Project description:Ethylene is one of the most important hormones for plant developmental processes and stress responses. However, the phosphorylation regulation in the ethylene signaling pathway is largely unknown. Here we report the phosphorylation of cap binding protein 20 (CBP20) at Ser245 is regulated by ethylene, and the phosphorylation is involved in root growth. The constitutive phosphorylation mimic form of CBP20 (CBP20S245E or CBP20S245D), while not the constitutive de-phosphorylation form of CBP20 (CBP20S245A) is able to rescue the root ethylene responsive phenotype of cbp20. By genome wide study with ethylene regulated gene expression and microRNA (miRNA) expression in the roots and shoots of both Col-0 and cbp20, we found miR319b is up regulated in roots while not in shoots, and its target MYB33 is specifically down regulated in roots with ethylene treatment. We described both the phenotypic and molecular consequences of transgenic over-expression of miR319b. Increased levels of miR319b (miR319bOE) leads to enhanced ethylene responsive root phenotype and reduction of MYB33 transcription level in roots; over expression of MYB33, which carrying mutated miR319b target site (mMYB33) in miR319bOE is able to recover both the root phenotype and the expression level of MYB33. Taken together, we proposed that ethylene regulated phosphorylation of CBP20 is involved in the root growth and one pathway is through the regulation of miR319b and its target MYB33 in roots.
Project description:We report that CBP20 phosphorylation can regulate root growth in ethylene. We examined the gene expression in roots and shoots of wild type (Col) and cbp20 mutant (in Col background). Ethylene is one of the most essential hormones for plant developmental processes and stress responses. EIN2 is a key factor in ethylene signaling pathway and its function is regulated by phosphorylation. However, the phosphorylation regulation in the ethylene signaling pathway is largely unknown. Here we report the phosphorylation of CBP20 is regulated by ethylene, and the phosphorylation is involved in root elongation. The constitutive phosphorylation format of CBP20 rescues the cbp20 root ethylene hyposensitive phenotype, while the constitutive de-phosphorylation format of CBP20 is unable to rescue the root phenotype of cbp20 in response to ethylene. Genome wide study on ethylene regulated gene expression and microRNA expression in the roots and shoots of both Col and cbp20, together with the result of genetics validation suggest that ethylene induced phosphorylation of CBP20 is involved in root growth and one pathway is through the regulation of microRNAs and their target genes in roots.
Project description:We report that CBP20 phosphorylation can regulate root growth in ethylene. We examined the small RNA expression in roots and shoots of wild type (Col) and cbp20 mutant (in Col background). Ethylene is one of the most essential hormones for plant developmental processes and stress responses. EIN2 is a key factor in ethylene signaling pathway and its function is regulated by phosphorylation. However, the phosphorylation regulation in the ethylene signaling pathway is largely unknown. Here we report the phosphorylation of CBP20 is regulated by ethylene, and the phosphorylation is involved in root elongation. The constitutive phosphorylation format of CBP20 rescues the cbp20 root ethylene hyposensitive phenotype, while the constitutive de-phosphorylation format of CBP20 is unable to rescue the root phenotype of cbp20 in response to ethylene. Genome wide study on ethylene regulated gene expression and microRNA expression in the roots and shoots of both Col and cbp20, together with the result of genetics validation suggest that ethylene induced phosphorylation of CBP20 is involved in root growth and one pathway is through the regulation of microRNAs and their target genes in roots.
Project description:Cytokinins and ethylene control plant development via sensors from the histidine kinase (HK) family. However, downstream signaling pathways for the key phytohormones are distinct. Here we report that not only cytokinin but also ethylene is able to control root apical meristem (RAM) size through activation of the multistep phosphorelay (MSP) pathway. We found that both cytokinin and ethylene-dependent RAM shortening requires ethylene binding to ETR1 and the HK activity of ETR1. The receiver domain of ETR1 interacts with MSP signaling intermediates acting downstream of cytokinin receptors, further substantiating the role of ETR1 in MSP signaling. We revealed that both cytokinin and ethylene induce the MSP in similar and distinct cell types with ETR1-mediated ethylene signaling controlling MSP output specifically in the root transition zone. We identified members of the MSP pathway specific and common to both hormones and showed that ETR1-regulated ARR3 controls RAM size. ETR1-mediated MSP spatially differs from canonical CTR1/EIN2/EIN3 ethylene signaling and is independent of EIN2, indicating that both pathways can be spatially and functionally separated. Furthermore, we demonstrated that canonical ethylene signaling controls MSP responsiveness to cytokinin specifically in the root transition zone, presumably via regulation of ARR10, one of the positive regulators of MSP signaling in Arabidopsis.
Project description:CSLD3, a gene of the cellulose synthase-like D family, affects root hair elongation, but its interactions with ethylene signaling and phosphate-starvation are poorly understood. Here, we aim to understand the role of CSLD3 in the context of the ethylene signaling and phosphate starvation pathways in Arabidopsis plant growth. Therefore, we performed a comparative analysis of the csld3-1 mutant, CSLD3-overexpressing lines, and ethylene-response mutants, such as the constitutive ethylene-response mutant i-ctr1. We found that CSLD3 overexpression enhanced root and hypocotyl growth by increasing cell elongation, and that the root growth was highly sensitive to ethylene treatment (1 µM ACC), in particular under phosphate starvation. However, the CSLD3-mediated hypocotyl elongation occurred independently of the ethylene signaling pathway. Notably, the typical induction of root hair and root elongation by ethylene and phosphate-starvation was completely abolished in the csld3-1 mutant. Furthermore, i-ctr1 csld3-1 double-mutants were hairless like the csld3-1 parent, confirming that CSLD3 acts downstream of the ethylene signaling pathway during root growth. Moreover, the CSLD3 levels positively correlated with cellulose levels, indicating a role of CSLD3 in cellulose synthesis, which may explain the observed growth effects. Our results establish how CSLD3 works in the context of the ethylene signaling and phosphate-starvation pathways during root hair growth, cell elongation, and cell wall biosynthesis.
Project description:Exogenous abscisic acid (ABA) is known to either stimulate or inhibit root growth, depending on its concentration. In this study, the roles of ethylene and auxin in this biphasic effect of ABA on root elongation were investigated using chemical inhibitors and mutants. Inhibitors of ethylene perception and biosynthesis and an auxin influx inhibitor were all found to block the inhibitory effect of high ABA concentrations, but not the stimulatory effect of low ABA concentrations. In addition, three ethylene-insensitive mutants (etr1-1, ein2-1, and ein3-1), two auxin influx mutants (aux1-7, aux1-T) and an auxin-insensitive mutant (iaa7/axr2-1) were all insensitive to the inhibitory effect of high ABA concentrations. In the case of the stimulatory effect of low ABA concentrations, it was blocked by two different auxin efflux inhibitors and was less pronounced in an auxin efflux mutant (pin2/eir1-1) and in the iaa7/axr2-1 auxin-insensitive mutant. Thus it appears that the stimulatory effect seen at low ABA concentrations is via an ethylene-independent pathway requiring auxin signalling and auxin efflux through PIN2/EIR1, while the inhibitory effect at high ABA concentrations is via an ethylene-dependent pathway requiring auxin signalling and auxin influx through AUX1.