Brassica rapa L. is an important overwintering oilseed crop in Northwest China. Histone acetyltransferases (HATs) play an important role in epigenetic regulation, as well as the regulation of plant growth, development, and responses to abiotic stresses. To clarify the role of histone acetylation in the low-temperature response of B. rapa L., we identified 29 HAT genes in B. rapa L. using bioinformatics tools. We also conducted a comprehensive analysis of the physicochemical properties, gene structure, chromosomal localization, conserved structural domains and motifs, cis-acting regulatory elements, and evolutionary relationships of these genes. Using transcriptome data, we analyzed the expression patterns of BrHAT family members and predicted interactions between proteins; the results indicated that BrHATs play an important role in the low-temperature response of B. rapa L. HAT inhibitor (curcumin; CUR) and histone deacetylase inhibitor (Trichostatin A; TSA) were applied to four B. rapa L. varieties varying in cold resistance under the same low-temperature conditions, and changes in the physiological indexes of these four varieties were analyzed. The inhibitor treatment attenuated the effect of low temperature on seed germination, and curcumin treatment was most effective, indicating that the germination period was primarily regulated by histone acetylase. Both inhibitor treatments increased the activity of protective enzymes and the content of osmoregulatory substances in plants, suggesting that histone acetylation and deacetylation play a significant role in the response of B. rapa L. to low-temperature stress. The qRT-PCR analyses showed that the expression patterns of BrHATs were altered under different inhibitor treatments and low-temperature stress; meanwhile, we found three significantly differentially expressed genes. In sum, the process of histone acetylation is involved in the cold response and the BrHATs gene plays a role in the cold stress response.

Sugars will eventually be exported transporter (SWEET), a class of glucose transport proteins, is crucial in plants for glucose transport by redistribution of sugars and regulates growth, development, and stress tolerance. Although the SWEET family has been studied in many plants, little is known about its function in winter B. rapa (Brassica rapa L.). Bioinformatics approaches were adopted to identify the SWEET gene (BraSWEETs) family in B. rapa to investigate its role during overwintering. From the whole-genome data, 31 BraSWEET genes were identified. Gene expansion was realized by tandem and fragment duplication, and the 31 genes were classified into four branches by phylogenetic analysis. As indicated by exon–intron structure, cis-acting elements, MEME (Multiple EM for Motif Elicitation) motifs, and protein structure, BraSWEETs were evolutionarily conserved. According to the heat map, 23 BraSWEET genes were differentially expressed during overwintering, revealing their potential functions in response to low-temperature stress and involvement in the overwintering memory-formation mechanism. BraSWEET10 is mainly associated with plant reproductive growth and may be crucial in the formation of overwintering memory in B. rapa. The BraSWEET10 gene was cloned into B. rapa (Longyou-7, L7). The BraSWEET10 protein contained seven transmembrane structural domains. Real-time fluorescence quantitative PCR (qRT-PCR) showed that the BraSWEET10 gene responded to low-temperature stress. BraSWEET10 was localized to the cell membrane. The root length of overexpressing transgenic A. thaliana was significantly higher than that of wild-type (WT) A. thaliana under low temperatures. Our findings suggest that this gene may be important for the adaptation of winter B. rapa to low-temperature stress. Overall, the findings are expected to contribute to understanding the evolutionary links of the BraSWEET family and lay the foundation for future studies on the functional characteristics of BraSWEET genes.

N6-methyladenosine (m⁶A) is an mRNA modification considered essential in plants, and is a key player in gene regulation at the transcriptional and translational levels. In present study, we mapped Brassica rapa's whole transcriptome m⁶A profile under low-temperature stress in different cold tolerant varieties to elucidate the m⁶A methylation pattern. The distribution of m⁶A modifications changed significantly under low temperature stress. More 5'UTR m⁶A was deposited in strong cold-resistant varieties and responded positively to cold resistance by regulating mRNA expression abundance. The increase in m⁶A abundance was correlated with the increase in mRNA abundance after low temperature stress. ZAT12 might positively regulate its mRNA expression through m⁶A methylation. MYBC1 might be a negative regulator to cope with low-temperature stress. The hypothetical protein was involved in starch and sucrose metabolic pathways, and that the Low-quality protein was involved in the regulation of DNA binding, DNA-binding, transcription factor activity, and proline biosynthetic processes and leaf senescence pathways. In addition, a number of m⁶A methyltransferases and m⁶A demethylases play crucial roles in response to cold stress. These results revealed the critical role of m⁶A -modified genes under cold stress and provide new insights into the study of cold resistance in winter Brassica rapa.

