Potatoes are an important human food crop, but have a number of yield limiting factors, including disease susceptibility. Potato virus Y (PVY) is found worldwide, and is one of the main virus problems for potato growers. PVY is transmitted by aphids and mechanically by machinery, tools and people, and symptoms are variable across cultivars and strains, including being symptomless in some cultivars. Therefore, breeding resistant cultivars is the best way to control this virus. This study phenotypically screened 74 of the main commercial cultivars and a few other select cultivars grown in Australia, in order to identify sources of resistance to PVY. The cultivars were screened against PVY O and PVY NTN , with 23 out of 71 resistant to PVY O and 13 out of 74 resistant to PVY NTN , and all these 13 were resistant to both strains. When the phenotypic screening was compared to the results listed on the European Cultivated Potato Database, the majority of results were found to be consistent. We then evaluated three molecular markers RYSC3, M45, and STM0003 for the extreme resistance genes Ry adg and Ry sto , to validate the usefulness of the markers for marker-assisted selection (MAS) on Australian germplasm. The degree of correlation between the resistance phenotypes and the RYSC3, M45, and STM0003 markers for Ry adg and Ry sto conferred PVY resistance was determined. Three cultivars amplified the RYSC3 marker, while the M45 marker amplified the same 3 and an additional 9. Of the 12 cultivars, 11 phenotyped as resistant, but 1 was susceptible. The STM0003 marker was amplified from only 2 cultivars that both had resistant phenotypes. The RYSC3, M45, and STM0003 markers were therefore able to identify all the 13 cultivars that were resistant to both strains of PVY. Therefore, these markers will enable the identification of genotypes with resistance to PVY, and enable PVY resistant parents to be used for the development of superior progeny; these genetic markers can be used for MAS in the Australian potato breeding program.Genes 2020, 11, 429 2 of 15 mosaic symptoms on the leaves, and this can create a major risk for the spread of the virus in certified seed schemes [8]. Furthermore, the lack of symptoms in infected plants means that visual inspection will generally be ineffective, and that such plants provide a source of PVY inoculum in production areas. Therefore, breeding resistant cultivars is the best way to control this virus and remove inoculum.An effective potato breeding program aims to breed new cultivars that have traits that are superior or equivalent to those of current cultivars. In order to do this, potential parents need to be identified, which contain genes that control at least 40 desirable traits [9,10]. A list of traits that are important for the breeding of improved cultivars in Australia and their genetic control were listed by Slater et al. [10]. A number of these characters are considered to be controlled by single dominant genes, as they exhibit qualitative phenotypic variation. Simko et al.[11] l...

The Tobamovirus, Tomato mottle mosaic virus (ToMMV), was first reported in Mexico in 2013. The virus is thought to pose a serious risk to capsicum (Capsicum annuum) and tomato (Solanum lycopersicum) crops as it is may break resistance. In May 2019 a shipment of imported capsicum seeds was submitted for testing on-shore and using a one-step RT-PCR which detects Solanaceous tobamoviruses, an amplicon of 811 base pairs (bp) was detected and direct sequencing of this amplicon indicated that it had 98% -99% nucleotide (nt) identity to the same region in ToMMV isolates. A cDNA library was generated using the Illumina TruSeq Stranded Total RNA and sequenced using Illumina HiSeq 3000 technology, bioinformatic analysis confirmed the arrangement of a 6398 nt genome which was 98% -99% nt identity with the type strain of ToMMV. This is the first report of ToMMV in Capsicum annuum seed.

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