Project description:We provide evidence that heterosis for bacterial defense exists in hybrids crossed between some Arabidopsis accessions. Comparison of transcriptomes between hybrids exhibiting heterosis for disease resistance and their parents after inoculation with Pst DC3000 revealed that several key genes involved in salicylic acid (SA) biosynthesis were significantly up-regulated in hybrids. Consistently, in response to bacterial infection, more SA [both free SA and SA glycoside (SAG)] accumulated in hybrids compared with both parents. In addition, heterosis for bacterial defense was significantly compromised in hybrids of pad4 mutants in which the SA biosynthesis pathway was blocked. Moreover, we further revealed that increased histone H3 acetylation of the key genes involved in the SA biosynthesis pathway correlated with their up-regulated expression in hybrids. Around 30 inoculated leaves from Arabidopsis accessions Col-0 and Sei-0 as well as their reciprocal hybrids Fcs and Fsc, which showed best-parent heterosis for bacterial defense were pooled in each sample for mRNA Seq using HiSeq 2000 sequencing system (Illumina)
Project description:We provide evidence that heterosis for bacterial defense exists in hybrids crossed between some Arabidopsis accessions. Comparison of transcriptomes between hybrids exhibiting heterosis for disease resistance and their parents after inoculation with Pst DC3000 revealed that several key genes involved in salicylic acid (SA) biosynthesis were significantly up-regulated in hybrids. Consistently, in response to bacterial infection, more SA [both free SA and SA glycoside (SAG)] accumulated in hybrids compared with both parents. In addition, heterosis for bacterial defense was significantly compromised in hybrids of pad4 mutants in which the SA biosynthesis pathway was blocked. Moreover, we further revealed that increased histone H3 acetylation of the key genes involved in the SA biosynthesis pathway correlated with their up-regulated expression in hybrids.
Project description:Heterosis, or hybrid vigor, has been exploited in agriculture to deliver increases in crop yields for over a century, yet the molecular basis is not well understood We have studied the transcriptomes of 15 day old seedlings from intraspecific Arabidopsis hybrids with varying levels of heterosis and their parental lines in order to identify drivers of heterosis. The patterns of altered gene expression in the hybrids point to a reduction in basal defense levels that could reflect the antagonism between plant immunity and plant growth. Associated with this theme are changes to the salicylic acid and auxin regulated networks which are known to control abiotic and biotic defense responses as well as being important regulators of plant growth. Increased auxin response correlates with the heterotic phenotype of greater leaf cell numbers, whereas reduced salicylic acid levels and response promotes increased leaf cell size in hybrids involving C24. By manipulating salicylic acid levels in each of our hybrid systems, we can alter levels of heterosis, promote additional growth in the hybrids, and generate increased growth in the parents, especially C24.
Project description:Myzus persicae (green peach aphid) feeding on Arabidopsis thaliana induces a defense response, quantified as reduced aphid progeny production, in infested leaves but not in other parts of the plant. Similarly, infiltration of aphid saliva into Arabidopsis leaves causes only a local increase in aphid resistance. Further characterization of the defense-eliciting salivary components indicates that Arabidopsis recognizes a proteinaceous elicitor with a size between 3 to 10 kD. Genetic analysis using well-characterized Arabidopsis mutant shows that saliva-induced resistance against M. persicae is independent of the known defense signaling pathways involving salicylic acid, jasmonate, and ethylene. Among 78 Arabidopsis genes that were induced by aphid saliva infiltration, 52 had been identified previously as aphid-induced, but few are responsive to the well-known plant defense signaling molecules salicylic acid and jasmonate. Quantitative PCR analysis confirms expression of saliva-induced genes. In particular, expression of a set of O-methyltransferases, which may be involved in the synthesis of aphid-repellent glucosinolates, was significantly up-regulated by both M. persicae feeding and treatment with aphid saliva. However, this did not correlate with increased production of 4-methoxyindol-3-ylmethylglucosinolate, suggesting that aphid salivary components trigger an Arabidopsis defense response that is independent of this aphid-deterrent glucosinolate.
Project description:Myzus persicae (green peach aphid) feeding on Arabidopsis thaliana induces a defense response, quantified as reduced aphid progeny production, in infested leaves but not in other parts of the plant. Similarly, infiltration of aphid saliva into Arabidopsis leaves causes only a local increase in aphid resistance. Further characterization of the defense-eliciting salivary components indicates that Arabidopsis recognizes a proteinaceous elicitor with a size between 3 to 10 kD. Genetic analysis using well-characterized Arabidopsis mutant shows that saliva-induced resistance against M. persicae is independent of the known defense signaling pathways involving salicylic acid, jasmonate, and ethylene. Among 78 Arabidopsis genes that were induced by aphid saliva infiltration, 52 had been identified previously as aphid-induced, but few are responsive to the well-known plant defense signaling molecules salicylic acid and jasmonate. Quantitative PCR analysis confirms expression of saliva-induced genes. In particular, expression of a set of O-methyltransferases, which may be involved in the synthesis of aphid-repellent glucosinolates, was significantly up-regulated by both M. persicae feeding and treatment with aphid saliva. However, this did not correlate with increased production of 4-methoxyindol-3-ylmethylglucosinolate, suggesting that aphid salivary components trigger an Arabidopsis defense response that is independent of this aphid-deterrent glucosinolate. Experiment Overall Design: 3 biological replicates (control and treatment). Total number of samples: 6.