During a prolonged domestication and environmental selection, Brassica rapa has formed diverse morphological types during a cultivation process of up to 8000 years, such as root-type turnips (Brassica rapa var. rapa), leaf-type Chinese cabbage (Brassica rapa var. pekinensis), oil-type rapeseed (Brassica rapa L.), and other rich types. China is one of the origins of Brassica rapa L., which is spread all over the east, west, south, and north of China. Studying its origin and evolution holds significant importance for unraveling the cultivation history of Chinese oilseed crops, intraspecific evolutionary relationships, and the utilization value of genetic resources. This article summarizes the cultivation history, evolution, classification research progress, and germplasm resource diversity of Brassica rapa var. oleifera in China. Combining karyotype analysis, genomic information, and wild relatives of Brassica rapa var. oleifera discovered on the Qinghai–Tibet Plateau, it is proposed that Brassica rapa var. oleifera has the characteristic of polycentric origin, and Gansu Province in China is one of the earliest regions for its cultivation. Brassica rapa var. oleifera, originating from the Mediterranean region, was diffused to the East Asian continent through two independent transmission paths (one via the Turkish Plateau and the other via Central Asia and Siberia). Analyzing the genetic diversity characteristics and evolutionary trajectories of these two transmission paths lays a foundation for clarifying the origin and evolutionary process of Brassica rapa var. oleifera and accelerating the breeding of Brassica rapa var. oleifera in China. Despite existing research on the origin of Brassica rapa L., the domestication process of this species remains unresolved. Future studies will employ whole-genome resequencing to address this fundamental question.

Leaf color is a key trait influencing photosynthetic efficiency in plants. This study investigates the photosynthetic characteristics of differently colored leaves in Brassica juncea L. using green-leaved (SWJ) and purple-red-leaved (RLJ) varieties, their reciprocal F₁ hybrids, and F₂ populations. The results show that the net photosynthetic rate and chlorophyll content of SWJ were significantly higher than those of RLJ, while F₁ hybrids exhibited intermediate photosynthetic performance. All five measured photosynthetic traits—net photosynthetic rate, stomatal conductance, intercellular CO₂ concentration, transpiration rate, and chlorophyll content—segregated significantly in the F₂ generation and were identified as quantitative traits. Notably, transpiration rate was positively correlated with leaf color, whereas no correlation was found with net photosynthetic rate or intercellular CO₂ concentration. A key finding is the occurrence of purple-leaved plants with high photosynthetic rates and green-leaved plants with low photosynthetic rates in the F₂ generation, indicating the potential to combine high photosynthesis with anthocyanin-rich purple leaves. This study provides new genetic insights and a theoretical basis for breeding high-yield, stress-tolerant Brassica juncea varieties.

Q-type C2H2 zinc finger protein (ZFP) transcription factors, a plant-specific subfamily of C2H2 ZFP, have been implicated in regulating abiotic stress responses, growth, and developmental processes in plants. Rapeseed (Brassica napus L.) is a crucial oil crop widely used for the production of high-quality vegetable oil, animal feed, and biodiesel. Compared with studies on Q-type C2H2-ZFP genes in other plant species, systematic research has not been performed in B. napus. In this study, a comprehensive genome-wide analysis of Q-type C2H2-ZFPs in B. napus was conducted. A total of 216 Q-type C2H2-ZFP genes were identified, exhibiting extensive and uneven distribution across the 19 chromosomes. Phylogenetic analysis, based on homologs from Arabidopsis, classified these genes into eight distinct subfamilies, with each containing one to three conserved “QALGGH” motifs. Each subfamily exhibited similar motif compositions and gene structures. Evolutionary studies revealed that segmental duplication events played a crucial role in the expansion of the BnaQ-type C2H2-ZFP gene family. Expression pattern analysis in different tissues and under abiotic stress identified BnaA03g09250D, BnaC09g35160D, BnaC03g11570D, and BnaA10g25850D as candidate genes involved in the response to freezing stress. Overexpression of BnaC09g35160D provided preliminary evidence that it enhances freezing tolerance in plants. This comprehensive study of Q-type C2H2-ZFPs in B. napus will enhance our understanding of the BnaQ-type C2H2-ZFP gene family and provide valuable insights for further functional investigations of BnaC09g35160D.