Potential function of CbuSPL and gene encoding its interacting protein during flowering in Catalpa bungei

Zhi Wang,Erqin Fan,Junhui Wang,Guanzheng Qu,Wenjun Ma,Lisheng Kong,Tianqing Zhu,Fangqun Ouyang,Nan Lu,Shougong Zhang,Nan Wang,Guijuan Yang

doi:10.1186/s12870-020-2303-z

Abstract

Background“Bairihua”, a variety of the Catalpa bungei, has a large amount of flowers and a long flowering period which make it an excellent material for flowering researches in trees. SPL is one of the hub genes that regulate both flowering transition and development.ResultsSPL homologues CbuSPL9 was cloned using degenerate primers with RACE. Expression studies during flowering transition in “Bairihua” and ectopic expression in Arabidopsis showed that CbuSPL9 was functional similarly with its Arabidopsis homologues. In the next step, we used Y2H to identify the proteins that could interact with CbuSPL9. HMGA, an architectural transcriptional factor, was identified and cloned for further research. BiFC and BLI showed that CbuSPL9 could form a heterodimer with CbuHMGA in the nucleus. The expression analysis showed that CbuHMGA had a similar expression trend to that of CbuSPL9 during flowering in “Bairihua”. Intriguingly, ectopic expression of CbuHMGA in Arabidopsis would lead to aberrant flowers, but did not effect flowering time.ConclusionsOur results implied a novel pathway that CbuSPL9 regulated flowering development, but not flowering transition, with the participation of CbuHMGA. Further investments need to be done to verify the details of this pathway.

Highlights

Flowers allow flowering plants to have a broader evolutionary relationship and extend their ecological niche so that they can dominate the terrestrial ecosystem
A flowering-related cDNA of SQUAMOSA promoter-binding protein-LIKE (SPL) was cloning from “Bairihua” Full–length cDNAs of SPL from C. bungei were isolated by using homology-based cloning and RACE techniques
CbuSPL9 was predicted to be a target of microRNA 156 (miR156) (Additional file 5), which is consistent with previous reports of SPL in Arabidopsis involving in flowering process

Summary

Introduction

Flowers allow flowering plants to have a broader evolutionary relationship and extend their ecological niche so that they can dominate the terrestrial ecosystem. SPLs have been shown to regulate flowering time and flower organ development in both herbs and woody plants, such as Gossypium hirsutum [23], maize [24], birch [25], Prunus mume [26], Platanus acerifolia [27], and Populus trichocarpa [28]. In the model plant Arabidopsis, AtSPLs have been shown to be a group of dominant regulators of the flowering process [29,30,31,32]. As a group of TFs, SPLs regulate the expression of other genes. Numerous downstream genes of SPLs have been identified; for example, AtSPL3 can directly upregulate the expression of LFY, FUL and AP1 by binding to their promoters [36,37,38]. The function of SPLs in woody plants is still in its infancy

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Results

Conclusion