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In this study, the effects of epidermal growth factor (EGF), transforming growth factor-alpha (TGF alpha), TGF beta 1, and activin-A on inhibin secretion were investigated in primary culture of human placental cells. Immunoreactive inhibin in the culture medium was measured by immunoenzymatic assay. EGF stimulated testosterone-induced inhibin secretion in placental cells. Although testosterone alone induced only a slight enhancement of inhibin release in the culture, treatment of trophoblast cells with EGF and testosterone caused a significant increase in inhibin secretion, with immunoreactive inhibin levels much higher than those of testosterone or EGF alone. TGF alpha combined with human placental lactogen (hPL) had a stimulatory effect on inhibin secretion in placental cell culture. Simple addition of either TGF alpha or hPL to the culture did not show any effect on inhibin secretion in placental cells. A remarkable augmentation of inhibin secretion was obtained after the trophoblasts were exposed to both TGF alpha and hPL simultaneously. TGF beta 1 and activin-A showed synergistic effects to suppress inhibin secretion in placental cells. TGF beta 1 alone did not show any action on inhibin secretion, and activin-A alone induced a small decrease in inhibin release in the culture. In the presence of activin-A, addition of TGF beta 1 to the culture induced a profound decrease in immunoreactive inhibin levels in the medium. Activin-A could also suppress hCG-induced inhibin secretion in placental cells. Addition of hCG alone resulted in a small, but not significant, increase in inhibin release in the cultured cells, whereas the presence of activin-A combined with hCG in the culture conversely decreased inhibin secretion in the culture, with immunoreactive inhibin levels significantly lower than those in the presence of hCG or activin-A alone. These findings suggest that EGF and TGF alpha, alone or in combination with other hormones, may be stimulators, and TGF beta and activin may act as suppressors of inhibin secretion in human placental cells.

Carotenoids are one of the most important pigments for the coloring in many plants, fruits and flowers. Recently, significant progress has been made in carotenoid metabolism. However, the specific understanding on transcriptional regulation controlling the expression of carotenoid metabolic genes remains extremely limited. Anemone-type chrysanthemum, as a special group of chrysanthemum cultivars, contain elongated disc florets in capitulum, which usually appear in different colors compared with the ray florets since accumulating distinct content of carotenoids. In this study, the carotenoid composition and content of the ray and disc florets of an anemone-type chrysanthemum cultivar ‘Dong Li Fen Gui’ were analyzed by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) and the key structural gene CmCCD4a-2, of which differential expression resulted in the distinct content of carotenoids accumulated in these two types of florets, was identified. Then the promoter sequence of CmCCD4a-2 was used as bait to screen a chrysanthemum flower cDNA library and two transcription factors, CmAP3 and CmUIF1 were identified. Y2H, BiFC and Y3H experiments demonstrated that these two TFs were connected by CmPI to form CmAP3-CmPI-CmUIF1 TF complex. This TF complex regulated carotenoid metabolism through activating the expression of CmCCD4a-2 directly. Furthermore, a large number of target genes regulated directly by the CmAP3-CmPI-CmUIF1 TF complex, including carotenoid biosynthetic genes, flavonoid biosynthetic genes and flower development-related genes, were identified by DNA-affinity purification sequencing (DAP-seq), which indicated that the CmAP3-CmPI-CmUIF1 TF complex might participate in multiple processes. These findings expand our knowledge for the transcriptional regulation of carotenoid metabolism in plants and will be helpful to manipulating carotenoid accumulation in chrysanthemum.

Polyacylated anthocyanins with multiple glycosyl and aromatic acyl groups tend to make flowers display bright and stable blue colours. However, there are few studies on the isolation and functional characterization of genes involved in the polyacylated anthocyanin biosynthesis mechanism, which limits the molecular breeding of truly blue flowers. Senecio cruentus is an important potted ornamental plant, and its blue flowers contain 3′,7-polyacylated delphinidin-type anthocyanins that are not reported in any other plants, suggesting that it harbours abundant gene resources for the molecular breeding of blue flowers. In this study, using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) analysis of blue, carmine and white colours of cineraria cultivars “Venezia” (named VeB, VeC, and VeW, respectively), we found that 3′,7-polyacylated anthocyanin, cinerarin, was the main pigment component that determined the blue colour of ray florets of cineraria. Based on the transcriptome sequencing and differential gene expression (DEG) analysis combined with RT- and qRT-PCR, we found two genes encoding uridine diphosphate glycosyltransferase, named ScUGT1 and ScUGT4; two genes encoding acyl-glucoside-dependent glucosyltransferases which belong to glycoside hydrolase family 1 (GH1), named ScAGGT11 and ScAGGT12; one gene encoding serine carboxypeptidase-like acyltransferase ScSCPL2; and two MYB transcriptional factor genes ScMYB2 and ScMYB4, that were specifically highly expressed in the ray florets of VeB, which indicated that these genes may be involved in cinerarin biosynthesis. The function of ScSCPL2 was analysed by virus-induced gene silencing (VIGS) in cineraria leaves combined with HPLC-MS/MS. ScSCPL2 mainly participated in the 3′ and 7-position acylation of cinerarin. These results will provide new insight into the molecular basis of the polyacylated anthocyanin biosynthesis mechanism in higher plants and are of great significance for blue flower molecular breeding of ornamental plants.