Project description:Soybean aphid is one of the major limiting factors for soybean production. However, the mechanism for aphid resistance in soybean is remain enigmatic, very little information is available about the different mechanisms between antibiosis and antixenosis genotypes. Here we dissected aphid infestation into three stages and used genome-wide gene expression profiling to investigate the underlying aphid-plant interaction mechanisms. Approximately 990 million raw reads in total were obtained, the high expression correlation in each genotype between infestation and non-infestation indicated that the response to aphid was controlled by a small subset of important genes. Moreover, plant response to aphid infestation was more rapid in resistant genotypes. Among the differentially expressed genes (DEGs), a total of 901 transcription factor (TF) genes categorized to 40 families were identified with distinct expression patterns, of which AP2/ERF, MYB and WRKY families were proposed to playing dominated roles. Gene expression profiling demonstrated that these genes had either similar or distinct expression patterns in genotypes. Besides, JA-responsive pathway was domination in aphid-soybean interaction compared to SA pathway, which was not involved plant response to aphid in susceptible and antixenotic genotypes but played an important role in antibiosis one. Throughout, callose were deposited in all genotypes but it was more rapidly and efficiently in antibiotic one. However, reactive oxygen species were not involved in response to aphid attack in resistant genotypes during aphid infestation. Our study helps uncover important genes associated with aphid-attack response in antibiosis and antixenotic genotypes of soybean.
Project description:Aphid attack induces defense responses in plants activating several signaling cascades that led to the production of toxic, repellent or antinutritive compounds and the consequent reorganization of the plant primary metabolism. Pepper (Capsicum annuum L.) leaf proteomic response against Myzus persicae (Sulzer) has been investigated and analyzed by LC-MS/MS coupled with bioinformatics tools. Infestation with an initially low density (20 aphids/plant) of aphids restricted to a single leaf taking advantage of clip cages resulted in 6 differentially expressed proteins relative to control leaves (3 proteins at 2 days post-infestation and 3 proteins at 4 days post-infestation). Conversely, when plants were infested with a high density of infestation (200 aphids/plant) 140 proteins resulted differentially expressed relative to control leaves (97 proteins at 2 days post-infestation, 112 proteins at 4 days post-infestation and 105 proteins at 7 days post-infestation). The majority of proteins altered by aphid attack were involved in photosynthesis and photorespiration, oxidative stress, translation, protein folding and degradation and amino acid metabolism. Other proteins identified were involved in lipid, carbohydrate and hormone metabolism, transcription, transport, energy production and cell organization. However proteins directly involved in defense were scarce and were mostly downregulated in response to aphids. The unexpectedly very low number of regulated proteins found in the experiment with a low aphid density suggests an active mitigation of plant defensive response by aphids or alternatively an aphid strategy to remain undetected by the plant. Under a high density of aphids, pepper leaf proteome however changed significantly revealing nearly all routes of plant primary metabolism being altered. Photosynthesis was so far the process with the highest number of proteins being regulated by the presence of aphids. In general, at short times of infestation (2 days) most of the altered proteins were upregulated. However, at longer times of infestation (7 days) the protein downregulation prevailed. Proteins involved in plant defense and in hormone signaling were scarce and mostly downregulated.
