Project description:Salicylic acid (SA)-induced defense responses are important factors during effector triggered immunity and microbe-associated molecular pattern (MAMP)-induced immunity in plants. This article presents evidence that a member of the Arabidopsis CBP60 gene family, CBP60g, contributes to MAMP-triggered SA accumulation. CBP60g is inducible by both pathogen and MAMP treatments. Pseudomonas syringae growth is enhanced in cbp60g mutants. Expression profiles of a cbp60g mutant after MAMP treatment are similar to those of sid2 and pad4, suggesting a defect in SA signaling. Accordingly, cbp60g mutants accumulate less SA when treated with the MAMP flg22 or a P. syringae hrcC strain that activates MAMP signaling. MAMP-induced production of reactive oxygen species and callose deposition are unaffected in cbp60g mutants. CBP60g is a calmodulin-binding protein with a calmodulin-binding domain located near the N-terminus. Calmodulin binding is dependent on Ca2+. Mutations in CBP60g that abolish calmodulin binding prevent complementation of the SA production and bacterial growth defects of cbp60g mutants, indicating that calmodulin binding is essential for the function of CBP60g in defense signaling. These studies show that CBP60g constitutes a calmodulin-dependent link between MAMP recognition and SA accumulation that is important for resistance to P. syringae. This experiment consists of three biological replicates. For each genotype, two leaves per plant were pooled from three pots to prepare total RNA.
Project description:Salicylic acid (SA)-induced defense responses are important factors during effector triggered immunity and microbe-associated molecular pattern (MAMP)-induced immunity in plants. This article presents evidence that a member of the Arabidopsis CBP60 gene family, CBP60g, contributes to MAMP-triggered SA accumulation. CBP60g is inducible by both pathogen and MAMP treatments. Pseudomonas syringae growth is enhanced in cbp60g mutants. Expression profiles of a cbp60g mutant after MAMP treatment are similar to those of sid2 and pad4, suggesting a defect in SA signaling. Accordingly, cbp60g mutants accumulate less SA when treated with the MAMP flg22 or a P. syringae hrcC strain that activates MAMP signaling. MAMP-induced production of reactive oxygen species and callose deposition are unaffected in cbp60g mutants. CBP60g is a calmodulin-binding protein with a calmodulin-binding domain located near the N-terminus. Calmodulin binding is dependent on Ca2+. Mutations in CBP60g that abolish calmodulin binding prevent complementation of the SA production and bacterial growth defects of cbp60g mutants, indicating that calmodulin binding is essential for the function of CBP60g in defense signaling. These studies show that CBP60g constitutes a calmodulin-dependent link between MAMP recognition and SA accumulation that is important for resistance to P. syringae.
Project description:In plants, the activation of immunity is often inversely correlated with growth. Mechanisms that plant growth in the context of pathogen challenge and immunity are unclear. Investigating Arabidopsis infection with the powdery mildew fungus, we find that the Arabidopsis atypical E2F DEL1, a transcriptional repressor known to promote cell proliferation, represses accumulation of the hormone salicylic acid (SA), an established regulator of plant immunity. DEL1 deficient plants are more resistant to pathogens and slightly smaller than wild type. The resistance and size phenotypes of DEL1 deficient plants are due to the induction of SA and activation of immunity in the absence of pathogen challenge. Moreover, Enhanced Disease Susceptibility 5 (EDS5), a SA transporter required for elevated SA and immunity, is a direct repressed target of DEL1. Together, these findings indicate that DEL1 control of SA levels contributes to regulating the balance between growth and immunity in developing leaves.
Project description:In plants, the activation of immunity is often inversely correlated with growth. Mechanisms that plant growth in the context of pathogen challenge and immunity are unclear. Investigating Arabidopsis infection with the powdery mildew fungus, we find that the Arabidopsis atypical E2F DEL1, a transcriptional repressor known to promote cell proliferation, represses accumulation of the hormone salicylic acid (SA), an established regulator of plant immunity. DEL1 deficient plants are more resistant to pathogens and slightly smaller than wild type. The resistance and size phenotypes of DEL1 deficient plants are due to the induction of SA and activation of immunity in the absence of pathogen challenge. Moreover, Enhanced Disease Susceptibility 5 (EDS5), a SA transporter required for elevated SA and immunity, is a direct repressed target of DEL1. Together, these findings indicate that DEL1 control of SA levels contributes to regulating the balance between growth and immunity in developing leaves. Mature, fully expanded leaves of 41/2-week-old Col-0 and del1-1 plants were harvested at 5 days after G. orontii infection and from uninfected control plants for RNA extraction and hybridization on Affymetrix microarrays.
