Glucosinolates (GLS) are critical for the defense, flavor, and sulfur storage of cruciferous plants; however, the regulatory mechanisms underlying their biosynthesis and metabolism remain largely elusive. This study aimed to systematically identify the key genes regulating GLS. To this end, a systematic screening and validation pipeline was established by integrating machine learning predictions (leveraging over 1000 RNA-seq samples from Brassica rapa and Arabidopsis thaliana), multidimensional bioinformatics validation (functional annotation, protein interaction networks), and molecular experimental validation. With this pipeline, 12 high-confidence candidate regulatory genes were identified, as potential targets for subsequently analyzing the multifaceted regulatory network governing GLS biosynthesis and metabolism. Further functional validation of the key candidate gene CYP89A6 through virus-induced gene silencing assays confirmed its role as a positive GLS biosynthesis regulator. Silencing CYP89A6 significantly reduced the total GLS content in B. rapa, with markedly reduced levels of key components including aliphatic GLS (PRO, GRA, GBN), aromatic GLS (NAS), and indole GLS (4 ME, GBC). Overall, this study validated the robustness of the machine learning and multidimensional bioinformatics screening pipeline, and advanced our understanding underlying the regulatory mechanisms of secondary metabolism in B. rapa.

Properly regulated flowering time is pivotal for successful plant reproduction. The floral transition from vegetative growth to reproductive growth is regulated by a complex gene regulatory network that integrates environmental signals and internal conditions to ensure that flowering takes place under favorable conditions. Brassica rapa is a diploid Cruciferae species that includes several varieties that are cultivated as vegetable or oil crops. Flowering time is one of the most important agricultural traits of B. rapa crops because of its influence on yield and quality. The transition to flowering in B. rapa is regulated by several environmental and developmental cues, which are perceived by several signaling pathways, including the vernalization pathway, the autonomous pathway, the circadian clock, the thermosensory pathway, and gibberellin (GA) signaling. These signals are integrated to control the expression of floral integrators BrFTs and BrSOC1s to regulate flowering. In this review, we summarized current research advances on the molecular mechanisms that govern flowering time regulation in B. rapa and compare this to what is known in Arabidopsis.

Flowering time is an important agronomic trait of Chinese cabbage with late flowering being a primary breeding objective. In our previous work, we obtained Chinese cabbage-cabbage translocation lines that contained several beneficial cabbage genes. Cabbage-specific molecular markers show that these genes were coming from chromosome C01 of cabbage. In this study, we investigated the inheritance of flowering time in a couple of translocation lines and analyzed the transmission rate of molecular markers in the offspring. Consequently, we obtained the late flowering Chinese cabbage-cabbage translocation line 'AT7–4' in which the flowering time was later than that of '85–1' by about 7 days under 4-week vernalization. Based on previous studies of the genomes of Chinese cabbage and cabbage, we located the cabbage-specific molecular markers that were closely linked at the top of the chromosome A01 in the F₂ mapping population generated by self-crossing F₁s derived from a cross between the translocation line 'AT7–4' and Chinese cabbage '14–36'. Five flowering-related genes in the alien fragment were found by functional annotation and their molecular markers were developed. This study lays the foundation for the future improvement of Chinese cabbage varieties using A-C translocation lines.