Vegetative Branching in Petunia

Drummond, Revel S.M.; Ledger, Susan E.; Simons, Joanne L.; Janssen, Bart; Snowden, Kimberley C.

doi:10.1007/978-0-387-84796-2_8

Cited by 4 publications

(5 citation statements)

References 62 publications

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“…Finally, we have shown that mutant scions grafted to a wild-type rootstock having both mutant and wild-type roots produce more branches than those with only wild-type roots. The CCD7 and CCD8 genes have now been cloned from four plant systems that are being studied in relation to the control of axillary branching at the molecular level (Arabidopsis, pea, rice, and petunia; for review, see Drummond et al, 2009). …”

Section: Discussionmentioning

confidence: 99%

“…However, xylem cytokinin has been shown to be reduced in strigolactone pathway mutants for Arabidopsis, pea, and petunia (Morris et al, 2001;Foo et al, 2007;Drummond et al, 2009). The observations that cytokinin is synthesized in the aerial parts of the plant (Nordströ m et al, 2004) and that increasing cytokinin production in the roots did not increase branching (Faiss et al, 1997) suggest that root-derived cytokinin is not the mobile positive branching signal seen in our experiments.…”

Section: Discussionmentioning

confidence: 99%

“…In petunia, Arabidopsis, and pea, some of the increased branching mutants (ccd7 and ccd8 mutants in particular) can be reverted to a wild-type phenotype by grafting mutant scions onto wild-type rootstocks (for review, see Drummond et al, 2009). Additionally, ccd8 mutant plant lines have been reverted to the wild type by the insertion of a small piece (approximately 2 mm) of wild-type hypocotyl into the hypocotyls of mutant petunia or by insertion of a small piece of epicotyl into the epicotyl of mutant pea (Napoli, 1996;Foo et al, 2001).…”

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Petunia hybrida CAROTENOID CLEAVAGE DIOXYGENASE7 Is Involved in the Production of Negative and Positive Branching Signals in Petunia

et al. 2009

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One of the key factors that defines plant form is the regulation of when and where branches develop. The diversity of form observed in nature results, in part, from variation in the regulation of branching between species. Two CAROTENOID CLEAVAGE DIOXYGENASE (CCD) genes, CCD7 and CCD8, are required for the production of a branch-suppressing plant hormone. Here, we report that the decreased apical dominance3 (dad3) mutant of petunia (Petunia hybrida) results from the mutation of the PhCCD7 gene and has a less severe branching phenotype than mutation of PhCCD8 (dad1). An analysis of the expression of this gene in wild-type, mutant, and grafted petunia suggests that in petunia, CCD7 and CCD8 are coordinately regulated. In contrast to observations in Arabidopsis (Arabidopsis thaliana), ccd7ccd8 double mutants in petunia show an additive phenotype. An analysis using dad3 or dad1 mutant scions grafted to wild-type rootstocks showed that when these plants produce adventitious mutant roots, branching is increased above that seen in plants where the mutant roots are removed. The results presented here indicate that mutation of either CCD7 or CCD8 in petunia results in both the loss of an inhibitor of branching and an increase in a promoter of branching.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Petunia hybrida CAROTENOID CLEAVAGE DIOXYGENASE7 Is Involved in the Production of Negative and Positive Branching Signals in Petunia

et al. 2009

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“…Basal branching ceases at or before the floral transition, with the axillary meristems above node eight not developing beyond small buds. The petunia inflorescence is then produced by a series of sympodial branches, while at the same time additional lateral branches develop in a basipetal wave down the main stem from the node immediately below the first flower (Snowden and Napoli, 2003 ; Drummond et al, 2009b ).…”

Section: Introductionmentioning

confidence: 99%

“…For many species, differences occur in growth habit between cultivars. In different petunia cultivars, the number of nodes that produce branches can vary, as well as the positioning of the basal branches along the shoot axis (Brunaud et al, 1977 ; Drummond et al, 2009b ).…”

