Plant gene expression response to Agrobacterium tumefaciens

To elucidate the nature of plant response to infection and transformation b y Agrobacterium tumefaciens, we compared the cDNA-amplified fragment length polymorphism (AFLP) pattern of Agrobacterium- and mock-inoculated Ageratum conyzoides plant cell cultures. From 16,000 cDNA fragments analyzed, 251 ( 1.6%) were differentially regulated (0.5% down-regulated) 48 h after cocult ivation, with Agrobacterium. From 75 strongly regulated fragments, 56 were already regulated 24 h after cocultivation. Sequence similarities were obta ined for 20 of these fragments, and reverse transcription-PCR analysis was carried out with seven to confirm their cDNA-AFLP differential pattern. The ir sequence similarities suggest a role for these genes in signal perceptio n, transduction, and plant defense. Reverse transcription-PCR analysis indi cated that four genes involved in defense response are regulated in a simil ar manner by nonpathogenic bacteria, whereas one gene putatively involved i n signal transduction appeared to respond more strongly to Agrobacterium. A nodulin-like gene was regulated only by Agrobacterium. These results demon strate a rapid plant cell response to Agrobacterium infection, which overla ps a general response to bacteria but also has Agrobacterium-specific featu res.