2026/05/25 by Chandrika Ghoshal, Mohammad Tasleem, Amitha Mithra Sevanthi +10
Biochemistry, Genetics and Molecular Biology · Agricultural and Biological Sciences · #Advances in Cucurbitaceae Research #Plant Virus Research Studies #Phytoplasmas and Hemiptera pathogens
paper · doi:10.1016/j.ygeno.2026.111264
Tomato leaf curl New Delhi virus (ToLCNDV), a bipartite begomovirus transmitted by the whitefly (Bemisia tabaci), has emerged as a significant limiting factor in cucumber (Cucumis sativus L.) cultivation across tropical and subtropical regions. Despite its economic significance, the genetic and molecular determinants of resistance to ToLCNDV in cucumber remain largely unexplored. The present study employed a QTL-seq-based approach to unravel the genetic architecture of ToLCNDV resistance and identify candidate genomic regions associated with this complex trait. Whole-genome resequencing of resistant (DC 91) and susceptible (DC 773) parental lines, along with resistant and susceptible F₂ bulks, was performed using the Illumina HiSeq platform. High-quality reads were aligned to the C. sativus reference genome to identify genome-wide single-nucleotide polymorphisms (SNPs). Δ(SNP-index) analysis revealed a major quantitative trait locus (QTL) on chromosome 7 (Cy-2) conferring ToLCNDV resistance, spanning approximately 1.8 Mb of the genomic region. Three closely linked markers, SSR00931, one InDel (AMS12), and one CAPS marker (AMS13) were identified and developed for future marker-assisted selection (MAS). Expression profiling of genes within the QTL region via qRT-PCR revealed several putative candidate genes involved in defense signaling cascades, including those encoding leucine-rich repeat (LRR) receptor-like kinases, pathogenesis-related proteins, and enzymes associated with secondary metabolite biosynthesis. These genes are likely to contribute to viral restriction by modulating host defense pathways, suppressing virus replication, and reinforcing cellular barriers. The discovery of this major-effect QTL and closely linked markers provides a valuable genomic resource for precision breeding of ToLCNDV-resistant cucumber cultivars. The present study sheds light on the molecular basis of begomovirus-host interactions in cucurbits.