Showing papers on "Heterodera avenae published in 1993"

Resistance to the cereal cyst nematode (Heterodera avenae Woll.) transferred from the wild grassAegilops ventricosa to hexaploid wheat by a "stepping-stone" procedure.

Abstract: Transfer of resistance toHeterodera avenae, the cereal cyst nematode (CCN), by a "stepping-stone" procedure from the wild grassAegilops ventricosa to hexaploid wheat has been demonstrated. The number of nematodes per plant was lower, and reached a plateau much earlier, in the resistant introgression line H93-8 (1-2 nematodes per plant) than in the recipient H10-15 wheat (14-16 nematodes per plant). Necrosis (hypersensitive reaction) near the nematode, little cell fusion, and few, often degraded syncytia were observed in infested H93-8 roots, while abundant, well-formed syncytia were present in the susceptible H10-15 wheat. Line H93-8 was highly resistant to the two Spanish populations tested, as well as the four French races (Fr1-Fr4), and the British pathotype Hall, but was susceptible to the Swedish pathotypes HgI and HgIII. Resistance was inherited as though determined by a single quasi-dominant factor in the F2 generations resulting from crosses of H93-8 with H10-15 and with Loros, a resistant wheat carrying the geneCre1 (syn.Ccn1). The resistance gene in H93-8 (Cre2 orCcn2) is not allelic with respect to that in Loros. RFLPs and other markers, together with the cytogenetical evidence, indicate that theCre2 gene has been integrated into a wheat chromosome without affecting its meiotic pairing ability. Introduction ofCre2 by backcrossing into a commercial wheat backgroud increases grain yield when under challenge by the nematode and is not detrimental in the absence of infestation.

Development of Heterodera avenae Woll. and host cellular responses in susceptible and resistant wheat

Abstract: Le developpement des juveniles du nematode a kystes des cereales (Heterodera avenae Woll), ainsi que l'anatomie et l'ultrastructure des syncitiums induits chez le ble par le nematode, sont etudies sur les lignees isogeniquement proches Prins (sensible) et AUS 10894 × Prins (resistante). Apres inoculations synchrones, le developpement des mâles va jusqu'a son achevement chez les deux cultivars tandis que celui des femelles est stoppe au quatrieme stade juvenile chez le cv. resistant. Chez les deux cultivars, la formation des syncitiums debute au quatrieme jour et ils se developpent de facon identique jusqu'au quinzieme jour. A ce stade, chez le cultivar sensible les syncitiums deviennent visiblement tres actifs, la taille des vacuoles diminuant tandis que le volume du cytoplasme augmente et que de nombreux organites apparaissent

Damage to Italian Crops caused by Cyst-forming Nematodes

Abstract: Investigations were undertaken in 1982-88 to estimate yield losses of carrot, sugarbeet, wheat, and potato caused by cyst-forming nematodes (Heterodera and Globodera species) in several provinces of Italy. Soil samples were collected at planting in 0.5-ha sampling areas distributed in each crop's major production area. Yield loss estimates were based on nematode population estimates and on curves derived earlier relating nematode densities with crop yields in Italy. Estimated yield loss values were based on the average prices reported for Italy in 1989. Heterodera carotae caused carrot yield losses in the Foggia (20%) and Venice (12%) provinces. Heterodera schachtii was common in our samples, but sugarbeet yield losses were highest in the province of L'Aquila (21%), followed by Ferrara (4.2%), Ravenna (3.3%), Modena (2.7%), and Rovigo (2.6%). Globodera rostochiensis and G. pallida were widespread in only a few of the major potato growing areas, but yield losses are remarkably high at Forli (17%) followed by Bari (9%), Catanzaro (6%), Foggia (3%), and Trento (3%). Heterodera avenae was common on wheat in the sampled provinces, but caused less than 1% yield reductions. Values of total estimated yield losses were 21.1 billion (Italian liras) for potato, 13.8 billion for sugarbeet, 3.2 billion for carrot, and 2.6 billion for wheat. Key words: Beta vulgaris, carrot, Daucus carota, Globodera rostochiensis, Globodera pallida, Heterodera avenae, Heterodera carotae, Heterodera schachtii, nematode, potato, Solanum tuberosum, sugarbeet, Triticum durum, wheat, yield loss.

