Result s
Identification of the Pi-tagene by DNA markers
The status of the Pi-tagene in all 141 accessions studied was
completely consistent using the dominant marker primer pair
YL155/YL87 (Fig. 1). As shown in Fig. 1, the presence of a
1086-bp amplification product when the YL155/YL87 pair was
used for the PCR indicates that an accession contains the Pi-ta
gene (Fig. 1a). Weak bands displayed in Fig. 1 were nonspecific
amplification product artefacts that could not be repeated, and
thus were disregarded. The absence of the resistant Pi-taallele
when this dominant marker was used could be due to a failed
reaction, and thus accessions without the 1086 bp amplification
were subjected to an additional PCR amplification using a
marker specific to the susceptible pi-ta allele (Fig. 1b). Simi-larly, the presence of the amplification product at 1087 bp when
the primer pair for marker YL183/YL87 was used indicates
that a susceptible pi-ta allele is in this accession (Fig. 1b,c).
To verify the presence and absence of the Pi-tagene, two
additional DNA markers that amplify different parts of the
Pi-tagene YL100/YL102 and YL153/YL154 were analysed
(Table 1). Pi-ta-containing rice cultivars have all three markers
for the Pi-tagene, and a total of 20 rice accessions containing
Pi-tawere identified from 141 rice cultivars (Table 1).