Identification of Differentially Expressed Sequence Tags in Rapidly Elongating Phyllostachys pubescens Internodes by Suppressive Subtractive Hybridization

Bamboo shoots grow quickly through the rapid elongation of internodes, but the precise molecular mechanisms underlying this process remain unknown. We used a combination of suppressive subtractive hybridization (SSH), dot blotting, sequencing and bioinformatics to identify Phyllostachys pubescens genes that are differentially expressed in rapidly elongating vs. static internodes (SIs). We isolated 1020 expressed sequence tags (ESTs) by SSH, 173 of which were shown to be differentially expressed by dot blotting. We then sequenced the 20 ESTs showing the greatest difference in expression, 13 of which were preferentially expressed in elongating internodes and seven in SIs. Functional characterization of the ESTs showed that rapid internode elongation requires meristem initiation and proliferation, high-level protein synthesis, cellular respiration, and cell wall synthesis, as well as the regulation of the activated methyl cycle, gibberellin and brassinosteroid biosynthesis, and their signal transduction pathways.