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13 pages, 6580 KiB

Open AccessArticle

Agave Wilt Susceptibility by Reduction of Free Hexoses in Root Tissue of Agave tequilana Weber var. azul Commercial Plants in the Fructan Accumulation Process

by Rodrigo Guillermo Mantilla-Blandon, Norma Alejandra Mancilla-Margalli, Joaquín Adolfo Molina-Montes, Jaime Xavier Uvalle-Bueno and Martín Eduardo Avila-Miranda

Int. J. Mol. Sci. 2024, 25(13), 7357; https://doi.org/10.3390/ijms25137357 - 4 Jul 2024

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Abstract

Agave tequilana stems store fructan polymers, the main carbon source for tequila production. This crop takes six or more years for industrial maturity. In conducive conditions, agave wilt disease increases the incidence of dead plants after the fourth year. Plant susceptibility induced for [...] Read more.

Agave tequilana stems store fructan polymers, the main carbon source for tequila production. This crop takes six or more years for industrial maturity. In conducive conditions, agave wilt disease increases the incidence of dead plants after the fourth year. Plant susceptibility induced for limited photosynthates for defense is recognized in many crops and is known as “sink-induced loss of resistance”. To establish whether A. tequilana is more prone to agave wilt as it ages, because the reduction of water-soluble carbohydrates in roots, as a consequence of greater assembly of highly polymerized fructans, were quantified roots sucrose, fructose, and glucose, as well as fructans in stems of agave plants of different ages. The damage induced by inoculation with Fusarium solani or F. oxysporum in the roots or xylem bundles, respectively, was recorded. As the agave plant accumulated fructans in the stem as the main sink, the amount of these hexoses diminished in the roots of older plants, and root rot severity increased when plants were inoculated with F. solani, as evidence of more susceptibility. This knowledge could help to structure disease management that reduces the dispersion of agave wilt, dead plants, and economic losses at the end of agave’s long crop cycle. Full article

(This article belongs to the Special Issue Plant Response to Insects and Microbes 2.0)

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13 pages, 2783 KiB

Open AccessArticle

Investigating the Roles of Coat Protein and Triple Gene Block Proteins of Potato Mop-Top Virus Using a Heterologous Expression System

by Hira Kamal, Kasi Viswanath Kotapati, Kiwamu Tanaka and Hanu R. Pappu

Int. J. Mol. Sci. 2024, 25(13), 6990; https://doi.org/10.3390/ijms25136990 - 26 Jun 2024

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Abstract

Potato mop-top virus (PMTV) is an emerging viral pathogen that causes tuber necrosis in potatoes. PMTV is composed of three single-stranded RNA segments: RNA1 encodes RNA-dependent RNA polymerase, RNA2 contains the coat protein (CP), and RNA3 harbors a triple gene block (TGB 1, [...] Read more.

Potato mop-top virus (PMTV) is an emerging viral pathogen that causes tuber necrosis in potatoes. PMTV is composed of three single-stranded RNA segments: RNA1 encodes RNA-dependent RNA polymerase, RNA2 contains the coat protein (CP), and RNA3 harbors a triple gene block (TGB 1, TGB2, and TGB3). CP plays a role in viral transmission, while TGB is known to facilitate cell-to-cell and long-distance systemic movement. The role of CP in symptom development, specifically in the presence of TGB genes, was investigated using potato virus X (PVX) as a delivery vehicle to express PMTV genes in the model plant Nicotiana benthamiana. Plants expressing individual genes showed mild symptoms that included leaf curling and crumpling. Interestingly, symptom severity varied among plants infected with three different combinations: CP with TGB1, CP with TGB2, and CP with TGB3. Notably, the combination of CP and TGB3 induced a hypersensitive response, accompanied by stunted growth and downward curling and crumpling. These results suggest the potential role of TGB co-expressed with CP in symptom development during PMTV infection. Additionally, this study demonstrates the use of the PVX-based expression system as a valuable platform for assessing the role of unknown genes in viral pathogenicity. Full article

