Insights into the expression of DNA (de)methylation genes responsive to nitric oxide signaling in potato resistance to late blight disease

Our previous study concerning the pathogen-induced biphasic pattern of nitric oxide (NO) burst revealed that the decline phase and a low level of NO, due to S-nitrosoglutathione reductase (GSNOR) activity, might be decisive in the upregulation of stress-sensitive genes via histone H3/H4 methylation in potato leaves inoculated with avr P. infestans. The present study refers to the NO-related impact on genes regulating DNA (de)methylation, being in dialog with histone methylation. The excessive amounts of NO after the pathogen or GSNO treatment forced the transient upregulation of histone SUVH4 methylation and DNA hypermethylation. Then the diminished NO bioavailability reduced the SUVH4-mediated suppressive H3K9me2 mark on the R3a gene promoter and enhanced its transcription. However, we found that the R3a gene is likely to be controlled by the RdDM methylation pathway. The data revealed the time-dependent downregulation of the DCL3, AGO4, and miR482e genes, exerting upregulation of the targeted R3a gene correlated with ROS1 overexpression. Based on these results, we postulate that the biphasic waves of NO burst in response to the pathogen appear crucial in establishing potato resistance to late blight through the RdDM pathway controlling R gene expression

Assessment of Potato Resistance to Synchytrium Endobioticum

In Poland the Plant Breeding and Acclimatization Institute - National Research Institute (IHAR-PIB) is responsible for officially assessing the resistance of potato breeding lines and cultivars to Synchytrium endobioticum. In the official assessment of wart resistance the modified Glynne-Lemmerzahl method is used. A full cycle of assessment of the wart disease resistance requires 42 - 45 tubers per cultivar/breeding line. Forty two tubers are used in laboratory tests. To complete the laboratory tests, another 10 tubers are inoculated with winter sporangia of the fungus, using ring test. The final results are available after 3 years of investigation. If necessary, the full cycle of resistance tests to S. endobioticum can be performed during one year on 15 tubers in each of the 3 replications (45 tubers in total). Molecular verification of potato genotypes resistance to pathotype 1(D1) is possible with the use of SCAR marker Nl25-1400. Nevertheless, an official phenotypical assessment of advanced breeding lines, as the final verification of their resistance, is required

Evaluation of the Length of the Vegetation Period of the Potato

Potato cultivars are classified into maturity groups according to the length of the vegetation period required to produce a harvestable product. Although accurate classification of potato cultivars to a specific maturity group is of great practical importance, there is no standard method to characterize the maturity type of potato cultivars. In this work, the method of evaluation of vegetation period routinely used at IHAR-PIB, Młochów Research Center is described

Field Evaluation of Potato Resistance Against Phytophthora Infestans Under Natural Infection Pressure

Although development of potato cultivars resistant to late blight has long been one of the primary goals of potato breeding programs, several different methods of field resistance evaluation have been used by potato breeders. Recently, within the EucaBlight network (www.euroblight.net), common methods of late blight evaluation have been agreed on, and these methods are currently highly recommended for use by all those interested in evaluating the resistance of the potato to late blight. Here, we describe a method of evaluating potato resistance in field conditions routinely used at Młochów Research Center, which is compliant with recommendations of the EucaBlight protocol