Author: slquinlan

Plant J. 2026 Mar;125(5):e70754. doi: 10.1111/tpj.70754.

ABSTRACT

Glycosyltransferases (GTs) are the primary enzymes responsible for the biosynthesis of the complex polysaccharides in plant cell walls. Given the important role of GTs in plants, it is necessary to undertake their functional characterization to better understand plant cell wall synthesis pathways to develop improved feedstocks for efficient conversion into fuels and products to support the emerging bioeconomy. The GT47 family in plants represents a unique target for characterization due to the substantial diversity of donor and acceptor substrates observed within a single family. Here, we have carried out the biochemical characterization of MUR3 and XLT2 orthologs from the aquatic monocot Spirodela polyrhiza. Our findings support existing genetic and phylogenetic data classifying these enzymes as regio-specific galactosyltransferases involved in xyloglucan (XyG) sidechain biosynthesis. In addition, we have identified novel characteristics for both enzymes, such as in vitro arabinopyranosyltransferase activity and distinctiveness in xyloglucan reducing end specificity.

PMID:41784714 | DOI:10.1111/tpj.70754

Theor Appl Genet. 2026 Mar 5;139(3):87. doi: 10.1007/s00122-026-05177-x.

ABSTRACT

A paralog of Cell Size Regulator (CSR), CSR-like1, underlies the novel fw6.2 QTL in tomato. The gene and locus regulate fruit weight by increasing pericarp cell size and its function on fruit weight appears to be conserved in other crops. Fruit weight is a quantitative trait that was under strong selection during the domestication of fruit and vegetable crops such as tomato (Solanum lycopersicum). While numerous fruit weight QTLs have been identified, only three tomato fruit weight genes have been cloned. In this study, we utilized a genetically diverse tomato panel, the Varitome collection, to identify additional genetic loci that control fruit weight. We mapped and fine mapped two fruit weight QTLs on chromosome 6, fw6.1 and fw6.2, by using Genome Wide Association studies (GWAS) and linkage mapping in bi-parental populations. We identified a member of the Cell Size Regulator family, CSR-like1, as the likely candidate underlying fw6.2. The near isogenic lines (NILs) carrying the derived allele of fw6.2 produced heavier fruits with larger fruit pericarp cells than lines with wildtype (WT) allele. Transgenic downregulation of CSR-like1 led to a decrease in fruit weight and pericarp cells, supporting the role of this gene at the fw6.2 locus. The haplotype analysis implied that the CSR-like1-Derived (CSR-like1-D) allele was selected in the transition from the fully wild S. pimpinellifolium to the earliest S. lycopersicum cerasiforme accessions. Four single nucleotide polymorphisms (SNPs) were identified in the regulatory region of CSR-like1 that were conserved in the accessions carrying CSR-like1-WT and were significantly associated with lower fruit weight and pericarp cell size at the locus. Moreover, a pepper GWAS identified a CSR-like1 ortholog that was associated with fruit weight. Together, our findings established CSR-like1 as a novel fruit weight gene likely conserved in other crops in the Solanaceae family.

PMID:41784692 | DOI:10.1007/s00122-026-05177-x

New Phytol. 2026 Mar 3. doi: 10.1111/nph.71037. Online ahead of print.

ABSTRACT

Soybean (Glycine max) plants counteract soybean cyst nematode (SCN, Heterodera glycines Ichinohe) infection through an impairment of soluble N-ethylmaleimide-sensitive factor (NSF) attachment protein (α-SNAP) – NSF interactions and vesicular trafficking leading to cellular toxicity in response to nematode feeding. Through the use of a bi-parental mapping population from a cross between the SCN-resistant soybean cultivars Pickett × Peking, a major QTL on chromosome 14 was mapped to a confidence interval containing the GmSNAP14 gene. SCN-resistant genotypes were found to carry one of two variant GmSNAP14 alleles harboring either a deletion or an insertion in GmSNAP14. Expression of full-length transcripts was absent or markedly lower in plants carrying these alleles when compared to susceptible plants. Additionally, the generation of deleted and/or alternatively spliced isoforms coding for GmSNAP14 C-terminal variant proteins was pronounced in resistant plants, suggesting that SCN resistance may result from a combination of diminished GmSNAP14 expression and GmSNAP14 protein variants. CRISPR/Cas9-mediated knockout of GmSNAP14 enhanced resistance to SCN, consistent with susceptibility gene behavior indicating GmSNAP14 as a potential nematode virulence target. Our findings can be leveraged through the use of genome editing and conventional breeding techniques utilizing native alleles to develop resistant soybean cultivars.

PMID:41776743 | DOI:10.1111/nph.71037

J Exp Bot. 2026 Mar 3:erag117. doi: 10.1093/jxb/erag117. Online ahead of print.

