Auxin response factors ARF6 and ARF8 promote jasmonic acid production and flower maturation

Nagpal, Punita; Ellis, Christine M.; Weber, Hans; Ploense, Sara E.; Barkawi, Lana S.; Guilfoyle, Tom J.; Hagen, Gretchen; Alonso, José M.; Cohen, Jerry D.; Farmer, Edward E.; Ecker, Joseph R.; Reed, Jason W.

doi:10.1242/dev.01955

Cited by 635 publications

(635 citation statements)

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“…ARF2 acts as a transcriptional repressor (39,40) and is a negative regulator of cell division in Arabidopsis (41). In contrast, PU01758, which encodes a poplar homolog of the Arabidopsis factor ARF6 that has an activator domain and appears to be a transcriptional activator (18,42), is down-regulated during the transition to dormancy (32). These results suggest that upregulation of negatively acting ARFs, with simultaneous downregulation of activator ARFs, could lead to a general reduction in auxin responsiveness during the transition to dormancy.…”

Section: Sd0 Sd28 Sd42 Sd56 Sd0 Sd28 Sd42 Sd56mentioning

confidence: 91%

Activity–dormancy transition in the cambial meristem involves stage-specific modulation of auxin response in hybrid aspen

Baba

Karlberg²,

Schmidt³

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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The molecular basis of short-day-induced growth cessation and dormancy in the meristems of perennial plants (e.g., forest trees growing in temperate and high-latitude regions) is poorly understood. Using global transcript profiling, we show distinct stagespecific alterations in auxin responsiveness of the transcriptome in the stem tissues during short-day-induced growth cessation and both the transition to and establishment of dormancy in the cambial meristem of hybrid aspen trees. This stage-specific modulation of auxin signaling appears to be controlled via distinct mechanisms. Whereas the induction of growth cessation in the cambium could involve induction of repressor auxin response factors (ARFs) and down-regulation of activator ARFs, dormancy is associated with perturbation of the activity of the SKP-Cullin-F-box TIR (SCF TIR ) complex, leading to potential stabilization of repressor auxin (AUX)/indole-3-acetic acid (IAA) proteins. Although the role of hormones, such as abscisic acid (ABA) and gibberellic acid (GA), in growth cessation and dormancy is well established, our data now implicate auxin in this process. Importantly, in contrast to most developmental processes in which regulation by auxin involves changes in cellular auxin contents, day-length-regulated induction of cambial growth cessation and dormancy involves changes in auxin responses rather than auxin content.short days | meristem identity P erennial plants growing in temperate and high-latitude regions anticipate the approach of winter by sensing the associated reduction in day length (1), and when the day length becomes shorter than the critical length permitting growth [short-day signal (SD)], cell division terminates in the meristems (1). Immediately following cessation of cell division, exposure of plants to permissive conditions (e.g., long days) leads to the reversal of growth arrest (2), and this stage of growth arrest is referred to as ecodormancy. Continued exposure of ecodormant plants to short days brings about the transition from ecodormancy to endodormancy (2). The endodormant state is characterized by the inability of the meristems to respond to growth-promotive signals in contrast to the ecodormant state. Exposure to chilling temperatures is required to restore the ability of endodormant meristems to respond to growth-promotive signals and to reinitiate growth subsequently (3).Recently, the photoreceptor PHYA (4) and homologs of the flowering time genes CONSTANS and FT (5, 6) have been shown to be early-acting components in SD-induced growth cessation in trees. The targets and signaling intermediates of the SD pathway downstream of these early-acting components in growth cessation and dormancy remain largely unexplored (7). Although ecodormant and endodormant states can be distinguished physiologically, the molecular mechanisms underlying the establishment of endodormancy and the inability of endodormant meristems to respond to growth-promotive signals have remained elusive.We investigated whether the SD-regulated induction o...

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Section: Sd0 Sd28 Sd42 Sd56 Sd0 Sd28 Sd42 Sd56mentioning

confidence: 91%

Activity–dormancy transition in the cambial meristem involves stage-specific modulation of auxin response in hybrid aspen

Baba

Karlberg²,

Schmidt³

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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“…During stamen development, auxin and GA stimulate the expression of the JA biosynthetic gene DAD1 (Yu et al, 2004;Nagpal et al, 2005;Ito et al, 2007;Cheng et al, 2009;Tabata et al, 2010;Reeves et al, 2012). Elevated biosynthesis of JA in anthers leads to expression of MYB21, MYB24, and MYB57, which are involved in filament elongation, pollen maturation, and anther dehiscence (Mandaokar et al, 2006;Mandaokar and Browse, 2009;Reeves et al, 2012).…”

