Reaction of winter wheat cultivars to eyespot assessed visually and by real-time PCR

Abstract

The reaction of twelve winter wheat cultivars frequently grown in the Czech Republic and twenty-five new breeding lines to inoculation with Oculimacula yallundae and Oculimacula acuformis was evaluated in small plot trials from 2017–2018. The assessment was carried out visually by symptoms and by a quantitative real-time polymerase chain reaction (qPCR). The aims of the study were to compare the results of both methods, to evaluate the effect of the resistance gene Pch1 to eyespot, and to select new breeding lines resistant to eyespot. The relationship between the eyespot symptoms and the pathogen DNA content in plant tissues followed a moderate linear regression. Low levels of eyespot were observed in the cultivars/lines possessing the resistance gene Pch1 (Annie, Hermann, Rebell, SG-S1215-14, SG-S1825-14, SG-S791-13) and also in the line SG-SU630-15. The qPCR method was able to detect low levels of the pathogens in the plant tissue and to distinguish two eyespot pathogens. O. acuformis was detected in very low concentrations in the inoculated plants compared with O. yallundae. The eyespot infection rate was significantly higher in 2017 than in the next agricultural season due to extremely dry and warm spring weather in 2018.

The Use of Real-Time PCR for the Pathogen Quantification in Breeding Winter Wheat Varieties Resistant to Eyespot

“…Oculimacula yallundae was more aggressive to the wheat samples. This is consistent with previous reports [ 17 ]. Oculimacula yallundae might grow more rapidly through leaf sheaths than O. acuformis at the beginning of infection [ 9 ].…”

“…The linear regression analysis indicates that the relation of visual assessment and relative quantity obtained from qPCR showed a low correlation coefficient, which means a weak relationship between the symptoms and pathogen DNA content in plant tissues. In a previous study [ 17 ], the relationship between the eyespot symptoms and the pathogen DNA content in plant tissues followed a moderate linear regression. In the current study, qPCR results of O. yallundae DNA content in plant tissues and visual symptoms followed a moderate linear regression only in 2021.…”

“…Samples of the lower parts of the stem base (approximately 20 mm long segments) were collected annually in the milk-wax growth stage (end of June). Stem bases (20 pcs) of each cultivar were thoroughly dried, homogenized to a fine powder and subsequently processed according to the methodology published in previous work by Palicová et al [ 17 ]. All tested winter wheat cultivars were evaluated by quantitative real-time PCR (qPCR) by using primers: Oculimacula-R (universal reverse), Ac F-D (specific to OA) and Yall F-H (specific to OY), and reference gene phenylalanine ammonia-lyase (primers WpalF/R) previously published by Walsh et al [ 12 ].…”