ABSTRACT

The plant cell wall hemicellulose xyloglucan in most dicot species consists of repeating units of three consecutive xylosylated Glc residues followed by an unsubstituted Glc (XXXG). Available evidence suggests that galactosylation of the second and the third Xyl side chains of XXXG is carried out regiospecifically by two xyloglucan galactosyltransferases XLT2 and MUR3, respectively, resulting in XLXG and XXLG units, but the mechanism underlying their regiospecificity remains elusive. In this report, we demonstrated that recombinant MUR3 and XLT2 proteins of Arabidopsis, poplar and duckweed were able to regiospecifically galactosylate not only XXXG, but also XLXG and XXLG, respectively, to generate XLLG. Interestingly, they were also able to galactosylate mono- and di-xylosylated xyloglucan oligomers. Protein structural modeling revealed that Arabidopsis and poplar MUR3 proteins contained an α-helical lid-like domain covering their active site clefts and its deletion led to increased galactosyltransferase activity. Molecular docking of the structural models of MUR3 and XLT2 identified amino acid residues interacting with UDP-Gal and XXXG in their active site clefts. Furthermore, site-directed mutagenesis uncovered critical roles of these substrate-interacting residues in the catalytic activity. Together, these findings provide biochemical insights into the molecular determinants of the regiospecificity of MUR3 and XLT2 in xyloglucan galactosylation.

PMID:41773316 | DOI:10.1093/jxb/erag117

Front Plant Sci. 2026 Feb 10;17:1733839. doi: 10.3389/fpls.2026.1733839. eCollection 2026.

ABSTRACT

Real-time monitoring of photosynthetic efficiency can improve our understanding of plant stress responses. In this study, we used a high-frequency chlorophyll fluorescence (CF) monitoring system to investigate the effects of combined temperature and light effects on lettuce. Plants were exposed to three temperatures (18, 25, and 32 °C) and two light intensities (150 and 500 μmol·m^-2·s^-1) for one week, and CF parameters were measured every 30 minutes. Gas exchange measurements were conducted at 2 and 7 days after treatment (DAT). High light combined with low temperature initially suppressed Φ_PSII but gradually improved via reductions in quantum yield of non-regulated energy dissipation (Φ_NO), indicating adjustments in the photosynthetic machinery. While the quantum yield of non-photochemical quenching (Φ_NPQ) decreased sharply only on the first day, Φ_NO continued to decline, highlighting its role in longer-term acclimation. In contrast, high temperatures enhanced CO₂ assimilation through elevated stomatal conductance; however, the maximum efficiency of PSII (F _v/F _m) remained suppressed (~0.81), suggesting sustained photoinhibition. The relationship between electron transport rate (ETR) and photosynthetic rate (A) varied with temperature and time, indicating that the efficiency of converting photochemical energy into carbon assimilation depended on stress conditions and the acclimation stage. However, cumulative ETR integrated over the experiment period was significantly associated with shoot dry weight independent of temperature conditions, indicating that temporally integrated CF metrics retain predictive value for growth, unlike instantaneous CF parameters. These findings demonstrate that high-resolution CF monitoring captures subtle and dynamic photosynthetic responses that are not detectable via single-point gas exchange measurements alone. The ability to interpret changes in CF parameters in real-time provides valuable insights into plant acclimation and stress physiology for the optimization of environmental conditions in controlled environment agriculture systems.

PMID:41743201 | PMC:PMC12929122 | DOI:10.3389/fpls.2026.1733839

Front Plant Sci. 2026 Feb 10;16:1628122. doi: 10.3389/fpls.2025.1628122. eCollection 2025.

ABSTRACT

INTRODUCTION: Onion (Allium cepa L.) is a globally important crop severely affected by Pantoea ananatis, the causal agent of onion center rot (OCR). The pathogen’s virulence is driven by the chromosomally located HiVir cluster, which produces the phytotoxin pantaphos. Despite its economic significance, resistant Allium genotypes against P. ananatis have not been identified.

METHODS: We screened 982 Allium genotypes under field conditions to evaluate resistance against pantaphos-producing P. ananatis and conducted in vivo transcriptome sequencing of resistant vs. susceptible genotypes under controlled growth-chamber conditions.

RESULTS: Only one genotype, DPLD 19-39, exhibited consistent resistant phenotype, displaying reduced foliar necrosis and bulb rot. Transcriptomic analyses revealed differential regulation of key defense-associated pathways, including cell wall reinforcement, oxidative stress regulation, and programmed cell death.

DISCUSSION: These findings provide the first evidence of a resistant A. cepa genotype against pantaphos-producing P. ananatis. The identified molecular responses highlight potential targets for developing onion cultivars with durable resistance to onion center rot.

PMID:41742960 | PMC:PMC12929489 | DOI:10.3389/fpls.2025.1628122

Trends Genet. 2026 Feb 24:S0168-9525(26)00002-8. doi: 10.1016/j.tig.2026.01.002. Online ahead of print.

ABSTRACT

The sunflower genus, Helianthus, not only includes two crops (cultivated sunflower and Jerusalem artichoke) but also comprises approximately 50 diverse wild species that have served both as a model for foundational studies of adaptation and speciation and as a source of alleles for crop improvement. Extensive genomic resources, including genome assemblies, association populations, and a comprehensive expression atlas, have facilitated both evolutionary and agronomic studies. Despite these advances, sunflower remains recalcitrant to genetic transformation, which impedes functional analyses. The development of tools for functional genetics and genomics, including a graph-based pangenome, improved transformation methods, and doubled haploid technology, is needed to accelerate sunflower improvement and enhance its utility as an evolutionary model.