Ultrastructure of Infection of Cyst Nematode Eggs By the Nematophagous Fungus Verticillium Suchlaspori Um

Abstract: Ultrastructural studies showed that strains of Verticillium suchlasporium isolated from eggs of Heterodera avenae, infected in vitro eggs of H. avenae and Globodera pallida. In H. avenae, V suchlasporium formed appressoria at the point of infection. In serial sections it was observed that a narrow penetration hypha perforated the egg-shell and formed an infection bulb. Other types of penetration hyphae and germinating conidia were also found. Areas of low electron-density were frequently observed, suggesting the secretion of enzymes by V. suchlasporium to weaken the egg-shell. Penetration of eggs of G. pallida was similar to that described for H. avenae, but the egg-shell of G. pallida was twice as thick as that of H. avenae (approximately 500 nm). Ultrastructure of infection of cyst nematode eggs by V. suchlasporium has features in common with other nematophagous fungi.

Partial Resistance to Heterodera avenae in Wheat Lines with the 6M v Chromosome from Aegilops ventricosa.

Abstract: Lines of wheat with the 6M[supv] chromosome from Aegilops ventricosa display partial resistance to both pathotypes Hal2 and Ha41 of Heterodera avenae. With either pathotype, the effect of this alien chromosome on cyst production, size, and fecundity was expressed in resistance tests. Partial resistance of five 6M[supv](6D) substitution lines varied according to the intrinsic cyst-forming capacity of the nematode pathotypes and the recipient germplasms. Such partial resistance can be utilized in wheat breeding lines for integrated management of the cereal cyst nematode. Key words: addition line, Aegilops ventricosa, breeding, cereal cyst nematode, gene, Heterodera avenae, nematode, partial resistance, pathotype, resistance, resistance test, substitution line, Triticum aestivum.

A contribution to the ecology of fungi associated with females and cysts of heterodera avenae in eastern scotland

Abstract: Infected field soil was used to investigate the colonisation of cereal roots by fungi associated with Heterodera avenae in eastern Scotland. Results indicated that Verticillium invaded cereal roots before females of H. avenae and that the fungus colonised wheat roots more rapidly than oats while barley roots were invaded least rapidly. A greater number of H. avenae juveniles were found associated with roots infected by Veticillium compared with uninfected controls. After surface sterilization with sodium hypochlorite, white females of H. avenae developed only Verticillium colonies, suggesting that the fungus colonizes the female at an early stage of development. There was also evidence that Verticillium may produce metabolites that stimulate premature hatching of the juveniles contained in the eggs.

Barley grass control with herbicides in subterranean clover. 2. Effect on pasture and wheat in the year following spraying

Abstract: Barley grass (Hordeum spp.) in a subterranean clover pasture was controlled using herbicides at different growth stages in 1988. The residual effects of these treatments on a naturally regenerating pasture and on wheat were investigated in 1989. Barley grass control carried over into 1989 but there was no increase in subterranean clover seedling density 1 resulting from legume dominance in 1988. Dry matter I production in early winter, on plots treated with herbicide in 1988, was reduced by up to 62% compared with unsprayed pasture, and the proportion of other broadleaf weed species increased. Wheat yields were increased by 3-11% where barley grass was controlled with fluazifop-p in the previous pasture. Available soil moisture at sowing was lowest following pasture that was unsprayed in 1988. No effect on the level of take-all (caused by Gaumannomyces graminis var. tritici) was evident. A replacement graminaceous species should be introduced into the pasture following barley grass control so that animal production and soil conservation are not disadvantaged. A disease break for a following cereal crop can be maintained by sowing an oat cultivar that is resistant to cereal cyst nematode (Heterodera avenae).

Respuesta de Dactylis glomerata L. al nematodo de los cereales, Heterodera avenae Woll.

Abstract: ZANCADA, M C , SANCHEZ, A. y LINDNER, R. (1993): Respuesta de Dactylis glomerata L. al nematodo de los cerales, Heterodera avenae Woll. Bol. San. Veg. Plagas, 19(1): 37-41. Fourteen populations of Dactylis glomerata L. have been screened for resistance to Heterodera avenae Woll. pathotype Ha22. The test has included diploid and tetraploid plants in order to find out differences in response to the attack of the nematode between the two cytotypes. Results indicate there is no correlation between the level of ploidy of the populations screened and their resistance/susceptibility to the parasite.

Distribution of heterodera avenae in czecho-slovakia

Abstract: The cereal-cyst nematode, Heterodera avenae occurred in Czecho-Slovakia in 59.3% of localities sampled. The highest population density of the nematode was found in the region with intensive cereal cultivation.