Showing papers on "Heterodera avenae published in 2019"

A Novel G16B09-Like Effector From Heterodera avenae Suppresses Plant Defenses and Promotes Parasitism.

Abstract: Plant parasitic nematodes secrete effectors into host plant tissues to facilitate parasitism. In this study, we identified a G16B09-like effector protein family from the transcriptome of Heterodera avenae, and then verified that most of the members could suppress programmed cell death triggered by BAX in Nicotiana benthamiana. Ha18764, the most homologous to G16B09, was further characterized for its function. Our experimental evidence suggested that Ha18764 was specifically expressed in the dorsal gland and was dramatically upregulated in the J4 stage of nematode development. A Magnaporthe oryzae secretion system in barley showed that the signal peptide of Ha18764 had secretion activity to deliver mCherry into plant cells. Arabidopsis thaliana overexpressing Ha18764 or Hs18764 was more susceptible to Heterodera schachtii. In contrast, BSMV-based host-induced gene silencing (HIGS) targeting Ha18764 attenuated H. avenae parasitism and its reproduction in wheat plants. Transient expression of Ha18764 suppressed PsojNIP, Avr3a/R3a, RBP-1/Gpa2, and MAPK kinases (MKK1 and NPK1Nt)-related cell death in Nicotiana benthamiana. Co-expression assays indicated that Ha18764 also suppressed cell death triggered by four H. avenae putative cell-death-inducing effectors. Moreover, Ha18764 was also shown strong PTI suppression such as reducing the expression of plant defense-related genes, the burst of reactive oxygen species, and the deposition of cell wall callose. Together, our results indicate that Ha18764 promotes parasitism, probably by suppressing plant PTI and ETI signaling in the parasitic stages of H. avenae.

RNAi-Based Biocontrol of Wheat Nematodes Using Natural Poly-Component Biostimulants

Abstract: With the growing global demands on sustainable food production, one of the biggest challenges to agriculture is associated with crop losses due to parasitic nematodes. While chemical pesticides have been quite successful in crop protection and mitigation of damage from parasites, their potential harm to humans and environment, as well as the emergence of nematode resistance, have necessitated the development of viable alternatives to chemical pesticides. One of the most promising and targeted approaches to biocontrol of parasitic nematodes in crops is that of RNA interference (RNAi). In this study we explore the possibility of using biostimulants obtained from metabolites of soil streptomycetes to protect wheat (Triticum aestivum L.) against the cereal cyst nematode Heterodera avenae by means of inducing RNAi in wheat plants. Theoretical models of uptake of organic compounds by plants, and within-plant RNAi dynamics, have provided us with useful insights regarding the choice of routes for delivery of RNAi-inducing biostimulants into plants. We then conducted in planta experiments with several streptomycete-derived biostimulants, which have demonstrated the efficiency of these biostimulants at improving plant growth and development, as well as in providing resistance against the cereal cyst nematode. Using dot blot hybridization we demonstrate that biostimulants trigger a significant increase of the production in plant cells of si/miRNA complementary with plant and nematode mRNA. Wheat germ cell-free experiments show that these si/miRNAs are indeed very effective at silencing the translation of nematode mRNA having complementary sequences, thus reducing the level of nematode infestation and improving plant resistance to nematodes. Thus, we conclude that natural biostimulants produced from metabolites of soil streptomycetes provide an effective tool for biocontrol of wheat nematode.

Heterodera avenae GLAND5 Effector Interacts With Pyruvate Dehydrogenase Subunit of Plant to Promote Nematode Parasitism.

Abstract: Heterodera avenae mainly infects cereal crops and causes severe economic losses. Many studies have shown that parasitic nematodes can secrete effector proteins to suppress plant immune responses and then promote parasitism. In this study, we showed that HaGland5, a novel effector of H. avenae, was exclusively expressed in dorsal esophageal gland cell of nematode, and up-regulated in the early parasitic stage. Transgenic Arabidopsis thaliana lines expressing HaGland5 were significantly more susceptible to H. schachtii than wild-type control plants. Conversely, silencing of HaGland5 through barley stripe mosaic virus-medicated host-induced gene silencing technique substantially reduced the infection of H. avenae in wheat. Moreover, HaGland5 could suppress the plant defense responses, including the repression of plant defense-related genes, reducing deposition of cell wall callose and the burst of reactive oxygen species. Mass spectrometry, co-immunoprecipitation, and firefly luciferase complementation imaging assays confirmed that HaGland5 interacted specifically with Arabidopsis pyruvate dehydrogenase subunit (AtEMB3003).

Two venom allergen-like proteins, HaVAP1 and HaVAP2, are involved in the parasitism of Heterodera avenae.

