvector interactions (Asselbergh et al, 2008;Erb et al, 2011;Davis et al, 2015b;Nachappa et al, 2016).…”

Section: Overview Of General Molecular Responses Of Plants To Biotic mentioning

confidence: 99%

Plant-Vector-Pathogen Interactions in the Context of Drought Stress

Szczepaniec¹,

Finke

2019

Front. Ecol. Evol.

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Plants regularly encounter stress, and their responses to abiotic and biotic stressors have been a focus of research for decades. Stress caused by drought is one of the most often studied abiotic stresses owing to the increase in the incidence of drought driven by climate change. Severe drought has been shown to elicit a whole-plant response guided by key phytohormones, which not only respond to water stress but also play a critical role in the response of plants to biotic stress imposed by herbivores and pathogens. This is especially relevant for insect-transmitted pathogen systems, where plants, herbivores, and pathogens are linked in a web of direct and indirect interactions. Few studies have thus far explored the complex nature of drought-mediated tripartite interactions, however, and our ability to generalize and predict how plants respond to herbivore-transmitted pathogens while simultaneously countering the consequences of drought remains limited. The goal of this mini-review is to assess the current state of the field regarding the molecular mechanisms underlying plant responses to the combined effects of drought and simultaneous herbivory and pathogen transmission and their ecological consequences. We discuss plant responses to drought, herbivory, and pathogens as distinct and concurrent stresses, and highlight the implications of the tripartite interactions on insect vector and pathogen suppression in agroecosystems. This review provides a framework for future research linking generalized molecular responses in drought-stressed plants to tripartite species interactions and the ecology of insect-transmitted pathogens in the context of modern agriculture and water deficit driven by climate change.

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Evidence for additive effects of virus infection and water availability on phytohormone induction in a staple crop

Cited by 18 publications

References 31 publications

Jasmonic acid regulation of the anti‐herbivory mechanism conferred by fungal endophytes in grasses

Jasmonic acid regulation of the anti‐herbivory mechanism conferred by fungal endophytes in grasses

Barley yellow dwarf virus Infection Leads to Higher Chemical Defense Signals and Lower Electrophysiological Reactions in Susceptible Compared to Tolerant Barley Genotypes

Plant-Vector-Pathogen Interactions in the Context of Drought Stress

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