CARBON Newsletter (18 September 2026) - Your Latest News About CRISPR in AgroBio

Top picks

• AI-evolved bridge RNA-guided recombinases now enable programmable deletions, insertions and inversions of 1.8 to 315 kb in plants, with variants up to 29.8-fold more active after rational mutagenesis and AI-assisted directed evolution. Editing efficiencies reached 24% in regenerated rice, and a 315-kb chromosomal inversion rewired endogenous promoter activity to produce herbicide-resistant plants – pointing to a platform for chromosome-scale precision breeding.
• A protoplast-based CRISPR activation screen using dCas9-TV has identified OsTV1, a papillae-specific receptor kinase, as a positive regulator of fungal resistance in rice. Overexpression increased silicon deposition, leaf rigidity and basal defence gene expression, giving broad-spectrum resistance without a growth penalty. The gain-of-function screen should be adaptable to other cellular processes in plants.

Technical advances

• By engineering chimeric attachment sites for the Bxb1 recombinase, researchers have boosted targeted integration in rice protoplasts 4.4-fold, with the attB(V111) variant reaching 36% efficiency. Paired with a mutant Bxb1 catalytic domain, the system inserted a 5.8 kb herbicide-resistance cassette at a defined rice locus in 24% of regenerated plants, confirmed by long-read sequencing and heritable in T1 progeny.
• Editing of European beech (Fagus sylvatica) has been achieved in a transient protoplast platform. PEG-mediated transformation reached 59% efficiency, and temperature-tolerant ttLbCas12a edited the PHYTOENE DESATURASE gene in 4.75-32.69% of cases. Reproducibility varied strongly with season, and a regeneration system is still lacking, so edited trees remain some way off.
• An optimised regeneration and transformation route has made multiplex CRISPR-Cas9 editing feasible in pea (Pisum sativum), a legume long held back by recalcitrant tissue culture. Dicotyledonary nodes proved the best explant, giving 100% shoot bud induction and transient transformation efficiencies of up to 90%. Editing was demonstrated on the phytoene desaturase (PsPDS) gene.
• Researchers have made CRISPR-Cas9 work in the fern Ceratopteris richardii by flanking the guide RNA with self-cleaving ribozymes, targeting components of the KARRIKIN INSENSITIVE 2 (KAI2)-dependent signalling pathway. Constructs built for Marchantia polymorpha yielded no edits in 23 transformants, whereas the ribozyme-gRNA-ribozyme (RGR) vector, driven throughout by CaMV35S, edited CrKAI2 in 10 of 21 transgenic plants, along with CrSMXL and CrMAX2. Crkai2 mutants lost their response to the KAI2 agonist (−)-GR24.

Disease and stress control

• Overexpression of the R2R3-MYB transcription factor OsMYBR17 improved rice seedling thermotolerance, while CRISPR-Cas9 knockouts proved markedly heat-hypersensitive. Overexpressors accumulated fewer reactive oxygen species, showed lower lipid peroxidation and higher ascorbate peroxidase activity, and maintained chloroplast integrity under prolonged heat. DAP-seq and RNA-seq pointed to OsLEA4 as a direct target.
• Two flavonoid intermediates, dihydrokaempferol and dihydroquercetin, act as drought-mitigating signals in soybean, promoting abscisic acid-dependent stomatal closure. CRISPR-Cas9 gmf3hs double mutants were severely drought-hypersensitive, with compromised redox homeostasis and defective stomatal regulation, and were rescued by applying the two compounds. The effect held across dicots, including tobacco.
• CRISPR-Cas9 tpk09 mutants of tomato became more susceptible to Botrytis cinerea and Fusarium oxysporum, whereas transgenic expression of the kinase improved resistance. Disease was worse under LED than fluorescent light, and uninfected mutants developed necrosis and accumulated hydrogen peroxide under LEDs. TPK09 interacts with the Botrytis cell-death inducer BcCrh1.
• CRISPR-Cas9 Bnein2 mutants of oilseed rape showed enhanced resistance to clubroot (Plasmodiophora brassicae), along with ethylene insensitivity and reduced ACC and SAM accumulation. Resistance was accompanied by lower auxin biosynthesis and degradation of trans-zeatin, and inhibitors of ethylene biosynthesis or signalling reproduced the effect. Ethylene signalling therefore acts as a negative regulator.

