USE OF DIFFERENTIAL DISPLAY TO IDENTIFY NOVEL SESBANIA-ROSTRATA GENESENHANCED BY AZORHIZOBIUM-CAULINODANS INFECTION

Upon infection of the tropical legume Sesbania rostrata with Azorhizob ium caulinodans ORS571, nodules are formed on the roots as well as on the stems, Stem nodules appear at multiple predetermined sites consist ing of dormant root primordia, which are positioned in vertical rows a long the stem of the plant, We used the differential display method to isolate and characterize three cDNA clones (differential display; did i-2, didi-13, and didi-20), corresponding to genes whose expression is enhanced in the dormant root primordia after inoculation, Database se arches revealed that the deduced (partial) didi-2 gene product shares significant similarity with hydroxyproline-rich cell wall proteins, Th e (partial) didi-13 and didi-20 products are similar to chitinases and chalcone reductases, respectively, Transcripts corresponding to the c DNA clones didi-2 and didi-13 were first detectable 1 day after inocul ation. In contrast, didi-20 transcripts were found at low levels in un infected root primordia and were enhanced significantly around 3 days after inoculation, In addition, a cDNA was isolated (didi-42) that cor responds to the previously identified leghemoglobin gene Srlb6, These studies show that differential display is a useful method for the isol ation of infection-related genes.