A Novel Role for Banana MaASR in the Regulation of Flowering Time in Transgenic Arabidopsis.

Peiguang Sun,Biyu Xu,Jianbin Zhang,Hongxia Miao,Anbang Wang,Zhiqiang Jin,Jingyi Wang,Juhua Liu,Zhuo Wang,Xiaomeng Yu,Caihong Jia,Wang-Jin Lu

doi:10.1371/journal.pone.0160690

Peiguang Sun, Biyu Xu + Show 10 more

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https://doi.org/10.1371/journal.pone.0160690

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Abstract

The abscisic acid (ABA)-, stress-, and ripening-induced (ASR) protein is a plant-specific hydrophilic transcriptional factor involved in fruit ripening and the abiotic stress response. To date, there have been no studies on the role of ASR genes in delayed flowering time. Here, we found that the ASR from banana, designated as MaASR, was preferentially expressed in the banana female flowers from the eighth, fourth, and first cluster of the inflorescence. MaASR transgenic lines (L14 and L38) had a clear delayed-flowering phenotype. The number of rosette leaves, sepals, and pedicel trichomes in L14 and L38 was greater than in the wild type (WT) under long day (LD) conditions. The period of buds, mid-flowers, and full bloom of L14 and L38 appeared later than the WT. cDNA microarray and quantitative real-time PCR (qRT-PCR) analyses revealed that overexpression of MaASR delays flowering through reduced expression of several genes, including photoperiod pathway genes, vernalization pathway genes, gibberellic acid pathway genes, and floral integrator genes, under short days (SD) for 28 d (from vegetative to reproductive transition stage); however, the expression of the autonomous pathway genes was not affected. This study provides the first evidence of a role for ASR genes in delayed flowering time in plants.

Highlights

Flowering time is crucial for pollination and reproductive success in higher plants [1, 2], which is regulated through four major pathways, the photoperiod, vernalization, autonomous, and gibberellic acid (GA)-dependent pathways, in Arabidopsis [3,4,5]
Flowering in some plants can be stimulated by exposure to long periods of low non-freezing temperatures, which is known as varnalization, and is regulated by the FRIGIDA (FRI) and FLOWERING LOCUS C (FLC) genes [4, 8]
The cDNA of ASR from banana, MaASR, was 747 bp in length containing a 432 bp open reading frame (ORF), which encoded a protein of 143 amino acids with a 251 bp 50 untranslated region (UTR) and a 64 bp 30 UTR

Summary

Introduction

Flowering time is crucial for pollination and reproductive success in higher plants [1, 2], which is regulated through four major pathways, the photoperiod-, vernalization-, autonomous-, and gibberellic acid (GA)-dependent pathways, in Arabidopsis [3,4,5]. Photoperiod, or the duration of light in a given day, is a critical cue that flowering plants utilize to effectively assess seasonal information and coordinate their reproductive development in synchrony with the external environment [6]; photoperiod controls flowering time by regulating the expression of a number of key genes, such as CONSTANS (CO), EARLY FLOWERING4 (ELF4), and EARLY. Recent studies have reported that floral regulatory pathways regulate the expression of floral integrator genes such as SUPPRESSOR OF OVEREXPRESSION OF CO1 (SOC1) and LEAFY (LFY) [10, 11]. A series of transcription factors including CO, FLC, SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL), and CAPRICE (CPC) control flowering time by regulating the target genes expression of these pathways [6, 10, 12,13,14]

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