Long Wang

Transposable elements (TEs) are major components of plant genomes and play crucial roles in adaptive genome evolution and stress tolerance. Under abiotic stress, activated TEs can generate abundant genetic variation and regulate the expression of stress-responsive genes. As a pioneer species in desert and saline–alkali environments, Tamarix chinensis L. has been little studied with respect to the abundance and evolutionary relationships of its LTR retrotransposons, particularly their activation patterns under salt and alkali stresses. This study aimed to investigate the characteristics of the reverse transcriptase (RT) domain of LTR retrotransposons in T. chinensis and to determine their patterns of activation in response to salt and alkali stresses. A total of 629 Ty1-copia and 607 Ty3-gypsy RT nucleotide sequences, which displayed high AT/GC ratios and evidence of stop codon insertions, were identified in T. chinensis by amplicon sequencing. Among these, 211 Ty1-copia and 117 Ty3-gypsy RT sequences with potential transpositional activity each contained distinct domains, suggesting a high degree of conservation. Phylogenetic analysis revealed that the RT sequences of T. chinensis are closely related to those of mangrove, wild potato, and Ipomoea, and may have undergone horizontal transfer. Expression analysis showed that 634 and 181 RT sequences were activated under salt and alkali stresses, respectively, with the majority belonging to salt-induced Ty1-copia families. Compared with the control group, under salt and alkali stresses, the cTy1-copia elements (Ty1-copia with amplificated from cDNA of T. chinensis, the same below) with dominant abundance were mainly concentrated in the Angela subfamily, while the cTy3-gypsy elements induced by alkali stress were primarily distributed in the Tekay and Reina subfamilies. Furthermore, four cTy1-copia and five cTy3-gypsy were identified as candidate key LTR retrotransposons responsive to salt and alkali stresses. Overall, this study provides new insights into the epigenetic mechanisms underlying the adaptation of T. chinensis to saline and alkali stresses and offers a theoretical basis for its potential applications in saline–alkali land reclamation.

Background: The BBR-BPC gene family is a relatively conservative group of transcription factors, playing a key role in plant morphogenesis, organ development, and responses to abiotic stress. Brassica napus L. (B. napus), commonly known as oilseed rape, is an allopolyploid plant formed by the hybridization and polyploidization of Brassica rapa L. (B. rapa) and Brassica oleracea L. (B. oleracea), and is one of the most important oil crops. However, little is known about the characteristics, conservation, and expression patterns of this gene family in B. napus, especially under abiotic stress. Methods: To explore the characteristics and potential biological roles of the BBR-BPC gene family members in B. napus, we conducted identification based on bioinformatics and comparative genomics methods. We further analyzed the expression patterns through RNA-seq and qRT-PCR. Results: We identified 25 BBR-BPC members, which were classified into three subfamilies based on phylogenetic analysis, and found them to be highly conserved in both monocots and dicots. The conserved motifs revealed that most members contained Motif 1, Motif 2, Motif 4, and Motif 8. After whole-genome duplication (WGD), collinearity analysis showed that BBR-BPC genes underwent significant purifying selection. The promoters of most BBR-BPC genes contained cis-acting elements related to light response, hormone induction, and stress response. RNA-seq and qRT-PCR further indicated that BnBBR-BPC7, BnBBR-BPC15, BnBBR-BPC20, and BnBBR-BPC25 might be key members of this family. Conclusions: This study provides a theoretical foundation for understanding the potential biological functions and roles of the BBR-BPC gene family, laying the groundwork for resistance breeding in B. napus.

