A new pathotype characterization of Daxing and Huangyuan populations of cereal cyst nematode(Heterodera avenae) in China

The cereal cyst nematode（CCN, Heteroder aavenae） causes serious yield loss on cereal crops, especially wheat, worldwide. Daxing population in Beijing City and Huangyuan population in Qinghai Province, China, are two CCN populations. In this study, the CCN pathotypes of Daxing and Huangyuan populations were characterized by tests on 23 standard ＂International Test Assortment＂ with the local species Wenmai 19 as the susceptible control. Tested materials were grouped by three nematode populations＇ virulence on resistant genes（Rha1, Rha2, Rha3, Cre1） and nonresistant genes, varieties and lines. Both Daxing and Huangyuan populations were avirulent to Ortolan（Ha1）. Barley cvs. Ortolan, Siri, Morocco, Bajo Aragon 1-1, and Martin 403-2 were all resistant to both populations. Cultivars Herta, Harlan 43 and wheat Iskamish-K-2-light were all susceptible to Huangyuan population, all of them, however, were resistant to Daxing population. The other five oats were all resistant to the two tested CCN populations. Except Iskamisch K-2-light, all the other wheat cultivars（Capa, Loros×Koga, AUS 10894, and Psathias） were susceptible to Daxing population. Because the pathotypes of the two tested CCN populations in Beijing and Qinghai were not identical to any of the 13 pathotypes previously characterized by the test assortment, we classified Daxing and Huangyuan populations as the new pathotypes, named Ha91.

Golden Promise barley(Hordeum vulgare) is a suitable candidate model host for investigation interaction with Heterodera avenae

Heterodera avenae （cereal cyst nematode, CCN） infects many cereal crops and causes serious yield losses worldwide. Interaction studies investigating H. avenae and its hosts are still in their infancy. In this study, a barley model plant, the Hordeum vulgare cultivar Golden Promise, was investigated for its potential as a candidate model host to study its inter- action with H. avenae. CCN-infective juveniles were attracted by the root tips and gathered around the root elongation zones of Golden Promise on 0.7% water agar plates. The juveniles invaded the roots and developed successfully until maturation at 40 days after inoculation in sterile sand soil. The cryotomy and syncytium measurements indicated that the syncytia enlarged gradually throughout the development of the nematodes and caused the corresponding root regions to swell obviously. Quantitative real-time PCR analysis showed that the down-regulation of defence-related barley genes and up-regulation Of development-related barley ger^es contribute to the understanding of compatible interaction between H. avenae and Golden Promise. Barley stripe mosaic virus （BSMV） virus-induced gene silencing （VIGS） can be used in the roots of Golden Promise. In conclusion, the Hordeum vulgare cultivar Golden Promise is a suitable candidate model host for interaction studies with Heterodera avenae. The studies presented above document the first CCN host that no.t only has published genome context but also be compatible to BSMV VIGS.

Molecular Characterization and Functional Analysis of a New Acid Phosphatase Gene(Ha-acp1) from Heterodera avenae

For sedentary endo-parasitic nematodes, parasitism genes encoding secretory protein expressed in the subventral glands cells always play an important role during the early parasitic process. A new acid phosphatase gene （Ha-acp1） expressed in the subventral glands of the cereal cyst nematode （Heterodera avenae） was cloned and the characteristics of the gene were analyzed. Results showed that the gene had a putative signal peptide for secretion and in situ hybridization showed that the transcripts of Ha-acp1 accumulated speciifcally in the subventral gland cells of H. avenae. Southern blot analysis suggested that Ha-acp1 belonged to a multigene family. RT-PCR analysis indicated that this transcription was strong at the pre-parasitic juveniles. Knocking down Ha-acp1 using RNA interference technology could reduce nematode infectivity by 50%, and suppress the development of cyst. Results indicated that Ha-acp1 could play an important role in destroying the defense system of host plants.

Morphological and molecular characterizations of cereal cyst nematode Heterodera avenae Wollenweber, 1924 from the Czech Republic

The cereal cyst nematode,Heterodera avenae Wollenweber,1924,is a major pest of cereal crops throughout the world and causes serious yield losses,especially of wheat.Previous studies have shown that this species is widely distributed in the Czech Republic.In this study,seven populations of H.avenae were molecularly studied,and one population was morphologically described.Three regions（18S,28S,and internal transcribed spacer 1）of ribosomal DNA were sequenced and the analysis of the 18S gene of six populations did not reveal any variation,whereas the internal transcribed spacer 1and 28S sequences of six populations differed by only two nucleotides from a population in？ilina.Precise and quick identification of cereal cyst nematodes is important for effective control measures and ribosomal sequence analyses of seven populations in this study will be useful in future phylogenetic studies of Heterodera spp.occurring in the Czech Republic.

Resistance of barley varieties to Heterodera avenae in the Qinghai–Tibet Plateau,China

The cereal cyst nematode,Heterodera avenae,is one of the most economically important pathogens impacting the worldwide production of cereals and is widely distributed in more than 16 regions in China.The present study used the numbers of nematodes inside the plant roots to evaluate the resistance/susceptibility of different subpopulations of barley Hordeum vulgare(QH2R,QH6R and TB2R)to H.avenae under field and pot conditions.Nematode development in two highly resistant varieties was also evaluated by in vivo experiment and microscopic observation.Analyses of 186selected varieties showed the numbers of susceptible varieties identified with the number of females/cysts per plant(NFP)method were significantly higher than those identified with the Pf/Pi ratio(PPR)method,which indicated that the NFP method rather than the PPR method is more reliable to evaluate the resistance of barley.The field and pot experiment results indicated that the QH2R subpopulation had lower females/cysts numbers than QH6R and TB2R subpopulations,and eight HR varieties(Sunong 7617,Sunong 7635,Dongyuan 87-14,Rudong 14-46,Rudong 87-57,Rudong 87-8-45,Rudong 88-14-2,and Rudong 88-67-1)were identified in QH2R,with the NFP numbers below 4.2.Further microscopic observation of nematode development suggested that H.avenae often penetrated less into highly resistant varieties(Sunong 7635 and Dongyuan 87-14)and more frequently failed to develop into females than the susceptible barleys.The promising resistant varieties identified in the present research might be helpful for breeders to develop CCN-resistant cultivars and control H.avenae populations effectively at low costs.

Host status of Brachypodium distachyon to the cereal cyst nematode

Cereal cyst nematode（Heterodera avenae, CCN） distributes worldwide and has caused severe damage to cereal crops, and a model host will greatly aid in the study of this nematode. In this research, we assessed the sensitivity of 25 inbred lines of Brachypodium distachyon to H. avenae from Beijing, China. All lines of B. distachyon were infested by secondstage juveniles（J2s） of H. avenae from Daxing District of Beijing population, but only 13 inbred lines reproduced 0.2–3 cysts/plant, showing resistance. The entire root system of the infested B. distachyon appeared smaller and the fibrous roots were shorter and less numerous. We found that a dose of 1 000 J2s of H. avenae was sufficient for nematode infestation. We showed that Koz-1 of B. distachyon could reproduce more cysts than TR2A line. Line Koz-1 also supported the complete life cycles of 5 CCN geographical populations belonging to the Ha1 or Ha3 pathotype group. Our results suggest that B. distachyon is a host for CCN.