An official website of the United States government
Summary Vascular bundles transport water and photosynthate to all organs, and increased bundle number contributes to crop lodging resistance. However, the regulation of vascular bundle formation is poorly understood in the Arabidopsis stem.We report a novel semi‐dominant mutant with high vascular activity,hva‐d, showing increased vascular bundle number and enhanced cambium proliferation in the stem. The activation of a C2H2 zinc finger transcription factor,AT5G27880/HVA, is responsible for thehva‐dphenotype. Genetic, biochemical, and fluorescent microscopic analyses were used to dissect the functions of HVA.HVA functions as a repressor and interacts with TOPLESS via the conserved Ethylene‐responsive element binding factor‐associated Amphiphilic Repression motif. In contrast to the HVA activation line, knockout ofHVAfunction with a CRISPR‐Cas9 approach or expression of HVA fused with an activation domain VP16 (HVA‐VP16) resulted in fewer vascular bundles. Further, HVA directly regulates the expression of the auxin transport efflux facilitatorPIN1, as a result affecting auxin accumulation. Genetics analysis demonstrated that PIN1 is epistatic to HVA in controlling bundle number.This research identifies HVA as a positive regulator of vascular initiation through negatively modulating auxin transport and sheds new light on the mechanism of bundle formation in the stem.
more »
« less
This content will become publicly available on December 1, 2026
RABBIT EARS directly regulates WOX4 transcription and inhibits secondary growth in Arabidopsis stem
Summary Plant secondary growth drives stem thickening and biomass accumulation, but its regulation is not yet fully understood.We have identified a novel semi‐dominant mutant,rbe‐d, characterized by a significant reduction in cambium cells and a complete absence of secondary growth in interfascicular regions in the stem. Gene cloning experiments indicated that the activation of the C2H2 zinc finger transcription factor, AT5G06070/RABBIT EARS (RBE), is responsible for therbe‐dphenotype.Transgenic analysis confirmed that overexpression of RBE represses secondary growth, while therbe‐2mutant increased the width of the interfascicular cambium‐derived (ICD) region. TheRBEgene is expressed in the procambium and cambium regions. Transcriptomic analysis showed that genes of the tracheary element differentiation inhibitory factor‐phloem intercalated with xylem (TDIF‐PXY) central regulatory pathway are repressed in therbe‐dmutant plants. Biochemical analyses confirmed that RBE binds directly to the promoter of WUSCHEL‐related homeobox (WOX4), a TDIF‐PXY downstreamWOXgene that regulates cambium cell proliferation. Moreover, genetic analysis confirmed thatWOX4is epistatic toRBEin secondary growth.Our results indicate that RBE inhibits cambium proliferation and thereby impacts secondary growth by directly repressingWOX4. These findings offer valuable new insight into the regulation of secondary growth in the Arabidopsis stem.
more »
« less
- Award ID(s):
- 2049926
- PAR ID:
- 10657218
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- New Phytologist
- Volume:
- 248
- Issue:
- 6
- ISSN:
- 0028-646X
- Page Range / eLocation ID:
- 3010 to 3023
- Subject(s) / Keyword(s):
- Arabidopsis, cambium activity, regulation, secondary growth, transcription factor.
