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 CodeSubsetInfection type produced on host lines with Sr
I5219e7b
II1168a9g
III369b3013+17
IV9a9d10Tmp
V243138McN

BLowLowLowLow
CLowLowLowHigh
DLowLowHighLow
FLowLowHighHigh
GLowHighLowLow
HLowHighLowHigh
JLowHighHighLow
KLowHighHighHigh
LHighLowLowLow
MHighLowLowHigh
NHighLowHighLow
PHighLowHighHigh
QHighHighLowLow
RHighHighLowHigh
SHighHighHighLow
THighHighHighHigh

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].