Project description:Heterosis, or hybrid vigor, has been exploited in agriculture to deliver increases in crop yields for over a century, yet the molecular basis is not well understood We have studied the transcriptomes of 15 day old seedlings from intraspecific Arabidopsis hybrids with varying levels of heterosis and their parental lines in order to identify drivers of heterosis. The patterns of altered gene expression in the hybrids point to a reduction in basal defense levels that could reflect the antagonism between plant immunity and plant growth. Associated with this theme are changes to the salicylic acid and auxin regulated networks which are known to control abiotic and biotic defense responses as well as being important regulators of plant growth. Increased auxin response correlates with the heterotic phenotype of greater leaf cell numbers, whereas reduced salicylic acid levels and response promotes increased leaf cell size in hybrids involving C24. By manipulating salicylic acid levels in each of our hybrid systems, we can alter levels of heterosis, promote additional growth in the hybrids, and generate increased growth in the parents, especially C24. Aerial tissues of 15 days after sowing seedlings from C24, Ler, Col and their reciprocal hybrid offspring. In total 7 biological replicates for both the C24 and Ler parents, 2 biological replicates for Col, 10 biological replicates for C24/Ler and 4 biological replicates for both C24/Col and Col/Ler were sequenced and analysed. Each replicated consisted of a pools of 5-15 seedlings (see publication for more details)
Project description:The goal of the microarray was to investigate the transcriptome changes induced by exogenous NAD+ in the wild-type Col-0 plants. Results showed that exogenous NAD+-induced dramatic transcriptional changes in Arabidopsis. Particularly, a large group of salicylic acid pathway genes including NPR1 and its traget genes were induced by NAD+, whereas the jasmonic acid/ethylene pathway defense marker gene PDF1.2 was inhibited by NAD+ treatment. In addition, a group of the pathogen-associated molecular pattern pathway genes were also induced by exogenous NAD+. These results indicate that exogenous NAD+ induces defense pathways against (hemi)biotrophic pathogens but suppresses defense against necrotrophs.
Project description:Plants are aerobic organisms that rely on molecular oxygen for respiratory energy production. Hypoxic conditions, with oxygen levels ranging between 1% and 5%, usually limit aerobic respiration and affect plant growth and development. Here, we demonstrate that hypoxic microenvironment induced by active cell proliferation during the two-step plant regeneration process intrinsically represses the regeneration competence of callus in Arabidopsis thaliana. Hypoxia-repressed plant regeneration was mediated by the RELATED TO APETALA 2.12 (RAP2.12) protein, a member of the Ethylene Response Factor VII (ERF-VII) family. The hypoxia-activated RAP2.12 protein promoted salicylic acid (SA) biosynthesis and defense responses, inhibiting pluripotency acquisition and de novo shoot regeneration in calli. RAP2.12 could bind directly to the SALICYLIC ACID INDUCTION DEFICIENT 2 (SID2) gene promoter and activate SA biosynthesis, repressing plant regeneration via a PLETHORA (PLT)-dependent pathway. The rap2.12 mutant calli exhibited enhanced shoot regeneration, which was impaired by SA treatment. Taken together, our findings demonstrate that cell proliferation-dependent hypoxic microenvironment reduces cellular pluripotency and plant regeneration through the RAP2.12–SID2 module.
Project description:Plants are aerobic organisms that rely on molecular oxygen for respiratory energy production. Hypoxic conditions, with oxygen levels ranging between 1% and 5%, usually limit aerobic respiration and affect plant growth and development. Here, we demonstrate that hypoxic microenvironment induced by active cell proliferation during the two-step plant regeneration process intrinsically represses the regeneration competence of callus in Arabidopsis thaliana. Hypoxia-repressed plant regeneration was mediated by the RELATED TO APETALA 2.12 (RAP2.12) protein, a member of the Ethylene Response Factor VII (ERF-VII) family. The hypoxia-activated RAP2.12 protein promoted salicylic acid (SA) biosynthesis and defense responses, inhibiting pluripotency acquisition and de novo shoot regeneration in calli. RAP2.12 could bind directly to the SALICYLIC ACID INDUCTION DEFICIENT 2 (SID2) gene promoter and activate SA biosynthesis, repressing plant regeneration via a PLETHORA (PLT)-dependent pathway. The rap2.12 mutant calli exhibited enhanced shoot regeneration, which was impaired by SA treatment. Taken together, our findings demonstrate that cell proliferation-dependent hypoxic microenvironment reduces cellular pluripotency and plant regeneration through the RAP2.12–SID2 module.