De novo sequencing of the transcriptome of Fargesia macclureana (Poaceae) reveals regulators of the floral transition and ecological adaptations to high altitude

Abstract

Background Fargesia macclureana (Poaceae) is a woody bamboo species found on the Qinghai–Tibet Plateau (QTP) approximately 2,000 ~ 3800 m above sea level. It rarely blossoms in the QTP, but it flowered 20 days after growing in our lab, which is in a low-altitude area outside the QTP. To date, little is known regarding the molecular mechanism of bamboo flowering, and no studies of flowering have been conducted on wild bamboo plants growing in extreme environments. Here, we report the first de novo transcriptome sequence for F. macclureana to investigated the putative mechanisms underlying the flowering time control used by F. macclureana to adapt to its environment. Results Illumina deep sequencing of the F. macclureana transcriptome generated 140.94 Gb of data, assembled into 99,056 unigenes. A comprehensive analysis of the broadly, specifically and differentially expressed unigenes (BEUs, SEUs, and DEUs) and a weighted gene co-expression network analysis (WGCNA) revealed that changes in expressions of unigenes related to the circadian cycle may account for the differences in the floral transition of F. macclureana after being transplanted from the QTP to a laboratory outside. In addition, there were differences in active carbohydrate metabolism and signal transduction between the flowering and non-flowering plants. Moreover, we detected the expression of unigenes related to DNA repair and plant-pathogen interactions, which may be of adaptive importance. Finally, we detected 9,296 simple sequence repeats (SSRs) that may be useful for further molecular marker-assisted breeding. Conclusions F. macclureana may have evolved specific reproductive strategies for flowering-related pathways in response to photoperiodic cues to ensure long vegetation growing period. Our findings will provide new insights to future investigations into the mechanisms of flowering time control and adaptive evolution in plants growing at high altitudes.