Transcriptomic dynamics in soybean near-isogenic lines differing in alleles for an aphid resistance gene, following infestation by soybean aphid biotype 2
Abstract:BackgroundGenetic resistance of soybean [Glycine max (L.) Merr] against Aphis glycines provides effective management of this invasive pest, though the underlying molecular mechanisms are largely unknown. This study aimed to investigate genome-wide changes in gene expressions of soybean near-isogenic lines (NILs) either with the Rag5 allele for resistance or the rag5 allele for susceptibility to the aphid following infestation with soybean aphid biotype 2.ResultsThe resistant (R)-NIL responded more rapidly to a… Show more
“…This outcome was not surprising and has been reported previously. For example, Lee et al [ 37 ] found higher number of DEGs in resistant soybean in response to soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae) in comparison to an aphid-susceptible soybean line. Fig.…”
Section: Resultsmentioning
confidence: 99%
“…3 ). On the other hand, genes involved in detoxification, which is one of the defenses linked to plant response to aphid herbivory [ 37 , 45 , 46 ] was up-regulated in both 2- and 6-wk resistant genotype and in the 2-wk susceptible genotype (Fig. 3a, b and c ).…”
Section: Resultsmentioning
confidence: 99%
“…3a, b and c ). The up-regulation of genes involved in oxidative-reduction process has been reported in several plants in response to herbivory, such as in barly in response to Diuraphis noxia Kurdjumov (Hemiptera: Aphididae) [ 47 ], in switchgrass exposed to greenbug [ 48 ], in soybean at both compatible and incompatible interactions with soybean aphid [ 37 , 49 ], and in cotton in response to Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae) [ 46 ]. Our outcomes corroborate these studies and suggest that oxidative responses that are elicited in the resistant genotype are may be the key components of sorghum resistance to sugarcane aphids.…”
Section: Resultsmentioning
confidence: 99%
“…Over the last few years, however, as it became apparent that transcriptional re-programming is the backbone of many plant defense responses, the research has shifted toward transcriptomic analysis of herbivore-plant interactions. Aphid-resistant cultivars respond to aphid feeding by up-regulation of diverse genes that contribute to aphid resistance [ 37 – 39 ]. These genes have been found to be involved in phytohormone signaling pathways, particularly salicylic acid (SA), jasmonic acid (JA), and ethylene (ET) [ 40 – 42 ].…”
BackgroundSugarcane aphid (Melanaphis sacchari) outbreaks in sorghum that were first reported in 2013 are now the most significant threat to this crop in all major sorghum production areas in the U.S. The outcomes of interactions between sugarcane aphid and sorghum and thus the severity of the outbreaks depend on sorghum genotype and potentially also on the phenology of sorghum. Mechanisms underlying these interactions are not known, however. Thus, the goal of this research was to characterize transcriptional changes in a commercially available resistant and a susceptible genotype of sorghum at 2- and 6-wk post-emergence exposed to M. sacchari herbivory. The effects of sorghum age and genotype on the daily change in aphid densities were also evaluated in separate greenhouse experiments.ResultsA higher number of diffentially expressed genes (DEGs) was recovered from the 2-wk plants exposed to aphid herbivory compared to the 6-wk plants across genotypes. Further, gene ontology and pathway analysis indicated a suite of transcriptional changes in the resistant genotype that were weak or absent in the susceptible sorghum. Specifically, the aphid-resistant genotype exposed to M. sacchari up-regulated several genes involved in defense, which was particularly evident in the 2-wk plants that showed the most robust transcriptional responses. These transcriptional changes in the younger resistant sorghum were characterized by induction of hormone-signaling pathways, pathways coding for secondary metabolites, glutathion metabolism, and plant-pathogen interaction. Furthermore, the 2-wk resistant plants appeared to compensate for the effects of oxidative stress induced by sugarcane aphid herbivory with elevated expression of genes involved in detoxification. These transcriptional responses were reflected in the aphid population growth, which was significantly faster in the susceptible and older sorghum than in the resistant and younger plants.ConclusionThis experiment provided the first insights into molecular mechanisms underlying lower population growth of M. sacchari on the resistant sorghum genotype. Further, it appears that the younger resistant sorghum was able to mount a robust defense response following aphid herbivory, which was much weaker in the older sorghum. Several pathways and specific genes provide specific clues into the mechanisms underlying host plant resistance to this invasive insect.Electronic supplementary materialThe online version of this article (10.1186/s12864-018-5095-x) contains supplementary material, which is available to authorized users.
