Pm34: a new powdery mildew resistancegene transferred from Aegilops tauschii Coss. to common wheat
Name:SONGLIli Major:Biological Sciences
Powdery mildew is a major fungal disease in wheat growing areas worldwide.
Plant material Methods Results
the powdery mildew resistant germplasm line NC97BGTD7 the powdery mildew susceptible cultivar Saluda Chinese Spring nullitetrasomic Nulli5D-tetra5A and ditelosomic Dt5DL lines a single spore culture isolate
(1)Cross experiments (2)Microsatellite markers analysis (3)The PRC reactions (4)Data analysis Chi-square(x2)tests for goodness-of-fit MAPMAKER\Exp Version3.0b
NC97BGTD7 (R) ╳ Saluda(S) ↓ shortened NCD7(R) ╳ Saluda(S) ↓ F1 hybrid ╳ F1 hybrid ↓ F2 ╳ F2 ↓ F2:3 ↓ F2:4
(①in the greenhouse ② in the field the F2:3 lines grew in 2002-2003 the F2:4 lines grew in 2003-2004)
Table 1 Segregation ratios for powdery mildew reaction of F2 derived families from the NCD7 X Saluda cross
F2:3 generation The chi-square test value was in good agreement with the expected (X21:2:1 = 2.47, P = 0.29).
? The phenotypic classi Wcation of the 10 F2:3lines
is shown in Table 1.
? The chi-square test value was ingood agreement with the expected 1:2:1 ratio of amonogenic trait (21:2:1= 2.47, P = 0.29). ? The observed pheno-typic classes also Wtted the 1:2:1 ratio (21:2:1= 2.48,P = 0.29) conWrming a single gene controlled resistance
Table 2 Segregation ratios for Microsatellite (SSR) markers among F2 individuals in the NCD7 X Saluda population
a AA homozygous for the NCD7 allele b H heterozygous c BB homozygous for the Saluda allele
The three microsatellite makers were co-dominant and segregated in the expected 1:2:1 ratio (Table 2).
No other marker locus order was within a LOD score of 3.0 from this most likely order.
?GISH with an St-genomic probe clearly answered questions about chromosome composition and structure of wheat-Th. intermedium partial amphiploids. ? These results indicate that resistance to WSMV, BYDV, rust, and powdery mildew are not located on St-genome chromosome sbut on J- or J S -genome chromosomes.
?In the present study, not only J-genome chromosomes but also JS –genome chromosomes were identified in TE253 and the resistance to powdery mildew and stripe rust may be located either on Jgenome or on J S -genome chromosomes. ?We are presently developing chromosome addition and substitution lines to identify the chromosome location of the powdery mildew and stripe rust resistance genes.