Ricardo Holgado
OAP
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Ning Wang Huan Peng Shi-ming Liu Wen-kun Huang Ricardo Holgado Jihong Liu Clarke De-liang PengAbstract
Soybean cyst nematode (SCN, Heterodera glycines (I.)) is one of the most important soil-borne pathogens for soybeans. In plant parasitic nematodes, including SCN, lysozyme plays important roles in the innate defense system. In this study, two new lysozyme genes (Hg-lys1 and Hg-lys2) from SCN were cloned and characterized. The in situ hybridization analyses indicated that the transcripts of both Hg-lys1 and Hg-lys2 accumulated in the intestine of SCN. The qRT-PCR analyses showed that both Hg-lys1 and Hg-lys2 were upregulated after SCN second stage juveniles (J2s) were exposed to the Gram-positive bacteria Bacillus thuringiensis, Bacillus subtilis or Staphylococcus aureus. Knockdown of the identified lysozyme genes by in vitro RNA interference caused a significant decrease in the survival rate of SCN. All of the obtained results indicate that lysozyme is very important in the defense system and survival of SCN.
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Harrison Mburu Laura Cortada Grace Mwangi Kelvin Gitau Agnes Kiriga Zachary Kinyua George Ngundo Wilson Ronno Daniel Leigh Coyne Ricardo Holgado Solveig HaukelandAbstract
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Ricardo HolgadoAbstract
Bruk av husdyrgjødsel er stadig mer brukt til å produsere biogass. Rester (bio- avfall) etter biogass prosesser, kan bli bruk som gjødsel. Hvis ugressfrø, plante patogener og nematoder overlever anaerob prosessen, bruk av bioavfall kan bli en fytosanitær risiko. Litteratur om effektene av mesofil temperatur spesielt på (to) ugress (en) plantepatogen og potetcystnematode-levedyktighet ble gjennomgått. Ifølge den tilgjengelige litteraturen må det konkluderes at behandlinger som vanligvis brukes i mesofil prosess ikke vil være tilstrekkelige for fullstendig inaktivering av plantepatogener. Dette refererer til patogener av potet som er oppført i norsk regulering (Matloven) og EU-direktiv 2000/29 / EF, spesielt Synchytrium endobioticum.
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Few studies have reported findings on the use of Pochonia chlamydosporia for the management of plant-parasitic nematodes under field conditions. In this chapter we describe experiences of P. chlamydosporia application in temperate crops grown in the UK, Norway and Poland. To date, the fungus has been recovered from different endoparasitic nematodes from a range of locations across Europe. Pochonia chlamydosporia is an egg parasite as well as a saprophyte and plant endophyte and is primarily applied as a biological control agent to reduce nematode multiplication. In the UK, several field and micro-plot experiments have demonstrated that the fungus is capable of causing ca 50% reductions in the multiplication of Globodera pallida in potatoes. Further work was undertaken to evaluate the compatibility between P. chlamydosporia applications and the fungicide azoxystrobin which is used for managing the soil borne fungus Rhizoctonia solani. Although P. chlamydosporia is sensitive to azoxystrobin, there is evidence to suggest that it may not affect its efficacy as a biological control agent. In Norway, the fungus has been isolated from various cyst nematodes (Heterodera spp. and Globodera spp.), however, under in vitro conditions it was found to lose pathogenicity. Work undertaken in Poland has shown that strains of P. chlamydosporia can reduce populations of H. schachtii in sugar beet. Sugar beet grown in a 3 year rotation in combination with a mustard green manure increased egg parasitism by P. chlamydosporia in comparison to other treatments which included the addition of straw or manure. Further work is discussed on the ability of strains of P. chlamydosporia to parasitize eggs of Meloidogyne incognita, M. hapla and M. arenaria at a range of temperatures.