“…This outcome was not surprising and has been reported previously. For example, Lee et al [ 37 ] found higher number of DEGs in resistant soybean in response to soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae) in comparison to an aphid-susceptible soybean line. Fig.…”
Section: Resultsmentioning
confidence: 99%
“…3 ). On the other hand, genes involved in detoxification, which is one of the defenses linked to plant response to aphid herbivory [ 37 , 45 , 46 ] was up-regulated in both 2- and 6-wk resistant genotype and in the 2-wk susceptible genotype (Fig. 3a, b and c ).…”
Section: Resultsmentioning
confidence: 99%
“…3a, b and c ). The up-regulation of genes involved in oxidative-reduction process has been reported in several plants in response to herbivory, such as in barly in response to Diuraphis noxia Kurdjumov (Hemiptera: Aphididae) [ 47 ], in switchgrass exposed to greenbug [ 48 ], in soybean at both compatible and incompatible interactions with soybean aphid [ 37 , 49 ], and in cotton in response to Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae) [ 46 ]. Our outcomes corroborate these studies and suggest that oxidative responses that are elicited in the resistant genotype are may be the key components of sorghum resistance to sugarcane aphids.…”
Section: Resultsmentioning
confidence: 99%
“…Over the last few years, however, as it became apparent that transcriptional re-programming is the backbone of many plant defense responses, the research has shifted toward transcriptomic analysis of herbivore-plant interactions. Aphid-resistant cultivars respond to aphid feeding by up-regulation of diverse genes that contribute to aphid resistance [ 37 – 39 ]. These genes have been found to be involved in phytohormone signaling pathways, particularly salicylic acid (SA), jasmonic acid (JA), and ethylene (ET) [ 40 – 42 ].…”
BackgroundSugarcane aphid (Melanaphis sacchari) outbreaks in sorghum that were first reported in 2013 are now the most significant threat to this crop in all major sorghum production areas in the U.S. The outcomes of interactions between sugarcane aphid and sorghum and thus the severity of the outbreaks depend on sorghum genotype and potentially also on the phenology of sorghum. Mechanisms underlying these interactions are not known, however. Thus, the goal of this research was to characterize transcriptional changes in a commercially available resistant and a susceptible genotype of sorghum at 2- and 6-wk post-emergence exposed to M. sacchari herbivory. The effects of sorghum age and genotype on the daily change in aphid densities were also evaluated in separate greenhouse experiments.ResultsA higher number of diffentially expressed genes (DEGs) was recovered from the 2-wk plants exposed to aphid herbivory compared to the 6-wk plants across genotypes. Further, gene ontology and pathway analysis indicated a suite of transcriptional changes in the resistant genotype that were weak or absent in the susceptible sorghum. Specifically, the aphid-resistant genotype exposed to M. sacchari up-regulated several genes involved in defense, which was particularly evident in the 2-wk plants that showed the most robust transcriptional responses. These transcriptional changes in the younger resistant sorghum were characterized by induction of hormone-signaling pathways, pathways coding for secondary metabolites, glutathion metabolism, and plant-pathogen interaction. Furthermore, the 2-wk resistant plants appeared to compensate for the effects of oxidative stress induced by sugarcane aphid herbivory with elevated expression of genes involved in detoxification. These transcriptional responses were reflected in the aphid population growth, which was significantly faster in the susceptible and older sorghum than in the resistant and younger plants.ConclusionThis experiment provided the first insights into molecular mechanisms underlying lower population growth of M. sacchari on the resistant sorghum genotype. Further, it appears that the younger resistant sorghum was able to mount a robust defense response following aphid herbivory, which was much weaker in the older sorghum. Several pathways and specific genes provide specific clues into the mechanisms underlying host plant resistance to this invasive insect.Electronic supplementary materialThe online version of this article (10.1186/s12864-018-5095-x) contains supplementary material, which is available to authorized users.
“…Another enriched pathway in the resistant cultivar was photosynthesis. Previous transcriptomic study on soybean near-isogenic lines differing in alleles for an aphid resistance gene, Rag5 following infestation by soybean aphid biotype 2 has shown DEGs enriched for photosynthesis [71]. Physiologically, photosynthesis rates have been reduced up to 50% on soybean aphid infested leaflets [72].…”
Soybean aphid (SBA) is one of the major pests of soybean (Glycine max) in the United States of America. The main objective of this research was to characterize interactions between two different biotypes of soybean aphids in susceptible and resistant soybean cultivars. Demographic and transcriptomic responses of susceptible and resistant (Rag1) soybean cultivars to aphid feeding were investigated in soybean plants colonized by aphids (biotype 1) in the presence or absence of inducer population (biotype 2) at day 1 and day 11. Leaves tissues collected at day 1 and day 11 post infestation were used for RNA sequencing, and ten RNA datasets with 266,535,654 sequence reads were analyzed. In the presence of inducer population, we found 746 and 243 differentially expressed genes (DEGs) in susceptible and resistant cultivars, respectively at day 1, whereas 981 and 377 DEGs were found in susceptible and resistant cultivars, respectively at day 11. Enrichment analysis showed a response to chitin, lignin catabolic and metabolic process, asparagine metabolic process, response to chemical unique to treatment with no inducer population, whereas, response to reactive oxygen species, photosynthesis, regulation of endopeptidase activity unique to treatment with inducer population. Furthermore, 14 DEGs were observed in Rag QTLs regions, particularly six DEGs in Rag1 containing QTL. The identified DEGs in the experiment in both resistant and susceptible cultivars during the interaction of soybean and SBA are potential candidates for furthering investigation into induced susceptibility.
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