Comparative Transcriptome Analysis Revealed Two Alternative Splicing bHLHs Account for Flower Color Alteration in Chrysanthemum.

Lili Xiang,Kunsong Chen,Yanna Shi,Yajing Li,Xiaofen Liu,Fang Li,Weidong Li

doi:10.3390/ijms222312769

Lili Xiang, Kunsong Chen + Show 5 more

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https://doi.org/10.3390/ijms222312769

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Abstract

‘Jimba’ is a white chrysanthemum cultivar, which occasionally and spontaneously produces red flower petals under natural cultivation due to cyanidin-based anthocyanin accumulation. To investigate the underlying mechanism of this process, a comparative transcriptome was analyzed between white and turning red ‘Jimba’. The structural and regulatory genes of anthocyanin pathway were significantly up-regulated in turning red ‘Jimba’. Among them, two alternative splicings, CmbHLH2 and CmbHLH2.1, showed the most significantly up-regulated in turning red tissue. Transiently over-expressed 35S::CmMYB6-CmbHLH2 strongly induced anthocyanin accumulation in ‘Jimba’ flower petals, while moderate amount of anthocyanin was detected when over-expressed 35S::CmMYB6-CmbHLH2.1. Both CmbHLH2 and CmbHLH2.1 could interact with CmMYB6 to activate CmDFR promoter according to Yeast two-hybrid and dual-luciferase assay. Moreover, CmMYB6-CmbHLH2 but not CmMYB6-CmbHLH2.1 could activate the CmbHLH2 promoter to provide positive feedback loop regulation. Taken together, it suggested that both CmbHLH2 and CmbHLH2.1 involved in regulation flower color alteration in turning red ‘Jimba’, and CmbHLH2 played a predominant role in this process.

Highlights

Hunan Key Laboratory of Germplasm Innovation and Comprehensive Utilization of Landscape Flowers, Academic Editor: Hye Ryun Woo
‘Jimba’ is a white chrysanthemum cultivar, but it occasionally and spontaneously produces red flower petals under natural cultivation, which is attribute to cyanidin-based anthocyanin accumulation based on previous study [2]
CmMYB6-CmbHLH2.1 had regulatory itable variation is generally due to gene mutation, such as insertions of transposons or effects on CmMYB#7 and CmMYB6 promoter

Summary

Introduction

Hunan Key Laboratory of Germplasm Innovation and Comprehensive Utilization of Landscape Flowers, Academic Editor: Hye Ryun Woo. Abstract: ‘Jimba’ is a white chrysanthemum cultivar, which occasionally and spontaneously produces red flower petals under natural cultivation due to cyanidin-based anthocyanin accumulation. The structural and regulatory genes of anthocyanin pathway were significantly up-regulated in turning red ‘Jimba’. Two alternative splicings, CmbHLH2 and CmbHLH2.1, showed the most significantly up-regulated in turning red tissue. Over-expressed 35S::CmMYB6-CmbHLH2 strongly induced anthocyanin accumulation in ‘Jimba’ flower petals, while moderate amount of anthocyanin was detected when over-expressed. CmMYB6-CmbHLH2 but not CmMYB6-CmbHLH2.1 could activate the CmbHLH2 promoter to provide positive feedback loop regulation. Taken together, it suggested that both CmbHLH2 and

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