Root-knot Nematode Meloidogyne Chitwoodi Research Articles

Host plant status and damage threshold of spinach (Spinacia oleracea) for the temperate root-knot nematode Meloidogyne chitwoodi

Summary Problems with plant-parasitic nematodes remain a major challenge in most field vegetable crops worldwide. In agricultural fields in Belgium, these problems have increased in recent years. A major problem is the quarantine root-knot nematode Meloidogyne chitwoodi. The host plant status of the most commonly grown cultivars of spinach (Spinacia oleracea) and the damage threshold for M. chitwoodi were determined in a climate-controlled glasshouse and in a naturally infested field. The yield data with the final population densities were fitted to Seinhorst’s yield and population dynamic models, respectively. The damage threshold values (T) for the relative fresh weight yield were 0.14, 1.08, 11.53 J2 (100 cm3 soil)−1, minimum yield (m) of 0.84, 0.64, 0.52 and maximum yield () of 12.51, 12.44 and 9.60 for ‘Gnu’, ‘Meerkat’ and ‘Whale’ spinach cultivars, respectively. The maximum multiplication rates (a) were 3.81, 2.38 and 2.72, whilst the maximum population densities (M) were 563, 916, and 922 J2 (100 cm3 soil)−1 for ‘Gnu’, ‘Meerkat’ and ‘Whale’, respectively. Meloidogyne chitwoodi had an impact on the spinach yield. The higher the nematode density the lower the yield and vice versa. The tested cultivars were all hosts for M. chitwoodi but differences between cultivars occurred. ‘Kolibri’ and ‘Rhino’ were tested as the least sensitive cultivars for M. chitwoodi during the host screening test and bring opportunities for resistance breeding. This is the first report of spinach as a host for M. chitwoodi.

Enhancing potato resistance against root-knot nematodes using a plant-defence elicitor delivered by bacteria

The root-knot nematode Meloidogyne chitwoodi is a pest that affects potato production in the Pacific Northwest of the United States. Here, to develop new strategies against M. chitwoodi infection of potato, we engineered Bacillus subtilis to secrete the plant-defence elicitor peptide StPep1. Pre-treatment of potato roots with the bacteria secreting StPep1 substantially reduced root galling, indicating that a bacterial secretion of a plant elicitor is an effective strategy for plant protection.

The Arabidopsis thaliana papain-like cysteine protease RD21 interacts with a root-knot nematode effector protein

The root-knot nematode Meloidogyne chitwoodi secretes effector proteins into the cells of host plants to manipulate plant-derived processes in order to achieve successful parasitism. Mc1194 is a M. chitwoodi effector that is highly expressed in pre-parasitic second-stage juvenile nematodes. Yeast two-hybrid assays revealed Mc1194 specifically interacts with a papain-like cysteine protease (PLCP), RD21A in Arabidopsis thaliana. Mc1194 interacts with both the protease and granulin domains of RD21A. PLCPs are targeted by effectors secreted by bacterial, fungal and oomycete pathogens and the hypersusceptibility of rd21-1 mutants to M. chitwoodi indicates RD21A plays a role in plant-parasitic nematode infection.

Quarantine Nematodes in Potato: Practical Solutions Using Molecular Tools

The potato cyst nematodes (PCN) Globodera rostochiensis and G. pallida and the rootknot nematodes Meloidogyne chitwoodi and M. fallax are important nematodes for potato production. Not only are they causing direct damage but also their status as quarantine nematodes jeopardizes international trade. Early detection of these species is of paramount importance. During the last decade, molecular tools have been developed that allow accurate identification and quantification. The challenge is to validate the methods and evaluate their performance for routine use. Specificity, sensitivity, selectivity and repeatability are of major importance to enable high throughput analysis. Examples from validation for M. chitwoodi and M. fallax were given during the workshop. Methods with high sensitivity (able to detect low numbers) are not always as specific (able to differentiate target species from others in mixtures) as other methods which on their turn are less sensitive. However, most errors will be made before the molecular analysis. Sampling and extraction of nematodes from the matrix (e.g., soil, potato peels, roots) is a limiting factor. During the discussion, it was clear that sampling Potato Research (2014) 57:365–366 DOI 10.1007/s11540-014-9281-1

