Genome-wide identification and expression analysis of MYB gene family under nitrogen stress in Panax notoginseng

Comparative plastome analyses and evolutionary relationships of 25 East Asian species within the medicinal plant genus Scrophularia (Scrophulariaceae)

Backgroud

Scrophularia L., a genus of the Scrophulariaceae, is a group of important medicinal plants used for eliminating heat and detoxifying. East Asia has an abundance of potentially medicinal Scrophularia species, and it serves as a secondary diversity center of the genus. However, the genomic resources available for germplasm identification and pharmaceutical exploration of East Asian Scrophularia are insufficient, hindering its commercial and industrial development. Additionally, the interspecific relationships of most East Asian Scrophularia species remain unclear.

Methods

In this study, we sequenced the leaves of 25 East Asian species of the genus Scrophularia, assembled and annotated the complete chloroplast genomes, and subsequently performed comparative and phylogenetic analyses on these genomes.

Results and discussion

The conserved plastome length of these 25 species ranged from 151,582 bp to 153,239 bp, containing a total of 132 coding genes, including 18 duplicated genes and 114 unique genes. Through genome alignment of these 25 species, 38-53 repeated sequences and 7 shared SSRs were identified, along with regions with high nucleotide polymorphism (Pi), which could potentially serve as molecular markers for species identification. The genome structure, gene content, and arrangement showed conservation, while variations were observed in the IR boundary regions and IGS. Phylogenetic inferences based on whole plastomes or on coding sequences (CDS) only yielded congruent results. We categorized the 25 East Asian Scrophularia species into six distinct clades and further explored their interspecies relationships using morphological characteristics, such as flower color, the relative position of stamens and corolla, and plant height. This could lay a genetic basis for future resource development of Scrophularia in East Asia.

Genome-Wide Identification of the TGA Gene Family and Expression Analysis under Drought Stress in Brassica napus L

TGA transcription factors belong to Group D of the bZIP transcription factors family and play vital roles in the stress response of plants. Brassica napus is an oil crop with rich economic value. However, a systematic analysis of TGA gene family members in B. napus has not yet been reported. In this study, we identified 39 full-length TGA genes in B. napus, renamed TGA1~TGA39. Thirty-nine BnTGA genes were distributed on 18 chromosomes, mainly located in the nucleus, and differences were observed in their 3D structures. Phylogenetic analysis showed that 39 BnTGA genes could be divided into five groups. The BnTGA genes in the same group had similar structure and motif compositions, and all the BnTGA genes had the same conserved bZIP and DOG1 domains. Phylogenetic and synteny analysis showed that the BnTGA genes had a close genetic relationship with the TGA genes of the Brassica juncea, and BnTGA11 and BnTGA29 may play an important role in evolution. In addition, qRT-PCR revealed that three genes (BnTGA14/17/23) showed significant changes in eight experimental materials after drought treatment. Meanwhile, it can be inferred from the results of drought treatment on different varieties of rapeseed that the stress tolerance of parental rapeseed can be transmitted to the offspring through hybridization. In short, these findings have promoted the understanding of the B. napus TGA gene family and will contribute to future research aimed at B. napus resistant breeding.

Overexpression of BnMYBL2-1 improves plant drought tolerance via the ABA-dependent pathway

Drought stress is a major environmental challenge that poses considerable threats to crop survival and growth. Previous research has indicated anthocyanins play a crucial role in alleviating oxidative damage, photoprotection, membrane stabilization, and water retention under drought stress. However, the presence of MYBL2 (MYELOBBLASTOSIS LIKE 2), an R3-MYB transcription factor (TF) which known to suppress anthocyanin biosynthesis. In this study, four BnMYBL2 members were cloned from Brassica napus L, and BnMYBL2-1 was overexpressed in Triticum aestivum L (No BnMYBL2 homologous gene was detected in wheat). Subsequently, the transgenic wheat lines were treated with drought, ABA and anthocyanin. Results showed that transgenic lines exhibited greater drought tolerance compared to the wild-type (WT), characterized by improved leaf water content (LWC), elevated levels of soluble sugars and chlorophyll, and increased antioxidant enzyme activity. Notably, transgenic lines also exhibited significant upregulation in abscisic acid (ABA) content, along with the transcriptional levels of key enzymes involved in ABA signalling under drought. Results also demonstrated that BnMYBL2-1 promoted the accumulation of ABA and anthocyanins in wheat. Overall, the study highlights the positive role of BnMYBL2-1 in enhancing crop drought tolerance through ABA signalling and establishes its close association with anthocyanin biosynthesis. These findings offer valuable insights for the development of drought-resistant crop varieties and enhance the understanding of the molecular mechanisms underlying plant responses to drought stress.

Analysis of WAK Genes in Nine Cruciferous Species with a Focus on Brassica napus L

The wall-associated kinase family contributes to plant cell elongation and pathogen recognition. Nine Cruciferous species were studied for identification and molecular evolution of the WAK gene family. Firstly, 178 WAK genes were identified. A phylogenetic tree was constructed of the Cruciferous WAK proteins into four categories, of which the Brassica rapa, Brassica oleracea and Brassica napus genes in the U's triangle were more closely related. The WAK gene family was unevenly distributed in B. napus chromosomal imaging, with the largest number of BnWAK genes located on chromosome C08. In the expression analysis, the expression patterns of the WAK gene family varied under different stress treatments, and some members of BnWAKs were significantly different under stress treatments. This study lays a foundation for further revealing the functional mechanisms of the WAK gene family in Brassica napus.