Conditional Auxin Response and Differential Cytokinin Profiles in Shoot Branching Mutants
File(s)RMS auxin response Young PlPh14.pdf (1.12 MB)
Published version
Author(s)
Type
Journal Article
Abstract
Strigolactone (SL), auxin, and cytokinin (CK) are hormones that interact to regulate shoot branching. For example, several ramosus (rms) branching mutants in pea (Pisum sativum) have SL defects, perturbed xylem CK levels, and diminished responses to auxin in shoot decapitation assays. In contrast with the last of these characteristics, we discovered that buds on isolated nodes (explants) of rms plants instead respond normally to auxin. We hypothesized that the presence or absence of attached roots would result in transcriptional and hormonal differences in buds and subtending stem tissues, and might underlie the differential auxin response. However, decapitated plants and explants both showed similar up-regulation of CK biosynthesis genes, increased CK levels, and down-regulation of auxin transport genes. Moreover, auxin application counteracted these trends, regardless of the effectiveness of auxin at inhibiting bud growth. Multivariate analysis revealed that stem transcript and CK changes were largely associated with decapitation and/or root removal and auxin response, whereas bud transcript profiles related more to SL defects. CK clustering profiles were indicative of additional zeatin-type CKs in decapitated stems being supplied by roots and thus promoting bud growth in SL-deficient genotypes even in the presence of added auxin. This difference in CK content may explain why rms buds on explants respond better to auxin than those on decapitated plants. We further conclude that rapid changes in CK status in stems are auxin dependent but largely SL independent, suggesting a model in which auxin and CK are dominant regulators of decapitation-induced branching, whereas SLs are more important in intact plants.
Date Issued
2014-06-05
Date Acceptance
2014-06-03
Citation
Plant Physiology, 2014, 165 (4), pp.1723-1736
ISSN
1532-2548
Publisher
American Society of Plant Biologists
Start Page
1723
End Page
1736
Journal / Book Title
Plant Physiology
Volume
165
Issue
4
Copyright Statement
© 2014 American Society of Plant Biologists. All rights reserved.
Sponsor
Biotechnology and Biological Sciences Research Council (BBSRC)
Grant Number
P18282
Subjects
Science & Technology
Life Sciences & Biomedicine
Plant Sciences
PEA AXILLARY BUDS
APICAL DOMINANCE
INDOLE-3-ACETIC-ACID LEVELS
VASCULAR TISSUE
ACTS DOWNSTREAM
PISUM-SATIVUM
ARABIDOPSIS
STRIGOLACTONE
OUTGROWTH
TRANSPORT
Plant Biology & Botany
06 Biological Sciences
07 Agricultural And Veterinary Sciences
Publication Status
Published