Transcriptome analysis provides insights into xylogenesis formation in Moso bamboo (Phyllostachys edulis) shoot.

Maturation-related changes in cell wall composition and the molecular mechanisms underlying cell wall changes were investigated from the apical, middle and basal segments in moso bamboo shoot (MBS). With maturation extent from apical to basal regions in MBS, lignin and cellulose content increased, whereas heteroxylan exhibited a decreasing trend. Activities of phenylalanine amonnialyase (PAL), cinnamyl alcohol dehydrogenase (CAD) and cinnamate-4-hydroxylase (C4H), which are involved in lignin biosynthesis, increased rapidly from the apex to the base sections. The comparative transcriptomic analysis was carried out to identify some key genes involved in secondary cell walls (SCW) formation underlying the cell wall compositions changes including 63, 8, 18, and 31 functional unigenes encoding biosynthesis of lignin, cellulose, xylan and NAC-MYB-based transcription factors, respectively. Genes related to secondary cell wall formation and lignin biosynthesis had higher expression levels in the middle and basal segments compared to those in the apical segments. Furthermore, the expression profile of PePAL gene showed positive relationships with cellulose-related gene PeCESA4, xylan-related genes PeIRX9 and PeIRX10. Our results indicated that lignification occurred in the more mature middle and basal segments in MBS at harvest while lignification of MBS were correlated with higher expression levels of PeCESA4, PeIRX9 and PeIRX10 genes.

Alleviation of drought stress in Phyllostachys edulis by N and P application.

The aim of this study was to explore whether nutrition supply can improve the drought tolerance of Moso bamboo under dry conditions. One-year-old seedlings were exposed to two soil water content levels [wellwatered, 70 ± 5% soil-relative-water-content (SRWC) and drought stress, 30 ± 5% SRWC] and four combinations of nitrogen (N) and phosphorus (P) supply (low-N, low-P, LNLP; low-N, high-P, LNHP; high-N, high-P, HNHP; and high-N, low-P, HNLP) for four months. Plant growth, photosynthesis, chlorophyll fluorescence, water use efficiency and cell membrane stability were determined. The results showed that drought stress significantly decreased total biomass, net-photosynthesis (Pn), stomatal-conductance (gs), leaf-chlorophyll-content (Chlleaf), PSII-quantum-yield (ΦPSII), maximum-quantum-yield-of-photosynthesis (Fv/Fm), photochemical-quenching-coefficient (qP), leaf-instantaneous-water-use efficiency (WUEi), relative-water-content (RWC), photosynthetic-N-use-efficiency (PNUE), and photosynthetic-P-use-efficiency (PPUE). N and P application was found to be effective in enhancing the concentration of leaf N, gs, and Pn while reducing the production of reactive oxygen species under both water regimes. Under LNHP, HNHP and HNLP treatments, the decreases in total biomass, Pn, Chlleaf and Fv/Fm of drought-stressed were less evident than the decreases under LNLP. The study suggests that nutrient application has the potential to mitigate the drastic effects of water stress on Moso bamboo by improving photosynthetic rate, water-use efficiency, and increasing of membrane integrity.