Wenting He

NAC transcription factors play important roles in plant growth and development. In this study, ClVND1 was cloned from the NAC transcription factor of Chrysanthemum lavandulifolium. Through bioinformatics analysis, the gene was found to belong to the OsNAC7 subfamily with an open reading frame (ORF) of 1164 bp and encoding 387 amino acids. Through paraffin sectioning and stress treatment, it was found that this gene could increase the thickness of the secondary cell wall of transgenic Arabidopsis stems and lead to the growth of more lateral roots to improve the tolerance of Arabidopsis seedlings to salt or low temperature. Moreover, the inflorescence elongation rate and height of wild-type Arabidopsis were greater than those of transgenic Arabidopsis, but the flowering period was later than that of transgenic Arabidopsis. These results indicate that ClVND1 may resist external stress by regulating root growth and can inhibit inflorescence growth and promote flowering. The purpose of this study was to improve stress resistance and promote the growth and development of C. morifolium by regulating the expression of ClVND1, which is of great significance for the study of chrysanthemum resistance to abiotic stress and growth and development.

The Asteraceae are widely distributed throughout the world, with diverse functions and large genomes. Many of these genes remain undiscovered and unstudied. In this study, we discovered a new gene ClNUM1 in Chrysanthemum lavandulifolium and studied its function. In this study, bioinformatics, RT-qPCR, paraffin sectioning, and tobacco transgenics were utilized to bioinformatically analyze and functionally study the three variable splice variants of the unknown gene ClNUM1 cloned from C. lavandulifolium. The results showed that ClNUM1.1 and ClNUM1.2 had selective 3′ splicing and selective 5′ splicing, and ClNUM1.3 had selective 5′ splicing. When the corresponding transgenic tobacco plants were subjected to abiotic stress treatment, in the tobacco seedlings, the ClNUM1.1 gene and the ClNUM1.2 gene enhanced salt and low-temperature tolerance and the ClNUM1.3 gene enhanced low-temperature tolerance; in mature tobacco plants, the ClNUM1.1 gene was able to enhance salt and low-temperature tolerance, and the ClNUM1.2 and ClNUM1.3 genes were able to enhance low-temperature tolerance. In summary, there are differences in the functions of the different splice variants and the different seedling stages of transgenic tobacco, but all of them enhanced the resistance of tobacco to a certain extent. The analysis and functional characterization of the ClNUM1 gene provided new potential genes and research directions for abiotic resistance breeding in Chrysanthemum.

Ajania purpurea is a small semi-shrub in the Asteraceae family. Its corolla is purplish red from the middle to the top, and its leaves and flowers are all fragrant. It can be introduced and cultivated as ornamental plants. In order to survive adversity, plants actively regulate the expression of stress response genes and transcripts. Alternative splicing is a common phenomenon and an important regulation mode of eukaryotic gene transcription, which plays an important role in various biological processes. In this study, four splice variants of the NST1 gene were identified from A. purpurea, and the molecular mechanism of NST1 alternative splice variants involved in abiotic stress was explored through bioinformatics, transgenics and paraffin sectionalization. The analysis of amino acid sequences showed that ApNST1.1 had alternative 5′splicing, ApNST1.2 had alternative 3′splicing and ApNST1 had the two splicing types. The main conclusions from studying transgenic tobacco seedlings and adult seedlings under abiotic stress were as follows: ApNST1, ApNST1.1 and ApNST1.3 showed salt tolerance at seedling stage, especially ApNST1.3. At the mature seedling stage, the stem height of ApNST1.1 increased significantly, and ApNST1.1 showed obvious salt tolerance, while ApNST1.2 showed obvious cold resistance. Compared to Super35S::GFP, the xylem of ApNST1 thickened by 94 μm, and the cell wall thickened by 0.215 μm. These results are of great significance to the breeding and application of ApNST1 to select splice variants with more resistance to abiotic stress, and to future study in this area. At the same time, they provide a new direction for A. purpurea breeding, and increase the possibility of garden applications.

Leucanthemella linearis is a marsh plant in the family Compositae. It has good water and moisture resistance and ornamental properties, which makes it one of the important materials for chrysanthemum breeding and genetic improvement. The NST1 (NAC secondary wall enhancement factor 1) gene is associated with the thickening of the secondary walls of fiber cells in the plant ducts and the secondary xylem and plays an important role in plant stress resistance. In this study, two variable spliceosomes of the NST1 gene were identified from a chrysanthemum plant by using bioinformatics, qRT-PCR, transgene, and paraffin section methods to explore the molecular mechanism of the variable splicing of NST1 under abiotic stress. The results show that only three amino acids were found to be different between the two LlNST1 variants. After being treated with salt, drought, and low temperatures, analysis of the expression levels of the LlNST1 and LlNST1.1 genes in Ll showed that LlNST1.1 could respond to low temperatures and salt stress and had a weak response to drought stress. However, the expression level of LlNST1 under the three treatments was lower than that of LlNST1.1. LlNST1 transgenic tobacco showed increased saline–alkali resistance and low-temperature resistance at the seedling stage. LlNST1.1 transgenic tobacco also showed enhanced saline–alkali resistance and drought resistance at the seedling stage. In conclusion, the functions of the two variable spliceosomes of the NST1 gene are very different under abiotic stress. Therefore, this study verified the function of the variable spliceosome of NST1 and improved the stress resistance of the chrysanthemum plant under examination by regulating the expression of the NST protein, which lays a material foundation for the improvement of plant stress resistance materials and has important significance for the study of the resistance of chrysanthemum plants to abiotic stress.

Transcription factors (TFs) in the homeodomain-leucine zipper (HD-ZIP) family serve as essential regulators of plant development and control responses to environmental stimuli. To date, however, the HD-ZIP gene family in Prunus nana remains to be fully characterized. Accordingly, a genome-wide analysis of P. nana HD-ZIP family genes was performed using the most recent genomic data available, leading to the classification of 30 HD-ZIP TFs. These genes were annotated and subjected to systematic analyses of phylogenetic relationships, protein physicochemical properties, sequence-based structural characteristics, chromosomal distributions, and associated cis-acting regulatory elements. High levels of diversity were observed with respect to the gene structures for these PnaHD-Zip genes and the cis-regulatory elements found in the promoter regions upstream of these genes, suggesting that they play diverse roles in a range of biological contexts. These 30 PnaHD-Zip genes were further classified into four subgroups based on the results of phylogenetic, gene structure, and conserved motif analyses. Subsequent qPCR analyses indicated that PnaHD-Zip1 and PnaHD-Zip7 expression levels tended to increase was continuously inhibited in response to cold stress, suggesting that proteins in this HD-ZIP gene family may exhibit distinct responses to low-temperature stress exposure. Overall, these results offer a robust foundation for future studies seeking to explore the functional roles that HD-ZIP TFs play as regulators of cold stress tolerance in P. nana, in addition to offering more general insight regarding the regulatory functions and characteristics of these different HD-ZIP genes in P. nana.