An ortholog of LEAFY in Jatropha curcas regulates flowering time and floral organ development.

Mingyong Tang,Qiantang Fu,Longjian Niu,Yan-Bin Tao,Yaling Song,Zeng-Fu Xu

doi:10.1038/srep37306

Abstract

Jatropha curcas seeds are an excellent biofuel feedstock, but seed yields of Jatropha are limited by its poor flowering and fruiting ability. Thus, identifying genes controlling flowering is critical for genetic improvement of seed yield. We isolated the JcLFY, a Jatropha ortholog of Arabidopsis thaliana LEAFY (LFY), and identified JcLFY function by overexpressing it in Arabidopsis and Jatropha. JcLFY is expressed in Jatropha inflorescence buds, flower buds, and carpels, with highest expression in the early developmental stage of flower buds. JcLFY overexpression induced early flowering, solitary flowers, and terminal flowers in Arabidopsis, and also rescued the delayed flowering phenotype of lfy-15, a LFY loss-of-function Arabidopsis mutant. Microarray and qPCR analysis revealed several flower identity and flower organ development genes were upregulated in JcLFY-overexpressing Arabidopsis. JcLFY overexpression in Jatropha also induced early flowering. Significant changes in inflorescence structure, floral organs, and fruit shape occurred in JcLFY co-suppressed plants in which expression of several flower identity and floral organ development genes were changed. This suggests JcLFY is involved in regulating flower identity, floral organ patterns, and fruit shape, although JcLFY function in Jatropha floral meristem determination is not as strong as that of Arabidopsis.

Highlights

The LFY gene was identified by Weigel et al.[14] in Arabidopsis, and its orthologous gene, FLORICAULA (FLO), was identified by Coen et al.[15] in Antirrhinum majus
In Arabidopsis lfy mutants, floral meristem (FM) development is dramatically delayed with late flowering[32], flower buds are surrounded by extra bracts, and the early flowers are completely transformed into inflorescence shoots
Full length JcLFY cDNA sequence was obtained from Jatropha flower bud tissue by RT-PCR and RACE

Summary

Introduction

The LFY gene was identified by Weigel et al.[14] in Arabidopsis, and its orthologous gene, FLORICAULA (FLO), was identified by Coen et al.[15] in Antirrhinum majus. LFY is the central flower meristem identity gene; it is mainly expressed in inflorescence and flower primordia[14,15,18]. In Arabidopsis lfy mutants, FM development is dramatically delayed with late flowering[32], flower buds are surrounded by extra bracts, and the early flowers are completely transformed into inflorescence shoots. In Arabidopsis, GA regulates LFY transcription to promote flower initiation[34,35,36]. We cloned JcLFY from Jatropha and analyzed the function of JcLFY by transforming both wild-type (WT) and lfy-15 mutant Arabidopsis. We further analyzed JcLFY function in flowering induction and floral organ specification using JcLFY overexpression and co-suppression in transgenic Jatropha plants

Methods

Results

Conclusion