Project description:Our previous study on CBP60g, a calmodulin binding protein that is important for disease resistance and microbe-associated molecular pattern (MAMP)-induced SA accumulation, led to our discovery of a closely related family member CBP60h. CBP60h is also important for defense against P. syringae but is induced differently by pathogen and MAMP stimulus. Transcriptome profiling of cbp60h mutants suggested that CBP60h might be primarily functioning in response against P. syringae. We constructed a double mutant of cbp60g and cbp60h, which demonstrated severely defective defense against P. syringae and SA accumulation. Profiling of the cbp60g/h showed that its expression pattern is very similar to that of pad4. Transient expression in Tobacco showed that both CBP60g and CBP60h localized to nucleus. Our observation suggest that CBP60g and CBP60h share partially redundant but critical role in defense response and SA signaling. This experiment consists of three biological replicates. For each genotype, two leaves per plant were pooled from three pots to prepare total RNA.
Project description:Our previous study on CBP60g, a calmodulin binding protein that is important for disease resistance and microbe-associated molecular pattern (MAMP)-induced SA accumulation, led to our discovery of a closely related family member CBP60h. CBP60h is also important for defense against P. syringae but is induced differently by pathogen and MAMP stimulus. Transcriptome profiling of cbp60h mutants suggested that CBP60h might be primarily functioning in response against P. syringae. We constructed a double mutant of cbp60g and cbp60h, which demonstrated severely defective defense against P. syringae and SA accumulation. Profiling of the cbp60g/h showed that its expression pattern is very similar to that of pad4. Transient expression in Tobacco showed that both CBP60g and CBP60h localized to nucleus. Our observation suggest that CBP60g and CBP60h share partially redundant but critical role in defense response and SA signaling.
Project description:In this study we show the comparative transcriptome of constitutive subtilisin3 (csb3) plants, an Arabidopsis mutant showing strikingly enhanced resistance to biotrophic pathogens. CSB3 encodes a 1-hydroxy-2-methyl-2-butenyl 4-diphosphate synthase, the enzyme controlling the penultimate step of the biosynthesis of isopentenyl diphosphate via the 2-C-methyl-d-erythritol-4-phosphate (MEP) pathway in the chloroplast. It has been proposed that CSB3 represents a point of metabolic convergence modulating the magnitude of SA-mediated disease resistance to biotrophic pathogens. We show that csb3 have increased expression of a set of genes encoding defense-related proteins and enzymes, which includes two subtilisins. In essence our results substantiates an important role of these two subtilases in the activation of defense-related signaling pathways against biotrophic pathogens.
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:Arabidopsis ABA hpersensitive germination2-1 mutant shows an enhanced sensitivity to ABA. This mutant has higher levels of endogenous ABA. This mutant also exhibited SA hypersensitivity and dwarf phenotype. Regarding SA hypersensitivity, ahg2-1 exhibits higher endogenous SA level and an enhanced resistance to pathogenic bacteria. Since AHG2 encodes the Arabidopsis polyA specific ribonuclease that is involved in mRNA degradation, presumably abnormal accumulation of some mRNAs confers the unique phenotype. Transcriptome analyses are expected to offer information on the target of AHG2. In order to eliminate secondary effects of higher levels of ABA and SA, ahg2-1abi1-1 and ahg2-1sid2-2 double mutants were also examined. The transcriptome data revealed that; ahg2-1 confers unique gene expression profiles, ABA and SA affect the expression profiles of this mutant but many genes are independent of those plant hormone responses. Comparing with expression profiles of other mutants indicated that the ahg2-1 might affect mitochondrial function. Keywords: strain comparison, ABA, SA
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)