Nematode Race Research Articles

On the races of plant parasitic nematodes with special reference to the soybean cyst nematode

On the races of plant parasitic nematodes with special reference to the soybean cyst nematode

Evaluation of Nematicides and Resistant Cultivar for Control of Soybean Cyst Nematode Race 4

Evaluation of Nematicides and Resistant Cultivar for Control of Soybean Cyst Nematode Race 4

Reniform nematode resistance in potato clones

SeveralSolatium tuberosum clones were tested for resistance to the reniform nematode,Rotylenchulus reniformis. Commercial cultivars La Rouge and possibly Red La Soda had high levels of resistance to the reniform nematode.R. reniformis resistance was found to exist independently of the H1, H2, or H3 genes for resistance to races of potato cyst nematodes,Globodera rostochiensis andG. pallida. In addition to reniform nematode resistance, B7642-2, B7154-8 and B7680-6 contained the H1 gene and breeding linePI 377741 contains the H1 and H2 gene for potato cyst nematode resistance. Over a three month period reniform nematode counts were significantly lower in pots where resistant varieties were grown.

Intraspecific Variation in Ditylenchus Dipsaci I. Compatibility Tests With Races

Hybridization was attempted with ten stem nematode races in 44 different combinations and a total of nearly 900 single crossings, using Melilotus dentatus seedlings as the bridging and occasionally callus tissue and potato tubers. Fertile hybrid populations were obtained in most combinations, but there was a consistent failure in some cases where one combination was successful but the reciprocal one with the same two races failed, producing only eggs which did not hatch. This happened most notably where the lucerne, red clover and white clover races were involved. The significance of these observations is discussed with reference to host specialization and reproductive isolation that approaches the sibling species concept. Host specificity tests indicated that at least some of the hybrid populations combined the host range characteristics of the parental races. No resistance-breaking features were observed among the hybrid nematodes.

Studies of Ditylenchus Dipsaci Races Using Electrophoresis in Acrylamide Gel

The technique of electrophoresis in polyacrylamide gel was adopted to study homogenates of Ditylenchus dipsaci races and Aphelenchoides ritzemabosi. An unequivocal difference in protein patterns was found between the two nematode species. Differences in intensity and position of protein bands were found between the four stem nematode races, but further investigations are needed to establish the reliability of the observed differences with regard to a possible race characterization.

Crossing Experiments With Races of Ditylenchus Dipsaci On Callus Tissue Cultures

Using callus tissue cultures derived from different ley legume species it was shown that the red clover and lucerne races of Ditylenchus dipsaci can interbreed and produce a fertile progeny. The hybrid population seems to be more polyphagous than are the parents. Callus tissue cultures provide a very suitable substrate for experiments of this kind and must be considered as advantageous over the use of living plants. It is probable that all stem nematode races can be reared on calluses of very different origin.