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Christer Magnusson Ricardo Holgado Keith Davies Deliang Peng Marte Persdatter Tangvik Ingunn BurudAbstract
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The root-knot nematode Meloidogyne graminicola is a major constraint in rice production in the world. Using rDNA-ITS sequences data alignments, the genetic variation among twenty-one populations of M. graminicola (sixteen from Myanmar and five from China) was investigated. The results showed that all the populations were clearly separated from other species and that there was a low level of genetic variation among the isolates. A set of species-specific primers was designed to develop a species-specific molecular tool for the precise identification of M. graminicola. The primer reliability, specificity and sensitivity tests showed that the primer set (Mg-F3 and Mg-R2) amplified the expected fragment size of 369 bp from the template DNA of target nematode populations but not from non-target organisms. A duplex PCR test allows for saving diagnostic time and costs by amplifying the species of interest from a nematode mixture. Therefore, this species-specific primer set may be a powerful tool to improve taxonomic identification by non-specialists and the design of successful management practices as well.
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Ricardo Holgado Christer Magnusson Bonsak Hammeraas Irene Rasmussen Kari-Ann Strandenæs Holger Heuer Randi KnudsenAbstract
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Ricardo HolgadoAbstract
Integrated management of Potato Cyst Nematode (Globodera Spp.) for more than half century in Norway Potato cyst nematodes (PCN) Globodera spp. are thought to have originated in the Andean region of South America, and have been introduced into Europe after 1850. In the Nordic region PCN were detected in Sweden 1922, Denmark 1928, Finland 1946, Faroe Island 1951, Island 1953, and Norway 1955 (Videgård, 1969, Øydvin, 1978). Since its first record in Norway, PCN has been managed for more than 50 years. Initially extensive surveys were carried out and strict regulations prohibiting the introduction and spread of PCN with soil and plant materials were implemented. Early control strategies included the use of chemical fumigants and resistant potato cultivars in infested fields. Much emphasis was placed on documenting freedom from PCN in the certified seed potato production. The import and movement of all kinds of potato seed was prohibited, in order to prevent the introduction of new PCN populations, and nematode spread to uninfested land. Fields infested with PCN were placed under strict quarantine. In addition to this proper crop rotation involving resistant cultivars was enhanced (Øydvin, 1978). The taxonomic separation of the yellow Globodera rostochiensis and the white species G. pallida, and the emerging information on pathotypes changed the use of resistant cultivars to avoid the increase of resistant breaking populations. Chemical fumigants, organophosphates or carbamate nematicides have not been used in Norway since more than 40 years. Today, non-virulent G. rostochiensis is managed by crop rotation, while infestations by G. pallida or virulent G. rostochiensis results in 40-years ban on growing potato (Holgado & Magnusson, 2010; 2012). The use of non-host crops and alternating susceptible and resistant potato is important, but also complicated due to restricted acreage suitable for long rotations. The safe use of resistant cultivars requires knowledge on the species and pathotypes present (Holgado & Magnusson, 2010; 2012). In a recent project the identity of several populations from the main potato districts was studied using PCR amplification of ITS regions (Bulman & Marshall, 1997). Most populations were identified as G. rostochiensis, with the exception of one, which belonged to G. pallida. The PCR amplification and sequencing of the non-coding scmt mitochondrial region confirmed the species identification, and demonstrated a close relationship to common European populations. Studies on vap1 patterns demonstrated several variants of the vap-1 gene to be present in each population, and that differences in allele frequencies between populations are minor. References Bulman SR, Marshall JW, 1997. New Zealand Journal of Crop and Horticultural Science 25, 123-129. Holgado R, Magnusson C, 2010. Aspects of Applied Biology, 3rd Symposium on Potato Cyst Nematodes 103:87-92. Holgado R, Magnusson C, 2012. Potato Research 55, 269-278. Videgård G, 1969. Potatis 1969, 26–28. Øydvin J, 1978. Växtskyddsrapporter Avhandlingar 2, 1–37.
