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Catalase activity in freshly sampled Diprion pini tissues and secretions (median, interquartile range, minimum/maximum). Statistical differences evaluated by Kruskal–Wallis H test. Different letters above boxes indicate significant differences (P < 0.05) evaluated by Dunn-test with Benjamini–Hochberg correction
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Main conclusion:
Pinus sylvestris responds to insect egg deposition by ROS accumulation linked with reduced activity of the ROS scavenger catalase. Egg mortality in needles with hypersensitive response (HR)-like symptoms is enhanced. Aggressive reactive oxygen species (ROS) play an important role in plant defence against biotic stressors, includin...
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Insect pheromones have been intensively studied with respect to their role in insect communication. However, scarce knowledge is available on the impact of pheromones on plant responses, and how these in turn affect herbivorous insects. A previous study showed that exposure of pine (Pinus sylvestris) to the sex pheromones of the pine sawfly Diprion...
Citations
... Superoxide dismutase (SOD) (EC 1.15.1.1) negates the harmful effect of superoxide radicals by dismutation into oxygen and water (13,14). The polyphenols play an important role by neutralizing the ROS, while polyphenol oxidase (PPO) (EC 1.10.3.2 or EC 1.14.18.1) catalyses the oxygen-dependent oxidation of polyphenols to quinones. ...
Background
White rust disease caused by the biotrophic oomycete Albugo candida is one of the most serious impediments in realizing the production potential of Brassica juncea. Moreover, due to the obligate nature of the pathogen, R-gene-based resistance is unstable as the newer virulent races emerge quickly. Therefore, a deeper understanding of the molecular basis of resistance is essential for developing durable resistant varieties. In this study, we selected susceptible cultivar, ‘Pusa Jaikisan’ and its single R-gene-based resistant NIL, ‘Pusa Jaikisan WRR’ for elucidating the defense mechanism in B. juncea against A. candida.
Results
Comparative histochemical analysis at 12 dpi showed higher callose deposition in the resistant cultivar than in the susceptible cultivar which hints towards its possible role in defense mechanism. Based on the biochemical markers observation, total protein was found to have a negative correlation with the resistance. The antioxidant enzymes (POX, CAT, and SOD) and non-enzymatic ROS scavenging compounds such as polyphenols and proline showed a positive correlation with the white rust resistance. The PPO, total chlorophyll and total carotenoids were also found to show higher activity in the ‘Pusa Jaikisan WRR’. According to the heat map analysis, PAL was identified to be the most induced enzyme involved in the defense mechanism. Furthermore, the expression analyses of defense related markers such as salicylic acid (SA) associated PR protein genes (PR1 and PR2) and jasmonic acid (JA) associated PR protein genes (PR3 and PR12) were done by qRT-PCR. Based on the results, PR2 emerged as the best possible gene for defense against A. candida followed by PR1. PR3 and PR12 also showed positive correlation with the disease resistance which may be due to the JA pathway acting complementary to the SA pathway, thus indicating a synergistic JA-SA hormonal crosstalk in case of B. juncea-A. candida interaction.
Conclusion
The present study establishes a major role of simulated response of the defense molecules which can stop the disease progression thus incurring resistance. This may be used in the future for developing resistance against the biotrophic pathogen especially A. candida in B. juncea.
... In recent years, oxidative changes and the activation of antioxidant enzymes in plants after insect attack have received a lot of attention. The increase or decrease of various physiological and oxidative stress responses to feeding by different insects can vary depending on the type of insect feeding (chewing or phloem -feeding) and has been studied in many plant species [43][44][45][46][47]. There is a lack of data considering the physiological and oxidative stress responses of carrot to B. trigonica infestation. ...
... This baseline level of H 2 O 2 production was observed during the egg-laying phase (four days), and another peak was observed during the nymphal and imago phases (26 days) of B. trigonica feeding. Some plants can produce ROS in response to insect eggs, effectively combating future larval herbivory [47], which is not the case for carrots in response to B. trigonica eggs. The carrot plants that were constantly exposed to insects produced the highest H 2 O 2 content. ...
