2006 Volume 99 Pages 245-257
Heterologous hybridization was carried out with a 5.8-k Arabidopsis cDNA macroarray and cDNA synthesized from total RNA of cultured cells of the liverwort, Marchantia polymorpha. Total RNA from Arabidopsis thaliana cells was also hybridized with the macroarray for comparison. Genes with signal intensities three-fold greater than that of λ DNA (negative control) were defined as the expressed genes. The gene expression profiles of cultured cells of A. thaliana and M. polymorpha were compared with those of whole A. thaliana plants and M. polymorpha thalli, respectively. About 50% of the expressed genes of A. thaliana showed cell-type-specific expression patterns. In contrast, the gene expression profile of cultured cells of M. polymorpha was similar to that of the thalli. A comparison of the gene expression profiles of both types of cultured cells had identified, among the genes expressed in both A. thaliana plants and M. polymorpha thalli, 110 genes that were expressed in cultured cells of M. polymorpha, but not in suspension cultures of A. thaliana. Ten of these genes were selected and the corresponding A. thaliana genes were isolated using reverse transcription-polymerase chain reaction. Northern hybridization with the 10 Arabidopsis genes demonstrated that all of the genes were expressed in cultured cells of M. polymorpha and in whole plants of both species, but none was detectably expressed in cultured cells of A. thaliana, confirming the results of the macroarray analysis. These results suggest that hybridization of Arabidopsis macroarrays with cDNAs of a bryophyte can be used to screen for novel genes that are expressed under specific conditions, such as in suspension cultures.