(This article belongs to the Special Issue Plant Response to Insects and Microbes 2.0)

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14 pages, 3219 KiB

Open AccessArticle

Molecular Basis of CO₂ Sensing in Hyphantria cunea

by Jian Zhang, Shiwen Duan, Wenlong Wang, Duo Liu and Yinliang Wang

Int. J. Mol. Sci. 2024, 25(11), 5987; https://doi.org/10.3390/ijms25115987 - 30 May 2024

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Abstract

Carbon dioxide (CO₂) released by plants can serve as a cue for regulating insect behaviors. Hyphantria cunea is a widely distributed forestry pest that may use CO₂ as a cue for foraging and oviposition. However, the molecular mechanism underlying its [...] Read more.

Carbon dioxide (CO₂) released by plants can serve as a cue for regulating insect behaviors. Hyphantria cunea is a widely distributed forestry pest that may use CO₂ as a cue for foraging and oviposition. However, the molecular mechanism underlying its ability to sense CO₂ has not been elucidated. Our initial study showed that CO₂ is significantly attractive to H. cunea adults. Subsequently, 44 H. cunea gustatory receptors (GRs) were identified using transcriptome data, and 3 candidate CO₂ receptors that are specifically expressed in the labial palps were identified. In vivo electrophysiological assays revealed that the labial palp is the primary organ for CO₂ perception in H. cunea, which is similar to findings in other lepidopteran species. By using the Xenopus oocyte expression system, we showed that the HcunGR1 and HcunGR3 co-expressions produced a robust response to CO₂, but HcunGR2 had an inhibitory effect on CO₂ perception. Finally, immunohistochemical staining revealed sexual dimorphism in the CO₂-sensitive labial pit organ glomerulus (LPOG). Taken together, our results clarified the mechanism by which H. cunea sense CO₂, laying the foundation for further investigations into the role of CO₂ in the rapid spread of H. cunea. Full article

(This article belongs to the Special Issue Plant Response to Insects and Microbes 2.0)

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31 pages, 8706 KiB

Open AccessArticle

Arabidopsis Transcriptomics Reveals the Role of Lipoxygenase2 (AtLOX2) in Wound-Induced Responses

by Diljot Kaur, Andreas Schedl, Christine Lafleur, Julian Martinez Henao, Nicole M. van Dam, Jean Rivoal and Jacqueline C. Bede

Int. J. Mol. Sci. 2024, 25(11), 5898; https://doi.org/10.3390/ijms25115898 - 28 May 2024

Cited by 1 | Viewed by 1014

Abstract

In wounded Arabidopsis thaliana leaves, four 13S-lipoxygenases (AtLOX2, AtLOX3, AtLOX4, AtLOX6) act in a hierarchical manner to contribute to the jasmonate burst. This leads to defense responses with LOX2 playing an important role in plant resistance against caterpillar herb-ivory. In this [...] Read more.

In wounded Arabidopsis thaliana leaves, four 13S-lipoxygenases (AtLOX2, AtLOX3, AtLOX4, AtLOX6) act in a hierarchical manner to contribute to the jasmonate burst. This leads to defense responses with LOX2 playing an important role in plant resistance against caterpillar herb-ivory. In this study, we sought to characterize the impact of AtLOX2 on wound-induced phytohormonal and transcriptional responses to foliar mechanical damage using wildtype (WT) and lox2 mutant plants. Compared with WT, the lox2 mutant had higher constitutive levels of the phytohormone salicylic acid (SA) and enhanced expression of SA-responsive genes. This suggests that AtLOX2 may be involved in the biosynthesis of jasmonates that are involved in the antagonism of SA biosynthesis. As expected, the jasmonate burst in response to wounding was dampened in lox2 plants. Generally, 1 h after wounding, genes linked to jasmonate biosynthesis, jasmonate signaling attenuation and abscisic acid-responsive genes, which are primarily involved in wound sealing and healing, were differentially regulated between WT and lox2 mutants. Twelve h after wounding, WT plants showed stronger expression of genes associated with plant protection against insect herbivory. This study highlights the dynamic nature of jasmonate-responsive gene expression and the contribution of AtLOX2 to this pathway and plant resistance against insects. Full article

