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The Tinkerbell (Tink) Mutation Identifies the Dual-Specificity MAPK Phosphatase INDOLE-3-BUTYRIC ACID-RESPONSE5 (IBR5) as a Novel Regulator of Organ Size in Arabidopsis.

Johnson KL, Ramm S, Kappel C, Ward S, Leyser O, Sakamoto T, Kurata T, Bevan MW, Lenhard M - PLoS ONE (2015)

Bottom Line: Organ size and shape regulation by IBR5 acts independently of the KLU growth-regulatory pathway.Microarray analysis of tink/ibr5-6 mutants identified a likely role for this phosphatase in male gametophyte development.We show that IBR5 may influence the size and shape of petals through auxin and TCP growth regulatory pathways.

View Article: PubMed Central - PubMed

Affiliation: ARC Centre of Excellence in Plant Cell Walls, School of Botany, University of Melbourne, Royal Parade, Parkville, Victoria, 3010, Australia.

ABSTRACT
Mitogen-activated dual-specificity MAPK phosphatases are important negative regulators in the MAPK signalling pathways responsible for many essential processes in plants. In a screen for mutants with reduced organ size we have identified a mutation in the active site of the dual-specificity MAPK phosphatase indole-3-butyric acid-response5 (IBR5) that we named tinkerbell (tink) due to its small size. Analysis of the tink mutant indicates that IBR5 acts as a novel regulator of organ size that changes the rate of growth in petals and leaves. Organ size and shape regulation by IBR5 acts independently of the KLU growth-regulatory pathway. Microarray analysis of tink/ibr5-6 mutants identified a likely role for this phosphatase in male gametophyte development. We show that IBR5 may influence the size and shape of petals through auxin and TCP growth regulatory pathways.

No MeSH data available.


Related in: MedlinePlus

Root phenotype of ibr5 alleles compared to wild-type.a. On standard growth medium (top panel) the ibr5-3 allele is indistinguishable from the wild-type (Col) whereas in medium containing 10 mM IAA, the ibr5-3 allele is insensitive to the inhibition of root growth seen in the wild-type (bottom panel). b. The tink/ibr5-6 allele shows reduced root growth compared to Ler on standard growth medium (upper panel) and medium containing 10 mM IAA (bottom panel). c. Inhibition of root length of Col, ibr5-3, Ler and tink/ibr5-6 plants grown on 10 mM IAA compared to un-supplemented medium. Col plants show a 38% reduction in root growth, compared to ibr5-3 mutants which are insensitive to the root growth inhibition (shown by *, p value ≤ 5.7e-14). Ler roots show a 55% decrease in root length when grown on 10 mM IAA compared to un-supplemented medium and tink/ibr5-6 plants show a similar root inhibition phenotype (p value ≤ 0.3). Scale is 1 cm. Values are shown as mean ± SEM, with n = 20.
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pone.0131103.g003: Root phenotype of ibr5 alleles compared to wild-type.a. On standard growth medium (top panel) the ibr5-3 allele is indistinguishable from the wild-type (Col) whereas in medium containing 10 mM IAA, the ibr5-3 allele is insensitive to the inhibition of root growth seen in the wild-type (bottom panel). b. The tink/ibr5-6 allele shows reduced root growth compared to Ler on standard growth medium (upper panel) and medium containing 10 mM IAA (bottom panel). c. Inhibition of root length of Col, ibr5-3, Ler and tink/ibr5-6 plants grown on 10 mM IAA compared to un-supplemented medium. Col plants show a 38% reduction in root growth, compared to ibr5-3 mutants which are insensitive to the root growth inhibition (shown by *, p value ≤ 5.7e-14). Ler roots show a 55% decrease in root length when grown on 10 mM IAA compared to un-supplemented medium and tink/ibr5-6 plants show a similar root inhibition phenotype (p value ≤ 0.3). Scale is 1 cm. Values are shown as mean ± SEM, with n = 20.

Mentions: To investigate if tink/ibr5-6 shows the characteristic reduced auxin sensitivity of other ibr5 mutants we performed root growth assays with or without the auxin IAA (Fig 3). Unlike ibr5-3, tink/ibr5-6 shows a very weak auxin insensitivity phenotype in the presence of 100 nm IAA (Fig 3B). The tink/ibr5-6 mutants show reduced root growth on standard growth media and a slight inhibition of root growth in the presence of auxin compared to the wild-type (Fig 3B and 3C). Previous complementation studies of IBR5 with a C-to-S phosphatase mutation in the ibr5-1 mutant background and the ibr5-4 allele which has a G-E transition in the catalytic domain show a weaker response than full loss of function ibr5 alleles [19, 23]. Additionally, ibr5-1 IBR5C-S lines fail to fully rescue 2,4-D resistance of ibr5-1 alleles [19]. These results suggest loss of IBR5 phosphatase activity has pleiotropic effects on root growth.


