Stage Specificity, the Dynamic Regulators and the Unique Orchid Arundina graminifolia.

Sagheer Ahmad,Jianpeng Jin,Jie Gao,Chuqiao Lu,Yonglu Wei,Genfa Zhu,Fengxi Yang,Chuanyuan Zheng

doi:10.3390/ijms222010935

Abstract

Orchids take years to reach flowering, but the unique bamboo orchid (Arundina graminifolia) achieves reproductive maturity in six months and then keeps on year round flowering. Therefore, studying different aspects of its growth, development and flowering is key to boost breeding programs for orchids. This study uses transcriptome tools to discuss genetic regulation in five stages of flower development and four tissue types. Stage specificity was focused to distinguish genes specifically expressed in different stages of flower development and tissue types. The top 10 highly expressed genes suggested unique regulatory patterns for each stage or tissue. The A. graminifolia sequences were blasted in Arabidopsis genome to validate stage specific genes and to predict important hormonal and cell regulators. Moreover, weighted gene co-expression network analysis (WGCNA) modules were ascertained to suggest highly influential hubs for early and late stages of flower development, leaf and root. Hormonal regulators were abundant in all data sets, such as auxin (LAX2, GH3.1 and SAUR41), cytokinin (LOG1), gibberellin (GASA3 and YAB4), abscisic acid (DPBF3) and sucrose (SWEET4 and SWEET13). Findings of this study, thus, give a fine sketch of genetic variability in Orchidaceae and broaden our understanding of orchid flower development and the involvement of multiple pathways.

Highlights

Orchidaceae, one of the largest family of angiosperms, contains ornamental orchids [1,2].More than 0.1 million orchid species are cultivated worldwide due to their immense horticultural importance
The chemical constituents and medicinal compounds have been discussed in numerous studies, the molecular pattering of floral regulation remains elusive for A. graminifolia
The juvenile phase of bamboo orchid completes in six months, which is quite fast as compared to other orchids, such as Cymbidium and Phalaenopsis, taking 2–3 years for vegetative growth

Summary

Introduction

Orchidaceae, one of the largest family of angiosperms, contains ornamental orchids [1,2].More than 0.1 million orchid species are cultivated worldwide due to their immense horticultural importance. The most popular orchid species, such as Cymbidium and Phalaenopsis, flower in specific times of the year [3]. The bamboo orchid blooms year round and produces peak flowering from September to January. It is mainly found in sub-tropical and tropical areas of Asia [4,5,6,7]. It is a rich source of phenols, stilbenoids, bibenzyls and flavonoids, possessing antioxidant, anti-tumor and anti-viral properties [8]. The chemical constituents and medicinal compounds have been discussed in numerous studies, the molecular pattering of floral regulation remains elusive for A. graminifolia

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Discussion

Conclusion