Leaf shape can reflect the survival and development of plants in different environments. In particular, leaf area, showing a scaling relationship with other leaf-shape indices, has been used to evaluate the extent of salt stress on plants. Based on the scaling relationships between leaf area and other leaf-shape indices in experiments at different levels of salt stress, we could examine which leaf-shape indices are also related to salt stress. In the present study, we explored the effects of different salt concentration treatments on leaf dry mass per unit area (LMA), the quotient of leaf perimeter and leaf area (QPA), the quotient of leaf width and length (QWL), the areal quotient (AQ) of left and right sides of a leaf and the standardized index (SI) for bilateral symmetry. We treated Pyrus betulifolia Bunge under NaCl salt solution of 2‰, 4‰ and 6‰, respectively, with fresh water with no salt as the control. The reduced major axis (RMA) was used to fit a linear relationship of the log-transformed data between any leaf trait measures and leaf area. We found that leaf fresh weight and dry weight decrease with salt concentration increasing, whereas the exponents of leaf dry weight versus leaf area exhibit an increasing trend, which implies that the leaves expanding in higher salt environments are prone to have a higher cost of dry mass investment to increase per unit leaf area than those in lower salt environments. Salt concentration has a significant influence on leaf shape especially QWL, and QWL under 6‰ concentration treatment is significantly greater than the other treatments. However, there is no a single increasing or decreasing trend for the extent of leaf bilateral symmetry with salt concentration increasing. In addition, we found that the scaling exponents of QPA versus leaf area for four treatments have no significant difference. It indicates that the scaling relationship of leaf perimeter versus leaf area did not change with salt concentration increasing. The present study suggests that salt stress can change leaf functional traits especially the scaling relationship of leaf dry weight versus leaf area and QWL, however, it does not significantly affect the scaling relationships between leaf morphological measures (including QPA and the extent of leaf bilateral symmetry) and leaf area.

Anthocyanin biosynthesis and accumulation is closely associated with tissue/organ coloring in plants. To gain insight into the physiological and molecular mechanisms of leaf coloring in Acer palmatum, a deciduous tree during autumnal senescence, we first investigated concentration dynamics of pigments (i.e., chlorophyll, carotenoid and anthocyanin) in leaves with differential coloring. It was found that compared to green leaves (GN), anthocyanins were accumulated actively in semi-red (SR) and total-red (TR) leaves, accompanied with chlorophyll and carotenoid degradation. Then transcriptional profiling on GN and SR leaves identified thousands of transcripts with differential expression in SR compared to GN leaves. An annotation search showed that the entire flavonoid/anthocyanin biosynthesis pathway from the production of naringenin chalcone to modification of flavonoid backbone was extensively activated at the transcriptional level in SR leaves. Phylogenetic analysis of putative MYB proteins identified ApMYB1 as a putative regulator promoting anthocyanin biosynthesis. Expression of ApMYB1 in leaves was induced by exogenous hormones including abscisic acid. Stable overexpression of ApMYB1 in tobacco resulted in leaves with higher accumulation of anthocyanins. Collectively, our results identified ApMYB1 as a positive regulator associated with leaf coloring in Acer palmatum during autumnal senescence, which may be regarded a potential target for breeding color-leafed plants.

Common oat (Avena sativa L.) is one of the important minor grain crops in China, and drought stress severely affects its yield and quality. To investigate the drought resistance characteristics of oat seedlings, this study used Baiyan 2, an oat cultivar at the three-leaf stage, as the experimental material. Drought stress was simulated using polyethylene glycol (PEG) to treat the seedlings. The photosynthetic parameters and physicochemical indices of the treatment groups at 6 h and 12 h were measured and compared with the control group at 0 h. The results showed that drought stress did not significantly change chlorophyll content, but it significantly reduced net photosynthetic rate and other photosynthetic parameters while significantly increasing proline content. Transcriptome analysis was conducted using seedlings from both the control and treatment groups, comparing the two treatment groups with the control group using Tbtool software (v2.136). This analysis identified 344 differentially expressed genes. Enrichment analysis of these differentially expressed genes revealed significant enrichment in physiological pathways such as photosynthesis and ion transport. Ten differentially expressed genes related to the physiological process of photosynthetic carbon assimilation were identified, all of which were downregulated. Additionally, seven differentially expressed genes were related to ion transport. Through gene co-expression analysis combined with promoter region structure analysis, 11 transcription factors (from MYB, AP2/ERF, C2C2-dof) were found to regulate the expression of 10 genes related to photosynthetic carbon assimilation. Additionally, five transcription factors regulate the expression of two malate transporter protein-related genes (from LOB, zf-HD, C2C2-Dof, etc.), five transcription factors regulate the expression of two metal ion transporter protein-related genes (from MYB, zf-HD, C2C2-Dof), five transcription factors regulate the expression of two chloride channel protein-related genes (from MYB, bZIP, AP2/ERF), and two transcription factors regulate the expression of one Annexin-related gene (from NAC, MYB). This study provides a theoretical foundation for further research on the molecular regulation of guard cells and offers a molecular basis for enhancing drought resistance in oats.

