Grafting on a Non-Transgenic Tolerant Tomato Variety Confers Resistance to the Infection of a Sw5-Breaking Strain of Tomato spotted wilt virus via RNA Silencing.
RNA silencing controls endogenous gene expression and drives defensive reactions against invasive nucleic acids like viruses. In plants, it has been demonstrated that RNA silencing can be transmitted through grafting between scions and silenced rootstocks to attenuate virus and viroid accumulation in the scions. This has been obtained mostly using transgenic plants, which may be a drawback in current agriculture. In the present study, we examined the dynamics of infection of a resistance-breaking strain of Tomato spotted wilt virus (RB-TSWV) through the graft between an old Apulian (southern Italy) tomato variety, denoted Sl-Ma, used as a rootstock and commercial tomato varieties used as scions. In tests with non-grafted plants, Sl-Ma showed resistance to the RB-TSWV infection as viral RNA accumulated at low levels and plants recovered from disease symptoms by 21 days post inoculation. The resistance trait was transmitted to the otherwise highly susceptible tomato genotypes grafted onto Sl-Ma. The results from the analysis of small RNAs hallmark genes involved in RNA silencing and virus-induced gene silencing suggest that RNA silencing is involved in the resistance showed by Sl-Ma against RB-TSWV and in scions grafted on this rootstock. The results from self-grafted susceptible tomato varieties suggest also that RNA silencing is enhanced by the graft itself. We can foresee interesting practical implications of the approach described in this paper.
Dipartimento di Scienze del Suolo della Pianta e Degli Alimenti, Università degli Studi di Bari Aldo Moro, Via Amendola 165/A, Bari, Italy; Istituto di Virologia vegetale del CNR, Unità Operativa di Supporto di Bari, Via Amendola 165/A, Bari, Italy.
Roberta
R
Spanò
Dipartimento di Scienze del Suolo della Pianta e Degli Alimenti, Università degli Studi di Bari Aldo Moro, Via Amendola 165/A, Bari, Italy; Istituto di Virologia vegetale del CNR, Unità Operativa di Supporto di Bari, Via Amendola 165/A, Bari, Italy.
Tiziana
T
Mascia
Laboratory of Virology, Wageningen University, Droevendaalsesteeg 1, Wageningen, The Netherlands.
Richard
R
Kormelink
Dipartimento di Scienze del Suolo della Pianta e Degli Alimenti, Università degli Studi di Bari Aldo Moro, Via Amendola 165/A, Bari, Italy; Istituto di Virologia vegetale del CNR, Unità Operativa di Supporto di Bari, Via Amendola 165/A, Bari, Italy.
Donato
D
Gallitelli
D002874:Chromosome Mapping; D060467:Disease Resistance; D018506:Gene Expression Regulation, Plant; D018745:Genome, Plant; D005838:Genotype; D018551:Solanum lycopersicum / Q000235:genetics / Q000821:virology*; D010935:Plant Diseases / Q000821:virology*; D030821:Plants, Genetically Modified; D034622:RNA Interference; D034443:RNA Transport; D018749:RNA, Plant / Q000378:metabolism; D058727:RNA, Small Untranslated / Q000378:metabolism; D017865:Tospovirus / Q000502:physiology*
D018749:RNA, Plant; D058727:RNA, Small Untranslated