Cherry Blossom Forecast Based on Transcriptome of Floral Organs Approaching Blooming in the Flowering Cherry (Cerasus × yedoensis) Cultivar 'Somei-Yoshino'.

Kenta Shirasawa,Sachiko Isobe,Akihiro Itai,Tomoya Esumi

doi:10.3389/fpls.2022.802203

Abstract

To gain insights into the genetic mechanisms underlying blooming and petal movement in flowering cherry (Cerasus × yedoensis), we performed time-course RNA-seq analysis of the floral buds and open-flowers of the most popular flowering cherry cultivar, ‘Somei-Yoshino.’ Independent biological duplicate samples of floral buds and open-flowers were collected from ‘Somei-Yoshino’ trees grown at three different locations in Japan. RNA-seq reads obtained from floral bud and open-flower samples collected in the current study (in 2019) and in a previous study (in 2017) were aligned against the genome sequence of ‘Somei-Yoshino’ to quantify gene transcript levels. Clustering analysis of RNA-seq reads revealed dynamic changes in the transcriptome, with genes in seven modules predominantly expressed at specific time points, ranging from 5 weeks before flowering to 2 weeks after flowering. Based on the identified gene modules and Gene Ontology (GO) terms enriched at different floral stages, we speculate that the genetic mechanisms underlying petal movement and flower opening in cherry involve the processes of development, cell wall organization, reproduction, and metabolism, which are executed by genes encoding transcription factors, phytohormones, transporters, and polysaccharide metabolic enzymes. Furthermore, we established a statistical model for cherry bloom forecasting, based on gene expression levels as RNA markers at different time points before flowering.

Highlights

IntroductionKnown as sakura, typically blooms in the spring and is valued as a popular ornamental flower across the world
Flowering cherry, known as sakura, typically blooms in the spring and is valued as a popular ornamental flower across the world
Subsequent weighted gene correlation network analysis (WGCNA) of the RNA sequencing (RNA-seq) data indicated that 1,541 genes belonging to seven modules were involved in blooming at stages from 4 to 5 weeks before flowering (WBF) to 1–2 weeks after flowering (WAF) (Figure 2 and Supplementary Tables 3, 4)

Summary

Introduction

Known as sakura, typically blooms in the spring and is valued as a popular ornamental flower across the world. The molecular mechanisms of floral bud initiation have been well studied in Arabidopsis thaliana and rice (Oryza sativa) as flowering models of long- and short-day plants, respectively, revealing that FLOWERING LOCUS T (FT) is the key gene involved in floral bud differentiation (Izawa et al, 2003). This mechanism is widely conserved across plant species (Higuchi, 2018). In our previous study for ‘Somei-Yoshino,’ transcriptome data from the developmental floral bud sample series suggested that endodormancy is almost completed in 2 months before the flower opening (Shirasawa et al, 2019). While the physiological aspect of the mechanism for bud break and flower opening following the ecodormancy has been thoroughly investigated, only a few studies have been conducted to explore the genetic basis of this mechanism (van Doorn and Van Meeteren, 2003)

Objectives

Methods

Results

Conclusion