Abstract

Nicotiana mutabilis is a recently discovered species within the genus Nicotiana. The aim of the present study was to evaluate its resistance to Potato virus Y (PVY) and Tomato spotted wilt virus (TSWV). Molecular analysis was performed to detect the Va gene determining susceptibility to PVY and the SCAR marker associated with resistance to TSWV. Resistance tests were carried out under greenhouse conditions through artificial inoculation with one TSWV and two PVY isolates. In order to confirm the presence of the viruses in plants, DAS-ELISA tests were performed using antibodies against PVY and TSWV. The results indicated the absence of the PVY susceptibility gene and the presence of the TSWV resistance gene in the genome of N. mutabilis. This species was considered tolerant to the two PVY isolates tested because, despite the positive DAS-ELISA results, the infected plants showed vein clearing and chlorotic spots but no vein necrosis. As a result of TSWV inoculation, N. mutabilis showed a hypersensitive response; however, after four months, 30% of the inoculated plants showed systemic infection. This species extends the genetic variation in the genus Nicotiana and, because of its tolerance to PVY and partial resistance to TSWV, it may be a potential source of resistance to these viruses.

Highlights

  • Species of the genus Nicotiana, a member of the Solanaceae family, occur naturally throughout North and South America, Australia and Africa [1]

  • Potato virus Y (PVY) resistance of some N. tabacum cultivars is determined by a recessive va gene that resulted from a genomic deletion within the susceptibility gene [57]

  • The affinity of N. mutabilis to N. alata and the confirmed presence of the SCAR marker ACC/CCC 172 indicate the need for more extensive studies. This is the first time such a detailed resistance test of N. mutabilis has been carried out and our results show that this species can be used as a potential source of resistance to Tomato spotted wilt virus (TSWV), expanding the pool of genetic variability

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Summary

Introduction

Species of the genus Nicotiana, a member of the Solanaceae family, occur naturally throughout North and South America, Australia and Africa [1]. The current systematics of the genus Nicotiana has been developed based on molecular studies and indicates the existence of 76 species divided into 13 sections [6]. The most recently discovered species of the genus Nicotiana, found in southern Brazil, is Nicotiana mutabilis. Under natural conditions, this species grows on forest edges, roadsides and abandoned fields. This species grows on forest edges, roadsides and abandoned fields It is pollinated in the morning and evening hours by hummingbirds and has been shown to have 18 chromosomes and to be self-compatible. It has been included in the section Alatae [8]

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