Limits...
Cytokinin as a positional cue regulating lateral root spacing in Arabidopsis.

Chang L, Ramireddy E, Schmülling T - J. Exp. Bot. (2015)

Bottom Line: Interestingly, mutation of CYP735A genes required for trans-zeatin biosynthesis caused strong defects in LR positioning, indicating an important role for this cytokinin metabolite in regulating LR spacing.Further it is shown that cytokinin and a known regulator of LR spacing, the receptor-like kinase ARABIDOPSIS CRINKLY4 (ACR4), operate in a non-hierarchical manner but might exert reciprocal control at the transcript level.Taken together, the results suggest that cytokinin acts as a paracrine hormonal signal in regulating root system architecture.

View Article: PubMed Central - PubMed

Affiliation: Institute of Biology/Applied Genetics, Dahlem Centre of Plant Sciences (DCPS), Freie Universität Berlin, Albrecht-Thaer-Weg 6, D- 14195 Berlin, Germany Present address: Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, College of Life Science, Hubei University, Wuhan 430062, China.

No MeSH data available.


Interaction between the cytokinin and ACR4 signalling pathways on gene expression level. (A) ACR4 expression analysis by qPCR in the roots of 11-d-old different cytokinin-deficient seedlings. (B) ACR4::H2B:YFP expression (green signals) is visible in LRP of wild type (WT) but is absent in cytokinin-deficient plants. Scale bar is 20 µM. (C) GLV gene expression analysis by qPCR in the roots of 11-d-old different cytokinin-deficient seedlings. (D) Transcript profiles of cytokinin metabolism and signalling genes in roots of 11-d-old acr4 single and double mutants. Error bars represent SEM from three (A) or two (C, D) biological replicates. Each biological replicate contained roots from at least six individual plants. In all cases the expression level of wild type was set to 1 and the statistical significance of differences of expression values in mutants compared to wild type was determined by Student’s t-test (*P < 0.05) (this figure is available in colour at JXB online).
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC4507779&req=5

Figure 5: Interaction between the cytokinin and ACR4 signalling pathways on gene expression level. (A) ACR4 expression analysis by qPCR in the roots of 11-d-old different cytokinin-deficient seedlings. (B) ACR4::H2B:YFP expression (green signals) is visible in LRP of wild type (WT) but is absent in cytokinin-deficient plants. Scale bar is 20 µM. (C) GLV gene expression analysis by qPCR in the roots of 11-d-old different cytokinin-deficient seedlings. (D) Transcript profiles of cytokinin metabolism and signalling genes in roots of 11-d-old acr4 single and double mutants. Error bars represent SEM from three (A) or two (C, D) biological replicates. Each biological replicate contained roots from at least six individual plants. In all cases the expression level of wild type was set to 1 and the statistical significance of differences of expression values in mutants compared to wild type was determined by Student’s t-test (*P < 0.05) (this figure is available in colour at JXB online).

Mentions: Because both the cytokinin and ACR4 pathways prevent neighbouring PCs from LRI, the relationship between these pathways was investigated. The expression of ACR4 in roots of 11-d-old seedlings of cytokinin-synthesis and -signalling mutants was analysed. Fig. 5A shows that the abundance of the ACR4 transcripts was lower in the roots of most plants with a reduced cytokinin status. The strongest reduction of ACR4 transcript abundance (~60% reduction compared to wild type) was noted in ipt3 5 7 triple mutants. Further, in wild type, pACR4-driven H2B:YFP expression was observed in the LRP while fluorescence of YFP was hardly detectable in the cytokinin-deficient 35S:CKX1 and ipt3 5 7 background (Fig. 5B). However, ACR4 transcript analysis at different time points following exogenous addition of cytokinin did not reveal a strong influence of cytokinin on the steady-state level of ACR4 mRNA (Brenner et al., 2012 and data not shown). Taken together, this shows that ACR4 expression is reduced in cytokinin-deficient plants but that ACR4 is not a primary cytokinin response gene. The reduced LR spacing in cytokinin-deficient plants might be partly accomplished through lowered expression of ACR4.


