Peroxidases in the early responses of different potato cultivars to infection by Potato virus Y^NTN

Abstract

Peroxidases (POXs) were investigated in three cultivars of potato ( Solanum tuberosum ) with different susceptibilities to infection by Potato virus Y NTN ( PVY NTN ). Soluble, ionically-bound and covalently-bound POXs were analysed over 24 h post inoculation (hpi) in bottom inoculated leaves, upper intact leaves, and in roots. The first changes were observed at 3 hpi when the activity of ionically-bound POXs increased significantly in the inoculated leaves of tolerant cv. Pentland Squire and of resistant cv. Santé. The most pronounced changes were found in the resistant variety, where the increase was twice that in control plants. In contrast, in the inoculated leaves of susceptible cv. Igor, there was a decrease in ionically-bound POXs, accompanied by a two fold increase in the activity of covalently-bound POXs. Also at 3 hpi, cv. Santé showed increased activity of all three types of POXs in the upper intact leaves. Over the period of the experiment, enhanced activity of soluble POXs, correlated with the virus infection, was observed in both types of leaves of the susceptible cv. Igor. However, in resistant cv. Santé, the upper intact leaves of virus-inoculated plants showed a more intense but transient early response of soluble POXs. Part of a new POX gene was isolated from leaves of potato cv. Igor. A nucleotide sequence of 394 bp was determined and the abundance of the POX transcript was analysed by real-time PCR. There was no correlation between PVY NTN infection and the abundance of the transcript.

PVYNTN elicits a diverse gene expression response in different potato genotypes in the first 12 h after inoculation

“…After 4 weeks growth in soil, the potato plants of each cultivar were divided into two groups of 15–18 plants each: virus‐inoculated and mock‐inoculated groups. The PVY NTN (isolate NIB‐NTN, G en B ank accession number AJ585342) inoculation procedure was carried out according to Milavec et al. (2008).…”

“…Similarly, the study by Whitham et al (2003) showed that the major differences in gene expression in Arabidopsis thaliana occurred 3-5 days rather than 1 or 2 days following inoculation with five different viruses. However, our experiment was based on previous studies, in which potato plants responded to PVY NTN at the biochemical level as early as 3 hpi (Milavec et al, 2008).…”

“…, 2005; Milavec et al. , 2001b, 2008) have shown a link between plant sensitivity and response of the selected molecules, but have not tracked the overall changes arising from the potato–virus interaction. Recently, a study has been published focusing on the disease response of cv.…”

“…Several studies of individual physiological and morphological parameters in early potato-PVY NTN interactions (for example, Kre ç i ç -Stres et al , 2005;Milavec et al , 2001bMilavec et al , , 2008 have shown a link between plant sensitivity and response of the selected molecules, but have not tracked the overall changes arising from the potato-virus interaction. Recently, a study has been published focusing on the disease response of cv.…”

Changes in Peroxidase Activity and Transcript Level of the MYB1 Gene in Transgenic Tobacco Plants Silenced for the RDR‐1 Gene After Systemic Infection with Potato virus Yo

“…A number of reports have indicated an increase in POX activity during or after PVY attack in both compatible and incompatible interactions (Nie 2006; Doubnerova et al. 2007; Milavec et al. 2008).…”