TAGGING XA-1, THE BACTERIAL-BLIGHT RESISTANCE GENE IN RICE, BY USING RAPD MARKERS

For identification of random amplified polymorphic DNA (RAPD) markers tightly linked to Xa-1, which is one of the bacterial blight resistanc e genes in rice, a near-isogenic line (NIL) for Xa-1 and a recurrent c ultivar were screened by RAPD primers. Two out of 280 primers produced DNA fragments tightly linked to Xa-1, namely U08(750) and Y03(700). N o recombinant was detected between Xa-1 and Y03(700), indicating that this RAPD fragment was closely linked to Xa-1. Y03(700) existed in IR- BB 1 and Kogyoku as a single copy sequence, but did not exist in IR 24 . UO8(750) was linked to Xa-1 at a distance of 1.4 +/- 1.4 cM. These R APD markers will facilitate selection of Xa-1 for breeding and will be starting points of gene cloning based on chromosome walking in near f uture.