Pathogenic Variability of Wheat Stem Rust Pathogen (Puccinia graminis f. sp. tritici) in Hararghe Highlands, Ethiopia

Table 2

The race nomenclature mechanisms (Pgt -code) for the 20 wheat stem rust differential hosts for Puccinia graminis f. sp. tritici in order of subsets of five.

Pgt Code	Subset	Infection type produced on host lines with Sr
	I	5	21	9e	7b
	II	11	6	8a	9g
	III	36	9b	30	13+17
	IV	9a	9d	10	Tmp
	V	24	31	38	McN
B		Low	Low	Low	Low
C		Low	Low	Low	High
D		Low	Low	High	Low
F		Low	Low	High	High
G		Low	High	Low	Low
H		Low	High	Low	High
J		Low	High	High	Low
K		Low	High	High	High
L		High	Low	Low	Low
M		High	Low	Low	High
N		High	Low	High	Low
P		High	Low	High	High
Q		High	High	Low	Low
R		High	High	Low	High
S		High	High	High	Low
T		High	High	High	High

Pgtcode consists of the designation for subset I followed by that for subset 2, etc. For examples, race TTTT is virulent (high infection type) on all 20 differential hosts and race BBBB is avirulent on all differential hosts. Low and High infection types indicate an incompatible and a compatible host-pathogen interaction, respectively; Differential sets I to V are described in Roelfs and Martens [15, 16]; IT 2++ produced on combination VII was considered as susceptible as indicated by Jin et al. [16].