Molecular biology of Cotton Leafroll Dwarf Virus (CLRDV) and potential application of CRISPR-Cas technology for developing virus-resistant cotton.

Cotton leafroll dwarf virus (CLRDV) poses an increasing threat to global cotton production. Transmitted by the cotton aphid (Aphis gossypii) in a persistent, circulative manner, CLRDV exhibits a wide geographical distribution, with documented presence in South America, Africa, Asia, and the USA. Infection can result in either cotton blue disease (CBD) in South America or cotton leafroll dwarf disease (CLRDD) in the USA, both of which are associated with CLRDV. The considerable genetic diversity and frequent recombination events within CLRDV populations contribute to this symptom variability and complicate both diagnosis and management. While resistant cultivars have reduced disease impact in South America, these lines remain susceptible to emerging US strains, underscoring the urgent need for region-specific resistance breeding. Current molecular diagnostics rely on RT-PCR, but there is a need for rapid, field-deployable detection tools. Recent advances, such as CRISPR-Cas13a based SHERLOCK assays, offer sensitive and specific detection of CLRDV, with potential for on-site applications. Efficient screening techniques, supported by next-generation sequencing and transcriptomics, are essential for identifying novel resistance sources and elucidating virus-host interactions. CRISPR-based genome editing holds significant promise, as demonstrated in other crops. Targeted disruption of host susceptibility genes using CRISPR-Cas9, or direct degradation of viral genomes with RNA-targeting systems such as Cas12/Cas13, could offer durable, broad-spectrum resistance. By integrating molecular virology, high-throughput genomics, and precision gene editing, this review outlines a roadmap for translating these advances into sustainable, field-level solutions for CLRDV management and long-term cotton productivity.