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Summary Phytoplasmas are specialized phloem‐limited bacteria that cause diseases on various crops, resulting in significant agricultural losses. This research focuses on the jujube witches' broom (JWB) phytoplasma and investigates the host‐manipulating activity of the effector SJP39.We found that SJP39 directly interacts with the plant transcription factor bHLH87 in the nuclei. SJP39 stabilizes the bHLH87 homologs inArabidopsis thalianaand jujube, leading to growth defects in the plants.Transcriptomic analysis indicates that SJP39 affects the gibberellin (GA) pathway in jujube. We further demonstrate that ZjbHLH87 regulates GA signaling as a negative regulator, and SJP39 enhances this regulation.The research offers important insights into the pathogenesis of JWB disease and identified SJP39 as a virulence factor that can contribute to the growth defects caused by JWB phytoplasma infection. These findings open new opportunities to manage JWB and other phytoplasma diseases.more » « less
-
Summary Establishment of symbiosis between plants and arbuscular mycorrhizal (AM) fungi depends on fungal chitooligosaccharides (COs) and lipo‐chitooligosaccharides (LCOs). The latter are also produced by nitrogen‐fixing rhizobia to induce nodules on leguminous roots. However, host enzymes regulating structure and levels of these signals remain largely unknown.Here, we analyzed the expression of a β‐N‐acetylhexosaminidase gene ofMedicago truncatula(MtHEXO2) and biochemically characterized the enzyme. Mutant analysis was performed to study the role ofMtHEXO2during symbiosis.We found that expression ofMtHEXO2is associated with AM symbiosis and nodulation.MtHEXO2expression in the rhizodermis was upregulated in response to applied chitotetraose, chitoheptaose, and LCOs.M. truncatulamutants deficient in symbiotic signaling did not show induction ofMtHEXO2. Subcellular localization analysis indicated that MtHEXO2 is an extracellular protein. Biochemical analysis showed that recombinant MtHEXO2 does not cleave LCOs but can degrade COs intoN‐acetylglucosamine (GlcNAc).Hexo2mutants exhibited reduced colonization by AM fungi; however, nodulation was not affected inhexo2mutants.In conclusion, we identified an enzyme, which inactivates COs and promotes the AM symbiosis. We hypothesize that GlcNAc produced by MtHEXO2 may function as a secondary symbiotic signal.more » « less
-
Summary Arsenic poses a global threat to living organisms, compromising crop security and yield. Limited understanding of the transcriptional network integrating arsenic‐tolerance mechanisms with plant developmental responses hinders the development of strategies against this toxic metalloid.Here, we conducted a high‐throughput yeast one‐hybrid assay using as baits the promoter region from the arsenic‐inducible genesARQ1andASK18fromArabidopsis thaliana, coupled with a transcriptomic analysis, to uncover novel transcriptional regulators of the arsenic response.We identified the GLABRA2 (GL2) transcription factor as a novel regulator of arsenic tolerance, revealing a wider regulatory role beyond its established function as a repressor of root hair formation. Furthermore, we found that ANTHOCYANINLESS2 (ANL2), a GL2 subfamily member, acts redundantly with this transcription factor in the regulation of arsenic signaling. Both transcription factors act as repressors of arsenic response.gl2andanl2mutants exhibit enhanced tolerance and reduced arsenic accumulation. Transcriptional analysis in thegl2mutant unveils potential regulators of arsenic tolerance.These findings highlight GL2 and ANL2 as novel integrators of the arsenic response with developmental outcomes, offering insights for developing safer crops with reduced arsenic content and increased tolerance to this hazardous metalloid.more » « less
-
Abstract MOV10 is an RNA helicase that associates with the RNA‐induced silencing complex component Argonaute (AGO), likely resolving RNA secondary structures. MOV10 also binds the Fragile X mental retardation protein to block AGO2 binding at some sites and associates with UPF1, a principal component of the nonsense‐mediated RNA decay pathway. MOV10 is widely expressed and has a key role in the cellular response to viral infection and in suppressing retrotransposition. Posttranslational modifications of MOV10 include ubiquitination, which leads to stimulation‐dependent degradation, and phosphorylation, which has an unknown function. MOV10 localizes to the nucleus and/or cytoplasm in a cell type‐specific and developmental stage‐specific manner. Knockout ofMov10leads to embryonic lethality, underscoring an important role in development where it is required for the completion of gastrulation. MOV10 is expressed throughout the organism; however, most studies have focused on germline cells and neurons. In the testes, the knockdown ofMov10disrupts proliferation of spermatogonial progenitor cells. In brain, MOV10 is significantly elevated postnatally and binds mRNAs encoding cytoskeleton and neuron projection proteins, suggesting an important role in neuronal architecture. HeterozygousMov10mutant mice are hyperactive and anxious and their cultured hippocampal neurons have reduced dendritic arborization. Zygotic knockdown ofMov10inXenopus laeviscauses abnormal head and eye development and mislocalization of neuronal precursors in the brain. Thus, MOV10 plays a vital role during development, defense against viral infection and in neuronal development and function: its many roles and regulation are only beginning to be unraveled. This article is categorized under:RNA Interactions with Proteins and Other Molecules > RNA‐Protein ComplexesRNA Interactions with Proteins and Other Molecules > Protein‐RNA Interactions: Functional Implicationsmore » « less
