Recognition of the folded conformation of plant hormone (auxin, IAA) conjugates with glutamic and aspartic acids and their amides

NALCN (Na+leak channel, non-selective) is a conserved, voltage-insensitive cation channel that regulates resting membrane potential and neuronal excitability. UNC79 and UNC80 are key regulators of the channel function. However, the behavioral effects of the channel complex are not entirely clear and the neurons in which the channel functions remain to be identified. In a forward genetic screen for C. elegans mutants with defective avoidance response to the plant hormone methyl salicylate (MeSa), we isolated multiple loss-of-function mutations in unc-80 and unc-79. C. elegans NALCN mutants exhibited similarly defective MeSa avoidance. Interestingly, NALCN, unc-80 and unc-79 mutants all showed wild type-like responses to other attractive or repelling odorants, suggesting that NALCN does not broadly affect odor detection or related forward and reversal behaviors. To understand in which neurons the channel functions, we determined the identities of a subset of unc-80-expressing neurons. We found that unc-79 and unc-80 are expressed and function in overlapping neurons, which verified previous assumptions. Neuron-specific transgene rescue and knockdown experiments suggest that the command interneurons AVA and AVE and the anterior guidepost neuron AVG can play a sufficient role in mediating unc-80 regulation of the MeSa avoidance. Though primarily based on genetic analyses, our results further imply that MeSa might activate NALCN by direct or indirect actions. Altogether, we provide an initial look into the key neurons in which the NALCN channel complex functions and identify a novel function of the channel in regulating C. elegans reversal behavior through command interneurons.

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Brassinosteroids repress the seed maturation program during the seed-to-seedling transition

Plant Physiology ◽

10.1093/plphys/kiab089 ◽

2021 ◽

Author(s):

Jiuxiao Ruan ◽

Huhui Chen ◽

Tao Zhu ◽

Yaoguang Yu ◽

Yawen Lei ◽

...

Keyword(s):

Arabidopsis Thaliana ◽

Transcription Factor ◽

Abscisic Acid ◽

Plant Hormone ◽

Flowering Plants ◽

Seed Maturation ◽

Domain Protein ◽

Abscisic Acid Insensitive3 ◽

Underlying Mechanisms ◽

Embryonic Structure

Abstract In flowering plants, repression of the seed maturation program is essential for the transition from the seed to the vegetative phase, but the underlying mechanisms remain poorly understood. The B3-domain protein VIVIPAROUS1/ABSCISIC ACID-INSENSITIVE3-LIKE 1 (VAL1) is involved in repressing the seed maturation program. Here we uncovered a molecular network triggered by the plant hormone brassinosteroid (BR) that inhibits the seed maturation program during the seed-to-seedling transition in Arabidopsis (Arabidopsis thaliana). val1-2 mutant seedlings treated with a BR biosynthesis inhibitor form embryonic structures, whereas BR signaling gain-of-function mutations rescue the embryonic structure trait. Furthermore, the BR-activated transcription factors BRI1-EMS-SUPPRESSOR 1 and BRASSINAZOLE-RESISTANT 1 bind directly to the promoter of AGAMOUS-LIKE15 (AGL15), which encodes a transcription factor involved in activating the seed maturation program, and suppress its expression. Genetic analysis indicated that BR signaling is epistatic to AGL15 and represses the seed maturation program by downregulating AGL15. Finally, we showed that the BR-mediated pathway functions synergistically with the VAL1/2-mediated pathway to ensure the full repression of the seed maturation program. Together, our work uncovered a mechanism underlying the suppression of the seed maturation program, shedding light on how BR promotes seedling growth.

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Transcriptomic and epigenomic remodeling occurs during vascular cambium periodicity in Populus tomentosa

Horticulture Research ◽

10.1038/s41438-021-00535-w ◽

2021 ◽

Vol 8 (1) ◽

Author(s):

Bo Chen ◽

Huimin Xu ◽

Yayu Guo ◽

Paul Grünhofer ◽

Lukas Schreiber ◽

...