Introduction: HD-Zip transcription factors are an important class of plant transcription factors involved in regulating plant growth and development as well as various stress responses. In order to explore the characteristics of oat HD-Zip transcription factors and their transcriptomic expression patterns under abiotic stress, this study identified members of the HD-Zip gene family in the oat genome through bioinformatics methods and analyzed their basic physicochemical properties, evolutionary relationships, conserved structural domains, gene duplication relationships, and expression profiles.Results: 74 HD-Zip gene sequences were identified in the oat genome, unevenly distributed in all chromosomes except the 4D chromosome. The 74 HD-Zip genes can be divided into four subfamilies (HD-Zip Ⅰ-Ⅳ), containing 30 (HD-Zip Ⅰ), 38 (HD-Zip Ⅱ), 4 (HD-Zip III), and 2 (HD-Zip IV) genes, respectively. The grouping of this study is completely consistent with the clustering results of family members in the oat HD-Zip gene phylogenetic tree, further supporting the reliability of the sequence grouping. In addition, there are significant differences in conserved motifs and gene lengths between subfamilies, but they are conserved within the same subfamily. Under drought and salt stress, the expression levels of a large number of oat HD-Zip genes were significantly induced or suppressed, indicating that these HD-Zip genes are likely to be involved in regulating the oat’s response to adversity.Conclusions: The results of this study provide excellent candidate HD-Zip genes for the study of oat resistance, and provide a reference for oat gene improvement and genetic breeding.

(1) Background: The genus Phyllostachys belongs to the subfamily Bambusoideae within the family Gramineae. Bamboos of this genus are distinguished by their remarkable genetic traits, including exceptional resistance to both cold and drought conditions. These species possess considerable economic, ecological, and aesthetic value, finding extensive use in forestry and landscape design across China. (2) Methods: This study employed Illumina’s second-generation sequencing technology to sequence the chloroplast genomes of eight Phyllostachys species, followed by their assembly and annotation. (3) Results: The chloroplast genomes of the genus exhibit a characteristic tetrad structure with an average sequence length of 139,699 bp and an average GC content of 38.9%. A total of 130 genes have been annotated across eight bamboo species, comprising 75 protein-coding genes, 28 tRNA genes, and four rRNA genes. Global alignment and nucleotide polymorphism analyses indicate that the chloroplast genome of Phyllostachys is highly conserved overall. The boundaries of the four chloroplast regions are relatively conserved and exhibit minimal differences. Among these regions, three coding region genes—atpH, trnQ-UUG, and petB—and five non-coding regions—rpl32-trnL-UAG, rpl14-rpl16, rpl22-rps19, rps12-clpP, and trnR-UCU-trnM-CAU—exhibit high polymorphism and can be used as potential hotspot areas for subsequent research. A total of 266 simple sequence repeat (SSR) loci were identified by SSR analysis in the chloroplast genomes of eight bamboo species; the largest number of mononucleotide repeats was 154, predominantly consisting of A/T. Codon bias in the chloroplast genomes of the eight bamboo species indicates a preference for codons ending with A and U. Additionally, the UUA codon, which encodes leucine (Leu), is positioned between codons encoding phenylalanine (Phe), lysine (Lys), leucine (Leu), serine (Ser), and tyrosine (Tyr), indicating certain differences among these species. (4) Conclusions: This study aims to offer novel insights into the population genetics, phylogenetic relationships, and evolutionary patterns of Phyllostachys.

Cryptochrome is an important class of blue light receptors involved in various physiological activities such as photomorphogenesis and abiotic stress regulation in plants. In order to investigate the molecular mechanism of blue light-induced color change in Chimonobambusa sichuanensis, we screened and cloned the gene encoding the blue light receptor Cryptochrome in Chimonobambusa sichuanensis, and analyzed the expression characteristics of Cryptochrome gene in Chimonobambusa sichuanensis under different light intensities, photoplasmas, and temperatures by qRT-PCR. Through homologous cloning, a total of four CsCRY genes were obtained in the Chimonobambusa sichuanensis genome, namely, CsCRY1a, CsCRY1b, CsCRY2, and CsCRY3. Structural domain analyses of the encoded proteins of the four genes revealed that all CsCRYs proteins had the typical photoreceptor structural domain, PRK. Phylogenetic tree analyses revealed that the four genes CsCRY1a, CsCRY1b, CsCRY2, and CsCRY3 could be categorized into three subfamilies, with CsCRY1a and CsCRY1b clustered in subfamily I, CsCRY2 classified in subfamily II, and CsCRY3 belonging to subfamily III. All CsCRYs had no signal peptide and the instability index was higher than 40, among which the isoelectric points of CsCRY1a, CsCRY1b, and CsCRY2 were around 5. qRT-PCR analysis revealed that the expression of all four CsCRYs genes was up-regulated at 75 µmol·m^-²·s^-1 blue light illumination for 4 h. In addition, under different treatments of light quality, the expression of CsCRY2 genes was significantly higher under blue light than under red light and a mixture of red light and blue light with a light intensity of 1:1; while under different temperature gradients, CsCRY2 genes were highly expressed under low temperature stress at -5 ℃ and 0 ℃. This study provides a basis for further research on blue light-induced color change in Chimonobambusa sichuanensis and expands the scope of Cryptochrome gene research.