It is demonstrated that Avr4 does not explain the resistance of Calcutta 4, suggesting that resistance is instead triggered by the recognition of other hitherto unknown effectors.
Abstract
Pseudocercospora fijiensis is the causal agent of Black Leaf Streak Disease (BLSD), also known as black Sigatoka, in banana. The disease affects many banana varieties, including the highly susceptible Cavendish banana that dominates global production and the export trade, and several cooking bananas that are a staple food for hundreds of millions of people worldwide. Currently, the disease is controlled using preventative fungicide treatments with up to 70 applications per year in Cavendish plantations, which accounts for approximately 30% of the production costs. Resistant cultivars are required for more sustainable production, but no resistance gene to BLSD has been identified. This is partly due to the poor genetic amenability of P. fijiensis and the lack of methods for functional gene analysis. To address these limitations, we developed a CRISPR/Cas9-mediated transformation system specifically optimized for P. fijiensis. We established a protocol to produce protoplasts, evaluated their capacity to regenerate into new colonies, and assessed antibiotic sensitivity. Subsequently, we confirmed the integration of foreign DNA, including resistance markers, using PEG-mediated transformation. We demonstrated targeted transformation using CRISPR-Cas9 to knockout the polyketide synthase gene PKS10-1, which is responsible for the production of the pigment melanin, and the mitogen-activated protein kinase (MAPK) gene Fus3. Following the successful generation of knockout mutants for these genes, achieving gene targeting efficiencies of respectively 96% and 58%, we subsequently generated knockout mutants of the renowned effector Avr4 in P. fijiensis. The resulting mutants exhibited no reduction in virulence on the susceptible banana cultivar Cavendish. In addition, we used the wild-type isolate and Avr4 knockout strains to test the resistant banana accession Calcutta 4. Contrary to a previous study, we demonstrate that Avr4 does not explain the resistance of Calcutta 4, suggesting that resistance is instead triggered by the recognition of other hitherto unknown effectors. The established CRISPR/Cas9-mediated disruption system is highly efficient and enables routine functional gene characterization, which will help to elucidate genes involved in banana-P. fijiensis interaction, thereby supporting the discovery of resistance genes against BLSD.
A multiplex CRISPR/Cas12a system is established in eggplant accession MEL3, representing, to the authors' knowledge, the first application of this nuclease for genome editing in eggplant and demonstrating the potential of Cas12a for functional genomics, allele engineering, and precision breeding in eggplant.
Marina Martínez-López, Andrea Solana, Andrea Arrones et al.· bioRxiv· 0 citations
A new protoplast-based platform enables transient transformation and proof-of-concept CRISPR/Cas12a-mediated genome editing in European beech, a key but recalcitrant forest tree species.
Virginia Zahn, Alice-Jeannine Sievers, B. Kersten et al.· Communications Biology· 0 citations
Compared with conventional homologous recombination, the CRISPR-Cas9 system substantially improved gene disruption efficiency, thereby overcoming a major limitation in the genetic manipulation of lichen-forming fungi.
Ze-Yi Wang, Niu-Niu Wang, Hai-Yu Zhang et al.· Journal of Fungi· 0 citations
Rice (Oryza sativa L.) is a staple food crop worldwide, and improving disease resistance is a core target in rice breeding. In this study, we employed CRISPR/Cas9 genome editing to modify the coding sequence (CDS) of two susceptibility genes, Bsr-d1 and Pi21, in the elite maintainer line Gengxiang B to enhance its blast resistance. We generated Bsr-d1/Pi21 double homozygous mutants via Agrobacterium-mediated genetic transformation. Quantitative RT-PCR revealed significantly suppressed transcript accumulation of both target genes in the edited lines compared with the wild type Gengxiang B. Upon inoculation with Magnaporthe oryzae, multiple defense-related marker genes were markedly upregulated in the double mutants. Phenotypic assays demonstrated significantly reduced disease severity for both leaf and panicle blast in the edited lines compared with the wild type. Importantly, no statistically detectable differences were found between the double mutants and wild-type plants for key agronomic or grain quality traits. Collectively, these results demonstrate that CRISPR/Cas9-mediated editing of susceptibility loci generates genetically stable blast-resistant rice germplasm without compromising agronomic traits or grain quality, providing valuable genetic resources for future rice varietal improvement.
Ke Lan, Lin Yuan, Da-Cheng Zhao et al.· Plants· 0 citations
Oil palm is a major commodity crop in Southeast Asia, particularly in Malaysia and Indonesia, but its productivity is severely threatened by basal stem rot (BSR) and upper stem rot (USR) caused by the white-rot fungus Ganoderma boninense. Infected palms can lose up to 80% yield and die within 6–24 months (young) or 2–3 years (mature). Despite extensive field management efforts, disease incidence continues to rise, especially after replanting. Understanding infection mechanisms and validating fungal virulence factors are crucial for effective control, yet functional genomics in G. boninense has been limited. Previous RNAi-based gene silencing provided initial insights but was constrained by off-target effects and transient activity. Here, we report the first successful application of CRISPR/Cas9 genome editing in G. boninense for functional gene studies. Two genes were targeted: pyrG, essential in uridine monophosphate (UMP) biosynthesis; and hyd-2, encoding a hydrophobin, a potential virulence determinant implicated in host invasion. The disruption of pyrG produced a uracil auxotroph, and the knockout was validated by screening on 5-FOA and validated our system as a functional molecular tool. Disruption of hyd-2 reduced infection capability of the fungus by ~72% to ~91% in vitro. Mutations in both gene disruptions, including insertions, deletions, and substitutions, were confirmed by sequencing. Sequencing analysis also revealed incomplete editing events, as wild-type gene sequences were detected alongside edited alleles in the mutants. Future enhancements should focus on improving editing efficiency of the system. This work establishes a robust platform for functional genetic analysis and dissecting pathogenicity in G. boninense, ultimately advancing strategies to mitigate basal stem rot disease in oil palm.
Anis Farhan Fatimi Ab Wahab, Mohd Azinuddin Ahmad Mokhtar, S. Vetaryan et al.· Journal of Fungi· 0 citations
Culicoides biting midges are small blood feeding insects responsible for the transmission of important arthropod-borne viruses (arboviruses) such as bluetongue virus (BTV), Schmallenberg virus (SBV) and epizootic hemorrhagic disease virus (EHDV), which cause major losses to livestock production worldwide. Culicoides sonorensis is the primary vector of BTV in North America and one of the few Culicoides species to be colonised and reared in artificial conditions. Gene editing technology has been used to explore virus-vector interactions in other vector groups, particularly within mosquitoes. Despite the availability of a reference genome since 2018, to date there have been no reports of gene editing in C. sonorensis. Here, we report the first instance of gene editing in C. sonorensis, achieved by intrathoracic injection of adult females with Cas9 and sgRNAs targeting the white gene. We generated heritable mutations in the white gene which produced both white eye and red eye phenotypes and went on to establish a homozygous knockout line carrying a single mutation. We observed gene editing efficiencies of up to 12.3%, making this an efficient protocol for genetic manipulation of Culicoides biting midges, opening the door to functional genomics studies and the development of control strategies in these important and understudied disease vectors.
Katherine Nevard, Estela Gonzalez, T. Harvey‐Samuel et al.· Scientific Reports· 0 citations