Desiccation is a kind of extreme form of drought stress and desiccation tolerance (DT) is an ancient trait of plants that allows them to survive tissue water potentials reaching −100 MPa or lower. ScDREB10 is a DREB A-5 transcription factor gene from a DT moss named Syntrichia caninervis, which has strong comprehensive tolerance to osmotic and salt stresses. This study delves further into the molecular mechanism of ScDREB10 stress tolerance based on the transcriptome data of the overexpression of ScDREB10 in Arabidopsis under control, osmotic and salt treatments. The transcriptional analysis of weight gene co-expression network analysis (WGCNA) showed that “phenylpropanoid biosynthesis” and “starch and sucrose metabolism” were key pathways in the network of cyan and yellow modules. Meanwhile, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis of differentially expressed genes (DEGs) also showed that “phenylpropanoid biosynthesis” and “starch and sucrose metabolism” pathways demonstrate the highest enrichment in response to osmotic and salt stress, respectively. Quantitative real-time PCR (qRT-PCR) results confirmed that most genes related to phenylpropanoid biosynthesis” and “starch and sucrose metabolism” pathways in overexpressing ScDREB10 Arabidopsis were up-regulated in response to osmotic and salt stresses, respectively. In line with the results, the corresponding lignin, sucrose, and trehalose contents and sucrose phosphate synthase activities were also increased in overexpressing ScDREB10 Arabidopsis under osmotic and salt stress treatments. Additionally, cis-acting promoter element analyses and yeast one-hybrid experiments showed that ScDREB10 was not only able to bind with classical cis-elements, such as DRE and TATCCC (MYBST1), but also bind with unknown element CGTCCA. All of these findings suggest that ScDREB10 may regulate plant stress tolerance by effecting phenylpropanoid biosynthesis, and starch and sucrose metabolism pathways. This research provides insights into the molecular mechanisms underpinning ScDREB10-mediated stress tolerance and contributes to deeply understanding the A-5 DREB regulatory mechanism.

Microbial-plant interactions protect plants from external stimuli, releasing various elicitor that activate the plants defense response and regulate its growth. Bacillus subtilis BS-Z15 was screened from cotton inter-rhizosphere soil, antagonized various plant pathogens, and protected cotton against Verticillium dahliae. This study showed that the BS-Z15 lipopeptide mycosubtilin homologue could act as an elicitor to induce systemic resistance (ISR) in plants. Mycosubtilin homologue induced ROS burst and deposition, callose deposition, MAPK cascade phosphorylation, and up-regulated PR1 and PDF1.2 gene expression in Arabidopsis seedlings, moreover enhanced resistance of Arabidopsis to Pseudomonas syringae pv. Tomato DC3000 (Pst DC3000) and V. dahliae. Transcriptome analysis was then used to evaluate the impact of mycosubtilin homologue on plant gene expression control. Mycosubtilin homologues activated Arabidopsis ISR on genes in metabolic pathways such as Arabidopsis plant-pathogen interactions, phenylpropanoid biosynthesis, MAPK signaling pathway, and phytohormone signaling. These analyses revealed that mycosubtilin homologues mediate the regulation of plant systemic resistance and growth and development by affecting related metabolites in glycolysis and gluconeogenesis, pentose phosphate pathway, tricarboxylic acid cycle, and amino acid metabolism in Arabidopsis. These findings confirmed that a mycosubtilin homologue could trigger the initiation of the Arabidopsis ISR by interacting with a variety of PTI components and transcriptional metabolic signaling pathways.

The desert moss Syntrichia caninervis has proven to be an excellent plant material for mining resistance genes. The aldehyde dehydrogenase 21 (ScALDH21) gene from S. caninervis has been shown to confer tolerance to salt and drought, but it is unclear how the transgene ScALDH21 regulates tolerance to abiotic stresses in cotton. In the present work, we studied the physiological and transcriptome analyses of non-transgenic (NT) and transgenic ScALDH21 cotton (L96) at 0 day, 2 days, and 5 days after salt stress. Through intergroup comparisons and a weighted correlation network analysis (WGCNA), we found that there were significant differences between NT and L96 cotton in the plant hormone, Ca²⁺, and mitogen-activated protein kinase (MAPK) signaling pathways as well as for photosynthesis and carbohydrate metabolism. Overexpression of ScALDH21 significantly increased the expression of stress-related genes in L96 compared to NT cotton under both normal growth and salt stress conditions. These data suggest that the ScALDH21 transgene can scavenge more reactive oxygen species (ROS) in vivo relative to NT cotton and improve cotton resistance to salt stress by increasing the expression of stress-responsive genes, responding quickly to stress stimuli, enhancing photosynthesis and improving carbohydrate metabolism. Therefore, ScALDH21 is a promising candidate gene to improve resistance to salt stress, and the application of this gene in cotton provides new insights into molecular plant breeding.

