Soybean MADS-box gene GmAGL1 promotes flowering via the photoperiod pathway

Xuanrui Zeng,Yingjun Chi,Hongyang Du,Deyue Yu,Wenming Yang,Hailun Liu,Sujing Wang,Fang Huang,Jiao Wang

doi:10.1186/s12864-017-4402-2

Abstract

BackgroundThe MADS-box transcription factors are an ancient family of genes that regulate numerous physiological and biochemical processes in plants and facilitate the development of floral organs. However, the functions of most of these transcription factors in soybean remain unknown.ResultsIn this work, a MADS-box gene, GmAGL1, was overexpressed in soybean. Phenotypic analysis showed that GmAGL1 overexpression not only resulted in early maturation but also promoted flowering and affected petal development. Furthermore, the GmAGL1 was much more effective at promoting flowering under long-day conditions than under short-day conditions. Transcriptome sequencing analysis showed that before flowering, the photoperiod pathway photoreceptor CRY2 and several circadian rhythm genes, such as SPA1, were significantly down-regulated, while some other flowering-promoting circadian genes, such as GI and LHY, and downstream genes related to flower development, such as FT, LEAFY, SEP1, SEP3, FUL, and AP1, were up-regulated compared with the control. Other genes related to the flowering pathway were not noticeably affected.ConclusionsThe findings reported herein indicate that GmAGL1 may promote flowering mainly through the photoperiod pathway. Interestingly, while overexpression of GmAGL1 promoted plant maturity, no reduction in seed production or oil and protein contents was observed.

Highlights

The MADS-box transcription factors are an ancient family of genes that regulate numerous physiological and biochemical processes in plants and facilitate the development of floral organs
GmAGL1 expression patterns differ in transgenic plants The MADS-box gene GmAGL1 (GenBank accession number: AW433203) was transformed into the soybean cultivar ‘Jack’, resulting in several GmAGL1 overexpression (GmAGL1-OX) transgenic plants
To investigate the tissue expression patterns of GmAGL1 in the control (WT Jack) and transgenic plants, real-time PCR was performed in roots, stems, leaves, flowers, pods and shoot apical meristem (SAM)

Summary

Introduction

The MADS-box transcription factors are an ancient family of genes that regulate numerous physiological and biochemical processes in plants and facilitate the development of floral organs. The photoperiod pathway, vernalization pathway, gibberellic acid (GA)-dependent pathway, and autonomous pathway, have been demonstrated to regulate flowering in Arabidopsis thaliana [36]. These four pathways, either alone or in combination, form a complex network that regulates plant flowering at the appropriate time based on changes in ambient conditions [8]. Short-day plants, such as soybean and rice, display precocious flowering under short-day conditions but delayed flowering or non-flowering under long-day conditions [20]. Photoreceptors receive a light signal and transduce it to genes that are linked to the plant’s biological clock to “turn on” the circadian rhythm, which is induced together with downstream floral organ

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