Comparative transcriptome analysis reveals the regulatory networks of cytokinin in promoting the floral feminization in the oil plant Sapium sebiferum

Abstract

BackgroundSapium sebiferum, whose seeds contain high level of fatty acids, has been considered as one of the most important oil plants. However, the high male to female flower ratio limited the seed yield improvement and its industrial potentials. Thus, the study of the sex determination in S. sebiferum is of significant importance in increasing the seed yield.ResultsIn this study, we demonstrated that in S. sebiferum, cytokinin (CK) had strong feminization effects on the floral development. Exogenous application with 6-benzylaminopurine (6-BA) or thidiazuron (TDZ) significantly induced the development of female flowers and increased the fruit number. Interestingly, the feminization effects of cytokinin were also detected on the androecious genotype of S. sebiferum which only produce male flowers. To further investigate the mechanism underlying the role of cytokinin in the flower development and sex differentiation, we performed the comparative transcriptome analysis of the floral buds of the androecious plants subjected to 6-BA. The results showed that there were separately 129, 352 and 642 genes differentially expressed at 6 h, 12 h and 24 h after 6-BA treatment. Functional analysis of the differentially expressed genes (DEGs) showed that many genes are related to the hormonal biosynthesis and signaling, nutrients translocation and cell cycle. Moreover, there were twenty one flowering-related genes identified to be differentially regulated by 6-BA treatment. Specifically, the gynoecium development-related genes SPATULA (SPT), KANADI 2 (KAN2), JAGGED (JAG) and Cytochrome P450 78A9 (CYP79A9) were significantly up-regulated, whereas the expression of PISTILLATA (PI), TATA Box Associated Factor II 59 (TAFII59) and MYB Domain Protein 108 (MYB108) that were important for male organ development was down-regulated in response to 6-BA treatment, demonstrating that cytokinin could directly target the floral organ identity genes to regulate the flower sex.ConclusionsOur work demonstrated that cytokinin is a potential regulator in female flower development in S. sebiferum. The transcriptome analysis of the floral sex transition from androecious to monoecious in response to cytokinin treatment on the androecious S. sebiferum provided valuable information related to the mechanism of sex determination in the perennial woody plants.Electronic supplementary materialThe online version of this article (10.1186/s12870-018-1314-5) contains supplementary material, which is available to authorized users.

Transcriptome Profiling of the Elongating Internode of Cotton (Gossypium hirsutum L.) Seedlings in Response to Mepiquat Chloride

“…This correlated well with other studies that other GA biosynthesis inhibitors such as PAC, uniconazole, and Pro-Ca increase CK levels in different plant tissues (Grossmann et al, 1994;Upreti et al, 2013;Liu et al, 2015). Active CKs are degraded mainly by CKX, which can be induced by exogenous CK (6-BA) owing to feedback mechanisms (Kieber and Schaller, 2018;Ni et al, 2018). Therefore, the MC mediated upregulation of CKX1, CKX6, and CKX7 might be attributed to the increased CK levels in cotton internodes.…”

“…Some important TFs are shown in Figure S6. Most of the MYBs were downregulated, including genes functioning in plant circadian clock and ABA accumulation (Adams et al, 2018) and those associated with the ABA signal pathway (Ni et al, 2018). The bHLH TFs play important roles in the control of cell elongation.…”

Screening and identification of miRNAs related to sexual differentiation of strobili in Ginkgo biloba by integration analysis of small RNA, mRNA, and degradome sequencing

“…Accumulated studies indicated that signi cant difference in CTK was usually detected between male and female owers [55,56,57]. For example, treatment with exogenous CTKon Mercurialis annua L., a dioecious plant led the ower primordia to differentiate into pistil [55].…”

The genetic basis of sex determination in grapevines (Vitis spp.)

“…APT proteins participate in cytokinin inactivation (Allen et al, 2002;Zhang et al, 2013). Cytokinins are involved in flower development and the regulation of the number of ovules per pistil, gynoecium size (Bartrina et al, 2011;Marsch-Martínez et al, 2012), and flower sex specification (Durand and Durand, 1991;Ni et al, 2018). In grapevine, cytokinin application restores normal female organ development, producing berries from male grapevine flowers (Negi and Olmo, 1966).…”