The combined use of Pochonia chlamydosporia and plant defence activators - a potential sustainable control strategy for Meloidogyne chitwoodi

Sustainable strategies are required for control of the root-knot nematode Meloidogyne chitwoodi to reduce dependence on toxic chemical pesticides. The efficacy of the nematophagous fungus Pochonia chlamydosporia in biocontrol could be enhanced by integration with control measures that reduce initial nematode infestations. The use of foliar sprays with plant defence activators can reduce the susceptibility of potato plants to M. chitwoodi . This study assessed effects of combined soil application of P. chlamydosporia with foliar sprays of benzothiadiazole (BTH) or cis -jasmone on infection of potatoes by M. chitwoodi . Solanum tuberosum, cv. Desiree plants were grown in soil mixed with 5000 chlamydospores g-1 of soil, sprayed twice with BTH or cis -jasmone and inoculated with 300 M. chitwoodi second-stage juveniles. Forty-five days after inoculation, nematode reproduction, numbers of colony-forming units of the fungus g-1 of soil and g-1 of root, and egg parasitism were assessed by standard techniques. Foliar sprays of BTH or cis -jasmone combined with the fungus reduced nematode reproduction (P<0.05, LSD). The presence of the fungus slightly increased the efficacy of cis -jasmone, as the number of eggs per egg mass was less in plants treated both with cis -jasmone and the fungus than in the plants treated only with the defence activator. The proportion of parasitized eggs was greater in the cis-jasmone treatment where rhizosphere colonisation was less, suggesting that P. chlamydosporia became a poorer rhizosphere coloniser but a more efficient nematode parasite. The addition of P. chlamydosporia to soil in combination with application of inducers of plant defence could be an alternative control strategy to be used against M. chitwoodi in potato.

Tracking the R Mc1 Gene for Resistance to Race 1 of Columbia Root-Knot Nematode (Meloidogyne chitwoodi) in Three Mexican Wild Potato Species with Different Ploidies

Resistance to Columbia Root-knot nematode was discovered in three wild species in a polyploidy series, Solanum bulbocastanum (2n = 2x), .S. fendleri (2n = 4x), and S. hougasii, 2n = 6x, respectively. After several generations of introgression into the cultivated gene pool, a single dominant monogene conditioning resistance to root propagation of race 1 of CRKN was theorized to be acting in breeding lines derived from each species. Coincidently, sequence tagged sites (STS) and cleaved amplified polymorphic site (CAPS) markers that associated with resistance with S. bulbocastanum were found to be informative in other segregating breeding populations regardless of the source of the gene. The utility of the markers across ploidies suggests that the original gene and genome of S. bulbocastanum or a modern derivative, is present in S. fendleri and S. hougasii. In this polyploidy series, knowledge that the S. bulbocastanum genome is the original source of useful genes guides future germplasm surveyors to search first and most intensively in the primitive Mexican diploid species that may have served as the contributor of a genome to descendants harboring this genome at higher ploidies.

Meloidogyne chitwoodi and Meloidogyne fallax

<i>Meloidogyne chitwoodi</i> and <i>Meloidogyne fallax</i>

Mustard biofumigation disrupts biological control by Steinernema spp. nematodes in the soil

Mustard green manures or seed meal high in glucosinolates, which produce a natural biofumigant upon incorporation into the soil, form an alternative to synthetic fumigants. However, the non-target impacts of these biofumigants in the field are unclear. We examined the effectiveness of soil incorporation of Brassica carinata seed meal both in controlling the plant-parasitic Columbia root-knot nematode ( Meloidogyne chitwoodi), and on the biological control exerted by the entomopathogenic nematodes Steinernema feltiae and Steinernema riobrave on root-knot nematodes and the Colorado potato beetle ( Leptinotarsa decemlineata). Singly, both the seed meal and Steinernema spp. reduced root-knot nematode damage to potato tubers and increased marketable tuber yields. However, there was a negative interaction between the two bioagents such that their combination did not further improve suppression of plant-parasitic nematodes. Thus, mustard seed meal applications harmful to the target root-knot nematode also disrupted the ability of Steinernema spp. to act as biocontrol agents. Further, we observed modest disruption of the biological control of potato beetles following biofumigation. But, the potato beetles were less likely to lay eggs on potato plants grown in mustard-amended soil, suggesting a counteracting benefit of mustard application. Multiple, complementary controls must be integrated to replace the very effective pest suppression typical of synthetic soil fumigants. Our study suggests significant interference between biofumigation and biocontrol agents in the soil, presenting challenges in combining these two environmentally friendly approaches to managing plant-parasitic nematodes and other pests.

