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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.


A decrease in cytokinin content or signalling increases the frequency of defects in positioning of LRP. (A) Percentage of LRP positioned immediately adjacent to each other in 11-d-old seedlings of cytokinin-synthesis mutants. n (number of roots analysed) = 12–16. (B) Proportion of LRP separated by zero to three PCs in wild type (WT; n = 30) and the cytokinin-synthesis mutants ipt3 5 7 and log4. n = 15–17. (C) Percentage of LRP positioned immediately adjacent to each other in 11-d-old seedlings of cytokinin-signalling mutants. n = 11–14. Significance of differences in (A-C) was analysed by two-tailed Student’s t-test. *P < 0.05; **P < 0.01; ***P < 0.001. Error bars indicate SEM.
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Figure 3: A decrease in cytokinin content or signalling increases the frequency of defects in positioning of LRP. (A) Percentage of LRP positioned immediately adjacent to each other in 11-d-old seedlings of cytokinin-synthesis mutants. n (number of roots analysed) = 12–16. (B) Proportion of LRP separated by zero to three PCs in wild type (WT; n = 30) and the cytokinin-synthesis mutants ipt3 5 7 and log4. n = 15–17. (C) Percentage of LRP positioned immediately adjacent to each other in 11-d-old seedlings of cytokinin-signalling mutants. n = 11–14. Significance of differences in (A-C) was analysed by two-tailed Student’s t-test. *P < 0.05; **P < 0.01; ***P < 0.001. Error bars indicate SEM.

Mentions: To further investigate the role of cytokinin synthesis genes in LR positioning, a detailed analysis was performed using single and higher order mutants. Single ipt mutants showed only weak (ipt3, ipt5) or no (ipt7) LRP positioning defects (Fig. 3A). The double mutants ipt3 5 and ipt3 7 showed an increased proportion of abnormally positioned LRP compared to wild type but only the difference seen for ipt3 5 was statistically significant. The proportion of misplaced LRP increased further to 13.6±2.0% (57 out of 416 LRP in 12 roots) in ipt3 5 7 roots (Fig. 3A). The misplaced LR in ipt mutants displayed a similar pattern to that shown in 35S:CKX1 plants and included different developmental stages ranging from LRP to emerging LR (Supplementary Fig. S2). The log4 mutant also exhibited LR spacing defects (7.0±1.4%) (Fig. 3A).


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

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

A decrease in cytokinin content or signalling increases the frequency of defects in positioning of LRP. (A) Percentage of LRP positioned immediately adjacent to each other in 11-d-old seedlings of cytokinin-synthesis mutants. n (number of roots analysed) = 12–16. (B) Proportion of LRP separated by zero to three PCs in wild type (WT; n = 30) and the cytokinin-synthesis mutants ipt3 5 7 and log4. n = 15–17. (C) Percentage of LRP positioned immediately adjacent to each other in 11-d-old seedlings of cytokinin-signalling mutants. n = 11–14. Significance of differences in (A-C) was analysed by two-tailed Student’s t-test. *P < 0.05; **P < 0.01; ***P < 0.001. Error bars indicate SEM.
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Related In: Results  -  Collection

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Figure 3: A decrease in cytokinin content or signalling increases the frequency of defects in positioning of LRP. (A) Percentage of LRP positioned immediately adjacent to each other in 11-d-old seedlings of cytokinin-synthesis mutants. n (number of roots analysed) = 12–16. (B) Proportion of LRP separated by zero to three PCs in wild type (WT; n = 30) and the cytokinin-synthesis mutants ipt3 5 7 and log4. n = 15–17. (C) Percentage of LRP positioned immediately adjacent to each other in 11-d-old seedlings of cytokinin-signalling mutants. n = 11–14. Significance of differences in (A-C) was analysed by two-tailed Student’s t-test. *P < 0.05; **P < 0.01; ***P < 0.001. Error bars indicate SEM.
Mentions: To further investigate the role of cytokinin synthesis genes in LR positioning, a detailed analysis was performed using single and higher order mutants. Single ipt mutants showed only weak (ipt3, ipt5) or no (ipt7) LRP positioning defects (Fig. 3A). The double mutants ipt3 5 and ipt3 7 showed an increased proportion of abnormally positioned LRP compared to wild type but only the difference seen for ipt3 5 was statistically significant. The proportion of misplaced LRP increased further to 13.6±2.0% (57 out of 416 LRP in 12 roots) in ipt3 5 7 roots (Fig. 3A). The misplaced LR in ipt mutants displayed a similar pattern to that shown in 35S:CKX1 plants and included different developmental stages ranging from LRP to emerging LR (Supplementary Fig. S2). The log4 mutant also exhibited LR spacing defects (7.0±1.4%) (Fig. 3A).

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.