Identification of Cadmium-regulated genes by cDNA-AFLP in the heavy metal accumulator Brassica juncea L.

In this study, cDNA-amplified fragment length polymorphism(cDNA-AFLP) analysis was employed toidentify genes that exhibited a modulated expressionfollowing cadmium (Cd) treatment in Brassica junceagrown in hydroponic culture. Plants were treatedfor 6 h, 24 h, and 6 weeks with 10 lM Cd(NO3)2 anduntreated 6-week-old plants were used as controls.Cd content was measured at these four time points.Long exposure to Cd affected root morphology: rootsappeared thinner and sent out side roots. Seventythreetranscript-derived fragments were identified asCd responsive. Fifty-two of them showed significanthomology to genes with known or putative function,10 transcript-derived fragments were homologous touncharacterized genes, while 11 transcript-derivedfragments did not show significant matches. Theexpression pattern of several of these genes wasconfirmed by northern blot analysis. Fifty-two genesof known or putative function were transcriptionalfactors, expression regulators, and stress respondingand transport facilitation genes, as well as genesinvolved in cellular metabolism and organization andthe photosynthetic process, suggesting that a multitudeof processes are implicated in Cd stress response.The transcription of drought- and abscisicacid-responsive genes observed in this study alsosuggested that Cd imposes water stress and thatabscisic acid may be involved in the Cd plantresponse.