Quality damage on carrots (Daucus carota L.) caused by the root-knot nematode Meloidogyne chitwoodi

AbstractIn the Belgian provinces Antwerp and Limburg, the root-knot nematode, Meloidogyne chitwoodi, is widespread. These regions are important production areas of carrot, Daucus carota, for the processing industry. Nineteen carrot cultivars were screened for potential resistance for M. chitwoodi. Egg masses of M. chitwoodi were found on all cultivars. However, there were no egg masses on more than 80% of plants of cvs Berlanda, Bolero, Chantenay, Nantucket and Parmex. By contrast, on cvs ABK, Douceur, Maxi and Merida egg masses were formed on all of the tested plants. To gain information about the damage caused by M. chitwoodi, carrots were grown in soil infected with different densities of nematodes. There was no effect of M. chitwoodi on the length, width and weight of the carrot taproot. Damage caused by M. chitwoodi was manifested by severe galling near the lenticels. Inoculation of nematodes 6 weeks after the carrots emerged resulted in a higher percentage of infected carrots and damaged taproots compared with earlier inoculation times. The effect of the time of harvest on nematode infection and damage was examined. When harvested 100 days after sowing in soil with low nematode densities (two second-stage juveniles (J2)/100 g soil), no damage was reported. Harvesting 120 and 140 days after sowing resulted in 10 and 20% damaged carrots, respectively. With initial M. chitwoodi densities of 25 J2/100 g soil, the percentage of damaged taproots increased from 10% when harvested 100 days after sowing to 70% when harvested 140 days after sowing. In a field trial, 11.5% of the carrots were damaged after a field period of 139 days and the initial M. chitwoodi population increased from 3 to 111 J2/100 g soil. It is recommended that growing carrots in M. chitwoodi-infested fields should be avoided. However, damage can be limited in fields with low initial nematode populations when the growing period is reduced.

Vertical distribution of the plant-parasitic nematode, Meloidogyne chitwoodi, under field crops

The root-knot nematode Meloidogyne chitwoodi is a severe pest on sandy soils in Belgium and causes quality damage to economically important crops such as carrot, potato and black salsify. Pre-planting soil sampling to detect infestations has proven useful to farmers when taking decisions on the crop rotation. To develop an adequate sampling strategy, the vertical distribution of M. chitwoodi was examined under summer barley, carrot, fodder beet, bean, marigold and black fallow on two fields with a sandy soil. Soil samples were collected at monthly intervals from April 2004 to April 2006. Cores were taken to a depth of 70 cm and split into 10 cm segments. Nematodes were extracted by zonal centrifugation. Fodder beet increased the population of M. chitwoodi immensely; carrot was also a good host. Barley was a moderate host and under bean and marigolds the population decreased. The relative distribution of M. chitwoodi over the different soil layers during two successive years was consistent in each field. The different successions with good, moderate and poor hosts did not influence this distribution significantly. A logistic model was fitted to the mean cumulative percentages of nematodes at increasing soil depth. Farmers are advised to take soil samples for detection of M. chitwoodi immediately after harvest, especially after crops with a long field period. Adapting the depth of the cores taken to the vertical distribution of the population can increase the chances of detection. Our results suggest that this distribution is persistent in crop rotations and depends on field characteristics.