Project description:Gene expression profiles in resistant (cv. Dowling) and susceptible (Williams 82) soybean genotypes [Glycine max (L.) Merrill] were compared at 6 and 12 h with and without aphid (Aphis glycines Matsumura) infestation using cDNA microarrays consisting of approximately 18,000 soybean-expressed sequence tags. More genes were induced in Dowling than Williams 82 at 6 h after infestation. Genes that were differentially expressed between aphid and control treatments were selected as aphid-response genes. Eighty-four genes showed specific responses in Dowling and included genes related to defense and other processes. Expression of three defense-related genes was examined at 6, 12, 24, 48, and 72 h after infestation in both genotypes by quantitative real-time PCR. The increases in the transcripts of three defense-related genes were earlier and stronger at 6, 12 and 24 h after infestation in Dowling compared to Williams 82. The differential gene expression between the two genotypes without aphids was determined, and five genes with constitutively higher expression levels were found in Dowling. Keywords = genomic Keywords = Defense Responses Keywords = plant Keywords = DNA-binding protein Keywords = PR proteins Keywords = plant resistance Keywords = signal transduction keywords = insect Keywords: susceptible vs resistant
Project description:Soybean aphids are phloem-feeding pests that can cause significant yield losses in soybean plants. Soybean aphids thrive on susceptible soybean lines but not on resistant lines. Aphids do not normally kill their host and colonize plants for long periods of time, up to several months in soybean. However, our knowledge of plant responses to long-term aphid colonization is very limited. We used microarrays to characterize the soybean plant's transcriptional response against aphids in two related cultivars, a susceptible line and a resistant line with the Rag1 aphid-resistance gene. We measured transcript levels in leaves after 21 days of aphid infestation.
Project description:Soybean aphids are phloem-feeding pests that can cause significant yield losses in soybean plants. Soybean aphids thrive on susceptible soybean lines but not on resistant lines. We used microarrays to characterize the soybean plant's transcriptional defense against aphids in two related cultivars, a susceptible line and a resistant line with the Rag1 aphid-resistance gene. We measured trancript levels in leaves after one and seven days of aphid infestation. This was a full-factorial experiment with three factors: soybean variety (susceptible SD01-76R,resistant LD05-16060), aphid treatment (control, aphids), and infestation duration (1 day, 7 days). There were three replicates per treatment, for a total of 24 samples. The experiment was carried out in a growth chamber. At the V3 growth stage, thirty aphids were added to the third trifoliate leaves of the aphid-treated plants. Each plant had a net to prevent aphid movement among different plants. The aphids were removed prior to sampling.
Project description:Environmentally induced changes in the epigenome help individuals to quickly adapt to fluctuations in the conditions of their habitats. Here we explored those changes in Arabidopsis thaliana plants subjected to multiple biotic and abiotic stresses, and identified transposable element (TE) activation in plants infested with the green peach aphid, Myzus persicae. We performed a genome-wide analysis of DNA methylation, mRNA expression, mRNA degradation and small RNAs accumulation. Our results demonstrate that aphid feeding induces loss of methylation of hundreds of loci, mainly TEs with labile chromatin characteristics. This loss of methylation has the potential to regulate gene expression and we found evidence that it is involved in the control of key plant immunity genes. Accordingly, we find that mutant plants deficient in epigenetic silencing show increased resistance to M.persicae infestation. Collectively, our results show that changes in DNA methylation play a significant role in the regulation of the plant transcriptional response and induction of defence response against aphid feeding.
Project description:Salicylic acid (SA) and jasmonic acid (JA) fulfill key signaling functions in plant responses to herbivores. However, the mechanisms that facilitate systemic signaling in response to phloem-feeding insects remain poorly defined. Rapid local and systemic transcriptome reprogramming patterns observed in Arabidopsis thaliana following infestation by the green peach aphid (Myzus persicae Sulzer) identify abscisic acid (ABA) and redox-signalling as key factors in the transmission of signals from local to systemic leaves. Moreover, aphid fecundity was increased in mutants that were defective in ABA-signaling through ABA-INSENSITIVE 4 and show constitutive up-regulation of SA- and JA-mediated defense pathways. Conversely, aphid fecundity was decreased and aphid vigor was impaired on vitamin C2 mutants that are defective in the major low molecular weight antioxidant of plant cells, ascorbic acid and show constitutive up-regulation of redox defense and SA-mediated pathways but reduced up-regulation of JA-mediated pathways. Crossing vtc2 with abi4 restored the wild type sensitivity to aphids. Hence aphid fecundity was attenuated by low ascorbate in a manner that was dependent on the functions of the ABI4 transcription factor. ABI4 is not only an important regulator of systemic defenses against aphids but it makes a significant contribution to the SA-mediated repression of JA signaling.
