Abstract
Potato virus X (PVX) is a widely distributed viral pathogen that causes significant losses in potato production by co-infecting with potato virus Y or potato virus A. In this study, the resistance of 23 potato cultivars to PVX was dissected in detail using a PVX infectious clone containing a yellow fluorescent protein (YFP). Among them, four potato cultivars (Longshu-3, Eugene, Atlantic and Waiyin-2) were found to carry an Rx gene that confers extreme resistance to PVX; one cultivar (Waiyin-1) displayed partial resistance and was able to delay PVX infection by ~ 5 days; while the rest eighteen potato cultivars were susceptible to PVX. Moreover, we found that the replication but not cell-to-cell or long-distance movement of PVX was inhibited in Waiyin-1. Finally, we determined that the expression of pathogenesis-related (PR) genes in Waiyin-1 was not triggered by PVX infection at early infection stage, whereas they were triggered in the Rx-carrying cultivar Atlantic during this period of time. In conclusion, our results confirm that Rx is a major type of resistance gene in potato cultivars in the Northeast part of China. Furthermore, the possible mechanism underlying Waiyin-1 resistance to PVX is discussed.
Highlights
Potato (Solanum tuberosum L.) is the world’s fourth most important food crop, with a global production of about 388 million tons per year according to the Food and Agriculture Organization of the United Nations (FAO) statistical databases
Resistance of different potato cultivars to Potato virus X (PVX) Reverse transcription-polymerase chain reaction (RTPCR) analysis showed that the tissue-culture plantlets of all 23 potato cultivars were free of PVX (Fig. 1a)
The results showed that the optical density values at 405 nm (OD405) of five cultivars, namely Longshu 3, Eugene, Atlantic, Waiyin-1 and Waiyin-2, were close to that of the negative control, whereas those of other 18 varieties were close to that of the positive control (Table 1)
Summary
Potato (Solanum tuberosum L.) is the world’s fourth most important food crop, with a global production of about 388 million tons per year according to the Food and Agriculture Organization of the United Nations (FAO) statistical databases (www.statista.com/statistics/ 192966/us-potato-production-since-2000). Potato production is being seriously threatened by virus infection, which causes yield and quality decline and induces seed degradation (Solomon-Blackburn and Barker 2001a). Potato virus X (PVX), the type species of the genus Potexvirus in the family Alphaflexiviridae, is one of the major viruses infecting potato plants worldwide (Kreuze et al 2020b). It does not induce severe symptoms on most potato cultivars, coinfection of PVX with other viruses, such as potato virus A (PVA) and potato virus Y (PVY), can cause serious yield and quality losses in potato production (Kreuze et al 2020a). Coinfection of PVX with potato virus A (PVA) and potato virus Y (PVY) results in
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