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Anchorene, identified as an endogenous bioactive carotenoid‐derived dialdehyde and diapocarotenoid, affects root development by modulating auxin homeostasis. However, the precise interaction between anchorene and auxin, as well as the mechanisms by which anchorene modulates auxin levels, remain largely elusive. In this study, we conducted a comparative analysis of anchorene's bioactivities alongside auxin and observed that anchorene induces multifaceted auxin‐like effects. Through genetic and pharmacological examinations, we revealed that anchorene's auxin‐like activities depend on the indole‐3‐pyruvate‐dependent auxin biosynthesis pathway, as well as the auxin inactivation pathway mediated by Group II Gretchen Hagen 3 (GH3) proteins that mainly facilitate the conjugation of indole‐3‐acetic acid (IAA) to amino acids, leading to the formation of inactivated storage forms. Our measurements indicated that anchorene treatment elevates IAA levels while reducing the quantities of inactivated IAA–amino acid conjugates and oxIAA. RNA sequencing further revealed that anchorene triggers the expression of numerous auxin‐responsive genes in a manner reliant on Group II GH3s. Additionally, our in vitro enzymatic assays and biolayer interferometry (BLI) assay demonstrated anchorene's robust suppression of GH3.17‐mediated IAA conjugation with glutamate. Collectively, our findings highlight the significant role of carotenoid‐derived metabolite anchorene in modulating auxin homeostasis, primarily through the repression of GH3‐mediated IAA conjugation and inactivation pathways, offering novel insights into the regulatory mechanisms of plant bioactive apocarotenoids. [ABSTRACT FROM AUTHOR]

SUMMARY: The cutting technique is extensively used in tea breeding, with key emphasis on promoting the growth of adventitious roots (ARs). Despite its importance in tea cultivation, the mechanisms underlying AR development in tea remain unclear. In this study, we demonstrated the essential role of auxins in the initiation and progression of AR and established that the application of exogenous 1‐naphthaleneacetic acid‐enhanced AR formation in tissue‐cultured seedlings and cuttings. Then, we found that the auxin‐responsive transcription factor CsSPL9 acted as a negative regulator of AR development by reducing the levels of free indole‐3‐acetic acid (IAA) in tea plants. Furthermore, we identified CsGH3.4 as a downstream target of CsSPL9, which was activated by direct binding to its promoter. CsGH3.4 also inhibited AR development and maintained low levels of free IAA. Thus, these results revealed the inhibitory effect of the auxin‐responsive CsSPL9‐CsGH3.4 module on AR development by reducing free IAA levels in tea. These findings have significant theoretical and practical value for enhancing tea breeding practices. Significance Statement: The cutting technique is extensively used in tea breeding, with key emphasis on promoting the growth of adventitious roots (ARs). Despite its importance in tea cultivation, the mechanisms underlying AR development in tea remain unclear. In present study, we revealed the inhibitory effect of the auxin‐responsive CsSPL9‐CsGH3.4 module on AR development by reducing free IAA levels in tea. These findings have significant theoretical and practical value for enhancing tea and other woody plant breeding practices. [ABSTRACT FROM AUTHOR]

SUMMARY: Jasmonoyl‐isoleucine (JA‐Ile) is a key signaling molecule that activates jasmonate‐regulated flower development and the wound stress response. For years, JASMONATE RESISTANT1 (JAR1) has been the sole jasmonoyl‐amino acid synthetase known to conjugate jasmonic acid (JA) to isoleucine, and the source of persisting JA‐Ile in jar1 knockout mutants has remained elusive until now. Here we demonstrate through recombinant enzyme assays and loss‐of‐function mutant analyses that AtGH3.10 functions as a JA‐amido synthetase. Recombinant AtGH3.10 could conjugate JA to isoleucine, alanine, leucine, methionine, and valine. The JA‐Ile accumulation in the gh3.10–2 jar1‐11 double mutant was nearly eliminated in the leaves and flower buds while its catabolism derivative 12OH‐JA‐Ile was undetected in the flower buds and unwounded leaves. Residual levels of JA‐Ile, JA‐Ala, and JA‐Val were nonetheless detected in gh3.10–2 jar1‐11, suggesting the activities of similar promiscuous enzymes. Upon wounding, the accumulation of JA‐Ile and 12OH‐JA‐Ile and the expression of JA‐responsive genes OXOPHYTODIENOIC ACID REDUCTASE3 and JASMONATE ZIM‐DOMAIN1 observed in WT, gh3.10–1, and jar1‐11 leaves were effectively abolished in gh3.10–2 jar1‐11. Additionally, an increased proportion of undeveloped siliques associated with retarded stamen development was observed in gh3.10–2 jar1‐11. These findings conclusively show that AtGH3.10 contributes to JA‐amino acid biosynthesis and functions partially redundantly with AtJAR1 in sustaining flower development and the wound stress response in Arabidopsis. Significance Statement: The identity of an enzyme that functions similarly to JASMONATE RESISTANT1 in conjugating jasmonic acid (JA) to amino acids has been unknown for years. Our study reveals that AtGH3.10 is the long‐sought jasmonoyl‐amido synthetase in Arabidopsis that contributes to the biosynthesis of bioactive JA‐isoleucine and other JA‐amido conjugates necessary for JA‐mediated processes like the wound stress response and flower development. [ABSTRACT FROM AUTHOR]

