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.
Highlights
Leaf and floral organs grow by two basic cellular processes, cell proliferation and cell expansion to reach a given organ size [1]
EMS mutagenesis of the klu-2 mutant in the Arabidopsis thaliana Landsberg erecta background was undertaken and approximately 2500 individual M2 lines were screened for reduced plant height and reduced petal size
Homozygous tink single-mutant plants show a 20% reduction in petal size compared to wildtype and this was due to a reduction in petal width (Fig 1F)
Summary
Leaf and floral organs grow by two basic cellular processes, cell proliferation and cell expansion to reach a given organ size [1]. Microarray analysis suggests IBR5 plays a role in male gametophyte development, auxin and TCP growth regulatory pathways. To determine how TINK regulates organ size, we followed the growth dynamics of petal and leaf primordia in tink mutant and wild-type plants (Fig 1 and S1 Fig).
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