The de novo transcriptome identifies important zinc finger signatures associated with flowering in the orchid Arundina graminifolia

Abstract

Orchids take years to produce the most precious and expensive flowers. Continuous flowering is a rare characteristic of bamboo orchid (Arundina graminifolia). Therefore, finding genetic regulators of this flowering pattern can set new directions for other orchids. Present study demonstrates transcriptome analysis to identify a number of zinc finger transcription factors (ZF TFs) from five stages of flower development and four tissue types. About 480 DEGs were annotated to the zinc finger category, which may involve multiple signaling pathways for flowering control. The highest number of ZF TFs belonged to CCCH domain, followed by BED and INDETERMINATE. Some important ZF TFs were found to control the flowering genes at transcriptional levels. LATE and B-box ZFs respond to photoperiod and hormone signaling. MAD1 and SUF4 control flowering time through FLC. BZR1 and ELF6 possibly respond to vernalization pathway and HUA1 controls flowering through AGAMOUS pathway. WGCNA-based ZF candidates BBX22 and BBX24 involve circadian and hormonal pathways in association with floral integrators to regulate flowering time in A. graminifolia. Thus, our ZF mining can do a great deal to understand the molecular mechanism of continuous flowering in A. graminifolia.