... Furthermore, balanced CAT activity in carrot leaves was observed throughout the period of oviposition and nymphal feeding of B. trigonica. We proposed that the observed balanced activity of this hydrogen peroxide-degrading enzyme was apparently specifically triggered by the eggs or the oviducts associated with the eggs, as has been reported for some other laid eggs of herbivorous insects [47]. Increased CAT activity has often been associated with plant defense against infestation by chewing insects [43,104]. ...
Abstract
Background Carrot is an important vegetable crop grown worldwide. The major economic problem in carrot cultivation is yellow disease caused by Bactericera trigonica, which induces biotic stress and has the greatest impact on crop
productivity. Comprehensive studies on the mechanism of carrot defense response to biotic stress caused by B. trigonica infestation have yet to be conducted.
Methods The changes in photosynthetic pigments, proline, TPC, H2O2 and MDA content, DPPH radical scavenging ability, and antioxidant enzyme activity of SOD, CAT, and POX in carrot leaves in response to insect sex (female and male), rapid response (during the frst six hours), and long-term response to B. trigonica infestation were evaluated.
Results The results of our study strongly suggest that B. trigonica infestation causes signifcant changes in primary and secondary metabolism and oxidative status of carrot leaves. Photosynthetic pigment content, TPC, and DPPH and CAT activities were signifcantly reduced in carrot leaves in response to insect infestation. On the other hand, proline, H2O2 content, and the activity of the antioxidant enzymes superoxide dismutase and peroxidase were increased in carrot leaves after B. trigonica infestation. The results indicate that B. trigonica attenuates and delays the oxidative stress responses of carrot, allowing long-term feeding without visible changes in the plant. Carrot responded to longterm B. trigonica infestation with an increase in SOD and POX activity, suggesting that these enzymes may play a key
role in plant defense mechanisms.
Conclusions This is the frst comprehensive study strongly suggesting that B. trigonica infestation causes signifcant changes in primary and secondary metabolism and an attenuated ROS defense response in carrot leaves that enables
long-term insect feeding. The information provides new insights into the mechanisms of carrot protection against B. trigonica infestation.
... Several studies have reported that ROS play a key role in defending plants against insects. For example, ROS are involved in the defense of wheat and rice against Mayetiola destructor larvae and in the egg deposition response of Pinus sylvestris against Diprion pini (Bittner et al. 2017;Liu et al. 2010). However, investigating reactive oxygen species (ROS) in the context of plant defense against insects is still preliminary. ...
Rice leaf folder, Cnaphalocrocis medinalis (Guenée), is one of the most serious pests on rice. At present, chemical control is the main method for controlling this pest. However, the indiscriminate use of chemical insecticides has non-target effects and may cause environmental pollution. Besides, leaf curling behavior by C. medinalis may indirectly reduce the efficacy of chemical spray. Therefore, it is crucial to cultivate efficient rice varieties resistant to this pest. Previous studies have found that three different rice varieties, Zhongzao39 (ZZ39), Xiushui134 (XS134), and Yongyou1540 (YY1540), had varying degrees of infestation by C. medinalis. However, it is currently unclear whether the reason for this difference is related to the difference in defense ability of the three rice varieties against the infestation of C. medinalis. To explore this issue, the current study investigated the effects of three rice varieties on the growth performance and food utilization capability of the 4th instar C. medinalis. Further, it elucidated the differences in defense responses among different rice varieties based on the differences in leaf physiological and biochemical indicators and their impact on population occurrence. The results showed that the larval survival rate was the lowest, and the development period was significantly prolonged after feeding on YY1540. This was not related to the differences in leaf wax, pigments, and nutritional components among the three rice varieties nor to the feeding preferences of the larvae. The rate of superoxide anion production, hydrogen peroxide content, and the activity of three protective enzymes were negatively correlated with larval survival rate, and they all showed the highest in YY1540 leaves. Compared to other tested varieties, although the larvae feeding on YY1540 had higher conversion efficiency of ingested food and lower relative consumption rate, their relative growth was faster, indicating stronger food utilization capability. However, they had a lower accumulation of protein. This suggests that different rice varieties had different levels of oxidative stress after infestation by C. medinalis. The defense response of YY1540 was more intense, which was not conducive to the development of the larvae population. These results will provide new insights into the interaction mechanism between different rice varieties and C. medinalis and provide a theoretical basis for cultivating rice varieties resistant to this pest.
