Ascorbate oxidase (AO) and skewed5 (SKU5)-similar (SKS) proteins belong to the multicopper oxidase (MCO) family and play important roles in plants in response to environmental stress via modulation of oxidoreduction homeostasis. Currently, reports on the response of Gossypium barbadense MCO to Verticillium wilt (VW) caused by Verticillium dahliae are still limited. Herein, RNA sequencing of two G. barbadense cultivars of VW-resistant XH21 and VW-susceptible XH7 under V. dahliae treatment, combined with physiological and genetic analysis, was performed to analyze the function and mechanism of multicopper oxidases GbAO and GbSKS involved in V. dahliae resistance. The identified differentially expressed genes are mainly involved in the regulation of oxidoreduction reaction, and extracellular components and signaling. Interestingly, ascorbate oxidase family members were discovered as the most significantly upregulated genes after V. dahliae treatment, including GbAO3A/D, GbSKS3A/D, and GbSKS16A/D. H₂O₂ and Asc contents, especially reductive Asc in both XH21 and XH7, were shown to be increased. Silenced expression of respective GbAO3A/D, GbSKS3A/D, and GbSKS16A/D in virus-induced gene silencing (VIGS) cotton plants significantly decreased the resistance to V. dahliae, coupled with the reduced contents of pectin and lignin. Our results indicate that AO might be involved in cotton VW resistance via the regulation of cell wall components.

In previous research on the resistance of cotton to Verticillium wilt (VW), Gossypium hirsutum and G. barbadense were usually used as the susceptible and resistant cotton species, despite their different genetic backgrounds. Herein, we present data independent acquisition (DIA)-based comparative proteomic analysis of two G. barbadense cultivars differing in VW tolerance, susceptible XH7 and resistant XH21. A total of 4,118 proteins were identified, and 885 of them were differentially abundant proteins (DAPs). Eight co-expressed modules were identified through weighted gene co-expression network analysis. GO enrichment analysis of the module that significantly correlated with V. dahliae infection time revealed that oxidoreductase and peroxidase were the most significantly enriched GO terms. The last-step rate-limiting enzyme for ascorbate acid (AsA) biosynthesis was further uncovered in the significantly enriched GO terms of the 184 XH21-specific DAPs. Additionally, the expression of ascorbate peroxidase (APX) members showed quick accumulation after inoculation. Compared to XH7, XH21 contained consistently higher AsA contents and rapidly increased levels of APX expression, suggesting their potential importance for the resistance to V. dahliae. Silencing GbAPX1/12 in both XH7 and XH 21 resulted in a dramatic reduction in VW resistance. Our data indicate that APX-mediated oxidoreductive metabolism is important for VW resistance in cotton.

Cotton is a crucial economic crop that supplies natural fibers for the textile industry, with fiber quality being greatly impacted by abiotic stress throughout its growth stages. The Golden2-Like (GLK) gene family plays a key role in plant development and adaptation to abiotic stress. However, the specific functions and regulatory mechanisms of GLK members in cotton remain largely unexplored. In this study, a thorough analysis of GLK in four cotton species (Gossypium arboreum, G. raimondii, G. hirsutum, and G. barbadense) was conducted. A total of 198 GLK genes were identified in cotton. Conserved sequence analysis revealed that most GLK proteins contain two highly conserved domains: a MYB DNA-binding domain and a C-terminal (GCT) box. Promoter element analysis results show that the GLK gene family contains many stress response-related elements. Expression analysis demonstrated that GhGLK2, GhGLK11, GhGLK16, and GhGLK30 responded significantly to drought, salt, and temperature stresses. And GhGLK2, GhGLK13, GhGLK38, GhGLK42, and GhGLK46 responded significantly to cotton development. Yeast one-hybrid, yeast two-hybrid, and dual-luciferase assay results indicate that GhGLK2 interacts with GhGUN5, GhPIL6, GhNAC6, GhTPX2, and GhERF10. These findings suggest that these GhGLKs may play crucial roles in regulating the response to abiotic stress. Overall, this study provides a solid theoretical foundation for understanding the role of the GLK gene family in cotton’s response to abiotic stress.

This research centers on the sand-fixing plant known as Stipagrostis pennata, from which the β-glucosidase gene SpBGLU25 was successfully cloned using the molecular cloning method. SpBGLU25 encodes a hydrophilic and stable protein made up of 193 amino acids, located in the cell membrane. qRT-PCR analysis indicated that the expression of the SpBGLU25 is closely linked to the drought stress tolerance of S. pennata. Following this, functional validation was performed using an Arabidopsis overexpression system. The overexpression of transgenic Arabidopsis lines showed significantly improved drought tolerance under PEG and mannitol treatments. Assessments of germination, root length, and physiological indicators such as proline, malondialdehyde content, soluble sugars, and relative leaf water content (RLWC) further confirmed the enhanced performance of the overexpressing plants. Additionally, the comparative transcriptomic analysis of SpBGLU25-OE Arabidopsis compared to the wild-type (WT) showed that differentially upregulated genes were primarily enriched in categories of “cellular process,” “cell,” and “catalytic activity.” KEGG pathway enrichment analysis indicated that the genes were mainly concentrated in the pathways of phenylpropanoid biosynthesis and plant hormone signal transduction. These findings provide a crucial foundation for further investigation into the function of the SpBGLU25 and its role in regulating plant tissue development and adaptation to stress. This research is anticipated to offer new theoretical insights and genetic resources for enhancing plant stress tolerance through genetic engineering.

Lipid transfer proteins (LTPs) play crucial regulatory roles in plant growth, development, and abiotic stress responses. Stipagrostis pennata is a species of grass widely distributed in arid and semi-arid regions, particularly adapted to desert and steppe environments. Under extreme drought conditions, it exhibits a variety of physiological and morphological adaptation mechanisms, making it an important species for studying plant drought tolerance. Recently, LTPs have been found to exhibit upregulated expression under drought stress in plants such as wheat and tobacco, enhancing their drought tolerance. However, the functional role of LTPs in S. pennata remains unexplored. In this study, the SpLTP1 gene was isolated from S. pennata via molecular cloning, encoding a 116-amino acid protein. Phylogenetic analysis revealed that this protein contains a highly conserved nsLTP1 (cd01960) domain and has high sequence similarity with LTPs of Setaria viridis, Setaria italica, Musa acuminata and Phragmites australis. qRT-PCR revealed that SpLTP1 was highly expressed and dynamically regulated under drought, suggesting its potential role in root rhizosheath formation and drought tolerance. To investigate SpLTP1 function, SpLTP1-overexpressing (SpLTP1-OE) and complementation (SpLTP1-atltp) Arabidopsis lines were generated using the floral dip method, in comparison with the existing wild-type (WT) and the LTP-deficient mutant (atltp). Drought stress phenotyping and physiological assays indicated that SpLTP1 likely enhances drought tolerance by elevating antioxidant enzyme activities and osmolyte accumulation. Comparative transcriptome analysis of SpLTP1-OE and WT plants further suggested that SpLTP1 modulates critical pathways, including phenylpropanoid biosynthesis, zeatin biosynthesis, and plant hormone signal transduction, thereby influencing plant growth and stress adaptation. These findings not only provide novel insights into the molecular mechanisms by which SpLTP1 regulates rhizosheath development in S. pennata but also establish a foundation for deciphering its role in extreme drought adaptation.