Identification of genes differentially expressed during the growth of Bambusa oldhamii.

Bamboos are ecologically and economically important grasses, and are distinguished by their rapid growth. To identify genes associated with bamboo growth, PCR-based mRNA differential display was used to clone genes that were differentially expressed in various tissues of bamboo (Bambusa oldhamii) shoots at different growth stages. In total, 260 different cDNA sequences were obtained. These genes displayed complex expression profiles across the different tissues and growth stages as revealed by a cDNA microarray analysis. Notable among them were genes that were temporally up-regulated or down-regulated in the internode-containing region of rapidly elongating shoots. These genes might participate in the rapid elongation of the bamboo culm. Of the 36 up-regulated and 46 down-regulated genes, 16 genes and 8 genes, respectively, were predicted to encode hypothetical proteins or were unknown sequences. Aside from these, genes involved in hormonal signaling and homeostasis, stress responses, peptide processing and signaling and lignin biosynthesis composed most of the up-regulated genes; genes involved in DNA replication, nucleic acid binding and signal transduction were highly represented among the down-regulated genes. These results suggested that genes associated with plant hormonal signaling and homeostasis, peptide signaling, reactive oxygen species signaling and homeostasis, several stress-related genes and a monocot-specific unknown gene, BoMSP41, play important roles in the elongation of bamboo internodes. Multiple signaling pathways might form a complex interconnected network that controls the rapid growth of this giant grass.