... Trees do not need to 'wait' until they are exposed to larval feeding damage; they can defend themselves beforehand against the initial egg deposition on their leaves Fatouros 2015, Reymond 2022). These egg-induced tree defences act, for instance, by releasing leaf volatiles that attract egg parasitoids or by changes of leaf chemistry that are harmful to the eggs (Meiners and Hilker 2000, Bittner et al. 2017. Thus, tree responses to insect eggs can reduce the number of surviving eggs. ...
... In the gymnosperm Pinus sylvestris L., several previous studies addressed the tree's responses to egg deposition and larval feeding damage by the common pine sawfly Diprion pini L. (Hilker et al. 2002, Beyaert et al. 2012, Bittner et al. 2017, Blomqvist et al. 2022). The tree mounts its defences against infestation by this sawfly already after egg deposition on the needles. ...
... A recent study showed that the elicitor of this indirect pine defence is an annexin-like protein, which is associated with the egg secretion that the sawfly female releases with her eggs into the needle pouch (Hundacker et al. 2022). In addition to this indirect defence, egg-laden Scots pine needles accumulate greater quantities of hydrogen peroxide, which might either directly harm the sawfly eggs or induce further pine reactions (such as lignification of needle tissue), which ultimately hinder egg survival (Bittner et al. 2017(Bittner et al. , 2019. ...
Plants can improve their resistance against feeding damage by insects if they have perceived insect egg deposition prior to larval feeding. Molecular analyses of these egg-mediated defence mechanisms have until now focused on angiosperm species. It is unknown how the transcriptome of a gymnosperm species responds to insect eggs and subsequent larval feeding. Scots pine (Pinus sylvestris) is known to improve its defences against larvae of the herbivorous sawfly Diprion pini if it has previously received sawfly eggs. Here, we analysed the transcriptomic and phytohormonal responses of Scots pine needles to D. pini eggs (E-pine), larval feeding (F-pine), and to both eggs and larval feeding (EF-pine). Pine showed strong transcriptomic responses to sawfly eggs and-as expected-to larval feeding. Many egg-responsive genes were also differentially expressed in response to feeding damage, and these genes play an important role in biological processes related to cell wall modification, cell death, and jasmonic acid signalling. EF-pine showed fewer transcriptomic changes than F-pine, whereas EF-treated angiosperm species studied so far showed more transcriptional changes to the initial phase of larval feeding than only feeding-damaged F-angiosperms. However, as with responses of EF-angiosperms, EF-pine showed higher salicylic acid concentrations than F-pine. Based on the considerable overlap of the transcriptomes of E- and F-pine, we suggest that the weaker transcriptomic response of EF-pine than F-pine to larval feeding damage is compensated by the strong, egg-induced response, which might result in maintained pine defences against larval feeding.
... Accumulation of hydrogen peroxide can directly kill insect eggs 34 . Accumulation of ROS can also elicit HR-like symptoms 26,29,[32][33][34] , which are known to be also formed after infection of plants with (hemi)biotrophic phytopathogens 35,36 . ...
Egg deposition by herbivorous insects is well known to elicit defensive plant responses. Our study aimed to elucidate the insect and plant species specificity of these responses. To study the insect species specificity, we treated Arabidopsis thaliana with egg extracts and egg-associated secretions of a sawfly (Diprion pini), a beetle (Xanthogaleruca luteola) and a butterfly (Pieris brassicae). All egg extracts elicited salicylic acid (SA) accumulation in the plant, and all secretions induced expression of plant genes known to be responsive to the butterfly eggs, among them Pathogenesis-Related (PR) genes. All secretions contained phosphatidylcholine derivatives, known elicitors of SA accumulation and PR gene expression in Arabidopsis. The sawfly egg extract did not induce plant camalexin levels, while the other extracts did. Our studies on the plant species specificity revealed that Solanum dulcamara and Ulmus minor responded with SA accumulation and cell death to P. brassicae eggs, i.e. responses also known for A. thaliana. However, the butterfly eggs induced neoplasms only in S. dulcamara. Our results provide evidence for general, phosphatidylcholine-based, egg-associated elicitors of plant responses and for conserved plant core responses to eggs, but also point to plant and insect species-specific traits in plant–insect egg interactions.