(This article belongs to the Special Issue Plant Response to Insects and Microbes 2.0)

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17 pages, 29000 KiB

Open AccessArticle

Odorant Receptors Expressing and Antennal Lobes Architecture Are Linked to Caste Dimorphism in Asian Honeybee, Apis cerana (Hymenoptera: Apidae)

by Haoqin Ke, Yu Chen, Baoyi Zhang, Shiwen Duan, Xiaomei Ma, Bingzhong Ren and Yinliang Wang

Int. J. Mol. Sci. 2024, 25(7), 3934; https://doi.org/10.3390/ijms25073934 - 1 Apr 2024

Cited by 1 | Viewed by 1165

Abstract

Insects heavily rely on the olfactory system for food, mating, and predator evasion. However, the caste-related olfactory differences in Apis cerana, a eusocial insect, remain unclear. To explore the peripheral and primary center of the olfactory system link to the caste dimorphism [...] Read more.

Insects heavily rely on the olfactory system for food, mating, and predator evasion. However, the caste-related olfactory differences in Apis cerana, a eusocial insect, remain unclear. To explore the peripheral and primary center of the olfactory system link to the caste dimorphism in A. cerana, transcriptome and immunohistochemistry studies on the odorant receptors (ORs) and architecture of antennal lobes (ALs) were performed on different castes. Through transcriptomesis, we found more olfactory receptor genes in queens and workers than in drones, which were further validated by RT-qPCR, indicating caste dimorphism. Meanwhile, ALs structure, including volume, surface area, and the number of glomeruli, demonstrated a close association with caste dimorphism. Particularly, drones had more macroglomeruli possibly for pheromone recognition. Interestingly, we found that the number of ORs and glomeruli ratio was nearly 1:1. Also, the ORs expression distribution pattern was very similar to the distribution of glomeruli volume. Our results suggest the existence of concurrent plasticity in both the peripheral olfactory system and ALs among different castes of A. cerana, highlighting the role of the olfactory system in labor division in insects. Full article

(This article belongs to the Special Issue Plant Response to Insects and Microbes 2.0)

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14 pages, 4400 KiB

Open AccessArticle

Wheat Transcriptional Corepressor TaTPR1 Suppresses Susceptibility Genes TaDND1/2 and Potentiates Post-Penetration Resistance against Blumeria graminis forma specialis tritici

by Pengfei Zhi, Rongxin Gao, Wanzhen Chen and Cheng Chang

Int. J. Mol. Sci. 2024, 25(3), 1695; https://doi.org/10.3390/ijms25031695 - 30 Jan 2024

Cited by 1 | Viewed by 957

Abstract

The obligate biotrophic fungal pathogen Blumeria graminis forma specialis tritici (B.g. tritici) is the causal agent of wheat powdery mildew disease. The TOPLESS-related 1 (TPR1) corepressor regulates plant immunity, but its role in regulating wheat resistance against powdery mildew remains to [...] Read more.

The obligate biotrophic fungal pathogen Blumeria graminis forma specialis tritici (B.g. tritici) is the causal agent of wheat powdery mildew disease. The TOPLESS-related 1 (TPR1) corepressor regulates plant immunity, but its role in regulating wheat resistance against powdery mildew remains to be disclosed. Herein, TaTPR1 was identified as a positive regulator of wheat post-penetration resistance against powdery mildew disease. The transient overexpression of TaTPR1.1 or TaTPR1.2 confers wheat post-penetration resistance powdery mildew, while the silencing of TaTPR1.1 and TaTPR1.2 results in an enhanced wheat susceptibility to B.g. tritici. Furthermore, Defense no Death 1 (TaDND1) and Defense no Death 2 (TaDND2) were identified as wheat susceptibility (S) genes facilitating a B.g. tritici infection. The overexpression of TaDND1 and TaDND2 leads to an enhanced wheat susceptibility to B.g. tritici, while the silencing of wheat TaDND1 and TaDND2 leads to a compromised susceptibility to powdery mildew. In addition, we demonstrated that the expression of TaDND1 and TaDND2 is negatively regulated by the wheat transcriptional corepressor TaTPR1. Collectively, these results implicate that TaTPR1 positively regulates wheat post-penetration resistance against powdery mildew probably via suppressing the S genes TaDND1 and TaDND2. Full article