PMID:41741285 | DOI:10.1016/j.tig.2026.01.002

Sci Rep. 2026 Feb 23. doi: 10.1038/s41598-026-40828-5. Online ahead of print.

ABSTRACT

High-throughput sequencing (HTS) has expanded our perspective on the distribution and diversity of plant viruses. Furthermore, improvements in HTS and decreasing sample costs have enabled the discovery of novel plant viruses in field-collected samples. This study examined the putative virome of cotton samples collected from fields across the southern United States. Leaf samples were collected, and total RNA was extracted. Library preparation was performed from pooled samples within locations before sequencing on an Illumina platform. Sequenced libraries were mapped to the cotton reference genome, and the resulting sequences were de novo assembled. A metatranscriptomics analysis revealed complete genome contigs of cotton leafroll dwarf virus in all tested samples. Additionally, 29 putative families of RNA and DNA plant viruses co-infecting cotton were found. Seven families of RNA viruses were more prevalent across all locations. These families included Botourmiaviridae, Hypoviridae, Mitoviridae, Narnaviridae, Partitiviridae, Solemoviridae, and Totiviridae. The information obtained in this investigation will help develop a broader perspective on cotton virus diversity and whether co-infections of viruses can influence (negatively or positively) plant physiology, product quality, and yield.

PMID:41730992 | DOI:10.1038/s41598-026-40828-5

J Biol Chem. 2026 Feb 20:111305. doi: 10.1016/j.jbc.2026.111305. Online ahead of print.

ABSTRACT

Plant cell walls are glycan-rich extracellular matrices that fundamentally impact essential cellular processes, such as growth, adhesion, and cell shape acquisition. Understanding plant cell wall glycans requires the identification and characterization of the biosynthetic enzymes that produce these polymers. Most successful in vitro protein expression studies of plant cell wall glycosyltranferases have relied on insect, fungal/yeast, or human cell expression systems, while prokaryotic expression systems have been generally unsuccessful. Here we show that Arabidopsis FRIABLE1 (FRB1)/Rhamnogalacturonan-I Rhamnosyltransferase 8 (RRT8) can be produced in E. coli RosettaGami2 cells as N-terminal maltose binding protein fusion proteins containing C-terminal 6X-His-tags. We also report the catalytic constants of FRB1/RRT8 with apparent K_M and K_cat values of 226 μM and 33 min^-1 for UDP-Rhamnose and 117 μM and 28.7 min^-1 for RG-I, respectively. We examine the catalytic activities of mutated FRB1/RRT8 proteins based on an AlphaFold3-generated FRB1/RRT8 protein structural model with a virtually docked UDP-Rha donor. Enzymatic characterization of the mutated and wild type FRB1/RRT8 protein confirmed that mutation of predicted catalytic site amino acid residues resulted in 20-fold reduction in RRT activity. FRB1 also robustly polymerizes RG-I in combination with RG-I Galacturonosyltransferase 1 (RGGAT1). These results show how a robust E. coli expression system combined with AI tools can be used to increase understanding of plant cell wall glycosyltransferase structure and function.

PMID:41724380 | DOI:10.1016/j.jbc.2026.111305

Front Plant Sci. 2026 Jan 30;16:1724403. doi: 10.3389/fpls.2025.1724403. eCollection 2025.

ABSTRACT

Whiteflies, particularly Bemisia tabaci-a rapidly evolving cryptic species complex comprising more than 40 biotypes including the invasive MEAM1 and MED-and Trialeurodes vaporariorum, remain among the most destructive pests of global vegetable production. Their adaptability, wide host range, and efficient virus transmission drive recurrent epidemics in crops such as tomato, pepper, eggplant, cucurbits, and snapbean. Over six decades, breeding for whitefly resistance has progressed from phenotypic selection to the identification of resistance mechanisms such as antibiosis, antixenosis, and tolerance, and to the exploitation of diverse sources from wild relatives and landraces. Recent advances in QTL mapping, pangenomics, multi-omics integration, genomic selection, and CRISPR-based modification of metabolic and structural defense traits have transformed the landscape of resistance breeding. Emerging AI-enabled tools-including machine-learning models for automated whitefly phenotype detection, hyperspectral stress diagnostics, and predictive modelling of resistance loci-are accelerating the dissection and deployment of complex traits. Importantly, durable whitefly resistance enhances climate resilience by reducing dependence on insecticides, stabilizing yields under abiotic-biotic stress combinations, and mitigating climate-driven surges in whitefly populations and virus epidemics. By integrating classical genetics, modern biotechnology, multi-omics, and AI-driven decision frameworks, breeding programs can more rapidly develop robust, climate-resilient vegetable cultivars capable of withstanding evolving whitefly threats.

PMID:41695528 | PMC:PMC12901495 | DOI:10.3389/fpls.2025.1724403