Whirly transcription factors are unique to plants, playing pivotal roles in managing leaf senescence and DNA repair. While present in various species, their identification in Brassica napus L. (B. napus) and their differences during hybridization and polyploidy has been elusive. Addressing this, our study delves into the functional and evolutionary aspects of the Whirly gene family during the emergence of B. napus, applying bioinformatics and comparative genomics. We identified six Whirly genes in B. napus. In Brassica rapa L. (B. rapa), three Whirly genes were identified, while four were found in Brassica oleracea L. (B. oleracea). The results show that the identified Whirly genes not only have homology but also share the same chromosomal positions. Phylogenetic analysis indicates that Whirly genes in monocots and dicots exhibit high conservation. In the evolutionary process, the Whirly gene family in B. napus experienced events of intron/exon loss. Collinearity insights point to intense purifying selection post-duplication. Promoter regions housed diverse cis-acting elements linked to photoresponse, anaerobic initiation, and methyl jasmonate responsiveness. Notably, elements tied to abscisic acid signaling and meristem expression were prominent in diploid ancestors but subdued in tetraploid B. napus. Tissue-specific expression unveiled analogous patterns within subfamily genes. Subsequent qRT-PCR analysis spotlighted BnAWHY1b’s potential significance in abiotic stress response, particularly drought. These findings can be used as theoretical foundations to understand the functions and effects of the Whirly gene family in B. napus, providing references for the molecular mechanism of gene evolution between this species and its diploid ancestors.

The NDPK gene family is an important group of genes in plants, playing a crucial role in regulating energy metabolism, growth, and differentiation, cell signal transduction, and response to abiotic stress. However, our understanding of the NDPK gene family in Brassica napus L. remains limited. This paper systematically analyzes the NDPK gene family in B. napus, particularly focusing on the evolutionary differences within the species. In this study, sixteen, nine, and eight NDPK genes were identified in B. napus and its diploid ancestors, respectively. These genes are not only homologous but also highly similar in their chromosomal locations. Phylogenetic analysis showed that the identified NDPK proteins were divided into four clades, each containing unique motif sequences, with most NDPKs experiencing a loss of introns/exons during evolution. Collinearity analysis revealed that the NDPK genes underwent whole-genome duplication (WGD) events, resulting in duplicate copies, and most of these duplicate genes were subjected to purifying selection. Cis-acting element analysis identified in the promoters of most NDPK genes elements related to a light response, methyl jasmonate response, and abscisic acid response, especially with an increased number of abscisic acid response elements in B. napus. RNA-Seq results indicated that NDPK genes in B. napus exhibited different expression patterns across various tissues. Further analysis through qRT-PCR revealed that BnNDPK genes responded significantly to stress conditions such as salt, drought, and methyl jasmonate. This study enhances our understanding of the NDPK gene family in B. napus, providing a preliminary theoretical basis for the functional study of NDPK genes and offering some references for further revealing the phenomenon of polyploidization in plants.

With the development of urban industrialization, the increasing ozone concentration (O₃) at ground level stresses on the survival of plants. Plants have to adapt to ozone stress. DNA methylation is crucial for a rapid response to abiotic stress in plants. Little information is known regarding the epigenetic response of DNA methylation of plants to O₃ stress. This study is designed to explore the epigenetic mechanism and identify a possible core modification of DNA methylation or genes in the plant, in response to O₃ stress. We investigated the agronomic traits and genome-wide DNA methylation variations of the Japonica rice cultivar Nipponbare in response to O₃ stress at three high concentrations (80, 160, and 200 nmol·mol⁻¹), simulated using open-top chambers (OTC). The flag leaf length, panicle length, and hundred-grain weight of rice showed beneficial effects at 80 nmol·mol⁻¹ O₃ and an inhibitory effect at both 160 and 200 nmol·mol⁻¹ O_3. The methylation-sensitive amplified polymorphism results showed that the O₃-induced genome-wide methylation alterations account for 14.72–15.18% at three different concentrations. Our results demonstrated that methylation and demethylation alteration sites were activated throughout the O₃ stress, mainly at CNG sites. By recovering and sequencing bands with methylation alteration, ten stress-related differentially amplified sequences, widely present on different chromosomes, were obtained. Our findings show that DNA methylation may be an active and rapid epigenetic response to ozone stress. These results can provide us with a theoretical basis and a reference to look for more hereditary information about the molecular mechanism of plant resistance to O₃ pollution.