Bacillus subtilis J-15 is a plant growth-promoting rhizobacteria isolated from the soil rhizosphere of cotton and is resistant to cotton verticillium wilt. This study evaluated the effects of metabolites of J-15 (J-15-Ms), including mycosubtilin, on plant growth using Arabidopsis and cotton plants. The results showed that J-15-Ms promoted Arabidopsis seeding growth at lower concentrations of 0.2 μg/mL but inhibited the growth at higher concentrations, such as 20 μg/mL. Similar results were obtained in cotton. Thus, J-15-Ms-treated plants showed low-concentration-induced growth promotion and high-concentration-induced growth inhibition. The J-15-Ms components were analyzed by liquid chromatography–mass spectrometry. Correlation analysis using the J-15 genomic databases suggested that J-15 may synthesize indoleacetic acid via the indole-3-pymvate pathway and indole-3-acetamide pathway. Treatment with mycosubtilin, a purified peptide from J-15-Ms, showed that the peptide promoted Arabidopsis growth at a low concentration (0.1 μg/mL) and inhibited plant growth at high concentrations (higher than 1 μg/mL), which also significantly increased plant lateral root number. Transcriptomic analysis showed that mycosubtilin might promote lateral root development and inhibit plant primary root growth by regulating the expression of the plant hormone signaling pathway. This study reveals the mechanism of Bacillus subtilis J-15 in affecting plant growth.

Syntrichia caninervis is the dominant species of biological soil crust in the desert, including the Gurbantunggut Desert in China. It is widely distributed in drylands and considered to be a new model of vegetative desiccation tolerance moss. Here, we cloned an ATG8 gene from S. caninervis and confirmed its function under multiple abiotic stresses, both in situ and in Physcomitrium patens. The results showed that the ScATG8 gene encoded a protein with a highly conserved ATG8 functional domain. ScATG8 gene was increasingly expressed under different abiotic stresses. Under desiccation stress, the overexpression of ScATG8 enhanced the tolerance of S. caninervis and its ability to scavenge ROS. In addition, ScATG8 overexpression promoted the growth of P. patens under multiple stress conditions. Thus, ScATG8 may be a multifunctional gene, and it plays a critical role in the survival of S. caninervis under various abiotic stresses. Our results provide new insights into the function of ATG8 in enabling desiccation tolerance and open up more possibilities for subsequent plant molecular breeding and the mining of the resistance genes of S. caninervis and other moss species.

Biotic stresses, particularly Verticillium wilt (VW), lead to a global decline in cotton yields. Here, we demonstrate that ectopic expression of ScALDH21 , a gene from the desiccation‐tolerant moss Syntrichia caninervis Mitt. and absent in angiosperms, enhances cotton's resistance to VW. Multi‐year, multiple location field evaluations showed that transgenic cotton lines consistently exhibited two major advantages: markedly improved resistance to VW, and significantly reduced yield loss, with an approximate 23.8% yield increase relative to non‐transgenic counterparts under pathogen infection conditions. This disease resistance is associated with enhanced capacity of the transgenic lines to scavenge reactive oxygen species (ROS), induced by pathogen infection. This finding aligns with the ScALDH21 ‐conferred detoxification function. Transcriptome analyses revealed a significant alteration in expression pattern of those genes that regulate phenylpropanoid and jasmonic acid (JA) pathways. Correspondingly, the accumulation of lignin and defence‐related metabolites (e.g., rutin, cyanidin and jasmonates) significantly increased, suggesting that ScALDH21 ‐mediated activation of the phenylpropanoid and JA pathways contributes to enhanced resistance. Analyses of ScALDH21 binding activity using CUT&Tag and EMSA assays showed that it can bind to specific gene promoters within the cotton genome, highlighting that ScALDH21 not only catalyses the detoxification of aldehydes but also gains transcriptional regulatory roles. In summary, we demonstrate that expression of the heterologous ScALDH21 in cotton leads to enhancement of resistance to VW and elucidated the mechanism. Our findings further demonstrate a promising strategy to improve biotic resistance in crops by utilizing unique functional genes from evolutionarily distant species in extreme environments.