... Firstly, our results that the RPW attack caused the reduced activity of CAT is interesting. These findings are consistent with those reported in Pinus sylvestris in response to wounding caused by sawfly (Diprion pini) oviposition (Bittner et al., 2017). The changes in expressions of CAT transcripts (COCNU_scaffold021643G000020 and OCNU_08G006310) in CK are consistent with these findings (Figure 4). ...
Red palm weevil (RPW, Rhynchophorus ferrugineus) is an invasive pest of palms. In China, coconut (Cocos nucifera) production is being significantly affected by the RPW attack. To develop a long-term RPW control strategy, host-plant resistance is the most sustainable option. In this regard, the availability of transcriptome sequencing data from RPW-infected coconut plants can be highly useful. Therefore, the present study assessed coconut leaf physiological responses and transcriptional changes after different days of RPW attack i.e., 5, 10, 15, 20, and 25 days after infestation (DAI). A comparison of physiological data indicated that populations with the higher number of RPW insects i.e., population C (15 males +21 females) and D (20 males +28 females) triggered higher antioxidant enzyme activities. We used this data to study the transcriptomic responses on 5 and 20 DAI. Of the 38,432 detected transcripts, 3,984, 1,981, 3,925, and 2,257 were differentially expressed in CK (control/no RPW)_vs._C (5 DAI), CK_vs._D (5 DAI), CK_vs._C (20 DAI), and CK_vs._D (20 DAI), respectively. These transcripts were enriched in plant-pathogen interaction, phenylpropanoid/flavonoid biosynthesis, amino sugar and nucleotide sugar metabolism, plant hormone signal transduction, mitogen-activated protein kinase, and reactive oxygen scavenging pathway. We discuss these results and present several candidate genes to be manipulated for developing a sustainable strategy to control RPW attack regarding host-plant resistance. Furthermore, these findings provide a basis for developing effective early and late RPW attack detection strategies.
... We also performed an additional time course experiment aimed at describing, with the help of microscopy tools, the physical damage observed in the Hass avocado pulp at 1, 20, and 40 days after the oviposition/pin treatments. Since the Lauraceae represent an ancient plant clade [74], and Hass avocados have had no close association with A. ludens, we suggest that its response to the "novel alien" would likely be a general mechanism the plant has developed over millions of years against other diseases and pests [75]. We also predicted that the defensive mechanisms triggered by A. ludens oviposition should be mediated by non-specific egg-derived compounds and that it is likely that the response of Hass avocados to A. ludens eggs also involves the biosynthesis of specialized metabolites with ovicidal properties. ...
... Finally, the presence of the potential ovicide metabolites opens the possibility of inducing these compounds in the plant to fend off the attacks of herbivores. Furthermore, given that the defense mechanism detected is apparently a generally conserved mechanism that some plants developed millions of years ago [75], our findings could have broader implications for pest andalso possibly pathogen management. ...
Citation: Aluja, M.; Vázquez-Rosas-Landa, M.; Cerqueda-García, D.; Monribot-Villanueva, J.L.; Altúzar-Molina, A.; Ramírez-Vázquez, M.; Velázquez-López, O.; Rosas-Saito, G.; Alonso-Sánchez, A.G.; Ortega-Casas, R.; et al. Assessment of the Molecular Responses of an Ancient Angiosperm against Atypical Insect Oviposition: The Case of Hass Avocados and the Tephritid Fly Anastrepha ludens. Int. J. Mol. Sci. 2023, 24, 2060. https:// (M.A.); enrique.ibarra@inecol.mx (E.I.-L.) † These authors contributed equally to this work and share first authorship. Abstract: Anastrepha spp. (Diptera: Tephritidae) infestations cause significant economic losses in commercial fruit production worldwide. However, some plants quickly counteract the insertion of eggs by females by generating neoplasia and hindering eclosion, as is the case for Persea americana Mill., cv. Hass (Hass avocados). We followed a combined transcriptomics/metabolomics approach to identify the molecular mechanisms triggered by Hass avocados to detect and react to the oviposition of the pestiferous Anastrepha ludens (Loew). We evaluated two conditions: fruit damaged using a sterile pin (pin) and fruit oviposited by A. ludens females (ovi). We evaluated both of the conditions in a time course experiment covering five sampling points: without treatment (day 0), 20 min after the treatment (day 1), and days 3, 6, and 9 after the treatment. We identified 288 differentially expressed genes related to the treatments. Oviposition (and possibly bacteria on the eggs' surface) induces a plant hypersensitive response (HR), triggering a chitin receptor, producing an oxidative burst, and synthesizing phytoalexins. We also observed a process of cell wall modification and polyphenols biosynthesis, which could lead to polymerization in the neoplastic tissue surrounding the eggs.
