Ty-6, a major begomovirus resistance gene on chromosome 10, is effective against Tomato yellow leaf curl virus and Tomato mottle virus

Upinder Gill,Samuel F Hutton,Hugh Smith,John W Scott,Eben Ogundiwin,David M Francis,Reza Shekasteband,Cees Schuit,Sung-Chur Sim

doi:10.1007/s00122-019-03298-0

Abstract

Key messageTy-6 is a major resistance gene on chromosome 10 of tomato that provides resistance against monopartite and bipartite begomoviruses and complements resistance conferred by the known Ty-3 and ty-5 genes.Resistance to monopartite and bipartite begomoviruses is an important breeding objective for cultivated tomato. Several begomovirus resistance genes have been introgressed from related Solanum species and are available for breeding purposes. In the present study, we mapped an additional locus, Ty-6, to chromosome 10 of tomato. Ty-6 is effective against both monopartite Tomato yellow leaf curl virus (TYLCV) and bipartite Tomato mottle virus (ToMoV). Gene action is incomplete dominance, with an intermediate resistance response when Ty-6 is heterozygous. Analysis of populations segregating for Ty-6 along with Ty-3 or ty-5 indicates that the highest level of resistance against TYLCV is attained when Ty-6 is combined with an additional resistance allele. Our results also demonstrate that ty-5 is ineffective against ToMoV. Although multiple SNPs linked to Ty-6 were identified and can be used for breeding purposes, none of these were consistently polymorphic between Ty-6 and ty-6 breeding lines. Further research is underway to generate resequencing data for several Ty-6 inbred lines for the discovery of additional sequence polymorphisms that can be used for fine mapping and characterizing the Ty-6 locus.

Highlights

Begomoviruses, from the family Geminiviridae, cause economically significant diseases of major vegetable crops in the world
0.16667 0 a disease severity index (DSI) based on a 0–4 scale where higher numbers indicate more severe virus symptoms; mean separations within either viral trial are based on 95% confidence intervals (CI) of relative marginal effects (RME) on ranked DSI data were confirmed polymorphic between the parents and segregating in the population
0.69438–0.79437 0.44655–0.50876 0.11554–0.20116 0.66903–0.77317 0.48853–0.56273 0.18101–0.29724 a Ty-6 genotype based on proprietary marker B_04 b DSI based on a 0–4 scale where higher numbers indicate more severe virus symptoms; mean separations within either viral trial are based on 95% confidence intervals (CI) of relative marginal effects (RME) on ranked DSI data

Summary

Introduction

Begomoviruses, from the family Geminiviridae, cause economically significant diseases of major vegetable crops in the world. Tomato yellow leaf curl virus (TYLCV) and African cassava mosaic virus (ACMV), were recently listed among top 10 crop viruses due to their scientific importance and global economic impact (Rybicki 2015). The begomoviruses that infect cultivated tomato (Solanum lycopersicum L.) in the USA and other tropical and subtropical regions include monopartite and bipartite viruses such as TYLCV, Tomato yellow leaf curl Thailand virus (TYLCTHV), Tomato mottle virus (ToMoV), and two newly identified viruses, Tomato leaf deformation virus (ToLDeV) and Tomato leaf curl purple vein virus (ToLCPVV) The begomoviruses that infect cultivated tomato (Solanum lycopersicum L.) in the USA and other tropical and subtropical regions include monopartite and bipartite viruses such as TYLCV, Tomato yellow leaf curl Thailand virus (TYLCTHV), Tomato mottle virus (ToMoV), and two newly identified viruses, Tomato leaf deformation virus (ToLDeV) and Tomato leaf curl purple vein virus (ToLCPVV) (Polston and Anderson 1997; Moriones and Navas-Castillo 2000; Macedo et al 2018; Melgarejo et al. Vol.:(0123456789)

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