Unveiling the seed transmission of tobacco streak virus infecting sunflower from India through multi assay tool kit using RT-PCR, RT-RPA and q-RT-PCR

UNVEILING SEED TRANSMISSION OF TSV INFECTING SUNFLOWER FROM INDIA

Abstract

Sunflower Necrosis Disease (SND), caused by tobacco streak virus (TSV) became a major threat to sunflower production in India. While the previous studies have reported the absence of TSV seed transmission in sunflower, this study provides the first conclusive evidence of vertical seed transmission under Indian conditions. TSV was detected by using sensitive molecular diagnostics such as reverse transcription-polymerase chain reaction (RT-PCR), reverse transcription-recombinase polymerase amplification (RT-RPA), and reverse transcription-quantitative PCR (RT-qPCR) from germplasm accessions (EC1119725, EC1119722, EC1119812, EC1119826 and EC1119832) and local Indian checks (DRSH-1) tested positive for the virus. RNA extracted from embryos and cotyledons (excluding seed coats) amplified successfully with a characteristic ~ 950 bp amplicon in RT-PCR, confirming embryo localization. RT-RPA assay using RNA and crude seed sap yielded a band of 275 bp at 38°C-39°C within 30 minutes. Seedlings raised from infected seeds exhibited early necrotic symptoms, RT-qPCR targeting the coat protein gene revealed high gene expression levels in the seedlings, confirming transgenerational transmission. These findings highlight the seed-transmission nature of TSV in sunflower and underscore need for stringent phytosanitary regulations and rapid field diagnostics ensure biosecurity and sustainable disease management.