No Evidence for Seed Transmission of Tomato Yellow Leaf Curl Sardinia Virus in Tomato

Abstract

Seed transmission is an important factor in the epidemiology of plant pathogens. Geminiviruses are serious pests spread in tropical and subtropical regions. They are transmitted by hemipteran insects, but a few cases of transmission through seeds were recently reported. Here, we investigated the tomato seed transmissibility of the begomovirus tomato yellow leaf curl Sardinia virus (TYLCSV), one of the agents inducing the tomato yellow leaf curl disease, heavily affecting tomato crops in the Mediterranean area. None of the 180 seedlings originating from TYLCSV-infected plants showed any phenotypic alteration typical of virus infection. Moreover, whole viral genomic molecules could not be detected in their cotyledons and true leaves, neither by membrane hybridization nor by rolling-circle amplification followed by PCR, indicating that TYLCSV is not a seed-transmissible pathogen for tomato. Examining the localization of TYLCSV DNA in progenitor plants, we detected the virus genome by PCR in all vegetative and reproductive tissues, but viral genomic and replicative forms were found only in leaves, flowers and fruit flesh, not in seeds and embryos. Closer investigations allowed us to discover for the first time that these embryos were superficially contaminated by TYLCSV DNA but whole genomic molecules were not detectable. Therefore, the inability of TYLCSV genomic molecules to colonize tomato embryos during infection justifies the lack of seed transmissibility observed in this host.

Occurrence, distribution, and management of tomato yellow leaf curl virus in China

“…While the significant reduction in TYLCV DNA load after surface disinfection of tomato seeds suggests that the virus can be the contaminant of the seed coat, transmission assays carried out with seven tomato genotypes and more than 3,000 tomato plants revealed no evidence of seed transmission from "surface-disinfected" or untreated seed for two Mediterranean isolates of TYLCV-IL (Pérez-Padilla et al 2020). Supporting this finding, Tabein et al (2021) also found no evidence for the tomato seed transmissibility of tomato yellow leaf curl Sardinia virus (TYLCSV), one of the agents inducing the TYLCD. Therefore, TYLCV-IL is seed-borne but is not seed transmitted in tomato or N. benthamiana, suggesting that transmission through seed is not a general property of TYLCV.…”

Further Molecular Diagnosis Determines Lack of Evidence for Real Seed Transmission of Tomato Leaf Curl New Delhi Virus in Cucurbits

“…In contrast, other works have observed no evidence for TYLCV seed transmissibility in Nicotiana benthamiana [38]. Likewise, recent studies on tomato have reported the absence of TYLCV and tomato yellow leaf curl Sardinia virus (TYLCSV) transmission through infected seeds in tests performed at different locations [39,40]. Finally, the seed transmission of SPLCV was not detected after the recent large-scale screening of sweet potato plants [33][34][35][36]41].…”

Emerging evidence of seed transmission of begomoviruses: implications in global circulation and disease outbreak

“…k. Tomato yellow leaf curl Sardinia virus (TYLCSV) is an important monopartite begomovirus responsible for worldwide spread of TYLCD in association with TYLCV and other TYLCV-like viruses ( Moriones and Navas-Castillo, 2000 ). The seed transmission nature of TYLCSV was studied in highly susceptible tomato cultivar Money Maker through agro-inoculation with 1.8mer TYLCSV construct ( Tabein et al., 2021 ). The agro-inoculated plants showed the typical symptoms of TYLCSV, viz ., severe leaf curling, cupping, and yellowing on newly emerged leaves.…”