Comparative transcriptome analysis of gynoecious and monoecious inflorescences reveals regulators involved in male flower development in the woody perennial plant Jatropha curcas.

KEY MESSAGE: ABCE model genes along with genes related to GA biosynthesis and auxin signalling may play significant roles in male flower development in Jatropha curcas. Flowering plants exhibit extreme reproductive diversity. Jatropha curcas, a woody plant that is promising for biofuel production, is monoecious. Here, two gynoecious Jatropha mutants (bearing only female flowers) were used to identify key genes involved in male flower development. Using comparative transcriptome analysis, we identified 17 differentially expressed genes (DEGs) involved in floral organ development between monoecious plants and the two gynoecious mutants. Among these DEGs, five floral organ identity genes, Jatropha AGAMOUS, PISTILLATA, SEPALLATA 2-1 (JcSEP2-1), JcSEP2-2, and JcSEP3, were downregulated in ch mutant inflorescences; two gibberellin (GA) biosynthesis genes, Jatropha GA REQUIRING 1 and GIBBERELLIN 3-OXIDASE 1, were downregulated in both the ch and g mutants; and two genes involved in the auxin signalling pathway, Jatropha NGATHA1 and STYLISH1, were downregulated in the ch mutant. Furthermore, four hub genes involved in male flower development, namely Jatropha SOMATIC EMBRYOGENESIS RECEPTOR-LIKE KINASE 1, CRYPTOCHROME 2, SUPPRESSOR OF OVEREXPRESSION OF CO 1 and JAGGED, were identified using weighted gene correlation network analysis. These results suggest that floral organ identity genes and genes involved in GA biosynthesis and auxin signalling may participate in male flower development in Jatropha. This study will contribute to understanding sex differentiation in woody perennial plants.