Despite being a brassicaceous vegetable that is widely consumed in winter and spring in Southwest China, there is lack of information available on baby mustard. The aim of this study was to determine the contents of soluble proteins, soluble sugars, chlorophylls, carotenoids, ascorbic acid, proanthocyanidins, flavonoids, total phenolics, and glucosinolates, as well as the antioxidant activity of the whole edible parts and seven individual edible parts (swollen stem: petioles, peel, flesh; lateral bud: leaves, petioles, peel, flesh) of baby mustard. The results showed that significant differences in health-promoting compounds and antioxidant activity existed between the different edible parts. The lateral bud of baby mustard possessed greater health-promoting compounds than the swollen stem. In particular, the lateral bud leaves possessed abundant antioxidant compounds and antioxidant activity, indicating that these should be conserved during harvesting due to their potential contribution to human health. Furthermore, aliphatic glucosinolates were predominant, and sinigrin was the most abundant glucosinolate in all the assessed parts of baby mustard, the content of which was 15.81 μmol g⁻¹ dry weight, accounting for more than 87% of the total glucosinolate content. However, the sinigrin content in baby mustard is lower than tuber mustard, which explains the less pungent flavor of baby mustard and its better suitability as a fresh vegetable. In addition, antioxidant activity was highly correlated with total phenolics, whereas gluconasturtiin and soluble sugars were negatively correlated with the majority of antioxidants.

Chinese kale (Brassica oleracea var. alboglabra) has high nutritional value. This study investigated the contents of glucosinolates, antioxidants (chlorophylls, carotenoids, vitamin C, and total phenolics), and antioxidant capacity in five organs from six varieties of Chinese kale. The highest concentrations of individual and total glucosinolates were in the roots and inflorescences, respectively. The highest levels of antioxidants and antioxidant capacity were in inflorescences and leaves. Plant organs played a predominant role in glucosinolate and antioxidant accumulation. Glucoiberin, glucoraphanin, and glucobrassicin, the main anticarcinogenic glucosinolates, could be enhanced simultaneously because of their high positive correlations. The relationship between glucosinolates and antioxidant capacity indicated that glucobrassicin might contribute to the total antioxidant capacity. These results provide useful information related to consumption, breeding of functional varieties, and use of the non-edible organs of Chinese kale.

The clustered regulatory interspaced short palindromic repeat-associated protein 9 (CRISPR/Cas9) system has developed into a powerful gene-editing tool that has been successfully applied to various plant species. However, studies on the application of the CRISPR/Cas9 system to cultivated Brassica vegetables are limited. Here, we reported CRISPR/Cas9-mediated genome editing in Chinese kale (Brassica oleracea var. alboglabra) for the first time. A stretch of homologous genes, namely BaPDS1 and BaPDS2, was selected as the target site. Several stable transgenic lines with different types of mutations were generated via Agrobacterium-mediated transformation, including BaPDS1 and BaPDS2 double mutations and BaPDS1 or BaPDS2 single mutations. The overall mutation rate reached 76.47%, and these mutations involved nucleotide changes of fewer than 10 bp. The clear albino phenotype was observed in all of the mutants, including one that harbored a mutation within an intron region, thereby indicating the importance of the intron. Cleavage in Chinese kale using CRISPR/Cas9 was biased towards AT-rich sequences. Furthermore, no off-target events were observed. Functional differences between BaPDS1 and BaPDS2 were also assessed in terms of the phenotypes of the respective mutants. In combination, these findings showed that CRISPR/Cas9-mediated targeted mutagenesis can simultaneously and efficiently modify homologous gene copies of Chinese kale and provide a convenient approach for studying gene function and improving the yield and quality of cultivated Brassica vegetables.

The composition and content of glucosinolates were investigated in the edible parts (petioles, peel and flesh) of tuber mustard, bamboo shoots mustard and baby mustard by high-performance liquid chromatography to reveal the association between the different cooking methods and their glucosinolate profiles. Eight glucosinolates were identified from tuber mustard and baby mustard, including three aliphatic glucosinolates, four indole glucosinolates and one aromatic glucosinolate. Only six of the eight glucosinolates were detected in bamboo shoots mustard. The results show that the distribution and content of glucosinolates varied widely among the different tissues and species. The highest contents of glucosinolates in tuber mustard, bamboo shoots mustard and baby mustard were found in flesh, petioles and peel, respectively. The content of total glucosinolates ranged from 5.21 µmol g ^–1 dry weight in bamboo shoots mustard flesh to 25.64 µmol g ⁻¹ dry weight in baby mustard peel. Aliphatic glucosinolates were predominant in the three stem mustards, followed by indole and aromatic glucosinolates. Sinigrin was the predominant glucosinolate in the three stem mustards. Sinigrin content in tuber mustard was slightly higher than that in baby mustard and much higher than that in bamboo shoots mustard, suggesting that the pungent-tasting stem mustards contained more sinigrin. In addition, a principal components analysis showed that bamboo shoots mustard was distinguishable from the other two stem mustards. A variance analysis indicated that the glucosinolates were primarily influenced by a species × tissue interaction. The correlations among glucosinolates were also analysed.

To increase the understanding of alkaloid biosynthesis in Nicotiana tabacum during whole plant growth periods, variations of the contents of alkaloids and the transcription of key biosynthetic genes in fresh leaves were investigated in three varieties at five developmental stages. Six alkaloids were analyzed by gas chromatograph–mass spectrometry (GC–MS) and the most abundant alkaloid was observed during the upper leaves maturing stage in the varieties, among which the alkaloid content of K326 was the highest. Considering the genetic effect, variance analysis indicated that the developmental stage played a predominant role in alkaloid accumulation. Moreover, the levels of biosynthetic gene transcripts in the leaves at the vigorous growing stage might contribute to the contents of alkaloids in the leaves during the maturing stages. To further illuminate the metabolism of alkaloid biosynthesis, a correlation among alkaloids was also documented.

Accurate analysis of gene expression requires selection of appropriate reference genes. In this study, we report analysis of eight candidate reference genes (ACTIN, UBQ, EF-1α, UBC, IF-4α, TUB, PP2A, and HIS), which were screened from the genome and transcriptome data in Brassica juncea. Four statistical analysis softwares geNorm, NormFinder, BestKeeper, and RefFinder were used to test the reliability and stability of gene expression of the reference genes. To further validate the stability of reference genes, the expression levels of two CYCD3 genes (BjuB045330 and BjuA003219) were studied. In addition, all genes in the xyloglucan endotransglucosylase/hydrolase (XTH) family were identified in B. juncea and their patterns at different periods of stem enlargement were analyzed. Results indicated that UBC and TUB genes showed stable levels of expression and are recommended for future research. In addition, XTH genes were involved in regulation of stem enlargement expression. These results provide new insights for future research aiming at exploring important functional genes, their expression patterns and regulatory mechanisms for mustard development.