Molecular evidence of novel Begomoviruses and associated Betasatellite complexes linked to Papaya Leaf Curl Disease (PLCD) in Indian Provinces

Abstract

Papaya leaf curl disease (PLCD) is caused by distinct begomoviruses affecting papaya globally. This study aims to identify and dissect the genetic complexities of begomoviruses-betasatellites associated with PLCD. Surveys in various Indian provinces to collect symptomatic papaya leaf samples. Molecular characterization of 15 DNA-A positives isolates revealed that PSB 8 and PSB 14 from Lucknow shared 89.69% and 87.25% nucleotide sequence identity with other reported begomoviruses and 85.36% with each other. Based on ICTV's species demarcation threshold, these isolates are proposed as novel begomoviruses, named papaya leaf curl Lucknow virus-1 (PaLCLV-1) and papaya leaf curl Lucknow virus-2 (PaLCLV-2). This study also reports a novel strain (PSB 63) of duranta leaf curl virus (DLCV) on papaya, with a 93.48% sequence identity with known DLCV. The samples did not amplify for DNA-B but did for betasatellites. Nine of the 15 DNA-A positive samples were associated with betasatellites, revealing a novel betasatellite (PSBB 34) from Gujarat, sharing 88.46% similarity with ludwigia leaf distortion betasatellite (LuLDB), named papaya leaf curl Lucknow betasatellite (PaLCLB). Another new strain, tomato leaf curl betasatellite (ToLCLB), shared 91.96% identity with other betasatellites. These begomoviruses are monopartite and likely originated in the Old World. This study is the first to show an association between LuLDB and PaLCV (PSB 34). Recombination analysis revealed that major viral genome regions were obtained from previously reported begomoviruses. The study identified eight papaya-infecting begomoviruses and seven associated betasatellites as prominent in the sampled regions.