Development of interspecific Solanum lycopersicum and screening for Tospovirus resistance

Abstract

Tospovirus has emerged as a serious viral pathogen for several crops including tomato. The tomato production is being severely affected worldwide by Tospovirus. Some reports have been published about the association of plant virus and development of human disease either by direct or indirect consumption. Resistance to this virus has been identified as good source in wild tomato species (Lycopersicum peruvianum). But the introgression of resistance genes into cultivated tomato lines and the development of interspecific hybrid are hampered due to incompatibility, fertilization barriers and embryo abortion. But this barrier has been broken by applying the embryo rescue methods. This study describes the development of interspecific hybrid tomato plants by highly efficient embryo rescue method and screening for Tospovirus resistance. The interspecific hybrid tomato plants were developed by making a cross between wild tomato species (L. peruvianum) and cultivated tomato (Solanum lycopersicum). The immature embryos were cultured in standardized medium and interspecific hybrids were developed from embryogenic callus. The immature embryos excised from 7 to 35 days old fruits were used for embryo rescue and 31 days old embryos showed very good germination capabilities and produced the highest number of plants. Developed plants were hardened enough and shifted to green house. The hybrid nature of interspecific plants was further confirmed by comparing the morphological characters from their parents. The F1, F2 and F3 plants were found to have varying characters especially for leaf type, color of stem, fruits, size, shapes and they were further screened for virus resistance both in lab and open field followed by Enzyme linked Immunosorbant Assay confirmation. Finally, a total of 11 resistant plants were selected bearing red color fruits with desired shape and size.

Resistance to Tospoviruses in Vegetable Crops: Epidemiological and Molecular Aspects

“…The search for natural resistance sources and resistance genes has intensified, and within the past three decades several resistance sources have been reported and incorporated into commercial tomato cultivars (35,46,102,106,108,119,120,129). Among these sources (40,93,108,128,130), recessive (sw2, sw3, and sw4) and dominant genes (Sw1a and Sw1b) have been reported; however, their resistance was quickly overcome upon challenging with TSWV (40,93,108,128,130).…”

“…Therefore, an ongoing search for new tospovirus resistance genes remains essential in all breeding programs of tomato (35,46,102,106,108,119,120,129). More recently, 105 Solanum (section Lycopersicum: Solanaceae) accessions were evaluated for their reaction against TSWV, TCSV, CSNV, and GRSV isolates (33).…”

Development of interspecific hybrids between Solanum lycopersicum L. and S. sisymbriifolium Lam. via embryo calli

“…These authors found that several crossing combinations with S. peruvianum made it possible to produce hybrid plants but that immature embryos needed to be cultured. The wild species S. peruvianum is resistant to TSWV (tomato spotted wilt virus), and tomato hybrids with S. peruvianum have been found to be resistant to this virus, which affects tomato production around the world (Sohrab et al 2015). The process of transferring genes from wild to cultivated species is often difficult.…”

Development and Validation of Marker-Free Constructs Based on Nucleocapsid Protein Gene of Watermelon Bud Necrosis Orthotospovirus in Watermelon

“…Managing orthotospoviruses poses a formidable challenge and this has received considerable attention due to their serious economic impact on crop production 2 . Extensive studies have attempted to engineer host resistance using partial or intact N gene sequences against orthotospoviruses which led to heritable immunity against homologous virus-species [11][12][13][14][15][16][17][18][19][20][21] . Further, RNAi approach has been demonstrated for development of transgenic against orthotospoviruses 22,23 including broadspectrum transgenic resistance 24 .…”