Keyword(s):

Signal Transduction ◽

Plant Hormone ◽

Target Genes ◽

Populus Tomentosa ◽

Differentially Expressed ◽

Vascular Cambium ◽

Differentially Methylated Region ◽

Gene Body Methylation ◽

Transcription Analysis ◽

Global Methylation

AbstractTrees in temperate regions exhibit evident seasonal patterns, which play vital roles in their growth and development. The activity of cambial stem cells is the basis for regulating the quantity and quality of wood, which has received considerable attention. However, the underlying mechanisms of these processes have not been fully elucidated. Here we performed a comprehensive analysis of morphological observations, transcriptome profiles, the DNA methylome, and miRNAs of the cambium in Populus tomentosa during the transition from dormancy to activation. Anatomical analysis showed that the active cambial zone exhibited a significant increase in the width and number of cell layers compared with those of the dormant and reactivating cambium. Furthermore, we found that differentially expressed genes associated with vascular development were mainly involved in plant hormone signal transduction, cell division and expansion, and cell wall biosynthesis. In addition, we identified 235 known miRNAs and 125 novel miRNAs. Differentially expressed miRNAs and target genes showed stronger negative correlations than other miRNA/target pairs. Moreover, global methylation and transcription analysis revealed that CG gene body methylation was positively correlated with gene expression, whereas CHG exhibited the opposite trend in the downstream region. Most importantly, we observed that the number of CHH differentially methylated region (DMR) changes was the greatest during cambium periodicity. Intriguingly, the genes with hypomethylated CHH DMRs in the promoter were involved in plant hormone signal transduction, phenylpropanoid biosynthesis, and plant–pathogen interactions during vascular cambium development. These findings improve our systems-level understanding of the epigenomic diversity that exists in the annual growth cycle of trees.

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Extended JAZ degron sequence for plant hormone binding in jasmonate co-receptor of tomato SlCOI1-SlJAZ

Scientific Reports ◽

10.1038/s41598-021-93067-1 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Rina Saito ◽

Kengo Hayashi ◽

Haruna Nomoto ◽

Misuzu Nakayama ◽

Yousuke Takaoka ◽

...

Keyword(s):

Arabidopsis Thaliana ◽

Plant Development ◽

Genetic Modification ◽

Tomato Plant ◽

Plant Hormone ◽

Herbivorous Insects ◽

Hormone Binding ◽

Plant Body

Abstract(+)-7-iso-Jasmonoyl-l-isoleucine (JA-Ile) is a lipid-derived phytohormone implicated in plant development, reproduction, and defense in response to pathogens and herbivorous insects. All these effects are instigated by the perception of JA-Ile by the COI1-JAZ co-receptor in the plant body, which in Arabidopsis thaliana is profoundly influenced by the short JAZ degron sequence (V/L)P(Q/I)AR(R/K) of the JAZ protein. Here, we report that SlJAZ-SlCOI1, the COI1-JAZ co-receptor found in the tomato plant, relies on the extended JAZ degron sequence (V/L)P(Q/I)AR(R/K)XSLX instead of the canonical JAZ degron. This finding illuminates our understanding of the mechanism of ligand perception by JA-Ile in this plant, and will inform both efforts to improve it by genetic modification of the SlCOI1-SlJAZ co-receptor, and the development of the synthetic agonists/antagonists.

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Identification, Phylogeny, and Comparative Expression of the Lipoxygenase Gene Family of the Aquatic Duckweed, Spirodela polyrhiza, during Growth and in Response to Methyl Jasmonate and Salt

International Journal of Molecular Sciences ◽

10.3390/ijms21249527 ◽

2020 ◽

Vol 21 (24) ◽

pp. 9527

Author(s):

Rakesh K. Upadhyay ◽

Marvin Edelman ◽

Autar K. Mattoo

Keyword(s):

Fatty Acids ◽

Gene Family ◽

Methyl Jasmonate ◽

Aquatic Plant ◽

Plant Hormone ◽

Feedback Regulation ◽

Spirodela Polyrhiza ◽

Opposite Trend ◽

Lipoxygenase Gene ◽

Lipoxygenase Gene Family

Lipoxygenases (LOXs) (EC 1.13.11.12) catalyze the oxygenation of fatty acids and produce oxylipins, including the plant hormone jasmonic acid (JA) and its methyl ester, methyl jasmonate (MeJA). Little information is available about the LOX gene family in aquatic plants. We identified a novel LOX gene family comprising nine LOX genes in the aquatic plant Spirodela polyrhiza (greater duckweed). The reduced anatomy of S. polyrhiza did not lead to a reduction in LOX family genes. The 13-LOX subfamily, with seven genes, predominates, while the 9-LOX subfamily is reduced to two genes, an opposite trend from known LOX families of other plant species. As the 13-LOX subfamily is associated with the synthesis of JA/MeJA, its predominance in the Spirodela genome raises the possibility of a higher requirement for the hormone in the aquatic plant. JA-/MeJA-based feedback regulation during culture aging as well as the induction of LOX gene family members within 6 h of salt exposure are demonstrated.

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