Transcriptome-Wide Analyses Provide Insights into Development of the Hedychium coronarium Flower, Revealing Potential Roles of PTL

Abstract

Background:The ower of Hedychium coronarium possesses highly specialized oral organs: a synsepalous calyx, petaloid staminodes and a labellum. The formation of these organs is controlled by two gene categories: oral organ identity genes and organ boundary genes, which may function individually or jointly during ower development. Although the oral organogenesis of H. coronarium has been studied at the morphological level, the underlying molecular mechanisms involved in its oral development still remain poorly understood. In addition, previous works analyzing the role of MADS-box genes in controlling oral organ speci cation in some Zingiberaceae did not address the molecular mechanisms involved in the formation of particular organ morphologies that emerge later in ower development, such as the synsepalous calyx formed through intercalary growth of adjacent sepals. Results:Here, we used comparative transcriptomics combined with Real-time quantitative PCR and mRNA in situ hybridization to investigate gene expression patterns of ABC-class genes in H. coronarium owers, as well as the homolog of the organ boundary gene PETAL LOSS (HcPTL). qRT-PCR detection showed that HcAP3 and HcAG were expressed in both the petaloid staminode and the fertile stamen. mRNA in situ hybridization showed that HcPTL was expressed in developing meristems, including cincinnus primordia, oral primordia, common primordia and almost all new initiating oral organ primordia. Conclusions:Our studies found that stamen/petal identity or stamen fertility in H. coronarium was not necessarily correlated with the differential expression of HcAP3 and HcAG. We also found a novel spatio-temporal expression pattern for HcPTL mRNA, suggesting it may have evolved a lineage-speci c role in the morphogenesis of the Hedychium ower. Our study provides a new transcriptome reference and a functional hypothesis regarding the role of a boundary gene in organ fusion that should be further addressed through phylogenetic analyzes of this gene, as well as functional studies.

Analyzing Morphology, Metabolomics, and Transcriptomics Offers Invaluable Insights into the Mechanisms of Pigment Accumulation in the Diverse-Colored Labellum Tissues of Alpinia

“…When assessing species similarity through Nr annotation, the highest similarity (70.46%, 87,060 unigenes) was observed with genes from Musa acuminata in the same order as Alpinia, followed by Elaeis guineensis (3.96%, 4888 unigenes) and Phoenix dactylifera (3.23%, 3991 unigenes). This pattern aligns with previous research conducted on Zingiber zerumbet and Hedychium coronarium, two species from the same family (Zingiberaceae) as Alpinia [23,24].…”