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My name is Tongtong Wang and I am a PhD student at School of Life Sciences, University of Warwick. My PhD subject is Plant and Enviromental Sciences and I started this study in October, 2012. My supervisor is Professor John A. Walsh who is the research leader of Plant-Virus Interactions Group based at the Wellesbourne campus of the University. I have obtained my master degree in Vegetable Molecular Breeding at Chinese Academy of Agricultural Sciences where I studied clubroot resistance in Brassica rapa (Chinese cabbage). For my PhD project I have been looking at the resistance to Tunip mosaic virus in brassicas (cabbage family vegetables).
Turnip mosaic virus (TuMV, family Potyviridae, genus Potyvirus) has the widest host range amongst potyviruses. Globally it was said to be the second most important virus infecting field vegetables. Brassica juncea (mustard, family Brassicaceae), is an amphidiploid plant species with the genome AABB, comprising the genomes of the two diploid species, Brassica rapa (AA) and Brassica nigra (BB). It is widely grown and has various uses including as a leaf, stem, or root vegetable, oilseed crop, forage crop, condiment and biofumigant. Most B. juncea cultivars are very susceptible to TuMV, resulting in severe losses. Research on TuMV resistance and the mapping and identification of natural resistance genes would be very useful in order to speed up breeding resistant crops through marker-assisted selection.
Sources of resistance to TuMV have been identified in B. juncea. The specificity of the resistances has been determined. A B. juncea DH line for which there is genomic information has been challenged with TuMV and found to be susceptible. This line has been used as a susceptible parent in crosses with resistant plants derived from different sources to develop segregating populations for mapping the resistance gene(s). Two BC1 populations (222 plants and 205 plants) and one F2 population (159 plants) have been phenotyped and segregation ratios were not significantly different from a Mendelian model based on the action of two recessive genes.
Parental lines and selected plants in the two BC1 populations have been analysed by SNPs genotyping using Illumina Infinium Chip. Genetic linkage maps have been constructed and QTLs have been mapped. Additionally, attempts are being made to identify a dominant TuMV resistance gene present in both Brassica napus and B. rapa. Inter-specific crossings have been made in order to introgress the gene in to B. juncea. Resynthesised B. juncea plants possessing this dominant resistance have been produced through ovule rescue and polyploidy induction of F1 plants from crosses between resistant B. rapa and susceptible B. nigra plants. BC2 plants have also been developed by crossing B. rapa and B. napus plants possessing the dominant TuMV resistance with a susceptible B. juncea plant line.
Tongtong dot Wang at warwick dot ac dot uk