Fig 1. Screening of Cd tolerance gene in Brassica rapa.

(A) Insert size of B. rapa cDNA library. Inserts of the B, rapa cDNA library in the pYES2 vector were amplified using PCR with vector linker primers, and electrophoresed in 1% agarose gel. (B) First selection of Cd tolerance genes in B. rapa. The Cd-sensitive yeast mutant (DTY167) was transformed with a cDNA library of B. rapa and grown on synthetic galactose (SG) agar plates supplemented with 70 μM CdCl₂ to select clones harboring Cd tolerance genes. (C, D) Second selection of Cd tolerance genes in B. rapa. The surviving clones from the 1’st screening were grown on synthetic dextrose (SD) and synthetic galactose (SG) media supplemented with 40 μM CdCl₂ to select real positive clones. False-positive clones surviving on SD supplemented with CdCl₂ were discarded. The clones growing on SG but not on SD were further analyzed.