Section: Introductionmentioning

confidence: 99%

The expression of petunia strigolactone pathway genes is altered as part of the endogenous developmental program

et al. 2012

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Analysis of mutants with increased branching has revealed the strigolactone synthesis/perception pathway which regulates branching in plants. However, whether variation in this well conserved developmental signaling system contributes to the unique plant architectures of different species is yet to be determined. We examined petunia orthologs of the Arabidopsis MAX1 and MAX2 genes to characterize their role in petunia architecture. A single ortholog of MAX1, PhMAX1 which encodes a cytochrome P450, was identified and was able to complement the max1 mutant of Arabidopsis. Petunia has two copies of the MAX2 gene, PhMAX2A and PhMAX2B which encode F-Box proteins. Differences in the transcript levels of these two MAX2-like genes suggest diverging functions. Unlike PhMAX2B, PhMAX2A mRNA levels change in leaves of differing age/position on the plant. Nonetheless, this gene functionally complements the Arabidopsis max2 mutant indicating that the biochemical activity of the PhMAX2A protein is not significantly different from MAX2. The expression of the petunia strigolactone pathway genes (PhCCD7, PhCCD8, PhMAX1, PhMAX2A, and PhMAX2B) was then further investigated throughout the development of wild-type petunia plants. Three of these genes showed changes in mRNA levels over a development series. Alterations to the expression patterns of these genes may influence the branching growth habit of plants by changing strigolactone production and/or sensitivity. These changes could allow both subtle and dramatic changes to branching within and between species.

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Strigolactone and karrikin signal perception: receptors, enzymes, or both?

Janssen¹,

Snowden²

2012

Front. Plant Sci.

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The signaling molecules strigolactone (SL) and karrikin are involved in seed germination, development of axillary meristems, senescence of leaves, and interactions with arbuscular mycorrhizal fungi. The signal transduction pathways for both SLs and karrikins require the same F-box protein (MAX2) and closely related α/β hydrolase fold proteins (DAD2 and KAI2). The crystal structure of DAD2 has been solved revealing an α/β hydrolase fold protein with an internal cavity capable of accommodating SLs. DAD2 responds to the SL analog GR24 by changing conformation and binding to MAX2 in a GR24 concentration-dependent manner. DAD2 can also catalyze hydrolysis of GR24. Structure activity relationships of analogs indicate that the butenolide ring common to both SLs and karrikins is essential for biological activity, but the remainder of the molecules can be significantly modified without loss of activity. The combination of data from the study of DAD2, KAI2, and chemical analogs of SLs and karrikins suggests a model for binding that requires nucleophilic attack by the active site serine of the hydrolase at the carbonyl atom of the butenolide ring. A conformational change occurs in the hydrolase that results in interaction with the F-box protein MAX2. Downstream signal transduction is then likely to occur via SCF (Skp-Cullin-F-box) complex-mediated ubiquitination of target proteins and their subsequent degradation. The role of the catalytic activity of the hydrolase is unclear but it may be integral in binding as well as possibly allowing the signal to be cleared from the receptor. The α/β hydrolase fold family consists mostly of active enzymes, with a few notable exceptions. We suggest that DAD2 and KAI2 represent an intermediate stage where some catalytic activity is retained at the same time as a receptor role has evolved.

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Vegetative Branching in Petunia

Cited by 4 publications

References 62 publications

Petunia hybrida CAROTENOID CLEAVAGE DIOXYGENASE7 Is Involved in the Production of Negative and Positive Branching Signals in Petunia

Petunia hybrida CAROTENOID CLEAVAGE DIOXYGENASE7 Is Involved in the Production of Negative and Positive Branching Signals in Petunia

The expression of petunia strigolactone pathway genes is altered as part of the endogenous developmental program

Strigolactone and karrikin signal perception: receptors, enzymes, or both?

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