Development and evaluation of potato breeding lines with introgressed resistance to Columbia root-knot nematode (Meloidogyne chitwoodi)

Columbia root-knot nematode (Meloidogyne chitwoodi) (CRN) is a serious pest of potato in the Pacific Northwest of the USA. Because this nematode can reproduce rapidly within a single growing season, small initial populations are capable of causing crop loss in the Columbia Basin of Washington or Oregon. Presently, soil fumigation is the main treatment for controlling CRN on potato. Developing potato varieties with resistance to CRN is highly desirable to reduce the cost of control and to alleviate concerns about the effects of fumigants on the environment. Resistance to CRN race 1 was found in two wildSolanum species. Resistance fromS. bulbocastanum was introduced via protoplast fusion and fromS. hougasii via sexual hybridization. Subsequent breeding consisted of repeated backcrossing and selection. The dominant monogenic inheritance was expressed in undiminished fashion across several backcross generations. When tested in replicated trials in three locations, selected resistant clones from the BC4 and BC5 of theS. bulbocastanum introgression populations had total marketable yields and yields of >113-g (4 oz) tubers as good or better than standard potato varieties tested in replicated yield trials in three locations. Percentage of tubers weighing more than 113 g in the highest yielding clones was not significantly different from commercial standards. The resistance phenotype, typified by failure of the nematode to reproduce on the root systems, was sufficiently effective to prevent economic damage in a field exposure. All CRN-resistant clones are pollen sterile. Germplasm listed is available upon request.

Potential uses of sicklepod ( Cassia obtusifolia)

Sicklepod ( Cassia obtusifolia) is a leguminous weed species that has become a severe problem in soybean production throughout the Southern United States. Economic incentives, such as premiums for low levels of foreign matter from cleaning soybeans prior to sale, could generate a large source of sicklepod seed in that area. This study was undertaken to evaluate C. obtusifolia seed for potential applications. As much as 41% of the seed was extractable. Some extracts were strong inhibitors of wheat, velvetleaf and sicklepod root growth, causing discoloration of the root meristems in a manner similar to that caused by naphthoquinones such as juglone and plumbagin. Some extracts increased weight gain in fall armyworm ( Spodoptera frugiperda) causing them to grow to 50–100% larger than controls in a 7-day trial. Survival of Columbia root-knot nematode ( Meloidogyne chitwoodi) in the soil was inversely correlated to the amount of ground whole sicklepod amendment. No phytotoxic effects of the meal amendment on tomato plants or inhibition of germination for several crop seeds was observed at the levels tested.

Unusual and strongly structured sequence variation in a complex satellite DNA family from the nematode Meloidogyne chitwoodi.

An AluI satellite DNA family has been isolated in the genome of the root-knot nematode Meloidogyne chitwoodi. This repeated sequence was shown to be present at approximately 11,400 copies per haploid genome, and represents about 3.5% of the total genomic DNA. Nineteen monomers were cloned and sequenced. Their length ranged from 142 to 180 bp, and their A + T content was high (from 65.7 to 79.1%), with frequent runs of As and Ts. An unexpected heterogeneity in primary structure was observed between monomers, and multiple alignment analysis showed that the 19 repeats could be unambiguously clustered in six subfamilies. A consensus sequence has been deduced for each subfamily, within which the number of positions conserved is very high, ranging from 86.7% to 98.6%. Even though blocks of conserved regions could be observed, multiple alignment of the six consensus sequences did not enable the establishment of a general unambiguous consensus sequence. Screening of the six consensus sequences for evidence of internal repeated subunits revealed a 6-bp motif (AAATTT), present in both direct and inverted orientation. This motif was found up to nine times in the consensus sequences, also with the occurrence of degenerated subrepeats. Along with the meiotic parthenogenetic mode of reproduction of this nematode, such structural features may argue for the evolution of this satellite DNA family either (1) from a common ancestral sequence by amplification followed by mechanisms of sequence divergence, or (2) through independent mutations of the ancestral sequence in isolated amphimictic nematode populations and subsequent hybridization events. Overall, our results suggest the ancient origin of this satellite DNA family, and may reflect for M. chitwoodi a phylogenetic position close to the ancestral amphimictic forms of root-knot nematodes.

Occurrence and Host Range of a New Root-Knot Nematode (Meloidogyne chitwoodi) in the Pacific Northwest

Occurrence and Host Range of a New Root-Knot Nematode (<i>Meloidogyne chitwoodi</i>) in the Pacific Northwest