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Nematodes as limiting factors in potato production in Norway Plant parasitic nematodes associated with potato feeds on roots and/or tubers. At least 68 species, representing 24 genera of have been found associated with potato. Since nematodes generally attack underground plant parts, there are no reliable foliar symptoms to show that nematodes may be the major cause of poor growth and reduced tuber yields. Potato roots damaged by nematodes may show the presence of lesions, females/cysts or galls. After a few weeks, however, roots may be attacked by other pathogens such as bacteria and fungi, and the original damage by nematodes may not be obvious. Therefore, nematode damage often may have been attributed to other factors. There are no estimations for potatoes yield losses in Scandinavia due to nematodes, however, in the United Kingdom, it is estimated that 9 % of the potato crop is lost annually because of the potato cyst nematodes (PCN), Globodera rostochiensis and G. pallida, and it is reasonable to assume that this percentage is also applicable to Scandinavia. However, if we consider the possible additional effects of other nematode species occurring in Norway, yield reductions could be as high as 20%. Besides direct yield losses, some nematodes affect tuber quality. Yield losses depend on the pathogenicity of the species of nematode, the nematode population density at planting, the susceptibility and tolerance of the host and by a range of environmental factors. In Norway, potato cyst nematodes (G. rostochiensis and G. pallida) are by far the most important nematodes in potato. Other important nematodes include root-lesion nematodes (Pratylenchus spp.), stubby root nematodes (Trichodorus spp. and Paratrichodorus spp.) and stem and tuber nematodes (Ditylenchus spp.). Nematodes considered less important include root knot nematode (Meloidogyne hapla) and needle nematodes (Longidorus spp.). In Norway, potato cyst nematodes (Globodera rostochiensis and G. pallida) are quarantine pests subjected to regulations. PCN infestations result in costly production systems and loss in sales value of farms. Their occurrences restrict acreage available for potato production as in some cases legislative regulations forbid potato production or make the production more difficult and more expensive. Furthermore societal consequences by far exceed yield losses. It is also compulsory to sample the soil for seed potato production to document freedom from PCN. When PCN is present in the field complete eradication is not possible. Effective management requires reliable information on virulence, decline rates of population densities and infectivity in soil. It is also crucial to know what conditions or practices increase these decline rates. Today in Norway, non-virulent G. rostochiensis is managed by crop rotation, while infestations by G. pallida or virulent G. rostochiensis pathotypes capable of breaking the resistance in potato cultivars in current use results in a 40-years prohibition for growing potato in the infected field. Root-lesion nematodes (Pratylenchus spp.) cause damage to the roots and induce scabby to sunken lesions on tubers. Stubby root nematodes (Trichodorus spp. and Paratrichodorus are nematode vectors of Tobacco Rattle Virus they causes the symptom called “Spraing” in tubers. Occasionally stem and tuber nematodes (Ditylenchus spp.), have been reported as problems both in field and storage, especially when weeds are not well controlled. Management strategies aim to prevent nematode multiplication and hence protect the potato crop from damage. An efficient method of controlling nematodes as Ditylenchus spp. and root-lesion nematodes is black fallow, but this may be difficult to achieve in many cases.
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Ricardo HolgadoAbstract
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Ricardo HolgadoAbstract
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Ricardo HolgadoAbstract
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Ricardo HolgadoAbstract
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Ricardo HolgadoAbstract
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Ricardo HolgadoAbstract
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Ricardo HolgadoAbstract
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Ricardo HolgadoAbstract
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Ricardo HolgadoAbstract
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Ricardo HolgadoAbstract
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Plant parasitic nematodes associated with potato feed on roots and/or tubers. About 70 species, representing 24 genera, have been reported from potato. Since nematodes attack underground plant parts, there are no reliable foliar symptoms to show that nematodes may be the major cause of poor growth and reduced tuber yields. Potato roots damaged by nematodes may show lesions, abnormal proliferation of lateral roots, emerging white females and brown cysts. Nematode attacks may render plants vulnerable to other pathogens, so disease caused by microorganisms may have nematodes as an etiological component. Therefore, nematode damage may often have been attributed to other factors. In Scandinavia, potato cyst nematodes (Globodera rostochiensis and Globodera pallida) are by far the most important nematodes on potato. In Norway, the cost of compensations schemes due to imposed statutory regulations of potato cyst nematodes may some years exceed the compensation for any other pests or diseases organism in agriculture. Other important nematodes include root lesion nematodes (Pratylenchus spp.), stubby root nematodes (Trichodorus spp. and Paratrichodorus spp.), and potato rot and stem nematodes (Ditylenchus spp.). Root knot nematode Meloidogyne hapla is considered less important. Meloidogyne chitwoodi and Meloidogyne fallax are not known to be present in Nordic countries. In the control, crop rotations using non-host crops, alternating susceptible and resistant potato cultivars, are an important control measure. However, the use of resistant potato cultivars requires knowledge of the species and pathotypes present in the field.
