Non-heading Chinese cabbage (cabbage) is an essential green leafy vegetable, and bolting and flowering are necessary for reproduction. However, further research is needed to study the effect of photoperiod on the bolting and flowering of cabbage, particularly on the development of the stem. In this study, we performed phenotypic analysis and measured endogenous gibberellin levels in the cabbage. We carried out these experiments under four different photoperiodic treatments, 12 h (light)/12 h (dark), 14 h (light)/10 h (dark), 16 h (light)/8 h (dark), and 18 h (light)/6 h (dark). The results showed that the time of bolting and flowering gradually decreased with increasing light duration. The development of stems was optimal under the 16 h (light)/8 h (dark) photoperiod treatment, and the same result was obtained via cytological observation. In addition, the changes in the endogenous gibberellin3 (GA₃) content under different photoperiodic treatments were consistent with the development of stems and peaked at 16 h (light)/8 h (dark). At the same time, qRT-PCR analysis showed that the relative expression of the key gibberellin synthase genes, BcGA3ox2 and BcGA20ox2, exhibited upregulation. When treated with exogenous GA₃ and its synthesis inhibitor, paclobutrazol (PAC), exogenous gibberellins significantly promoted bolting; conversely, gibberellin inhibitors suppressed the bolting, flowering, and stem elongation of cabbage. Therefore, the photoperiod may regulate cabbage bolting by regulating endogenous GA₃.

1-deoxy-D-xylulose-5-phosphate synthase (DXS) is a rate-limiting enzyme in terpene synthesis that can affect the accumulation of secondary metabolites in plants. In this study, three DXS gene family members were identified in the tomato genome-wide database. Using bioinformatics methods, we analyzed the gene structure, evolutionary affinities, and cis-acting elements of the SlDXS gene family members. Promoters of SlDXS genes contain plant hormone-responsive elements such as the CGTCA-motif, TGACG-motif, ABRE, TCA-element, TGA-element, ERE, CAT-box, and AACA-motif, which suggested that the SlDXS gene family may play an important role in hormone response. The RT-qPCR analysis showed that the tomato DXS2 gene was able to respond upon exposure to methyl jasmonate (MeJA). The construction of a virus-induced gene silencing (VIGS) vector for the SlDXS gene showed that the SlDXS2 gene was also able to respond to MeJA in silenced plants, but the induction level was lower relative to that of wild-type plants. The SlDXS1 gene is associated with the synthesis of photosynthetic pigments. This study provides a reference for the further elucidation of the DXS gene’s biological function in the terpenoid synthesis pathway in tomatoes.

Background: Lipoxygenases (LOXs) are key enzymes in the unsaturated fatty acid oxidation reaction pathway and play an important regulatory role in the synthesis of fruit aroma volatiles. Methods: LOX gene family members were identified in the whole genome database of bitter gourd and analyzed bioinformatically. An RT-qPCR was used to analyze the expression differences in different tissues. Monoterpenes were determined by gas chromatography-mass spectrometry (GC-MS) technique. Results: A total of 12 LOX gene family members were identified in the genome. The expression of LOX genes varied significantly among the tissues of roots, stems, leaves, flowers, fruits, seeds and tendrils. A total of 29 monoterpenes were detected in the fruits of five different fruit colors of bitter gourd, mainly containing six types of alcohols, aldehydes, terpenes, ketones, esters and alkynes, with the highest relative content of alcohols. Conclusions: The present study provides a reference for further elucidation of the biological functions of the LOX gene in the synthesis pathway of aroma volatiles in bitter gourd.