(This article belongs to the Special Issue Plant Response to Insects and Microbes 2.0)

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12 pages, 12790 KiB

Open AccessArticle

Plant Responses of Maize to Two formae speciales of Sporisorium reilianum Support Recent Fungal Host Jump

by Lukas Dorian Dittiger, Shivam Chaudhary, Alexandra Charlotte Ursula Furch, Axel Mithöfer and Jan Schirawski

Int. J. Mol. Sci. 2023, 24(21), 15604; https://doi.org/10.3390/ijms242115604 - 26 Oct 2023

Cited by 1 | Viewed by 1130

Abstract

Host jumps are a major factor for the emergence of new fungal pathogens. In the evolution of smut fungi, a putative host jump occurred in Sporisorium reilianum that today exists in two host-adapted formae speciales, the sorghum-pathogenic S. reilianum f. sp. reilianum [...] Read more.

Host jumps are a major factor for the emergence of new fungal pathogens. In the evolution of smut fungi, a putative host jump occurred in Sporisorium reilianum that today exists in two host-adapted formae speciales, the sorghum-pathogenic S. reilianum f. sp. reilianum and maize-pathogenic S. reilianum f. sp. zeae. To understand the molecular host-specific adaptation to maize, we compared the transcriptomes of maize leaves colonized by both formae speciales. We found that both varieties induce many common defense response-associated genes, indicating that both are recognized by the plant as pathogens. S. reilianum f. sp. reilianum additionally induced genes involved in systemic acquired resistance. In contrast, only S. reilianum f. sp. zeae induced expression of chorismate mutases that function in reducing the level of precursors for generation of the defense compound salicylic acid (SA), as well as oxylipin biosynthesis enzymes necessary for generation of the SA antagonist jasmonic acid (JA). In accordance, we found reduced SA levels as well as elevated JA and JA-Ile levels in maize leaves inoculated with the maize-adapted variety. These findings support a model of the emergence of the maize-pathogenic variety from a sorghum-specific ancestor following a recent host jump. Full article

(This article belongs to the Special Issue Plant Response to Insects and Microbes 2.0)

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15 pages, 4322 KiB

Open AccessArticle

Dynamic Reconfiguration of Switchgrass Proteomes in Response to Rust (Puccinia novopanici) Infection

by Nathan A. Palmer, Sophie Alvarez, Michael J. Naldrett, Anthony Muhle, Gautam Sarath, Serge J. Edmé, Satyanarayana Tatineni, Robert B. Mitchell and Gary Yuen

Int. J. Mol. Sci. 2023, 24(19), 14630; https://doi.org/10.3390/ijms241914630 - 27 Sep 2023

Cited by 2 | Viewed by 1242

Abstract

Switchgrass (Panicum virgatum L.) can be infected by the rust pathogen (Puccinia novopanici) and results in lowering biomass yields and quality. Label-free quantitative proteomics was conducted on leaf extracts harvested from non-infected and infected plants from a susceptible cultivar (Summer) [...] Read more.

