Sensors 2015, 15, 12498-12512; doi:10.3390/s150612498
sensors
ISSN 1424-8220
www.mdpi.com/journal/sensors
Article
Impedance of the Grape Berry Cuticle as a Novel Phenotypic
Trait to Estimate Resistance to Botrytis Cinerea
Katja Herzog *, Rolf Wind and Reinhard Töpfer
Julius Kühn-Institut-Federal Research Centre of Cultivated Plants, Institute for Grapevine
Breeding Geilweilerhof, Siebeldingen 76833, Germany; E-Mails: rolf.wind@kdwelt.de (R.W.);
reinhard.toepfer@jki.bund.de (R.T.)
* Author to whom correspondence should be addressed; E-Mail: Katja.herzog@jki.bund.de;
Tel.: +49-6345-41-124; Fax: +49-6345-91-9050.
Academic Editor: Gonzalo Pajares Martinsanz
Received: 23 February 2015 / Accepted: 20 May 2015 / Published: 27 May 2015
Abstract: Warm and moist weather conditions during berry ripening provoke
Botrytis cinerea (B. cinerea) causing notable bunch rot on susceptible grapevines with the
effect of reduced yield and wine quality. Resistance donors of genetic loci to increase
B. cinerea resistance are widely unknown. Promising traits of resistance are represented by
physical features like the thickness and permeability of the grape berry cuticle.
Sensor-based phenotyping methods or genetic markers are rare for such traits. In the
present study, the simple-to-handle I-sensor was developed. The sensor enables the fast
and reliable measurement of electrical impedance of the grape berry cuticles and its
epicuticular waxes (CW). Statistical experiments revealed highly significant correlations
between relative impedance of CW and the resistance of grapevines to B. cinerea. Thus,
the relative impedance Z
rel
of CW was identified as the most important phenotypic factor
with regard to the prediction of grapevine resistance to B. cinerea. An ordinal logistic
regression analysis revealed a R
2
McFadden
of 0.37 and confirmed the application of Z
rel
of
CW for the prediction of bunch infection and in this way as novel phenotyping trait.
Applying the I-sensor, a preliminary QTL region was identified indicating that the novel
phenotypic trait is as well a valuable tool for genetic analyses.
Keywords: sensor development; phenotyping; grapevine breeding; berry skin; objective data;
bunch compactness; Vitis vinifera
OPEN ACCESS
