Conservation and Divergence of the CONSTANS-Like (COL) Genes Related to Flowering and Circadian Rhythm in Brassica napus.

Yuxi Chen,Rijin Zhou,Wenliang Wei,Jia Liu,Qiong Hu

doi:10.3389/fpls.2021.760379

Abstract

The CONSTANS-LIKE (COL) genes are important signaling component in the photoperiod pathway and flowering regulation pathway. However, people still know little about their role in Brassica napus. To achieve a better understanding of the members of the BnaCOL gene family, reveal their evolutionary relationship and related functions involved in photoperiod regulation, we systematically analyzed the BnaCOL family members in B. napus genome. A total of 33 BnaCOL genes distributed unevenly on 16 chromosomes were identified in B. napus and could be classified into three subfamilies. The same subfamilies have relatively conservative gene structures, three-dimensional protein structures and promoter motifs such as light-responsive cis-elements. The collinearity analysis detected 37 pairs of repetitive genes in B. napus genome. A 67.7% of the BnaCOL genes were lost after B. napus genome polyploidization. In addition, the BnaCOL genes showed different tissue-specific expression patterns. A 81.8% of the BnaCOL genes were mainly expressed in leaves, indicating that they may play a conservative role in leaves. Subsequently, we tested the circadian expression profiles of nine homologous genes that regulate flowering in Arabidopsis. Most BnaCOL genes exhibit several types of circadian rhythms, indicating that these BnaCOL genes are involved in the photoperiod pathway. As such, our research has laid the foundation for understanding the exact role of the BnaCOL family in the growth and development of rapeseed, especially in flowering.

Highlights

Flowering is an important link in the process of plant reproduction (Fitter and Fitter, 2002)
We have identified 33 BnaCOL gene family members and performed bioinformatics analysis on their physical and chemical properties, evolutionary relationships, chromosome location, gene structure, three-dimensional protein structures, cis-acting elements of the promoter, gene ontology (GO) annotation enrichment analysis and gene duplication
The lengths of the proteins encoded by BnaCOL genes varied from 289 to 414 amino acids, the molecular weight (MW) ranged from 31.51 to 46.5 kDa, and the PI ranged from 5.08 to 8.10

Summary

Introduction

Flowering is an important link in the process of plant reproduction (Fitter and Fitter, 2002). BnaCOL Genes Act in Photoperiod are two important network regulation centers in the photoperiod induction pathway. CO/COL activates the transcription of FT to move the FT protein from the leaf phloem to the shoot apex meristem, thereby promoting plant flowering (Shim et al, 2017). The Arabidopsis CO/COL homologous gene HEADING DATE 1 (Hd1) appears to be a bifunctional regulator. It induces FT homologous HEADING DATE 3a (Hd3a) gene expression to promote flowering under SD conditions while under LD conditions Hd1 functions as an inhibitor of Hd3a transcription and flowering (Hayama et al, 2003)

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Conclusion