Ant 566 is a mutant induced from the cultivar Manker, which carries the ant13 gene (Jende-Strid, 1988). An allele at this locus was found to be linked to net blotch susceptibility in a cross between Ant 13-13 with the resistant cultivar Norbert (Metcalfe and Bendelow, 1981). Therefore, we decided to determine if negative associations existed between the gene in Ant 566 and resistance to net blotch, incited by Phyrenophora teres Drechs., and spot blotch, incited by Cochliobolus sativus (Ito and Kurib. in Kurib) Drechs. ex Dast., present in the resistant line NDB112.

Material for this study was derived from the cross Ant 566/NDBI12. Five plants were harvested from each of 15 F₃ families homozygous for the ant gene and from each of 15 families homozygous for normal pigmentation. A total of 150 F₃ derived F₄ families were examined for the two diseases in separate experiments. Seedlings were inoculated with single spore isolates of the two organisms as described by Berglund and Pederson (1981). The material was arranged in five sets, with each set containing ant and normal families. Three runs of each experiment separated at weekly intervals for net blotch, and daily intervals for spot blotch were conducted. Six days after inoculation disease reaction was scored based on a 0-9 scale.

Net blotch and spot blotch mean reactions (Table 1) of mutant and normal families were similar but significantly different in the two experiments (Table 2). Net blotch reaction was higher (3.9) for the mutant group compared to the normal group (3.7). This observed difference may be caused by an association of a factor determining net blotch susceptibility with ant13. Spot blotch reaction was higher for the normal group (4.2) than for the mutant group (3.6). This difference may be caused by a gene for resistance linked to the ant13 allele present in the mutant material.

Results obtained from these experiments suggest that genes having small effect on reaction to the two diseases are weakly associated with ant13 locus. Also, we can assume that the gene for net blotch resistance in Norbert (Metcalfe and Bendelow, 1981) is not present in NDBI12 or a stronger association between Ant 566 and net blotch susceptibility would have been observed. The range in disease reactions observed for ant selections and normal type families was very similar for the two diseases, indicating that resistant lines can be selected from either the ant or normal material.

References:

Berglund, D., and V.D. Pederson. 1981. Improved technique for screening barley lines against Cochliobolus sativus and Pyrenophora teres. Phytopathology 71:1115. (Abstr.)

Jende-Strid, B. 1988. Coordinator's report: Anthocyanin genes. Stock list of ant mutants kept at Carlsberg Laboratory. BGN 18:74-79.

Metcalfe, D.R., and V.M. Bendelow. 1981. Relations between barley polyphenol content and reaction to stem rust and net blotch. In Barley Genetics IV, Edinburgh, pp. 484-488.