Estimation of partial resistance in potato genotypes against Meloidogyne chitwoodi

Abstract

Three new potato genotypes, designated AR 04-4107, AR 04-4096 and AR 04-4098, with resistance towards Meloidogyne chitwoodi, and the susceptible cv. Désirée were grown at a range of population densities of M. chitwoodi in a climate-controlled glasshouse in order to establish the presence and degree of partial resistance. Tuber parts of about 12 g were planted at densities (Pi) of 0, 0.5, 1, 2, 4, 8, 16, 32, 64, 128 and 256 second-stage juveniles (J2) (g dry soil) −1 . The plants were allowed to grow for a period of 105 days. Tomato cv. Moneymaker was included and inoculated at Pi = 2 J2 (g soil) −1 to verify the quality of the inoculum by measuring the multiplication rate. Plant height was measured weekly over 11 weeks. At harvest, fresh shoot, root and tuber weights, and number of tubers were measured to express yield. Final population densities (Pf ) were calculated as the total number of nematodes found in soil and roots. Tubers were scored for visible symptoms and a root-knot index was calculated. The relation between pre-plant population densities (Pi) and nematode densities at harvest (Pf ) was fitted using R. The multiplication rate a of M. chitwoodi on AR 04-4107, AR 04-4096, AR 04-4098 and cv. Désirée was 0.55, 0.27, 0.91 and 32, respectively. Partial resistance rs a of AR 04-4107, AR 04-4096 and AR 04-4098 was 1.7%, 0.8% and 2.8%, respectively. Partial resistance expressed as rs M was 0.2%, 0.2% and 0.1%, respectively. It can be concluded that AR 04-4107, AR 04-4096 and AR 04-4098 are strongly partially resistant to M. chitwoodi. Also, the population dynamics curves run almost parallel between both the tested genotypes and the reference cultivar, indicating that a simple and cheap partial resistance test is feasible. When tuber yields were fitted to the Seinhorst model for yield reduction, cv. Désirée showed a minimum yield (m) of 0.86, while all three resistant genotypes suffered no yields losses at all (m = 1), which indicates that the observed resistance was associated with tolerance. As a result of the remarkably high partial resistance, quality damage was low compared with cv. Désirée. The root-knot index, which takes into account internal quality damage of the potato tuber, was below 10 for all genotypes with partial resistance, the lower damage threshold used for industrial processing of consumption potatoes. Visible symptoms on the tuber skin were absent up to densities of 32 J2 (g soil) −1 for genotypes AR 04-4098 and AR 04-4096 and 2 J2 (g soil) −1 for AR 04-4107, and significantly reduced at higher densities when compared with the susceptible cv. Désirée. However, when tuber peels were investigated, egg masses were detected in tubers at almost all initial population densities.

Damage thresholds and population dynamics of Pratylenchus penetrans on carrot (Daucus carota L. cv. Nerac) at three different seed densities

“…Different to P. penetrans, Heve et al (2015) observed increasing T q values with an increasing seed density for M. chitwoodi on the same carrot cultivar. In general, results confirm that quality loss by P. penetrans was more severe than yield loss; both for the parameters T and m as was also reported by Coosemans (1975) and for M. chitwoodi on carrot (Heve et al 2015) and potato (Norshie et al 2011).…”

From root to shoot; Quantifying nematode tolerance inArabidopsis thalianaby high-throughput phenotyping of plant development

“…Most of the studies that measure the effect of nematode infection on crop yield rely on destructive end-point measurements (i.e., crop yield (Sasanelli et al, 2013;Been et al, 2015)), leaving an information gap between start and endpoint of the experiment. Few time-series experiments were performed by measuring the effect of soybean cyst nematode Heterodera glycines on the root system by using a rhizotron (Miltner et al, 1991) or by measuring the effect of Meloidogyne chitwoodi densities on the height of potato plants (Norshie et al, 2011). Additionally, time-series measurements were also performed on the green canopy area upon nematode infection using a phenotyping design based on microplots (Joalland et al, 2016(Joalland et al, , 2017.…”

“…Up to now, tolerance to root-parasitic nematodes is mainly studied in field crops (Seinhorst, 1985; Norshie et al ., 2011; Sasanelli et al ., 2013; Been et al ., 2015; Moosavi, 2015), making it difficult to resolve the underlying mechanisms as to why plants differ in their tolerance limits. Knowledge of the genetic underpinnings of tolerance is important for understanding how plants differ in their tolerance limits to root-feeding nematodes.…”

“…So far, the Seinhorst Yield Loss Model (SYLM) is mostly used to determine the tolerance limit for plant-parasitic nematodes (Seinhorst, 1985; Norshie et al ., 2011; Sasanelli et al ., 2013; Been et al ., 2015; Moosavi, 2015). The SYLM models the density-yield relationship by an inverted sigmoid curve where loss of yield at a given timepoint is a derivative function of damage.…”

“…Most of the studies on tolerance to root-parasitic nematodes in potato focus on yield reduction, e.g., potato yield expressed in tuber weight and quality (Been et al, 2015; Teklu et al, 2022), which depend on single destructive endpoint measurement. Others also measure the effect of nematodes foliage or plant height which are not perse destructive (Norshie et al ., 2011), but these types of measurements are less often done because they are laborious. In A. thaliana , the green canopy growth, inflorescences, and the number of viable seeds can be used to measure tolerance to viruses (Shukla et al ., 2018).…”