Background: The Gretchen Hagen 3 (GH3) genes encode acyl acid amido synthetases, many of which have been shown to modulate the amount of active plant hormones or their precursors. GH3 genes, especially Group III subgroup 6 GH3 genes, and their expression patterns in economically important B. oleracea var. oleracea have not been systematically identified. Results: As a first step to understand regulation and molecular functions of Group III subgroup 6 GH3 genes, 34 GH3 genes including four subgroup 6 genes were identified in B. oleracea var. oleracea. Synteny found around subgroup 6 GH3 genes in B. oleracea var. oleracea and Arabidopsis thaliana indicated that these genes are evolutionarily related. Although expression of four subgroup 6 GH3 genes in B. oleracea var. oleracea is not induced by auxin, gibberellic acid, or jasmonic acid, the genes show different organ-dependent expression patterns. Among subgroup 6 GH3 genes in B. oleracea var. oleracea, only BoGH3.13–1 is expressed in anthers when microspores, polarized microspores, and bicellular pollens are present, similar to two out of four syntenic A. thaliana subgroup 6 GH3 genes. Detailed analyses of promoter activities further showed that BoGH3.13–1 is expressed in tapetal cells and pollens in anther, and also expressed in leaf primordia and floral abscission zones. Conclusions: Sixty-two base pairs (bp) region (− 340 ~ − 279 bp upstream from start codon) and about 450 bp region (− 1489 to − 1017 bp) in BoGH3.13–1 promoter are important for expressions in anther and expressions in leaf primordia and floral abscission zones, respectively. The identified anther-specific promoter region can be used to develop male sterile transgenic Brassica plants. [ABSTRACT FROM AUTHOR]

Key message: A Gretchen Hagen 3-like gene, LaGH3 from hybrid larch (Larix leptolepis × Larix olgensis), was identified, and the effects of abscisic acid (ABA) and indole-3-acetic acid (IAA) on its transcriptional levels and expression patterns during somatic embryogenesis were analyzed. A full-length cDNA sequence of a Gretchen Hagen 3 (GH3) gene was isolated from hybrid larch (Larix leptolepis × Larix olgensis) and designated LaGH3. The cDNA was 2053 bp in length and contained an 1848-bp open-reading frame encoding a predicted protein of 615 amino acids, characterized by four conserved motifs of the GH3 protein family: P-loop, α5, α6, and β8–β9. The 5′-flanking promoter region of LaGH3 was cloned using an improved TAIL-PCR technique. In this region, we identified several auxin- and abscisic acid (ABA)-inducible elements. Expression analysis showed that LaGH3 was induced by indole-3-acetic acid and that its transcript accumulation was inhibited by ABA. Further experiments demonstrated that ABA was the main factor in LaGH3 downregulation during the early stage of somatic embryogenesis, although the absence of auxin decreased LaGH3 expression slightly. LaGH3 transcripts gradually increased and peaked at 28 days with the rapid development of somatic embryos and then declined as the somatic embryos matured. We suggest that the level of LaGH3 transcripts partly represents the dynamics of endogenous auxin during somatic embryo development in larch. Taken together, our results provide evidence that GH3 genes play important roles in the crosstalk between auxin and ABA by maintaining auxin homeostasis during somatic embryo development. [ABSTRACT FROM AUTHOR]

Background: Coffee production relies on plantations with varieties from Coffea arabica and Coffea canephora species. The first, the most representative in terms of coffee consumption, is mostly propagated by seeds, which leads to management problems regarding the plantations maintenance, harvest and processing of grains. Therefore, an efficient clonal propagation process is required for this species cultivation, which is possible by reaching a scalable and cost-effective somatic embryogenesis protocol. A key process on somatic embryogenesis induction is the auxin homeostasis performed by Gretchen Hagen 3 (GH3) proteins through amino acid conjugation. In this study, the GH3 family members were identified on C. canephora genome, and by performing analysis related to gene and protein structure and transcriptomic profile on embryogenic tissues, we point a GH3 gene as a potential regulator of auxin homeostasis during early somatic embryogenesis in C. arabica plants. Results: We have searched within the published C. canephora genome and found 17 GH3 family members. We checked the conserved domains for GH3 proteins and clustered the members in three main groups according to phylogenetic relationships. We identified amino acids sets in four GH3 proteins that are related to acidic amino acid conjugation to auxin, and using a transcription factor (TF) network approach followed by RT-qPCR we analyzed their possible transcriptional regulators and expression profiles in cells with contrasting embryogenic potential in C. arabica. The CaGH3.15 expression pattern is the most correlated with embryogenic potential and with CaBBM, a C. arabica ortholog of a major somatic embryogenesis regulator. Conclusion: Therefore, one out of the GH3 members may be influencing on coffee somatic embryogenesis by auxin conjugation with acidic amino acids, which leads to the phytohormone degradation. It is an indicative that this gene can serve as a molecular marker for coffee cells with embryogenic potential and needs to be further studied on how much determinant it is for this process. This work, together with future studies, can support the improvement of coffee clonal propagation through in vitro derived somatic embryos. [ABSTRACT FROM AUTHOR]