Switchgrass (Panicum virgatum L.) can be infected by the rust pathogen (Puccinia novopanici) and results in lowering biomass yields and quality. Label-free quantitative proteomics was conducted on leaf extracts harvested from non-infected and infected plants from a susceptible cultivar (Summer) at 7, 11, and 18 days after inoculation (DAI) to follow the progression of disease and evaluate any plant compensatory mechanisms to infection. Some pustules were evident at 7 DAI, and their numbers increased with time. However, fungal DNA loads did not appreciably change over the course of this experiment in the infected plants. In total, 3830 proteins were identified at 1% false discovery rate, with 3632 mapped to the switchgrass proteome and 198 proteins mapped to different Puccinia proteomes. Across all comparisons, 1825 differentially accumulated switchgrass proteins were identified and subjected to a STRING analysis using Arabidopsis (A. thaliana L.) orthologs to deduce switchgrass cellular pathways impacted by rust infection. Proteins associated with plastid functions and primary metabolism were diminished in infected Summer plants at all harvest dates, whereas proteins associated with immunity, chaperone functions, and phenylpropanoid biosynthesis were significantly enriched. At 18 DAI, 1105 and 151 proteins were significantly enriched or diminished, respectively. Many of the enriched proteins were associated with mitigation of cellular stress and defense. Full article

(This article belongs to the Special Issue Plant Response to Insects and Microbes 2.0)

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16 pages, 1305 KiB

Open AccessArticle

Investigating the Regulatory Mechanism of the Sesquiterpenol Nerolidol from a Plant on Juvenile Hormone-Related Genes in the Insect Spodoptera exigua

by Hanyang Dai, Baosheng Liu, Lei Yang, Yu Yao, Mengyun Liu, Wenqing Xiao, Shuai Li, Rui Ji and Yang Sun

Int. J. Mol. Sci. 2023, 24(17), 13330; https://doi.org/10.3390/ijms241713330 - 28 Aug 2023

Cited by 5 | Viewed by 1447

Abstract

Various plant species contain terpene secondary metabolites, which disrupt insect growth and development by affecting the activity of juvenile hormone-degrading enzymes, and the juvenile hormone (JH) titers maintained in insects. Nerolidol, a natural sesquiterpenol belonging to the terpenoid group, exhibits structural similarities to [...] Read more.

Various plant species contain terpene secondary metabolites, which disrupt insect growth and development by affecting the activity of juvenile hormone-degrading enzymes, and the juvenile hormone (JH) titers maintained in insects. Nerolidol, a natural sesquiterpenol belonging to the terpenoid group, exhibits structural similarities to insect JHs. However, the impact of nerolidol on insect growth and development, as well as its underlying molecular mechanism, remains unclear. Here, the effects of nerolidol on Spodoptera exigua were investigated under treatment at various sub-lethal doses (4.0 mg/mL, 1.0 mg/mL, 0.25 mg/mL). We found that a higher dose (4.0 mg/mL) of nerolidol significantly impaired the normal growth, development, and population reproduction of S. exigua, although a relatively lower dose (0.25 mg/mL) of nerolidol had no significant effect on this growth and development. Combined transcriptome sequencing and gene family analysis further revealed that four juvenile hormone esterase (JHE)-family genes that are involved in juvenile hormone degradation were significantly altered in S. exigua larvae after nerolidol treatment (4.0 mg/mL). Interestingly, the juvenile hormone esterase-like (JHEL) gene Sexi006721, a critical element responsive to nerolidol stress, was closely linked with the significant augmentation of JHE activity and JH titer in S. exigua (R² = 0.94, p < 0.01). Taken together, we speculate that nerolidol can function as an analog of JH by modulating the expression of the enzyme genes responsible for degrading JH, resulting in JH disorders and ultimately disrupting the development of insect larvae. This study ultimately provides a theoretical basis for the sustainable control of S. exigua in the field whilst proposing a new perspective for the development of novel biological pesticides. Full article

(This article belongs to the Special Issue Plant Response to Insects and Microbes 2.0)

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15 pages, 1603 KiB

Open AccessArticle

Tomato Aphid (Aphis gossypii) Secreted Saliva Can Enhance Aphid Resistance by Upregulating Signaling Molecules in Tomato (Solanum lycopersicum)

by Khadija Javed, Yong Wang, Humayun Javed, Chen Wang, Chuang Liu and Yuqian Huang

Int. J. Mol. Sci. 2023, 24(16), 12768; https://doi.org/10.3390/ijms241612768 - 14 Aug 2023

Cited by 2 | Viewed by 1757

Abstract

This study investigated the impact of Aphis gossypii watery saliva on the induction of tomato (Solanum lycopersicum) plant resistance. To examine the role of A. gossypii saliva, we collected watery saliva from A. gossypii after a 48 h feeding period on [...] Read more.

