Biological and Molecular Properties of aTurnip mosaic virus(TuMV) Strain that Breaks TuMV Resistances inBrassica napus

Abstract

A new resistance-breaking strain of Turnip mosaic virus (TuMV) overcomes TuMV resistance genes that currently suppress spread of this virus in Brassica napus crops in the Liverpool Plains region of eastern Australia. Isolates 12.1 and 12.5 of this strain and three other isolates in TuMV pathotypes 1 (NSW-2), 7 (NSW-1), and 8 (WA-Ap1) were inoculated to plants of 19 B. napus cultivars and one breeding line. All plants of these cultivars and the breeding line proved susceptible to 12.1 and 12.5 but developed only resistance phenotypes with WA-Ap1 or mostly resistance phenotypes with NSW-1 and NSW-2. Five different TuMV resistance phenotypes occurred either alone or segregating in different combinations. When these five isolates were inoculated to plants of nine other crop or wild Brassicaceae spp. and four indicator hosts in other families, 12.1 and 12.5 resembled the other three in inducing TuMV resistance phenotypes in some Brassicaceae spp. but not others, and by inducing extreme resistance phenotypes in all inoculated plants of B. oleracea var. botrytis and Raphanus sativus. Therefore, the overall resistance-breaking properties of 12.1 and 12.5 were restricted to B. napus. When isolates 12.1, 12.5, and WA-Ap1 and additional Australian isolate WA-EP1 were sequenced and complete genomes of each compared, 12.1 and 12.5 grouped separately from the other 2 and from all 23 Australian isolates with complete genomes sequenced previously. In addition, there was evidence for at least six separate TuMV introductions to Australia. Spread of this B. napus resistance-breaking strain poses a significant threat to the B. napus oilseed industry. Breeding B. napus cultivars with resistance to this strain constitutes a critical priority for B. napus breeding programs in Australia and elsewhere.

Molecular and Biological Characterisation of Turnip mosaic virus Isolates Infecting Poppy (Papaver somniferum and P. rhoeas) in Slovakia

“…Despite the importance of TUMV and its negative effect to the production of many crops, mainly the studies focusing on Brassicaceae were reported [ 28 , 29 , 30 , 31 , 32 ]. On the contrary, there is no data about the TuMV/oilseed poppy relationship [ 6 ].…”

Resistance to Turnip Mosaic Virus in the Family Brassicaceae

“…showed segregating systemic resistance and extreme resistance (Nyalugwe et al, 2015a). Guerret et al (2017) examined responses to five isolates of TuMV (one each in pathotypes 1, 7, and 8, and two unpathotyped isolates) against one cultivar of each of three subspecies of B. oleracea, with the following results: (1) cauliflower was extremely resistant to all of the isolates;…”

“…(2) cabbage showed extreme resistance to pathotype 8, segregating extreme resistance and systemic resistance with symptomless local infection to pathotypes 1 and 7, and segregating extreme resistance and systemic infection with the two unpathotyped isolates: and (3) broccoli showed extreme resistance to pathotypes 1 and 7, local symptoms and systemic resistance to pathotype 8, and susceptibility to the unpathotyped isolates (Guerret et al, 2017).…”

Molecular characterization of disease resistance in Brassica juncea – The current status and the way forward

“…In Australia, blackleg and sclerotinia have been identified as the most destructive diseases for oilseed-and vegetable-type mustards (Murray and Brennan, 2012;Uloth et al, 2013Uloth et al, , 2014Uloth et al, , 2015aUloth et al, , 2015bVan de Wouw et al, 2016). However, there are several other diseases also identified as important in Australia, including TYV, downy mildew, white leaf spot, alternaria blight, bacterial leaf blight, and powdery mildew (Li et al, 2006a(Li et al, , 2007(Li et al, , 2008a(Li et al, , 2009bEshraghi et al, 2007;Murray and Brennan, 2012;Gunasinghe et al, 2014;Van de Wouw et al, 2016;Mohammed et al, 2017Mohammed et al, , 2018aMohammed et al, , 2018bMohammed et al, , 2019Al-lami et al, 2019aAl-lami et al, , 2019bAl-lami et al, , 2019cGuerret et al, 2017;Uloth et al, 2016Uloth et al, , 2018Murtza et al, 2019).…”

“…Several TuMV resistance phenotypes and/or single gene resistances are found in B. napus and B. carinata Jenner, 2002, 2006;Nyalugwe et al, 2014). However, a strain of TuMV that overcame all TuMV resistance genes in B. napus, failed to overcome dominant TuMV hypersensitive resistance gene TuRBJU01, found in B. juncea (Nyalugwe et al, 2016a(Nyalugwe et al, , 2016b(Nyalugwe et al, , 2016cGuerret et al, 2017). TuRBJU01 was identified by studying Mendelian segregation in a population arising from a cross that included TuMV-resistant B. juncea 'Oasis CL' as a parent (Nyalugwe et al, 2015a(Nyalugwe et al, , 2016a.…”