Integrative analysis of exogenous auxin mediated plant height regulation in Moso bamboo (Phyllostachys edulis)

Auxin is important in regulating bamboo growth and development. Morphological and anatomical analyses of naturally growing Moso bamboo treated with auxin revealed that auxin-mediated regulation of bamboo height mainly increased internode length rather than nodes number. For individual internodes, auxin regulated inter -node elongation mainly by promoting cell elongation. Targeted metabolomic assays of endogenous hormones found that exogenous auxin treatment affected the dynamic balance of endogenous hormones, resulting in increased levels of gibberellin and cytokinin. Transcriptome sequencing indicated that the regulation of inter -node length by auxin is mainly through phytohormone signaling pathway, amino acid synthesis and protein processing pathway, and energy metabolism pathway. The transcription factors that play major regulatory roles included the ethylene response factor, WRKY and MYB transcription factor, NAC structural domain protein and basic leucine zipper protein. By constructing a gene regulatory network, we found that auxin may crosstalk with multiple plant hormones. Yeast two-hybrid and transgenic experiments demonstrated that the auxin signaling factor PheAUX/IAA34 and the jasmonic acid signaling factor PheTIFY28 do interact and regulate growth in response to phytohormones. Overall we have obtained good quality bamboo internode material for industry through the auxin treatment and have preliminarily investigated the mechanism, which will provide a reference for bamboo plant height regulation.