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A survey of the prevalence of skin blemish diseases in potatoes after the growing seasons of 2008 and 2009 was carried out on 247 potato lots representing different cultivars and production regions in Norway. The results showed the presence of silver scurf (Helminthosporium solani) in all lots. Skin spot (Polyscytalum pustulans) and black scurf (Rhizoctonia solani) were found in 80% of the lots, and black dot (Colletotrichum coccodes) and common scab caused by Streptomyces spp. were present in 50–70%. Also, powdery scab (Spongospora subterranea) occurred in 65–80% of the lots, and root-lesion nematodes (Pratylenchus spp.) were detected in 60% of the sub-samples that exhibited symptoms of common scab.
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Ricardo HolgadoAbstract
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Ricardo HolgadoAbstract
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Ricardo HolgadoAbstract
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Nematodes, commonly known as round worms, are the most common multicellular animals on planet Earth. After 1000 million years of evolution members of the phylum Nematoda have a high bionomic diversity. As habitants of the soil and rhizosphere nematodes are involved en energy fluxes, and affect carbon and nutrient cycles. As plant parasites, either alone or in synergism with other pathogens, nematodes are responsible for plant disease complexes and major crop losses. A growth depression in a field of potato (Solanum tuberosum) cv. Saturna [resistant to pathotype Ro1 of potato cyst nematode (PCN) Globodera rostochiensis], suggestive of potato cyst nematode damage, was detected in Grue, eastern Norway. Analyses of soil samples did not detect PCN, but demonstrated the occurrence of a large number of lesion nematodes Pratylenchus penetrans .Tubers from the depressed part of the field had severe symptoms similar to those caused by the common scab bacterium Streptomyces scabies. Potato yield was reduced by 50% in the affected area of the field. Transect-sampling showed plant growth to be negatively correlated with densities of P. penetrans and suggested a damage threshold of potato to the nematode of 100 specimens per250 g of soil. Common scab (Streptomyces scabies) occurred frequently in the affected area. P. penetrans was present in roots, underground stems, stolons and tubers. Tubers from the depressed part of the field had severe symptoms similar to those caused by the common scab bacterium. In tubers, nematodes were detected inside cross-lesions typical symptoms of common scab, and occurred also in the outermost 0.5 mm tissue associated with such lesions. In pots with sterile sand, micro-tubers of potato cv. Saturna, produced from meristems, were grown in a green-house infected with, P. penetrans, S. scabies, and a combination of P. penetrans and, S. scabies. P. penetrans alone induced tuber lesions similar to those of common scab. Also, the combined inoculation of the bacterium and the nematode seemed to enhance symptom expression. Similar scab symptoms, in connection with lesion nematode infections, have been observed on potato tubers cv. Oleva, which also is relatively tolerant to common scab. Symptomatic tubers cv. Saturna first stored at 4o C for 20 weeks were transferred to pots with sterile sand and grown for 3 months in the green-house. In these cultures P. penetrans was first detected in soil 8 weeks after planting. Examination at harvest of soil, roots, stolons, tubers demonstrated symptoms typical of P. penetrans. Interestingly, P. penetrans survives storage of potatoes, from which new infections may develop. Hence, potato tubers do appear to be an important means for the spread of P. penetrans to new areas. The fact that the symptoms induced by this nematode may be mistaken for symptoms of common scab suggests that the frequency of S. scabies might have been overestimated in regular surveys. Infections by P. penetrans have important implications for scab control. This pertains in particular to recommended maintenance of high soil moisture at and during 4-9 weeks after tuber set. If symptoms are related to nematode infection rather than to the scab bacterium, this recommendation would allow for a rapid build-up of lesion nematodes resulting in a decrease in both yield and marketability of the tubers. Further studies are needed to investigate the extent of this problem.