Agronomic traits

• Multiplex CRISPR-Cas editing knocked out three negative regulators of metal uptake in rice – OsHRZ1, OsHRZ2 and OsLCT1 – in Cas9-free lines. Grown hydroponically under deficient and sufficient Fe/Zn, the edited plants showed higher seed protein and photosynthetic rates than wild type. Agronomic performance was unaffected, and the lines tolerated cadmium stress.
• CRISPR-Cas9 mutagenesis of the waxy gene encoding granule-bound starch synthase I created new waxy germplasm in the maize inbred B104, yielding homozygous 18-bp and 4-bp deletion mutants. Alongside the expected drop in amylose, kernels accumulated far more glucose and fructose and less sucrose. The mutation therefore reprograms carbon flux from starch towards soluble sugars.
• Knocking out menthofuran synthase (MFS) with CRISPR-Cas9 has lowered menthofuran, an off-flavour metabolite that limits the value of mint oil. The system was built for Mentha haplocalyx '738' by optimising protoplast transient assays and screening endogenous regulatory elements – a truncated mint U6 promoter and the tomato SlEF1α promoter drove sgRNA and Cas9 expression most effectively.
• CRISPR-Cas9 knockout of StFKF1, a diurnal oscillation component, delayed flowering in potato under long days, as predicted. Tuber formation was also delayed, contrary to expectation, and single-plant yield fell while tuber number held steady. The florigen gene StSP3D and tuberigen gene StSP6A shifted predictably, whereas StGI was upregulated.
• Knocking out CsSUN with CRISPR-Cas9 shortened cucumber fruits by 38–46%, confirming the IQ domain protein as the gene behind the major fruit-shape QTL FS1.1. Round-fruited lines carry a 161-bp deletion in the first exon and accumulated 15.2% more calcium, and the calmodulin gene CsCaM11 correlated negatively with fruit length.
• CRISPR-Cas9 knockout of CmGH3.1 promoted growth in a model citrus, even at an editing ratio below 40%, pinning dwarfism on auxin conjugation. Multiomics of dwarf and normal-height tangerine × trifoliate orange hybrids had flagged the auxin-conjugating enzyme gene PtGH3.1, which a PtARF6/PtARF8 heterodimer activates. All three genes are now targets for breeding dwarfing rootstocks.
• CRISPR-Cas9 knockout of the cysteine protease PAI1 gave rice partial rather than complete male sterility – roughly 50% pollen abortion, defective anther dehiscence and a 75% fall in seed set. Loss of PAI1 selectively depleted aromatic amino acids, cutting phenylpropanoid flux for endothecium lignification, without blocking programmed cell death.

Industry

• Vylor, Corteva’s seed and genetics business, due to become an independent company in October, has announced gene-edited, multi-disease-resistant maize programmes, including resistance to northern corn leaf blight, grey leaf spot, southern rust and anthracnose stalk rot. The maize programme will launch in 2027, while a similar programme for soybean is expected in the mid-2030s.
• Syngenta’s first-half 2026 results highlight commercial momentum in crop biotechnology, including preliminary Chinese approval for 17 genetically modified maize hybrids and increased biotechnology adoption in Indonesian maize. Syngenta uses CRISPR gene editing for its HI-Edit technology for haploid induction in maize.

Screening and functional genomics

• CRISPR-Cas9 editing of the C3H14 and C3H15 paralogues in soybean and rice caused a loss of meiocyte identity. The same defect appears in Arabidopsis double mutants, whose meiocytes arrest in meiosis and die. The two zinc-finger proteins clear mRNAs needed for archesporial and tapetal development – post-transcriptional RNA elimination guards this cell fate across flowering plants.
• A metabolite GWAS identified maize ZmTPS8 as the primary locus behind herbivore-induced emission of the sesquiterpene germacrene D. CRISPR-Cas9 tps8 mutants emitted less germacrene D, α-copaene and δ-cadinene under herbivory, confirming the enzyme's function in planta and its contribution to defence against pests and pathogens.
• A GWAS of 171 alfalfa accessions identified the U-box E3 ubiquitin ligase gene MsPUB6, whose promoter is bound and activated by the transcription factor MsDREB1C. CRISPR-Cas9 MsDREB1C mutants were drought-sensitive and expressed less MsPUB6, matching MsPUB6-silenced lines. Overexpression raised antioxidant enzyme activity and preserved chlorophyll and leaf water content.

Perspectives

• A Perspective in Plant Physiology discusses a broad-host geminivirus vector that delivers editing reagents systemically and so allows plant genome editing without tissue culture, addressing one of the field's main bottlenecks. The underlying study used Wheat dwarf India virus with Ageratum yellow leaf curl betasatellite to express Cas9, Cas12f and Cas12j with their guide RNAs from viral promoters, replacing external promoters and terminators with tRNA spacers to cut cargo size.

Reviews

• Advances in CRISPR multiplex gene editing to map and modify stress-responsive transcription factor networks for crop improvement. This review surveys advances in multiplex CRISPR-Cas editing for mapping and modifying stress-responsive transcription factor networks in crops.
• Bridging the bench-to-field gap: a quantitative multi-omics and CRISPR/Cas9 framework for climate-resilient agriculture. This review proposes a quantitative framework combining multi-omics with CRISPR-Cas9 editing to close the gap between laboratory findings and field performance in climate-resilient agriculture.
• Synthetic transcriptional repression systems in plants. This review examines how prokaryotic repressors can be repurposed in plants to build modular, chemically inducible systems for tunable transgene repression.
• Transforming Plant Viruses into Vectors for Next-Generation Agriculture-A Review. This review traces the development of plant viral vectors from tools for transient gene expression into platforms for precise genetic intervention in agriculture.
• Risk governance of transgenic plants: bridging science, policy, and public trust. This review considers the risk governance of transgenic plants and how science, policy and public trust might be bridged.
• Herbicide Resistance Genes in Crops: Mechanisms, Progress, and Future Perspectives. This review provides a theoretical framework and practical references for molecular breeding of herbicide-resistant crops.
• Genome Editing in Solanaceae: Harnessing CRISPR-Cas Technology for Precision Crop Improvement. This review synthesises recent advances, identifies critical limitations, and outlines future opportunities for deploying CRISPR/Cas technology to achieve next-generation breeding and food system resilience.
• CRISPR–Cas technologies for precision genome editing in plants: advances, applications, and future perspectives. This review synthesises recent CRISPR-Cas technologies for crop improvement and hybrid breeding, covering knockouts, base editing, targeted insertion and replacement, epigenome editing and transcriptional control.