One hundred and eighty three accessions identified with a Pi-ta
gene specific marker from a USDA core collection were used in the
study (Wang et al., 2010), and were obtained from the Genetic stock
oryza (GSOR) collection at DB NRRC (www.ars.usda.gov/spa/
dbnrrc/gsor). Twenty four rice monogenic lines (MLs) and rice variety LTH were grown in a greenhouse at 20
Ce30
C day/night
until seedlings were at the three to four leaf stages, approximately
two weeks after sowing, for DNA extraction and pathogenicity assays. The leaves (20 g per genotype) were collected in a 1.5 mL tube
and stored in a 80
C freezer for DNA extraction. Pathogenicity
assays were conducted as previously described by Jia et al. (Jia et al.,
2004). Plants were placed in plastic bags and sprayed with 35 mL of
a conidial suspension (2 10
5
conidia/mL). The inoculated bags
were sealed to maintain more than 90% humidity and maintained
in the dark at 25
Ce28
C. After 24 h, the inoculated seedlings were
moved to a greenhouse and maintained at 20
Ce30
C with 12 h
light/dark for five to six days for disease development. Pathogenicity assays were performed twice and the average of disease reaction of 6e14 seedlings per genotype was used for disease rating.
Disease reactions were rated with a scale of 0e5, with 0e2 indicating different resistant reactions (R), and 3 to 5 indicating
different susceptible reactions (S), respectively