Abstract: Despite the fact that venom allergen-like proteins (VAPs) have been identified in many animal- and plant-parasitic nematodes, studies on VAPs in Heterodera avenae, which is an important phytonematode, are still in their infancy. Here, we isolated, cloned and characterized two VAPs, named HaVAP1 and HaVAP2, from H. avenae. The two encoded proteins, HaVAP1 and HaVAP2, harbour an SCP-like domain each, but share only 38% identity with each other. HaVAP1 and HaVAP2 are expressed in subventral and dorsal oesophageal glands, respectively. HaVAP1 is expressed mainly at the early stages, whereas HaVAP2 accumulates principally at the late stages. Both HaVAP1 and HaVAP2 are secreted when expressed in Nicotiana benthamiana leaves, but HaVAP1 is delivered into chloroplasts, whereas HaVAP2 is translocated to the nucleus without signal peptides. Knocking down HaVAP1 increased the virulence of H. avenae. In contrast, silencing of HaVAP2 hampered the parasitism of H. avenae. Both HaVAP1 and HaVAP2 suppressed the cell death induced by BAX in N. benthamiana leaves. Moreover, HaVAP2 physically interacted with a CYPRO4-like protein (HvCLP) of Hordeum vulgare in the nucleus of the plant. It is reasonable to speculate that the changes in the transcript of HvCLP are associated with HaVAP2 during the parasitism of H. avenae. All results obtained in this study show that both HaVAP1 and HaVAP2 are involved in the parasitism of H. avenae, but they possess different functions, broadening our understanding of the parasitic mechanism of H. avenae.

Transcriptional profiling of wheat ( Triticum aestivum L.) during a compatible interaction with the cereal cyst nematode Heterodera avenae

Abstract: Cereal cyst nematode (CCN, Heterodera avenae) presents severe challenges to wheat (Triticum aestivum L.) production worldwide. An investigation of the interaction between wheat and CCN can greatly improve our understanding of how nematodes alter wheat root metabolic pathways for their development and could contribute to new control strategies against CCN. In this study, we conducted transcriptome analyses of wheat cv. Wen 19 (Wen19) by using RNA-Seq during the compatible interaction with CCN at 1, 3 and 8 days past inoculation (dpi). In total, 71,569 transcripts were identified, and 10,929 of them were examined as differentially expressed genes (DEGs) in response to CCN infection. Based on the functional annotation and orthologous findings, the protein phosphorylation, oxidation-reduction process, regulation of transcription, metabolic process, transport, and response process as well as many other pathways previously reported were enriched at the transcriptional level. Plant cell wall hydrolysis and modifying proteins, auxin biosynthesis, signalling and transporter genes were up-regulated by CCN infection to facilitate penetration, migration and syncytium establishment. Genes responding to wounding and jasmonic acid stimuli were enriched at 1 dpi. We found 16 NBS-LRR genes, 12 of which were down-regulated, indicating the repression of resistance. The expression of genes encoding antioxidant enzymes, glutathione S-transferases and UDP-glucosyltransferase was significantly up-regulated during CCN infection, indicating that they may play key roles in the compatible interaction of wheat with CCN. Taken together, the results obtained from the transcriptome analyses indicate that the genes involved in oxidation-reduction processes, induction and suppression of resistance, metabolism, transport and syncytium establishment may be involved in the compatible interaction of Wen 19 with CCN. This study provides new insights into the responses of wheat to CCN infection. These insights could facilitate the elucidation of the potential mechanisms of wheat responses to CCN.

Distribution of Cereal Cyst Nematodes (Heterodera avenae and H. filipjevi) in Eastern Washington State.

Abstract: Cereal cyst nematodes (CCN; Heterodera avenae and H. filipjevi), cause substantial worldwide yield loss in small grain cereals such as wheat, barley, and oat. H. avenae was first detected in the Un...

Fine mapping of Rha2 in barley reveals candidate genes for resistance against cereal cyst nematode

Abstract: The cereal cyst nematode resistance locus Rha2 was mapped to a 978 kbp region on the long arm of barley chromosome 2H. Three candidate genes are discussed. The cereal cyst nematode (CCN) Heterodera avenae is a soil-borne obligate parasite that can cause severe damage to cereals. This research involved fine mapping of Rha2, a CCN resistance locus on chromosome 2H of barley. Rha2 was previously mapped relative to restriction fragment length polymorphisms (RFLPs) in two mapping populations. Anchoring of flanking RFLP clone sequences to the barley genome assembly defined an interval of 5077 kbp. Genotyping-by-sequencing of resistant and susceptible materials led to the discovery of potentially useful single nucleotide polymorphisms (SNPs). Assays were designed for these SNPs and applied to mapping populations. This narrowed the region of interest to 3966 kbp. Further fine mapping was pursued by crossing and backcrossing the resistant cultivar Sloop SA to its susceptible ancestor Sloop. Evaluation of F2 progeny confirmed that the resistance segregates as a single dominant gene. Genotyping of 9003 BC2F2 progeny identified recombinants. Evaluation of recombinant BC2F3 progeny narrowed the region of interest to 978 kbp. Two of the SNPs within this region proved to be diagnostic of CCN resistance across a wide range of barley germplasm. Fluorescence-based and gel-based assays were developed for these SNPs for use in marker-assisted selection. Within the candidate region of the reference genome, there are nine high-confidence predicted genes. Three of these, one that encodes RAR1 (a cysteine- and histidine-rich domain-containing protein), one that is predicted to encode an acetylglutamate kinase and one that is predicted to encode a tonoplast intrinsic protein, are discussed as candidate genes for CCN resistance.

