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6 recordsLinked to original sources
PubMed2026

GA4+7 alleviates pear fruit semi-russeting partly by suppressing PRX-mediated lignin deposition.

Pear fruit semi-russeting is a surface disorder that frequently occurs during fruit development and significantly diminishes fruit appearance quality and commercial value. Although Gibberellin 4 + 7 (GA4+7) has been used to reduce fruit surface defects in horticultural crops, the physiological and molecular mechanisms underlying its inhibitory effect on pear fruit semi-russeting remain poorly understood. In this study, preharvest GA4+7 treatment of 'Cuiguan' pear significantly reduced russet coverage and lignin accumulation in mature fruit skin without adversely affecting fruit size, fruit shape index, or total soluble solids content. Integrated metabolomic and transcriptomic analyses revealed that GA4+7 treatment was associated with the repression of phenylpropanoid and lignin biosynthesis at both metabolic and transcriptional levels. Among the lignin-related differentially expressed genes, two class III peroxidase genes, PpyPRX22 and PpyPRX65, were strongly downregulated by both GA4+7 and bagging treatments. Both proteins localized to the cell wall, and transient expression assays in pear fruit skin supported positive roles for PpyPRX22 and PpyPRX65 in lignin deposition. Furthermore, dual-luciferase reporter assays combined with transient overexpression experiments suggested that several PpyMYB transcription factors may regulate PpyPRX expression and lignin accumulation, with PpyMYB138 and PpyMYB139 significantly activating PpyPRX22 and/or PpyPRX65 promoter activity. Taken together, these results suggest that GA4+7 alleviates pear fruit semi-russeting at least partly by reducing lignin deposition in the fruit skin, with PpyPRX22 and PpyPRX65 potentially contributing to this process.

Class III peroxidase↗
PubMed2026

GmMYB29 activates Gm4CL3 to enhance soybean resistance to Heterodera glycines.

Soybean cyst nematode is a devastating soil-borne pathogen that severely limits soybean yield worldwide. To uncover downstream target genes of the resistance-associated transcription factor GmMYB29, we combined ChIP-seq and RNA-seq data from T3-generation GmMYB29-overexpressing soybean plants, alongside Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses, to screen candidate genes carrying transcription factor binding peaks within the 2000 bp region upstream of transcription start sites (TSS). Four orthogonal molecular assays-yeast one-hybrid (Y1H), electrophoretic mobility shift assay (EMSA), dual-luciferase reporter (LUC) system, and GUS histochemical staining-collectively confirmed the specific physical interaction between GmMYB29 and the promoter of Gm4CL3. We generated transgenic soybean hairy roots overexpressing Gm4CL3 (OX-Gm4CL3) and CRISPR-Cas9-mediated Gm4CL3 knockout lines (KO-Gm4CL3), with wild-type (WT) plants serving as controls. Inoculation assays using SCN 3 demonstrated that OX-Gm4CL3 roots displayed substantially improved SCN resistance, while KO-Gm4CL3 roots were hypersusceptible to nematode infection. Mechanistic investigations revealed that Gm4CL3 promotes lignin deposition in root tissues to block SCN penetration. Furthermore, GmMYB29 and Gm4CL3 act synergistically to activate lignin biosynthetic pathways and strengthen soybean resistance against SCN 3 (SCN Race 3, the dominant physiological race in Northeast China). In summary, this study functionally characterizes Gm4CL3 and defines a previously unreported GmMYB29-Gm4CL3 regulatory cascade that mediates plant defense against SCN. This module functions independent of classic SCN resistance loci rhg1/Rhg4, providing new genetic resources for SCN-resistant soybean molecular breeding.

Glycine max↗
PubMed2026

DfCAD16 controls guaiacyl lignin biosynthesis during shoot development in Dendrocalamus farinosus.

Although bamboo can be an ideal raw material for pulp and paper industry, the depolymerization of its complex polymers needs to be facilitated. The deposition of lignin is influenced by cinnamyl alcohol dehydrogenase (CAD), an enzyme that catalyzes the formation of monolignol precursors. Here, we identified 18 DfCAD genes in Dendrocalamus farinosus and revealed using bioinformatics methods, DfCAD16 functions as the primary enzyme in the synthesis pathway of guaiacyl (G)-lignin. Phenotypic analysis of plants overexpression DfCAD16 exhibited remarkable increasing in G-lignin. Furthermore, we demonstrated that an R2R3-type MYB transcription factor DfMYB12 could directly bind to the promoter region of DfCAD16 and activate its expression both in vitro and in vivo. Our findings revealed that DfMYB12-DfCAD16 is a key regulatory factor governing G-lignin biosynthesis in D. farinosus. These insights can be used for improving bamboo varieties for pulp production.

Lignin↗
PubMed2026

Trimming galactose side chains of arabinogalactan proteins alters pectin and hemicellulose deposition in secondary cell walls of Arabidopsis thaliana floral stem internodes.

Shaping the cell wall composition and structure to meet the requirements of different tissues and developmental stages relies on multiple actors, including arabinogalactan proteins (AGPs). Although the specific role of these proteins in cell wall dynamics is still under debate, especially in events involving significant remodeling of the cell wall, their carbohydrate motif, type II arabinogalactan (AGII), seems to be crucial for their function. This study aims to investigate the function of AGII, specifically the galactose residues of its side chains, in the structural organization of the cell wall during the cessation of elongation and the transition to secondary growth. To achieve this, we characterized floral stem internodes of Arabidopsis thaliana plants overproducing the chickpea βV-galactosidase protein (35S::βV-Gal plants), an enzyme that specifically hydrolyzes the β-(1,3)- and β-(1,6)-galactosyl residues of AGII. Changes induced in the cell wall by trimming galactose residues of AGII resulted in a noticeable increase in homogalacturonan methyl esterification. Additionally, these neutral galactose side chains may regulate hemicellulose-cellulose interactions and influence xylan distribution through the cellulose network, which in turn affects the deposition of lignin and determines its recalcitrance to enzymatic degradation.

