Previous study showed that the exogenous application of cytokinin (6-benzyladenine, BA) on inflorescence buds significantly increases the female flower number and the ration of female and male flowers of Jatropha curcas. The results suggest that cytokinins are involved in Jatropha sex differentiation. However, the sex determination mechanism in J. curcas remains unclear.
Prof. XU Zengfu and his team of Xishuangbanna Tropical Botanical Garden (XTBG) performed a comparative transcriptome analysis between gynoecious and monoecious inflorescences. They aimed to investigate the regulatory mechanism of transition from monoecious to gynoecious plants. They used a gynoecious genotype of J.curcas, whose male flowers are aborted at early stage of inflorescence development, to identify the regulation networks that participate in sex differentiation of J. curcas.
They identified 3,749 genes differentially expressed in two developmental stages of inflorescences, among whom 32 genes were involved in floral development, and 70 in phytohormone biosynthesis and signaling pathways.
Different regulatory mechanisms of inflorescence development were present in monoecious and gynoecious Jatropha. Among the differentially expressed genes, KNOTTED1-LIKE HOMEOBOX GENE 6 (KNAT6), MYC2, SHI-RELATED SEQUENCE 5 (SRS5), SHORT VEGETATIVE PHASE (SVP), TERMINAL FLOWER 1 (TFL1), and TASSELSEED2 (TS2) were considered as strong candidate regulators of sex determination in J. curcas.
Their results suggested that some floral development genes and phytohormones (mainly gibberellic acid (GA) and jasmonic acid (JA)) likely coordinate to modulate sex expression in J. curcas. The expression of some key genes involved in abscisic acid (ABA), auxin, cytokinin (CK), ethylene (ETH), GA, and JA biosynthesis pathways was significantly changed during inflorescence development and sex expression in J. curcas, suggesting that these hormones may participate in these processes.
The study entitled “Comparative transcriptome analysis between gynoecious and monoecious plants identifies regulatory networks controlling sex determination in Jatropha curcas” has been published in Frontiers in Plant Science.
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
Tel: +86 691 8713051