Mapping resistance to WBNV through CIM, JICIM and QTL-meta analysis approaches in watermelon

Since past three decades, tospoviruses have been impacting severe economic losses causing heavy yield reduction in many crops. Watermelon bud necrosis disease caused by watermelon bud necrosis orthotospovirus (WBNV) is one such tospovirus that has emerged as a devastating disease of watermelon in India. Efforts are underway to develop resistant varieties at ICAR-IIHR and in the current study, efforts have been made to integrate WBNV resistance QTLs from wide range of populations and screening experiments for a comprehensive analysis through QTL-meta-analysis and joint inclusive composite interval mapping (JICIM). Comprehensive analyses for QTLs suggested MQTL_WBNV_2.1 on Chromosome 2, MQTL_WBNV_3.2 on Chromosome 3 and MQTL_WBNV_7.2 on Chromosome 7 as potential candidate QTL regions for WBNV resistance. The genes identified in these QTLs viz., Cla020173 encoding PR-1, Cla001733 encoding pathogenesis-related transcriptional factor and ethylene-responsive transcription (ERF), Cla001590 and Cla001591 genes encoding acid phosphatase, Cla019476 encoding TIR-NBS and Cla011771 belonging to TIR-NBS-LRR gene family may be investigated as putative candidates for WBNV resistance in watermelon. The results obtained in present study may provide way for functional validation of putative candidates and development of suitable markers for marker assisted selection (MAS) of WBNV resistance in watermelon.