This study investigated the impact of Aphis gossypii watery saliva on the induction of tomato (Solanum lycopersicum) plant resistance. To examine the role of A. gossypii saliva, we collected watery saliva from A. gossypii after a 48 h feeding period on an artificial diet. SDS-PAGE resolving gel 12% was used to separate the salivary proteins. Relative expression of gene analysis revealed that the intrusion of A. gossypii saliva dripping onto S. lycopersicum leaves triggered robust defense responses mediated by a signaling molecule, i.e., salicylic acid, while the signaling molecule’s jasmonic acid-dependent defense responses were moderately activated. Aphid saliva infiltrated S. lycopersicum leaves slowed the intrinsic rate of population growth of A. gossypii and significantly reduced the number of nymphs produced daily, compared to untreated leaves. During a choice test with untreated S. lycopersicum, aphids showed a repellent response towards saliva-infiltrated S. lycopersicum. Moreover, the (EPG) electrical penetration graph analysis demonstrated that the eating pattern of A. gossypii compared to untreated S. lycopersicum, that had been exposed to saliva was negatively impacted. These results provide compelling evidence for the involvement of salivary components of A. gossypii in inducing resistance against aphids in S. lycopersicum plants. Furthermore, the study underscores the crucial role of watery saliva in the intricate interactions between aphids and plants. The activation of pathways was also part of the defensive response (jasmonic acid (JA), salicylic acid (SA) signaling molecules). The findings of this research deliver valuable insights into the potential of watery aphid saliva as a natural defense mechanism against aphid infestations in S. lycopersicum crops. Full article

(This article belongs to the Special Issue Plant Response to Insects and Microbes 2.0)

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Review

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18 pages, 566 KiB

Open AccessReview

Signaling and Resistosome Formation in Plant Innate Immunity to Viruses: Is There a Common Mechanism of Antiviral Resistance Conserved across Kingdoms?

by Peter A. Ivanov, Tatiana V. Gasanova, Maria N. Repina and Andrey A. Zamyatnin, Jr.

Int. J. Mol. Sci. 2023, 24(17), 13625; https://doi.org/10.3390/ijms241713625 - 3 Sep 2023

Cited by 1 | Viewed by 2429

Abstract

Virus-specific proteins, including coat proteins, movement proteins, replication proteins, and suppressors of RNA interference are capable of triggering the hypersensitive response (HR), which is a type of cell death in plants. The main cell death signaling pathway involves direct interaction of HR-inducing proteins [...] Read more.

Virus-specific proteins, including coat proteins, movement proteins, replication proteins, and suppressors of RNA interference are capable of triggering the hypersensitive response (HR), which is a type of cell death in plants. The main cell death signaling pathway involves direct interaction of HR-inducing proteins with nucleotide-binding leucine-rich repeats (NLR) proteins encoded by plant resistance genes. Singleton NLR proteins act as both sensor and helper. In other cases, NLR proteins form an activation network leading to their oligomerization and formation of membrane-associated resistosomes, similar to metazoan inflammasomes and apoptosomes. In resistosomes, coiled-coil domains of NLR proteins form Ca²⁺ channels, while toll-like/interleukin-1 receptor-type (TIR) domains form oligomers that display NAD+ glycohydrolase (NADase) activity. This review is intended to highlight the current knowledge on plant innate antiviral defense signaling pathways in an attempt to define common features of antiviral resistance across the kingdoms of life. Full article

(This article belongs to the Special Issue Plant Response to Insects and Microbes 2.0)

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