Gibberellin Acts Positively Then Negatively to Control Onset of Flower Formation in<i>Arabidopsis</i>

Yamaguchi, Nobutoshi; Winter, Cara M.; Wu, Miin-Feng; Kanno, Yuka; Yamaguchi, Ayako; Seo, Mitsunori; Wagner, Doris

doi:10.1126/science.1250498

Cited by 253 publications

(259 citation statements)

References 68 publications

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“…S3D and S6D). Such a dual effect depending on the hormone levels or developmental stages also was reported for another hormone, abscisic acid (Charpentier et al, 2014), and for other GA-related responses (Yamaguchi et al, 2014). These results suggest that GA signaling is required for AM hyphal branching and colonization of the host root.…”

Section: Ga Signaling Is Required For Symbiosis Gene Expression Follosupporting

confidence: 52%

Gibberellins Interfere with Symbiosis Signaling and Gene Expression and Alter Colonization by Arbuscular Mycorrhizal Fungi in Lotus japonicus

et al. 2014

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Arbuscular mycorrhiza is a mutualistic plant-fungus interaction that confers great advantages for plant growth. Arbuscular mycorrhizal (AM) fungi enter the host root and form symbiotic structures that facilitate nutrient supplies between the symbionts. The gibberellins (GAs) are phytohormones known to inhibit AM fungal infection. However, our transcriptome analysis and phytohormone quantification revealed GA accumulation in the roots of Lotus japonicus infected with AM fungi, suggesting that de novo GA synthesis plays a role in arbuscular mycorrhiza development. We found pleiotropic effects of GAs on the AM fungal infection. In particular, the morphology of AM fungal colonization was drastically altered by the status of GA signaling in the host root. Exogenous GA treatment inhibited AM hyphal entry into the host root and suppressed the expression of Reduced Arbuscular Mycorrhization1 (RAM1) and RAM2 homologs that function in hyphal entry and arbuscule formation. On the other hand, inhibition of GA biosynthesis or suppression of GA signaling also affected arbuscular mycorrhiza development in the host root. Low-GA conditions suppressed arbuscular mycorrhiza-induced subtilisin-like serine protease1 (SbtM1) expression that is required for AM fungal colonization and reduced hyphal branching in the host root. The reduced hyphal branching and SbtM1 expression caused by the inhibition of GA biosynthesis were recovered by GA treatment, supporting the theory that insufficient GA signaling causes the inhibitory effects on arbuscular mycorrhiza development. Most studies have focused on the negative role of GA signaling, whereas our study demonstrates that GA signaling also positively interacts with symbiotic responses and promotes AM colonization of the host root.

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Section: Ga Signaling Is Required For Symbiosis Gene Expression Follosupporting

confidence: 52%

Gibberellins Interfere with Symbiosis Signaling and Gene Expression and Alter Colonization by Arbuscular Mycorrhizal Fungi in Lotus japonicus

et al. 2014

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“…Because of the well-established role of elevated GA levels in the termination of vegetative phase and the increasing expression of flower-promoting transcription factors such as SPLs and LFY (Yamaguchi et al, 2014), we asked whether this pathway might also play a role in the BBX19 negative regulation of flowering time under LD conditions. Thus, we exogenously treated various genotypes with GA and determined that there is a partial recovery of delayed flowering in OE44 and OE56 lines in response to the GA treatment ( Figures 7A and 7B).…”

Section: Bbx19-mediated Delayed Flowering Is Della Independentmentioning

confidence: 99%

BBX19 Interacts with CONSTANS to RepressFLOWERING LOCUS TTranscription, Defining a Flowering Time Checkpoint inArabidopsis

et al. 2014

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The timely transition of vegetative to reproductive development is coordinated through quantitative regulation of floral pathway genes in response to physiological and environmental cues. Here, we show that the circadian-controlled expression of the Arabidopsis thaliana floral transition regulators FLOWERING LOCUS T (FT) and CONSTANS (CO) is antiphasic to that of BBX19, a transcription factor with two B-Box motifs. Diminished expression of BBX19 by RNA interference accelerates flowering, and constitutive expression of BBX19 delays flowering under inductive photoperiods. This delay is not accompanied by the alteration of CO expression levels but rather by a reduction of transcript levels of FT and the FT-regulated genes SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1, LEAFY, and FRUITFUL. Similar to CO, BBX19 is expressed in vasculature. BBX19 and CO colocalize in the nucleus and interact physically in vivo. In transient assays, coinfiltration of 10-fold more CO overcomes the BBX19-mediated repression of FT activation. Substitution of the conserved Cys-25 to Ser in the BBX19 Box1 motif abolishes the BBX19-CO interaction and eliminates the negative regulation of flowering time, while the analogous C76S substitution in the Box2 motif is ineffective. Together, these results implicate BBX19 as a circadian clock output that depletes the active CO pool to accurately monitor daylength and precisely time FT expression.

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“…Yet petal number was insensitive to accelerated ageing in these genotypes, suggesting that petal number is not regulated by the age-sensing pathway comprised of miR156 and its targets in the SPL gene family. However, it is clear that individual SPL genes have specific roles in different developmental transitions that lead to flower formation in Arabidopsis (Yamaguchi et al, 2014;Hyun et al, 2016). Therefore, a comprehensive analysis of SPL gene function in C. hirsuta is required to fully understand the contribution of this ageing pathway to petal number variation.…”

Section: Regulation Of Petal Number By Endogenous Pathwaysmentioning

confidence: 99%

Seasonal Regulation of Petal Number

et al. 2017

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Four petals characterize the flowers of most species in the Brassicaceae family, and this phenotype is generally robust to genetic and environmental variation. A variable petal number distinguishes the flowers of Cardamine hirsuta from those of its close relative Arabidopsis (Arabidopsis thaliana), and allelic variation at many loci contribute to this trait. However, it is less clear whether C. hirsuta petal number varies in response to seasonal changes in environment. To address this question, we assessed whether petal number responds to a suite of environmental and endogenous cues that regulate flowering time in C. hirsuta. We found that petal number showed seasonal variation in C. hirsuta, such that spring flowering plants developed more petals than those flowering in summer. Conditions associated with spring flowering, including cool ambient temperature, short photoperiod, and vernalization, all increased petal number in C. hirsuta. Cool temperature caused the strongest increase in petal number and lengthened the time interval over which floral meristems matured. We performed live imaging of early flower development and showed that floral buds developed more slowly at 15°C versus 20°C. This extended phase of floral meristem formation, coupled with slower growth of sepals at 15°C, produced larger intersepal regions with more space available for petal initiation. In summary, the growth and maturation of floral buds is associated with variable petal number in C. hirsuta and responds to seasonal changes in ambient temperature.

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Gibberellin Acts Positively Then Negatively to Control Onset of Flower Formation inArabidopsis

Cited by 253 publications

References 68 publications

Gibberellins Interfere with Symbiosis Signaling and Gene Expression and Alter Colonization by Arbuscular Mycorrhizal Fungi in Lotus japonicus

Gibberellins Interfere with Symbiosis Signaling and Gene Expression and Alter Colonization by Arbuscular Mycorrhizal Fungi in Lotus japonicus

BBX19 Interacts with CONSTANS to RepressFLOWERING LOCUS TTranscription, Defining a Flowering Time Checkpoint inArabidopsis

Seasonal Regulation of Petal Number

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