Sr9d

(Knott, 1966) (Plate 3-10)

Synonym

Sr1 (Ausemus et al., 1946; Knott, 1966, 1968, 1971).

Low Infection Type

1- to 2+.

Environmental Variability

Probably low.

Origin

T. turgidum. Sr9d was originally transferred to the bread wheats Hope and H-44 from Yaroslav emmer (McFadden, 1930). Sr9d is present in the Stakman et al. (1962) durum differentials Mindum, Arnautka and Spelmar.

Pathogenic Variability

In North America, Sr9d was effective against race 56 but was not effective against race 15B which caused catastrophic epidemics in the early 1950s. In the international survey of Huerta-Espino (1992) virulence levels generally approached 100%, except for Turkey. Sr9d has always been ineffective in Australasia.

Reference Stocks

i: Hope/10*Marquis (Knott, 1968); H-44/10*Marquis (Knott, 1968); IHope 2B-Ra (Loegering and Harmon, 1969); Sr9d/8*LMPG (Knott, 1990).

v: Hope Sr2 Sr7b Sr17.

tv: Arnautka (Roelfs and Martens, 1988); Mindum (Roelfs and Martens, 1988); Spelmar (Roelfs and Martens, 1988).

Source Stocks

Australia: Hopps Sr2 (Sunderwirth and Roelfs, 1980). Lawrence Sr2 Sr7b Sr17. Spica Sr7b Sr17.

Canada: Selkirk Sr2 Sr6 Sr7b Sr17 Sr23. Redman Sr2 Sr7b Sr17; Renown Sr2 Sr7b Sr17.

USA: Shawnee; Sturdy. Scout Sr2 Sr17.

tv: Nugget.

 

A. Seedling leaves of (L to R): durums Mindum, Arnautka, Spelmar and common wheats IHope 2B-Ra (Sr9d), LMPC + Sr9d and LMPG; infected with an impure University of Missouri culture of 59-51A. The IT 2 pustules on the fourth and fifth leaves are typical of plants with Sr9d infected with avirulent cultures. Although the three durums carry Sr9d, a second more effective (non-designated) gene confers resistance to both culture 59-51A and the contaminating culture.

B. Seedling leaves of ISr9d-Ra infected with USDA Cereal Rust Laboratory culture BDCN. Courtesy AP Roelfs.

 

Use in Agriculture

Sr9d was of some use in both common wheats and durums in North America until the outbreaks of 15B in the early 1950s which affected both common and tetraploid wheats.