Jatropha curcas is a plant with high agro-industrial potential for biofuel production, whose economic value is derived from its seed oil. However, seed yields of Jatropha are limited by its poor flowering and fruiting ability. Thus, identifying flowering genes is one of the key steps to improve seed yield and enhance industrial use of Jatropha.

   Prof. XU Zengfu and his team of Xishuangbanna Tropical Botanical Garden (XTBG) cloned JcLFY, an ortholog of Arabidopsis thaliana LEAFY (LFY), from Jatropha and analyzed the function of JcLFY by transforming both wild-type (WT) and lfy-15 mutant Arabidopsis. They further analyzed JcLFY function in flowering induction and floral organ specification using JcLFY overexpression and co-suppression in transgenic Jatropha plants.

   The researchers used RT-PCR to investigate the expression of JcLFY across different organs and tissues. They found that JcLFY was highly expressed during the early-stage inflorescence buds and early-stage flower buds.

To determine whether JcLFY is involved in the regulation of flowering time, the researchers transformed JcLFY cDNA driven by the CaMV 35S promoter into WT Arabidopsis. They found that 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.

To further determine whether JcLFY is an AtLFY ortholog, the researchers transformed the 35S:JcLFY construct  into Arabidopsis lfy-15 mutant plants. The results showed that the constitutive expression of JcLFY complements increased branches (i.e., inflorescences) in later flowering stages and abnormal flowers in lfy-15 mutant; thus, JcLFY functions as a LFY homolog.

Jatropha expression profiles and Arabidopsis transgenic analyses suggested JcLFY is a floral identity gene in Jatropha. JcLFY overexpression in Jatropha induced early flowering. JcLFY co-suppression changed inflorescence structure and flower organ pattern. Altered expression of JcLFY affected fruit and seed development.

 The results suggested that 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.

The study entitled “An ortholog of LEAFY in Jatropha curcas regulates flowering time and floral organ development” has been published in Scientific Reports.

Contact

Prof. XU Zengfu Ph.D Principal Investigator
Key Laboratory of Tropical Plant Resources and Sustainable Use, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun 666303, Yunnan, China
E-mail: zfxu@xtbg.ac.cn
Tel: +86 691 8713051

Co-suppression of JcLFY in Jatropha led to severe deficiencies in inflorescences and flowers.

(Image by TANG Mingyong)