Gene expression analysis of Cyanophora paradoxa reveals conserved abiotic stress responses between basal algae and flowering plants.

Camilla Ferrari,Marek Mutwil

doi:10.1111/nph.16257

Abstract

The glaucophyte Cyanophora paradoxa represents the most basal member of the kingdom Archaeplastida, but the function and expression of most of its genes are unknown. This information is needed to uncover how functional gene modules, that is groups of genes performing a given function, evolved in the plant kingdom. We have generated a gene expression atlas capturing responses of Cyanophora to various abiotic stresses. The data were included in the CoNekT-Plants database, enabling comparative transcriptomic analyses across two algae and six land plants. We demonstrate how the database can be used to study gene expression, co-expression networks and gene function in Cyanophora, and how conserved transcriptional programs can be identified. We identified gene modules involved in phycobilisome biosynthesis, response to high light and cell division. While we observed no correlation between the number of differentially expressed genes and the impact on growth of Cyanophora, we found that the response to stress involves a conserved, kingdom-wide transcriptional reprogramming, which is activated upon most stresses in algae and land plants. The Cyanophora stress gene expression atlas and the tools found in the https://conekt.plant.tools/ database thus provide a useful resource to reveal functionally related genes and stress responses in the plant kingdom.

Highlights

The glaucophyte algae are a basally diverging group of unicellular taxa with four described genera and an estimated 15 species (Kies & Kremer, 2006)
Due to these unique traits, Cyanophora can provide invaluable insights into the ancestral state of the Archaeplastida host, its photosynthetic organelle, and the evolution of the functional gene modules found in the plant kingdom
The first is that co-expression networks require gene expression data capturing as many different observations as possible (Usadel et al, 2009)

Summary

Introduction

The glaucophyte algae are a basally diverging group of unicellular taxa with four described genera and an estimated 15 species (Kies & Kremer, 2006). The plastids of red and green algae participated in several other endosymbioses, leading to the appearance of diatoms, dinoflagellates, euglenids, and haptophytes (Reyes-Prieto et al, 2007) Glaucophytes, and their representative Cyanophora paradoxa, retain traits from the ancestral cyanobacterial endosymbiont, such as phycobilisomes, peptidoglycan (PG), an ancient, primitive RNA interference pathway (Gross et al, 2013), lack of chlorophyll-b (Löffelhardt, 2014) and presence of a bacterial-derived UhpC-type hexose-phosphate transporter used to translocate sugars from the plastid to the host cytosol, that is not found in land plants (Price et al, 2012). Due to these unique traits, Cyanophora can provide invaluable insights into the ancestral state of the Archaeplastida host, its photosynthetic organelle, and the evolution of the functional gene modules found in the plant kingdom

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