Analysis of the Barley Cereal Cyst Nematode Resistance Locus Rha2

Abstract: ...................................................................................................................................... 4 Thesis declaration ....................................................................................................................... 6 Acknowledgments ...................................................................................................................... 7 List of abbreviations ................................................................................................................... 9 List of figures ............................................................................................................................ 11 List of tables .............................................................................................................................. 16 List of appendices ..................................................................................................................... 17 Chapter

Effect of Crop Rotation with Legumes and Other Crops on Soil Health and Population of Heterodera avenae

Abstract: Two pot experiments were conducted under screen house condition in Department of Nematology, CCSHAU, Hisar. In first experiment, 5 kg capacity earthen pots filled with H. avenae infested soil in which wheat was rotated with fallow, resistant and susceptible wheat, gram, fenugreek, mustard, cabbage, garlic and onion for one season (2015–16). In the next year, susceptible wheat was sown in each pot and after harvest nematode population was recorded. Results revealed that rotation with all the crops, except susceptible wheat reduced nematode population. Crop rotation with gram and fenugreek improved maximum soil health but rotation with mustard reduced maximum nematode population as well as maintained soil heath in terms of nutrients status like N, P, K and Zn. In second experiment, penetration and development of cereal cyst nematode was observed in rotational crops. Results found that among rotational crops maximum number of juveniles was observed in susceptible wheat followed by resistant wheat. More number of males developed in resistant wheat.

Incidence of important plant parasitic nematode in wheat and barley in Haryana

Abstract: A survey was undertaken to determine the frequency and abundance of plant-parasitic nematodes associated with wheat (Triticum aestivum) in Haryana. During 2017 and 2018, in total 113 composite soil samples collected from Hisar and Fatehabad districts. Nematodes were extracted by Cobb’s Sieving and Decanting Technique followed by Modified Baermann’s Funnel Technique, identified to generic level and quantified. More than five genera of plant-parasitic nematodes were identified along with various type of free-living nematodes. Heterodera avenae was found in 32.3 % of the fields sampled during 2017 and 39.5 % during 2018. Pratylenchus sp. was identified in 38.4 % the fields sampled during 2017 and 35.4 during 2018.

Histopathological changes of some resistant and susceptible wheat cultivars caused by plant parasitic nematodes

Abstract: Root lesion nematodes, Pratylenchus thornei Sher & Allen, 1953 and Pratylenchus neglectus (Rensch, 1924) (Tylenchida: Pratylenchidae), and cereal cyst nematode, Heterodera avenae Wollenweber, 1924 (Tylenchida: Heteroderidae) are economically important migratory and sedentary endoparasites on host plant roots. In this study, cellular variations in roots of resistant and susceptible wheat cultivars infected by P. thornei , P. neglectus and H. avenae were investigated between 2017 and 2018. Wheat cultivars were infected with P. neglectus, P. thornei, and H. avenae, separately and H. avenae and P. thornei together. Twelve weeks after inoculation, roots were washed, embedded in paraffin, cut by microtome. The root cell slides were examined under light microscope for histopathological changes in the root cells. The root lesion nematodes moved from epidermal to cortical cells by damaging the cells along the feeding path. Due to the nematode infection, cortical cells of most wheat cultivars were destroyed by the development of many cavities in the root tissue. Also, it was observed that many root lesion nematodes fed collectively on the same site either stretched out or coiled in different cell layers. Heterodera avenae fed on the cortex cells as did root lesion nematode.

Genetic Background of the Resistance against Parasitic Nematodes in Wheat

Abstract: The state of the art in research on the genes responsible for the resistance of soft wheat Triticum aestivum L. against cereal cyst nematode Heterodera avenae and root lesion nematode Pratylenchus neglectus and the use of these genes in plant breeding programs are described. Most genes responsible for the resistance to these plant pathogens are listed and their chromosomal localization and resistance specificity are described. The sources of resistance genes widely used to control the cereal cyst nematode are presented. The alternative methods for transferring nematode resistance genes into wheat are outlined.

Identification of Resistance Sources to Cereal Cyst Nematode, Heterodera avenae Wollenweber in Barley (Hordeum vulgare L.)

Abstract: Ramanna Koulagi1, Simarjit Kaur2, S. P. Bishnoi3* and R. S. Kanwar4 1Department of Plant Pathology, Punjab Agricultural University, Ludhiana-141004, India 2Wheat section, Department of Plant Breeding and Genetics, Punjab Agricultural University, Ludhiana-141004, India 3Rajasthan Agricultural Research Institute (RARI), SKN Agricultural University, Durgapura, Jaipur-302 018, India 4Department of Nematology, CCS Haryana Agricultural University, Hisar-125004, India