| Rice blast disease,caused by Magnaporthe oryzae is one of the most destructive fungal diseases of rice and threatens the global food security.The rice blast pathosystem has become a model system for understanding plant-fungus interactions.The rice blast resistance gene Pi-d2 encodes a RLKs protein with a predicted extracellular domain of a bulb-type mannose specific binding lectin（B-lectin）and an intracellular serine-threonine kinase domain.The Pi-d2 protein is plasma membrane localized.The cognate M oryzae avirulence gene Avr-Pid2 was mapped to chromosome 7 in FJ81278.In order to elucidate the interaction between Pi-d2 and Avr-Pid2,we try to clone the Avr-Pid2 by map-based cloning.We compared the sequences of chromosome 7 in FJ81278 and GUY11,and thereby got 14 PATE markers,2 SSR markers and 1 Indel marker that linked to Avr-Pid2.The next markers on both side of Avr-Pid2 are InMGG18043 and P1.The genetic distance between Avr-Pid2 and InMGG18043,between Avr-Pid2 and P1 is 1.4cM and 2.6cM respectively.Interestingly,three molecular markers SSR7-67/68,ProAvrPiz-t and ProMGG18042 are cosegregated with the Avr-Pid2.This indicates that the cloned AvrPiz-t is tightly linked to the Avr-Pid2.Therefore,the sequences between the markers ProMGG18043 and P1 were analyzed,and thereby two Avr-Pid2 candidate genes,MGG 18042 and MGG18041（AvrPiz-t）were selected.The functional analysis of the two candidate genes showed that the AvrPiz-t also has the avirulence function of the Avr-Pid2. |
