Potato cultivar Etola exhibits hypersensitive resistance to PVY^NTN and partial resistance to PVY^Z‐NTN and PVY^N‐Wi strains and strain‐specific alterations of certain host miRNAs might correlate with symptom severity

Abstract

This study demonstrates the new sources of resistance available in potato cv. Etola, which represent multiple strain-specific resistance genes against three strains of Potato virus Y (PVY). Etola is the first documented cultivar of this sort in Europe that exhibits hypersensitive resistance (HR) to PVY NTN isolate PVY-3202, and different levels of partial resistance to PVY N-Wi isolate PVY-3411 and PVY Z -NTN isolate PVY-3303. The isolate PVY-3411 induced severe symptoms and faster systemic viral coat protein and RNA accumulation in the noninoculated upper leaves, whereas PVY-3303 caused mild symptoms and delayed viral spreading. This study provides the first example of strain-specific alteration of a set of host microRNAs (miRNAs) and their targets in the potato-PVY interaction. The tested miRNAs and targets are altered only in plants of cv. Etola infected with PVY-3411 but not those infected with PVY-3303 nor PVY-3202. The up-regulation of stu-miR162, stu-miR168a and miR172e, together with their target transcripts, DCL1, AGO1-2 and TOE3, respectively, in PVY-3411-infected plants correlates with high abundance of HC-Pro RNA encoding an RNA-silencing suppressor and might be linked with the severe symptoms in leaves. Moreover, PVY-3411 causes parallel increases in two members of stu-miR482 and their mRNA targets Gpa2 and CC-NBS-LRR that are involved in the defence response.

Accumulation of miRNA and mRNA Targets in Potato Leaves Displaying Temperature-Dependent Responses to Potato Virus Y

“…The abundance of the majority of tested tobacco miRNAs and targets was increased upon infection by PVY NTN and PVY N-Wi isolates, which induced severe symptoms (Yin et al 2019). Our findings indicated that the tested potato and tobacco miRNAs and their targets responded to PVY challenge (Yin et al 2017(Yin et al , 2019; and the alteration patterns of these PVYresponsive miRNAs were host-and strain-dependent and may relate to symptom severity in PVY-host interaction.…”

“…In another study from our group, a temperature-independent but strain type-dependent HR was demonstrated in potato cv. Etola, whereas HR resistance to PVY NTN isolate PVY-3202 and necrotic reaction to PVY Z -NTN isolate PVY-3303 and PVY N-Wi isolate PVY-3411 were observed at temperatures ranging from 20 to 28°C (Yin et al 2017). Recently, in a preliminary study from our group, we found a different type of temperature-dependent potato-PVY interaction in a diploid potato clone DG 81-68.…”

“…Previously, we showed that a set of potato miRNAs and targets was altered in cv. Etola plants displaying partial HR and severe symptoms after infection with the PVY N-Wi isolate but not in plants presenting HR resistance to the PVY NTN isolate or in plants displaying partial HR and necrosis to PVY Z -NTN (Yin et al 2017). Later on, these three PVY isolates were used to inoculate tobacco (cv.…”

Diagnostics of the Presence of Viruses in the Potato and Soil

“…PVY N-Wi and PVY NTN belong to the PVY N strain group, and PVY NTN elicits PTNRD in sensitive potato cultivars. In addition, potato cultivars Etola and Gwiazda are used as the indicator for HR (Yin et al, 2017).…”

“…The source for the available primers from the published data is summarized in Table 4. In addition, a method for PVY and TRV wholegenome sequencing and real-time quantitative RT-PCR (real-time RT-qPCR) detection of PVY HC-Pro RNA are referred to in Yin et al (2014Yin et al ( , 2017, and the primer sequences are listed in Table 5. The primer sequences used for detecting of TRV and PMTV by RT-PCR are shown in Table 6.…”