Sex expression and floral diversity in Jatropha curcas: a population study in its center of origin

Genome-Wide Identification and Analysis of Lbd Transcription Factor Genes in Jatropha curcas and Related Species

Lateral organ boundaries domain (LBD) proteins are plant-specific transcription factors that play important roles in organ development and stress response. However, the function of LBD genes has not been reported in Euphorbiaceae. In this paper, we used Jatropha curcas as the main study object and added rubber tree (Hevea brasiliensis), cassava (Manihot esculenta Crantz) and castor (Ricinus communis L.) to take a phylogenetic analysis of LBD genes. Of LBD, 33, 58, 54 and 30 members were identified in J. curcas, rubber tree, cassava and castor, respectively. The phylogenetic analysis showed that LBD members of Euphorbiaceae could be classified into two major classes and seven subclasses (Ia-Ie,IIa-IIb), and LBD genes of Euphorbiaceae tended to cluster in the same branch. Further analysis showed that the LBD genes of Euphorbiaceae in the same clade usually had similar protein motifs and gene structures, and tissue expression patterns showed that they also have similar expression profiles. JcLBDs in class Ia and Ie are mainly expressed in male and female flowers, and there are multiple duplication genes with similar expression profiles in these clades. It was speculated that they are likely to play important regulatory roles in flower development. Our study provided a solid foundation for further investigation of the role of LBD genes in the sexual differentiaion of J. curcas.

An ortholog of the MADS-box gene SEPALLATA3 regulates stamen development in the woody plant Jatropha curcas

Overexpression of JcSEP3 causes defective stamen development in Jatropha curcas, in which brassinosteroid and gibberellin signaling pathways may be involved. SEPALLATAs (SEPs), the class E genes of the ABCE model, are required for floral organ determination. In this study, we investigated the role of the JcSEP3 gene in floral organ development in the woody plant Jatropha curcas. Transgenic Jatropha plants overexpressing JcSEP3 displayed abnormal phenotypes such as deficient anthers and pollen, as well as free stamen filaments, whereas JcSEP3-RNA interference (RNAi) transgenic plants had no obvious phenotypic changes, suggesting that JcSEP3 is redundant with other JcSEP genes in Jatropha. Moreover, we compared the transcriptomes of wild-type plants, JcSEP3-overexpressing, and JcSEP3-RNAi transgenic plants. In the JcSEP3-overexpressing transgenic plants, we discovered 25 upregulated genes involved in anther and pollen development, as well as 12 induced genes in brassinosteroid (BR) and gibberellin (GA) signaling pathways. These results suggest that JcSEP3 directly or indirectly regulates stamen development, concomitant with the regulation of BR and GA signaling pathways. Our findings help to understand the roles of SEP genes in stamen development in perennial woody plants.

Molecular Mechanisms of the Floral Biology of Jatropha curcas: Opportunities and Challenges as an Energy Crop

Fossil fuel sources are a limited resource and could eventually be depleted. Biofuels have emerged as a renewable alternative to fossil fuels. Jatropha has grown in significance as a potential bioenergy crop due to its high content of seed oil. However, Jatropha's lack of high-yielding seed genotypes limits its potential use for biofuel production. The main cause of lower seed yield is the low female to male flower ratio (1:25-10), which affects the total amount of seeds produced per plant. Here, we review the genetic factors responsible for floral transitions, floral organ development, and regulated gene products in Jatropha. We also summarize potential gene targets to increase seed production and discuss challenges ahead.