The Tinkerbell (Tink) Mutation Identifies the Dual-Specificity MAPK Phosphatase INDOLE-3-BUTYRIC ACID-RESPONSE5 (IBR5) as a Novel Regulator of Organ Size in Arabidopsis.

Johnson KL, Ramm S, Kappel C, Ward S, Leyser O, Sakamoto T, Kurata T, Bevan MW, Lenhard M - PLoS ONE (2015)

Root phenotype of ibr5 alleles compared to wild-type.a. On standard growth medium (top panel) the ibr5-3 allele is indistinguishable from the wild-type (Col) whereas in medium containing 10 mM IAA, the ibr5-3 allele is insensitive to the inhibition of root growth seen in the wild-type (bottom panel). b. The tink/ibr5-6 allele shows reduced root growth compared to Ler on standard growth medium (upper panel) and medium containing 10 mM IAA (bottom panel). c. Inhibition of root length of Col, ibr5-3, Ler and tink/ibr5-6 plants grown on 10 mM IAA compared to un-supplemented medium. Col plants show a 38% reduction in root growth, compared to ibr5-3 mutants which are insensitive to the root growth inhibition (shown by *, p value ≤ 5.7e-14). Ler roots show a 55% decrease in root length when grown on 10 mM IAA compared to un-supplemented medium and tink/ibr5-6 plants show a similar root inhibition phenotype (p value ≤ 0.3). Scale is 1 cm. Values are shown as mean ± SEM, with n = 20.
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Related In: Results  -  Collection

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pone.0131103.g003: Root phenotype of ibr5 alleles compared to wild-type.a. On standard growth medium (top panel) the ibr5-3 allele is indistinguishable from the wild-type (Col) whereas in medium containing 10 mM IAA, the ibr5-3 allele is insensitive to the inhibition of root growth seen in the wild-type (bottom panel). b. The tink/ibr5-6 allele shows reduced root growth compared to Ler on standard growth medium (upper panel) and medium containing 10 mM IAA (bottom panel). c. Inhibition of root length of Col, ibr5-3, Ler and tink/ibr5-6 plants grown on 10 mM IAA compared to un-supplemented medium. Col plants show a 38% reduction in root growth, compared to ibr5-3 mutants which are insensitive to the root growth inhibition (shown by *, p value ≤ 5.7e-14). Ler roots show a 55% decrease in root length when grown on 10 mM IAA compared to un-supplemented medium and tink/ibr5-6 plants show a similar root inhibition phenotype (p value ≤ 0.3). Scale is 1 cm. Values are shown as mean ± SEM, with n = 20.
Mentions: To investigate if tink/ibr5-6 shows the characteristic reduced auxin sensitivity of other ibr5 mutants we performed root growth assays with or without the auxin IAA (Fig 3). Unlike ibr5-3, tink/ibr5-6 shows a very weak auxin insensitivity phenotype in the presence of 100 nm IAA (Fig 3B). The tink/ibr5-6 mutants show reduced root growth on standard growth media and a slight inhibition of root growth in the presence of auxin compared to the wild-type (Fig 3B and 3C). Previous complementation studies of IBR5 with a C-to-S phosphatase mutation in the ibr5-1 mutant background and the ibr5-4 allele which has a G-E transition in the catalytic domain show a weaker response than full loss of function ibr5 alleles [19, 23]. Additionally, ibr5-1 IBR5C-S lines fail to fully rescue 2,4-D resistance of ibr5-1 alleles [19]. These results suggest loss of IBR5 phosphatase activity has pleiotropic effects on root growth.

Bottom Line: Organ size and shape regulation by IBR5 acts independently of the KLU growth-regulatory pathway.Microarray analysis of tink/ibr5-6 mutants identified a likely role for this phosphatase in male gametophyte development.We show that IBR5 may influence the size and shape of petals through auxin and TCP growth regulatory pathways.

View Article: PubMed Central - PubMed

Affiliation: ARC Centre of Excellence in Plant Cell Walls, School of Botany, University of Melbourne, Royal Parade, Parkville, Victoria, 3010, Australia.

ABSTRACT
Mitogen-activated dual-specificity MAPK phosphatases are important negative regulators in the MAPK signalling pathways responsible for many essential processes in plants. In a screen for mutants with reduced organ size we have identified a mutation in the active site of the dual-specificity MAPK phosphatase indole-3-butyric acid-response5 (IBR5) that we named tinkerbell (tink) due to its small size. Analysis of the tink mutant indicates that IBR5 acts as a novel regulator of organ size that changes the rate of growth in petals and leaves. Organ size and shape regulation by IBR5 acts independently of the KLU growth-regulatory pathway. Microarray analysis of tink/ibr5-6 mutants identified a likely role for this phosphatase in male gametophyte development. We show that IBR5 may influence the size and shape of petals through auxin and TCP growth regulatory pathways.

No MeSH data available.


Related in: MedlinePlus