Bingxue Han

Background: Sulfate transporters (SULTRs) are integral membrane proteins responsible for sulfate uptake, translocation, and plant adaptation to abiotic stresses. However, knowledge regarding the SULTR gene family in the economically important crop, Brassica rapa (Chinese cabbage), limited. The aim of this study is to conduct a genome-wide identification and functional characterization of BrSULTR genes and to explore their potential functions under abiotic stress. Methods: We identified 19 BrSULTR genes in the B. rapa genome by performing homology searches with Arabidopsis thaliana SULTR sequences as queries. Subsequent bioinformatics analysis included phylogenetic classification, chromosomal localization, gene structure, conserved motif dissection, cis-regulatory element prediction, and protein–protein interaction (PPI) network analysis. Tissue-specific expression profiles of BrSULTRs were assessed using publicly available transcriptome data. Furthermore, their expression dynamics under salt (150 mM NaCl) and low-temperature (4 °C) stress were investigated by integrating transcriptomic, proteomic, and qRT-PCR data. Results: The 19 identified BrSULTR members were phylogenetically categorized into four subfamilies and were mapped unevenly across seven chromosomes. Promoter analysis identified an array of cis-regulatory elements associated with development, hormone response, and stress response. Expression profiles revealed distinct tissue-specific patterns in roots, stems, leaves, flowers, and siliques. Under salt stress, BrSULTR13 was significantly upregulated, while BrSULTR9 and BrSULTR11 were significantly suppressed under low-temperature stress. PPI network projection indicated that the Arabidopsis homologs of BrSULTR5 may physically interact with stress-regulating enzymes such as APS and APR. Conclusions: Our work presents a comprehensive genomic and functional overview of the BrSULTR gene family in B. rapa. The results underscore the potential functions of BrSULTRs, highlighting their involvement in sulfate transport and abiotic stress responses. These insights establish valuable insights and a foundation for further research aiming at improving stress tolerance in B. rapa through the manipulation of sulfur metabolism pathways.

Background: Formin proteins are crucial regulators of actin filament assembly and elongation in eukaryotic cells, playing important roles in plant development and abiotic stress responses. However, the functional characterization of formins in Brassica rapa L. remains undiscovered. Methods: A total of 27 formin family members (BrFHs) were identified through genome-wide alignment with Arabidopsis thaliana (L.) Heynh. Results: Phylogenetic analysis classified BrFH gene family into two distinct clades, designated Group I and Group II, which exhibit divergent protein architectures. Promoter analysis revealed that BrFHs contain multiple cis-regulatory elements related to growth and development, stress responses, and phytohormone signaling. These findings suggest that BrFHs may have diversified functions. Tissue-specific expression analysis revealed that BrFHs exhibit distinct expression patterns across various tissues. Notably, BrFH15 and BrFH18 are highly expressed in flowers, displaying expression profiles similar to those of floral development genes such as AP3, AGL10 and so on. Additionally, many BrFHs show dynamic expression patterns in response to cold stresses. In particular, BrFH2, BrFH19 and BrFH27 were up-regulated, and their co-expression within the gene network suggests potential roles in regulating cold stress. Conclusions: These results clarify the functional roles of BrFHs and shed light on the molecular mechanisms underlying their regulation of tissue development and responses to cold stress in Brassica rapa.

Background: Formin proteins are crucial regulators of actin filament assembly and elongation in eukaryotic cells, playing important roles in plant development and abiotic stress responses. However, the functional characterization of formins in Brassica rapa remains uncover. Methods: A total of 27 formin family members (BrFHs) were identified through genome-wide alignment with Arabidopsis thaliana. Results: Phylogenetic analysis classified BrFH gene family into two distinct clades, designated Group I and Group II, which exhibit divergent protein architectures. Promoter analysis revealed that BrFHs contain multiple cis-regulatory elements related to growth and development, stress responses, and phytohormone signaling. These findings suggest that BrFHs may have diversified functions. Tissue-specific expression analysis revealed that BrFHs exhibit distinct expression patterns across various tissues. Notably, BrFH15 and BrFH18 are highly expressed in flowers, displaying expression profiles similar to those of floral development genes such as AP3, AGL10 and so on. Additionally, many BrFHs show dynamic expression patterns in response to cold stresses. In particular, BrFH2, BrFH19 and BrFH27 were up-regulated, and their co-expression within the gene network suggests potential roles in regulating cold stress. Conclusions: These results clarify the functional roles of BrFHs and shed light on the molecular mechanisms underlying their regulation of tissue development and responses to abiotic stress in Brassica rapa.