Sr34

(McIntosh et al., 1982) (Plate 3-35)

Chromosome Location

2A (2A/2M, translocation), 2D (2D/2M translocation), 2M (McIntosh et al., 1982). Sr34 is present in wheats with Yr8.

Low Infection Type

1N to 3. 2C to 23CN (Huerta-Espino, 1992).

Environmental Variability

Most effective at low temperatures.

Origin

T. comosum.

Pathogenic Variability

Avirulence for Sr34 is relatively rare in Australia with only two older related pathotypes producing low ITs on tester stocks (McIntosh et al., 1982). Knott (1990) reported avirulence in a Canadian culture of race 111 which is known to be widely avirulent. In the survey of cultures carried out by Huerta-Espino (1992) avirulence was common with levels approaching 50% in south Asia (Pakistan and Nepal), Ethiopia, Kenya, the Malagasy Republic and South America. He found no virulence among collections from China but he cited unpublished 1984 results from CC Hu and AP Roelfs indicating a virulence level of 84%. Thus for international comparisons of pathogenicity, a line with Sr34 would be a useful differential.

Reference Stocks

i: Sr.34/6*LMPG (Knott, 1990); Compair; Chinese Spring 2D/2M 3/8 (C77.1); Chinese Spring 2A/2M 4/2 (C77.2) (McIntosh et al., 1982).

su: Chinese Spring 2M(2A) (McIntosh et al., 1982).

Source Stocks

None.

 

Seedling leaves of (L to R): Compair, CS 2D/2M 3/8 = C77.1 and Chinese Spring; infected with pt. 126-5, 6, 7, 11 and incubated at A. 18°C and B. 28/23°C. This and a closely related culture are the only Australian pathotypes avirulent for Sr34.

 

Use in Agriculture

Translocations with Sr34 have not been deployed in commercial cultivars.