Cytokinin as a positional cue regulating lateral root spacing in Arabidopsis.

Chang L, Ramireddy E, Schmülling T - J. Exp. Bot. (2015)

Interaction between the cytokinin and ACR4 signalling pathways on gene expression level. (A) ACR4 expression analysis by qPCR in the roots of 11-d-old different cytokinin-deficient seedlings. (B) ACR4::H2B:YFP expression (green signals) is visible in LRP of wild type (WT) but is absent in cytokinin-deficient plants. Scale bar is 20 µM. (C) GLV gene expression analysis by qPCR in the roots of 11-d-old different cytokinin-deficient seedlings. (D) Transcript profiles of cytokinin metabolism and signalling genes in roots of 11-d-old acr4 single and double mutants. Error bars represent SEM from three (A) or two (C, D) biological replicates. Each biological replicate contained roots from at least six individual plants. In all cases the expression level of wild type was set to 1 and the statistical significance of differences of expression values in mutants compared to wild type was determined by Student’s t-test (*P < 0.05) (this figure is available in colour at JXB online).
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4507779&req=5

Figure 5: Interaction between the cytokinin and ACR4 signalling pathways on gene expression level. (A) ACR4 expression analysis by qPCR in the roots of 11-d-old different cytokinin-deficient seedlings. (B) ACR4::H2B:YFP expression (green signals) is visible in LRP of wild type (WT) but is absent in cytokinin-deficient plants. Scale bar is 20 µM. (C) GLV gene expression analysis by qPCR in the roots of 11-d-old different cytokinin-deficient seedlings. (D) Transcript profiles of cytokinin metabolism and signalling genes in roots of 11-d-old acr4 single and double mutants. Error bars represent SEM from three (A) or two (C, D) biological replicates. Each biological replicate contained roots from at least six individual plants. In all cases the expression level of wild type was set to 1 and the statistical significance of differences of expression values in mutants compared to wild type was determined by Student’s t-test (*P < 0.05) (this figure is available in colour at JXB online).
Mentions: Because both the cytokinin and ACR4 pathways prevent neighbouring PCs from LRI, the relationship between these pathways was investigated. The expression of ACR4 in roots of 11-d-old seedlings of cytokinin-synthesis and -signalling mutants was analysed. Fig. 5A shows that the abundance of the ACR4 transcripts was lower in the roots of most plants with a reduced cytokinin status. The strongest reduction of ACR4 transcript abundance (~60% reduction compared to wild type) was noted in ipt3 5 7 triple mutants. Further, in wild type, pACR4-driven H2B:YFP expression was observed in the LRP while fluorescence of YFP was hardly detectable in the cytokinin-deficient 35S:CKX1 and ipt3 5 7 background (Fig. 5B). However, ACR4 transcript analysis at different time points following exogenous addition of cytokinin did not reveal a strong influence of cytokinin on the steady-state level of ACR4 mRNA (Brenner et al., 2012 and data not shown). Taken together, this shows that ACR4 expression is reduced in cytokinin-deficient plants but that ACR4 is not a primary cytokinin response gene. The reduced LR spacing in cytokinin-deficient plants might be partly accomplished through lowered expression of ACR4.

Bottom Line: Interestingly, mutation of CYP735A genes required for trans-zeatin biosynthesis caused strong defects in LR positioning, indicating an important role for this cytokinin metabolite in regulating LR spacing.Further it is shown that cytokinin and a known regulator of LR spacing, the receptor-like kinase ARABIDOPSIS CRINKLY4 (ACR4), operate in a non-hierarchical manner but might exert reciprocal control at the transcript level.Taken together, the results suggest that cytokinin acts as a paracrine hormonal signal in regulating root system architecture.

View Article: PubMed Central - PubMed

Affiliation: Institute of Biology/Applied Genetics, Dahlem Centre of Plant Sciences (DCPS), Freie Universität Berlin, Albrecht-Thaer-Weg 6, D- 14195 Berlin, Germany Present address: Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, College of Life Science, Hubei University, Wuhan 430062, China.

No MeSH data available.