Project description:Salicylic acid (SA) and jasmonic acid (JA) fulfill key signaling functions in plant responses to herbivores. However, the mechanisms that facilitate systemic signaling in response to phloem-feeding insects remain poorly defined. Rapid local and systemic transcriptome reprogramming patterns observed in Arabidopsis thaliana following infestation by the green peach aphid (Myzus persicae Sulzer) identify abscisic acid (ABA) and redox-signalling as key factors in the transmission of signals from local to systemic leaves. Moreover, aphid fecundity was increased in mutants that were defective in ABA-signaling through ABA-INSENSITIVE 4 and show constitutive up-regulation of SA- and JA-mediated defense pathways. Conversely, aphid fecundity was decreased and aphid vigor was impaired on vitamin C2 mutants that are defective in the major low molecular weight antioxidant of plant cells, ascorbic acid and show constitutive up-regulation of redox defense and SA-mediated pathways but reduced up-regulation of JA-mediated pathways. Crossing vtc2 with abi4 restored the wild type sensitivity to aphids. Hence aphid fecundity was attenuated by low ascorbate in a manner that was dependent on the functions of the ABI4 transcription factor. ABI4 is not only an important regulator of systemic defenses against aphids but it makes a significant contribution to the SA-mediated repression of JA signaling.
Project description:The soybean aphid, a plant sap sucking insect, is an important soybean pest in the USA causing significant yield losses. The Rag2 gene of soybean provides resistance to soybean aphid biotypes I and II. Transcriptomic analyses were performed on near isogenic lines (NILs) with the Rag2 allele for aphid resistance or rag2 for susceptibility at the Rag2 locus. Soybeans were infested with soybean aphids and leaves were collected at 0, 4, 8, 24, and 48 hours after infestation. RNA were extracted and a high throughput RNA-seq approach was used to examine mRNA expression in Rag2 and rag2 soybean leaves. The expression of ~43,000 genes was detected in both the Rag2 and rag2 leaves. Statistical analysis identified 2361 genes significantly regulated between the resistant and susceptible lines at different times after aphid infestation. Genes found up-regulated in the Rag2 line were annotated as involved in the cell wall, secondary and hormone metabolism, as well as in stress, signaling and transcriptional responses. Genes found up-regulated in the rag2 line were annotated as involved in photosynthesis and carbon metabolism. Interestingly, mRNAs of 2 genes (unknown and mitochondrial protease) located within the Rag2 locus were expressed significantly higher in the resistant genotype. The expression of the putative NBS-LRR resistant gene present in the Rag2 locus was not different between the two soybean lines. However, another NBL-LRR gene located just at the border of the Rag2 locus was and, therefore, may be involved in the differential resistance to aphid infestation exhibited by the two NIL genotypes analyzed.
Project description:In the field, plants usually have to face combined effects of abiotic and biotic stresses. In our study, two spring wheat cultivars Septima and Quintus were subjected to three water regimes (70, 50, 40 % soil water capacity SWC), aphid (Metopolophium dirhodum) infestation or the combination of both stresses, i.e., drought (50, 40% SWC) and aphids. The study has a 2x3x2 factorial design with three biological replicates. Our previous study (Saska et al. 2022) investigated plant morphophysiological characteristics and aphid life table. In the present study, the results of proteomic analysis using 2D-DIGE followed by MALDI-TOF/TOF protein identification are presented. Drought, but also aphid infestation led to alterations in 113 protein spots including proteins assigned to a variety of biological processes ranging from signalling via energy metabolism, redox regulation, stress and defense responses to secondary metabolism indicating a long-term adaptation to adverse conditions. The absence of specific proteins involved in plant response to herbivorous insects indicates a loss of resistance to aphids in modern wheat cultivars during the breeding process. Septima revealed enhanced tolerance with respect to Quintus as indicated by higher values of morphophysiological characteristics (above-ground biomass, leaf length, osmotic potential per full water saturation) and rel. abundance of proteins involved in mitochondrial respiration and ATP biosynthesis.