Suchergebnisse

Fatty acid-and retinol-binding proteins (FARs) are unique to nematodes, and are implicated in a wide range of metabolic and parasitic related functions. Along with the in silico analyses performed in this study, three different FAR members of this family were identified in Pratylenchus penetrans. The cDNA corresponding to the fatty acid-and retinol-binding Pp-far-1 gene was cloned and herein characterized at the molecular level for the first time for this genus. The translated 185 amino acid sequence of P. penetrans FAR-1 sequence, with a predicted molecular weight of 20.82 kDa and a pI of 5.49, shares highest sequence identity to FARs of other migratory nematodes of the Pratylenchidae family (90% to P. vulnus and 80% to Radopholus similis). In situ hybridization localizes Pp-far-1 transcripts in the hypodermis of the nematode. RT-qPCR detected Pp-far-1 transcripts for all nematode developmental stages, with highest expression levels found in juveniles, adult females and adult males, respectively. Pp-far-1 is also highly expressed during infection and establishment of P. penetrans in roots of different host plants, such as corn, lily and soybean. The importance of Pp-far-1 was studied by in planta RNA interference (RNAi) assays using stable soybean hairy root lines. Targeting Pp-far-1 decreased expression of the nematode Pp-far-1 and significantly reduced the reproduction of nematodes, with a total of between 44% and 70% fewer nematodes in comparison to the average number of nematodes counted for control lines. The results indicate that suppressing the expression levels of Pp-far-1 can act as an effective target gene to control P. penetrans. ; National Institute of Food and Agriculture, US Department of AgricultureUnited States Department of Agriculture (USDA) [11588909] ; The authors acknowledge the technical assistance of Sarah Shih. This material is based upon work that is supported by the National Institute of Food and Agriculture, US Department of Agriculture, under award number 11588909. Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the US Department of Agriculture. ; Public domain authored by a U.S. government employee

Lilium longiflorum cv. Nellie White, commonly known as Easter lily, is an important floral crop with an annual wholesale value of over $26 million in the United States. The root-lesion nematode, Pratylenchus penetrans, is a major pest of lily due to the significant root damage it causes. In this study, we investigated the cytological aspects of this plant-nematode interaction using bright-field and transmission electron microscopy. We took advantage of an in vitro culture method to multiply lilies and follow the nematode infection over time. Phenotypic reactions of roots inoculated with P. penetrans were evaluated from 0 to 60 d after nematode infection. Symptom development progressed from initial randomly distributed discrete necrotic areas to advanced necrosis along entire roots of each inoculated plant. A major feature characterizing this susceptible host response to nematode infection was the formation of necrosis, browning, and tissue death involving both root epidermis and cortical cells. Degradation of consecutive cell walls resulted in loss of cell pressure, lack of cytoplasmic integrity, followed by cell death along the intracellular path of the nematode's migration. Pratylenchus penetrans was never seen in the vascular cylinder as the layer of collapsed endodermal cells presumably blocked the progression of nematodes into this area of the roots. This study presents the first detailed cytological characterization of P. penetrans infection of Easter lily plants. ; National Institute of Food and Agriculture, U.S. Department of AgricultureUnited States Department of Agriculture (USDA) [11588909] ; The authors acknowledge the technical assistance of Sarah Shih. This material is based on work that is supported by the National Institute of Food and Agriculture, U.S. Department of Agriculture, under award number 11588909. ; Public domain authored by a U.S. government employee

In recent years, several newly discovered viruses infecting free-living nematodes, sedentary plant-parasitic nematodes, and migratory root lesion nematodes have been described. However, to the best of our knowledge, no comprehensive research focusing exclusively on metagenomic analysis of the soil nematode community virome has thus far been carried out. In this work, we have attempted to bridge this gap by investigating viral communities that are associated with soil-inhabiting organisms, particularly nematodes. This study demonstrates a remarkable diversity of RNA viruses in the natural soil environment. Over 150 viruses were identified in different soil-inhabiting hosts, of which more than 139 are potentially new virus species. Many of these viruses belong to the nematode virome, thereby enriching our understanding of the diversity and evolution of this complex part of the natural ecosystem. ; United States Department of Agriculture Agricultural Research Service CRISUnited States Department of Agriculture (USDA)USDA Agricultural Research Service [8042-21000-300-00D] ; Published version ; This project was supported by the United States Department of Agriculture Agricultural Research Service CRIS project number 8042-21000-300-00D. ; Public domain authored by a U.S. government employee

The root lesion nematode (RLN), Pratylenchus penetrans, is a migratory species that attacks a broad range of crops, including alfalfa. High levels of infection can reduce alfalfa forage yields and lead to decreased cold tolerance. Currently, there are no commercially certified varieties with RLN resistance. Little information on molecular interactions between alfalfa and P. penetrans, that would shed light on mechanisms of alfalfa resistance to RLN, is available. To advance our understanding of the host-pathogen interactions and to gain biological insights into the genetics and genomics of host resistance to RLN, we performed a comprehensive assessment of resistant and susceptible interactions of alfalfa with P. penetrans that included root penetration studies, ultrastructural observations, and global gene expression profiling of host plants and the nematode. Several gene-candidates associated with alfalfa resistance to P. penetrans and nematode parasitism genes encoding nematode effector proteins were identified for potential use in alfalfa breeding programs or development of new nematicides. We propose that preformed or constitutive defenses, such as significant accumulation of tannin-like deposits in root cells of the resistant cultivar, could be a key to nematode resistance, at least for the specific case of alfalfa-P. penetrans interaction. ; United States Department of Agriculture - Agricultural Research Service, CRIS project [8042-21000-268-00D] ; This research was supported by the United States Department of Agriculture - Agricultural Research Service, CRIS project 8042-21000-268-00D. ; Public domain authored by a U.S. government employee