Arabidopsis↗
PubMed2026

Addressing lignin composition and content via Arabidopsis arogenate dehydratase knockout and over-expression genotypes.

Following the down-selection of 14 Arabidopsis thaliana arogenate dehydratase (ADT) knockout and over-expression (OE) genotypes, the most highly contrasting quadruple knockout adt3/4/5/6 and ADT OE genotypes were subjected to proteomics, metabolomics, and scanning electron microscopy (SEM) analyses as needed, with results compared to Columbia wild-type (WT). The basal adt3/4/5/6 stem cross-sections, ∼70% lignin content reduced, exhibited buckled vessel cell walls and partially detached xylary fibers, in contrast to WT and ADT4m/5 m OE genotypes that did not. Anatomical defects primarily resulted from guaiacyl lignin level reductions in vessels with concomitant increased stem syringyl:guaiacyl (S/G) ratios. Phenylpropanoid and various upstream shikimate-chorismate pathway enzyme abundances, as well as specific monolignol oxidases (laccases/peroxidases), generally increased in adt3/4/5/6 at different stem and rosette leaf growth/development stages, relative to WT. Opposite effects were largely observed with the ADT5m OE genotype. By contrast, flavonoid and glucosinolate pathway enzyme amounts varied. Such enzyme abundance increases were overall unproductive as adt3/4/5/6 was unable to restore WT, ADT4 OE, ADT5 OE, ADT5m OE, and ADT4m/5 m OE secondary metabolite (lignin, phenylpropanoid, lignan, flavonoid, phenolic acid, and glucosinolate) levels. Conversely, ADT OE genotypes did not significantly increase programmed lignin levels or alter S/G compositions. In sum, proteomics analyses of adt3/4/5/6 and adt5 'perceived' that lignin and low molecular weight secondary metabolite amounts were not at 'programmed' levels as for WT and ADT OE genotypes but observed increases in relevant pathway protein abundances were futile. Notably though, proteomics analyses did not lead to predicting that lignin and associated biochemical pathways would have reduced metabolite levels, relative to WT and ADT OE genotypes. Genotype adt3/4/5/6, possibly the highest lignin level reduced genotype reported, did not utilize other phenolics to compensate. By contrast, the differential temporal and spatial deposition of cell wall oxidases again indicate the exquisite control over lignin deposition, and our lack of knowledge of precise lignin structure and assembly in subcellular regions of the lignified cell walls.

Lignin↗
PubMed2026

Zea mays Drought-Overly Sensitive1/TUBA4 Is Wilty3, and Transcriptome Co-Expression Analysis of Shoot Meristem Mutant Tissues Reveals Wilty2/TUB6:Wi3 Interactions Associated With Stem Vascular Bundle Development.

Plant vasculature is essential for the transport of water, nutrients, and signaling molecules across organs, while also providing critical mechanical support for growth and development. Disruptions in vascular bundle formation can therefore lead to severe physiological and developmental defects. In maize, ethyl methanesulfonate (EMS)-induced dominant nonallelic Wilty mutants exhibit a pronounced wilting phenotype even under well-watered conditions, indicating underlying defects in vascular function. In this study, we characterized the Wi3 mutant, identified as ZmDrought-Overly-Sensitive1/DOS1, and compared it with the previously described Wi2 mutant to uncover shared mechanisms underlying their phenotypes. We provide evidence, by bulk segregant resequencing linkage disequilibrium of SNPs adjacent to the causal Wilty SNPs in respective ß- and α-tubulin genes, for the personal communication from Gerry Neuffer that Wi2/ß-tub6 provenance is from ACR-related stock, whereas Wi3/α-tub4 allele is from Mo17, not B73 as claimed by the authors who cloned Dos1. Histochemical staining and Fourier-transform infrared (FTIR) spectroscopy of vascular bundles in Wi3 indicated apparent alterations in cellulose and lignin content consistent with those observed in Wi2. Transcriptome analysis of shoot meristems further indicated that similar sets of genes and pathways are differentially expressed in both mutants, suggesting convergence on common biological pathways. Using bulk-segregant whole-genome resequencing, we identified alpha-tubulin4 (TUA4) as the causal gene in Wi3 (ZmDOS1), harboring a C-to-T substitution within the N-terminal GTPase-binding domain. This mutation results in a glutamic acid196-to-lysine substitution. Given that α- and β-tubulin subunits heterodimerize, and in many plants and animal mutant alleles are dominant-negative gains-of-function, we infer Wi2, Wi3, and likely Wi4, based on very similar FTIR biophysical difference spectra, may act as effectors of vascular bundle cell wall deposition, potentially involving vesicle trafficking as recently shown for asymmetric cell divisions in maize stomatal development. Together, these findings highlight the functional interdependence of tubulin subunits and provide a plausible mechanistic framework for the striking biophysical, transcriptomic, and phenotypic similarities observed between Wi2, Wi3/ZmDOS1, and Wi4 mutants.

bulk segregant analysis↗