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Leaf rust, caused by
Puccinia triticina
, is one of the most widespread diseases in common wheat globally. The Chinese wheat cultivar Zhoumai 22 is highly resistant to leaf rust at the seedling and adult stages. Seedlings of Zhoumai 22 and 36 lines with known leaf rust resistance genes were inoculated with 13
P. triticina
races for gene postulation. The leaf rust response of Zhoumai 22 was different from those of the single gene lines. With the objective of identifying and mapping, the new gene(s) for resistance to leaf rust, F
1
, F
2
plants and F
2:3
lines from the cross Zhoumai 22/Chinese Spring were inoculated with Chinese
P. triticina
race FHDQ at the seedling stage. A single dominant gene, tentatively designated
LrZH22
, conferred resistance. To identify other possible genes in Zhoumai 22, ten
P
.
triticina
races avirulent on Zhoumai 22 were used to inoculate 24 F
2:3
lines. The same gene conferred resistance to all ten avirulent races. A total of 1300 simple sequence repeat (SSR) markers and 36 EST markers on 2BS were used to test the parents, and resistant and susceptible bulks. Resistance gene
LrZH22
was mapped in the chromosome bin 2BS1-0.53-0.75 and closely linked to six SSR markers (
barc183
,
barc55
,
gwm148
,
gwm410
,
gwm374
and
wmc474
) and two EST markers (
BF202681
and
BE499478
) on chromosome arm 2BS. The two closest flanking SSR loci were
Xbarc55
and
Xgwm374
with genetic distances of 2.4 and 4.8 cM from
LrZH22
, respectively. Six designated genes (
Lr13
,
Lr16
,
Lr23
,
Lr35
,
Lr48
and
Lr73
) are located on chromosome arm 2BS. In seedling tests,
LrZH22
was temperature sensitive, conferring resistance at high temperatures. The reaction pattern of Zhoumai 22 was different from that of RL 4031 (
Lr13
), RL 6005 (
Lr16
) and RL 6012 (
Lr23
),
Lr35
and
Lr48
are adult-plant resistance genes, and
Lr73
is not sensitive to the temperature. Therefore,
LrZH22
is likely to be a new leaf rust resistance gene or allele.