Section: Jam1 Is Involved In Male Fertilitymentioning

confidence: 99%

A bHLH-Type Transcription Factor, ABA-INDUCIBLE BHLH-TYPE TRANSCRIPTION FACTOR/JA-ASSOCIATED MYC2-LIKE1, Acts as a Repressor to Negatively Regulate Jasmonate Signaling inArabidopsis

et al. 2013

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Jasmonates (JAs) are plant hormones that regulate the balance between plant growth and responses to biotic and abiotic stresses. Although recent studies have uncovered the mechanisms for JA-induced responses in Arabidopsis thaliana, the mechanisms by which plants attenuate the JA-induced responses remain elusive. Here, we report that a basic helix-loophelix-type transcription factor, ABA-INDUCIBLE BHLH-TYPE TRANSCRIPTION FACTOR/JA-ASSOCIATED MYC2-LIKE1 (JAM1), acts as a transcriptional repressor and negatively regulates JA signaling. Gain-of-function transgenic plants expressing the chimeric repressor for JAM1 exhibited substantial reduction of JA responses, including JA-induced inhibition of root growth, accumulation of anthocyanin, and male fertility. These plants were also compromised in resistance to attack by the insect herbivore Spodoptera exigua. Conversely, jam1 loss-of-function mutants showed enhanced JA responsiveness, including increased resistance to insect attack. JAM1 and MYC2 competitively bind to the target sequence of MYC2, which likely provides the mechanism for negative regulation of JA signaling and suppression of MYC2 functions by JAM1. These results indicate that JAM1 negatively regulates JA signaling, thereby playing a pivotal role in fine-tuning of JA-mediated stress responses and plant growth.

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“…LOX2 is responsible for the generation of jasmonic acid (JA) and methyl jasmonate, well-known lipid derived signaling molecules operative in defense responses whose synthesis is initiated in the cholorplast. Given the apparent specificity of LOX2 for JA synthesis in response to wounding, however, it is unclear why it should be induced in leaves during the floral transition, although JA is necessary for flower maturation [33]. Of the seven lipoxygenase genes in Arabidopsis, LOX2, LOX3 and two LOX3-like proteins are predicted to have chloroplast targeting signals.…”

Section: Discussionmentioning

confidence: 99%

The developmental transition to flowering in Arabidopsis is associated with an increase in leaf chloroplastic lipoxygenase activity

Bañuelos¹,

Argumedo²,

Patel³

et al. 2008

Plant Science

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The developmental transition from vegetative growth to flowering in Arabidopsis is associated with a precipitous decline in the activity of leaf ascorbate peroxidase (APx), an enzymatic scavenger of hydrogen peroxide, and an increase in specific lipid peroxidation leading to the accumulation of 13-hydroperoxy-9,11,15 (Z,E,Z) octadecatrienoic acid (13 HOO-FA). The appearance of this specific isomer suggests that it is of enzymatic origin and may represent the activation of an oxylipin signaling pathway. We thus hypothesized that leaf 13-lipoxygenase (LOX) activity increases at the floral transition and leads to the observed elevation of 13-HOO-FA levels. Leaf protein extracts were prepared from seven distinct life stages of Arabidopsis plants and used to assay for LOX activity. We report that leaf 13-LOX enzymatic activity increases twoto three-fold from the vegetative stage to the immediate post-floral transition stage. We found two forms of LOX activity in cell extracts and show that the higher pH optimum form is the isoenzyme activated. This increase is correlated with a small increase in H 2 O 2 , perhaps resulting from the previously reported decline in leaf APx activity. Very low levels of exogenous H 2 O 2 activate the induced form in vegetative leaf extracts in vitro, suggesting that the floral transition-dependent APx decline and subsequent H 2 O 2 elevation are involved in activating plastid 13-LOX and thus a second messenger oxylipin pathway.

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Auxin response factors ARF6 and ARF8 promote jasmonic acid production and flower maturation

Cited by 635 publications

References 65 publications

Activity–dormancy transition in the cambial meristem involves stage-specific modulation of auxin response in hybrid aspen

Activity–dormancy transition in the cambial meristem involves stage-specific modulation of auxin response in hybrid aspen

A bHLH-Type Transcription Factor, ABA-INDUCIBLE BHLH-TYPE TRANSCRIPTION FACTOR/JA-ASSOCIATED MYC2-LIKE1, Acts as a Repressor to Negatively Regulate Jasmonate Signaling inArabidopsis

The developmental transition to flowering in Arabidopsis is associated with an increase in leaf chloroplastic lipoxygenase activity

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