... [63] But whether the effect is solely due to desiccation of the plant tissue or is accompanied by the additional action of toxic molecules is unknown. Oviposition-induced HR-like is often accompanied by ROS production [42,49,64] and in Solanum dulcamara the HR-like associated production of H 2 O 2 inhibited egg hatching. [49] Similarly, bruchins stimulated neoplasm formation on pea pods that physically impede larval entry. ...
Insect eggs deposited on plants constitute a threat that has led to the evolution of sophisticated defenses. The interactions between insect eggs and plants are governed by a diverse variety of chemicals that inform butterflies about suitable hosts, repel gravid females, alert plants about the presence of an egg, act as signal molecules to induce defenses, directly impair egg development, and indirectly attract egg parasitoids. In recent years, significant progress has been made on the chemical identification, perception and role of compounds associated with oviposition. Knowledge on the genetic basis of oviposition-induced responses is also accumulating. An emerging theme is that insect eggs are not passive structures on leaves but induce complex responses that result from million years of coevolution.
... For example, PAL catalyses the phenylpropanoid pathway, resulting in the biosynthesis of the precursors of lignin [62]. The plant's defence via lignification is a conserved basal mechanism in the plant's immune response against pathogens [63,64]. Therefore, the increase in the activity of defence-related enzymes could prevent pathogenic infection in plants due to silicon supplementation. ...
Silicon (Si) is known to stimulate plant resistance against different phytopathogens, i.e., bacteria, fungi, and nematodes. It is an efficient plant growth regulator under various biotic and abiotic stresses. Silicon-containing compounds, including silicon dioxide, SiO2 nanoparticles (NPs), nano-chelated silicon fertilizer (NCSF), sodium siliconate, and sodium metasilicate, are effective in damaging various nematodes that reduce their reproduction, galling, and disease severity. The defence mechanisms in plant-nematodes interaction may involve a physical barrier, plant defence-associated enzyme activity, synthesis of antimicrobial compounds, and transcriptional regulation of defence-related genes. In the current review, we focused on silicon and its compounds in controlling plant nematodes and regulating different defence mechanisms involved in plant-nematodes interaction. Furthermore, the review aims to evaluate the potential role of Si application in improving plant resistance against nematodes and highlight its need for efficient plant-nematodes disease management.
... Whether this results in enhanced (systemic) resistance to herbivores, is context dependent [69]. Respiratory burst oxidase homologue rbohd mutants were found to be susceptible to the generalist S. littoralis [70], but resistant to the generalists S. exigua and Trichoplusia ni [58], and recent studies indicate the involvement of ROS in resistance induced by insect egg deposition [71] and plant resistance to aphids [64,72e75]. ROS induction has been reported within minutes after inoculation of insect oral secretions in maize (Zea mays) and tomato [58]. ...
Rapid systemic signals travel within the first seconds and minutes after herbivore infestation to mount defense responses in distal tissues. Recent studies have revealed that wound-induced hydraulic pressure changes play an important role in systemic electrical signaling and subsequent calcium and reactive oxygen species waves. These insights raise new questions about signal specificity, the role of insect feeding guild and feeding style and the impact on longer term plant defenses. Here, we integrate the current molecular understanding of wound-induced rapid systemic signaling in the framework of insect-plant interactions.