Abstract – Managing Plant Nematodes for a sustainable production
Christer Magnusson, Ricardo Holgado
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Merete Wiken Dees Arild Sletten Ricardo Holgado Eldrid Lein Molteberg Tor J. Johansen May Bente Brurberg Vinh Hong Le Ragnhild Nærstad Arne HermansenAbstract
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In 1955 the potato cyst nematode (PCN) was recorded for the first time in Norway. This detection resulted in extensive surveys and measures were implemented based on the statutory regulation of 1916. The first statutory regulation for PCN was put in power in 1956, and later amended in several occasions. These regulations prohibit the introduction and spread of PCN with soil and plant materials. Early control strategies included the use of chemical fumigants and resistant potato cultivars in infested fields, and surveys detected new infestations which were placed under quarantine regulations. The recognition of G. rostochiensis and G. pallida, their pathotypes enabled a more precise use of resistant cultivars. Commercial chemical fumigants, organophosphates or carbamate nematicides have not been used in Norway since the early 1970s. Today, non-virulent G. rostochiensis is managed by crop rotation, while infestations by G. pallida or virulent G. rostochiensis results in at least 40-years ban for growing potato. Most Norwegian potato cultivars have the resistance genes, Gro-1 (H1) from Solanum tuberosum ssp. andigena. During the preceding decades great emphasis has been placed on documenting freedom from PCN in the production of certified seed potatoes, certified seed potato are used in combination with crop rotations using non-host crops, alternating susceptible and resistant cultivars. These are important control measures, but not easy to implement in Norway due to restricted acreage suitable for long rotations. The safe use of resistant potato cultivars requires a better knowledge on the presence of species and pathotypes in potato fields. In order to improve our information of the occurrence of PCN a new national survey program for the principal potato districts has started. These surveys will complemented by information generated from a new research project dealing with: studies of the virulence of selected PCN populations, decline rates of nematode field population densities and infection potential over time of populations from fields placed under quarantine regulations. studies on the occurrence and pathogenicity of microbial antagonistic parasitic on PCN, and their potential of future management of PCN, the safe use of early potato cultivars as a practical control method, and the potential for using Solanum sisymbriifolium as a trap crop, distinguish the degree of resistance of selected potato varieties available on the Norwegian market, and initial studies of the PCN-Potato-Pathosystem. These expected results of this project possibly will improve the management of PCN, and may alleviate present regulatory restrictions.
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In Nordic countries organic farming started as bio-dynamic farms in the 1930s, and still in the 1970s only a small number of farms were organic. Since then the acreage of organic farming has increased and in 2007 Sweden had 222 268 ha (7.9%), Finland 147 557 ha (6.4 %), Denmark 147 482 ha (5.4%), Norway 43 033 ha (4.7%) and Iceland 4 684 ha (0.27%). In northern areas the short vegetation period combined with low temperatures reducing mineralisation causing nutritional deficit may restrict yields. As mineral fertilizers are prohibited in organic farming, plant nutrition and yield depend on proper microbial activity for nutrient cycling. Plant parasitic nematodes (PPN) reduce plant growth, while microbivorous nematodes (MBN) increase nutrient accessibility. Nitrogen fixating legumes, used to improve soil nitrogen levels, may increase densities of PPN to levels causing crop damage. Management of PPN in organic farming relies on knowledge of population dynamics, damaging thresholds and cultural methods like weed control, sanitation, mulching, crop rotation and resistant cultivars. Keeping PPN below damaging levels and supporting beneficial MBN to improve mineralisation would increase yields and improve quality of organics crops in northern areas. Management of MBN is less well understood, but may be of crucial importance for organic farming in northern areas.