Stress biology最新文献

Plants are engaged in a constant battle for survival against pathogens, which triggers a multifaceted immune response characterized by pattern-triggered immunity (PTI) and effector-triggered immunity (ETI) to prevent infection. These two immune responses operate synergistically to enhance plant immunity. PTI is considered the first line of defense involving the recognition of pathogen-associated molecular patterns (PAMPs) by specific receptors in host cells known as pattern recognition receptors (PRRs), which initiate defense signaling. However, many pathogens often overcome the first line of defense (PTI) and successfully deploy effector proteins to promote virulence and subvert plant immunity, leading to host susceptibility. In the counter-defense, the ETI defense mechanism is activated by triggering resistance (R) genes in plants that usually encode nucleotide-binding-leucine-rich-containing (NLR) proteins. During plant-pathogen interactions, transcriptional reprogramming of defense-related genes such as pathogenesis-related proteins and generation of reactive oxygen species (ROS) are essential for facilitating programmed cell death at the infected location to inhibit pathogen proliferation. While ROS and PR protein are critical in plant-pathogen interaction, they are not universally required or effective against all pathogens. Hence, plants' multilayer immune layer is encrypted with the compensatory activation of ETI defense response towards the failure of one component of the defense system to maintain robust immunity.

It remains a great challenge to control weeds in rapeseed fields in China. Breeding herbicide-resistant rapeseed varieties and using corresponding herbicide formulations has become the most economical and effective way to control weeds in rapeseed field. Characterization of more herbicide-resistant genetic resources will provide opportunities for breeders to develop rapeseed herbicide-resistant varieties with good agronomic performance. Previously, we obtained the tribenuron methyl (TBM)-resistant mutant K4 from ZS9 (Brassica napus L.) through ethyl methyl sulfonate mutagenesis and TBM foliar-spray screening. In this study, the inheritance and molecular characterization of the mutant K4 are carried out. Genetic investigation indicated that the herbicide-resistance of the K4 was controlled by one dominant allele at a single nuclear gene locus. Molecular characterization showed that a single point substitution at position 535 from C to T in BnAHAS3 (BnAHAS3^535T), which resulted in a mutation at point 179 in BnAHAS3. The K4 showed a certain degree of resistance to TBM, bensulfuron methyl, and monosulfon sodium, which were 50, 30, and 5 times that of ZS9, respectively. AHAS enzyme assay, structural analysis of AHAS proteins, affinity detection between TBM and BnAHAS3 by surface plasmon resonance analysis, and the transgenic experiment in Arabidopsis using BnAHAS3^535T confirmed that BnAHAS3^535T endow the K4 with herbicides resistance. In addition, an allele-specific marker was developed to quickly distinguish the heterozygous and homozygous mutated alleles BnAHAS3^535T. In conclusion, our research identified and characterized one novel mutative AHAS allele in B. napus and enriched genetic resource for developing herbicide-resistant rapeseed cultivars.

Fruit quality and yield are reduced when cucumber (Cucumis sativus L.) plants are exposed to low temperature (LT) stress, yet, the inheritance and genes linked to cold tolerance in adult plants have not been reported yet. Here, the LT-tolerance of 120 cucumber accessions representing four ecotypes were evaluated by GWAS, and also, in 140 recombinant inbred lines (RILs) derived from a biparental cross. Plants were exposed to naturally occurring LT environments in a plastic greenhouse, in winter 2022, and 2023, and a low temperature injury index (LTII) was employed to evaluate plant performance. Genetic analysis revealed that the LT-tolerance evaluated in the adult cucumber plants was a multigenic quantitative trait, and that 18 of the 120 accessions were highly LT tolerant by our LTII assessment. Two loci (gLTT1.1 and gLTT3.1) exhibited strong signals that were consistent and stable in two environments. In addition, two QTLs-qLTT1.2 on chromosome (Chr.) 1, and qLTT3.1 on Chr. 3, were discovered in all tests using RIL population derived from a cross between LT-sensitive 'CsIVF0106', and LT-tolerant 'CsIVF0168'. qLTT1.2 was delimited to a 1.24-Mb region and qLTT3.1 was narrowed to a 1.43-Mb region. Interestingly, a peak single nucleotide polymorphism (SNP) at gLTT1.1 and gLTT3.1 was also found in qLTT1.2 and qLTT3.1, respectively. These loci were thus renamed as gLTT1.1 and gLTT3.1. In these regions, 25 genes were associated with the LT response. By identifying differences in haplotypes and transcript profiles among these genes, we identified four candidates: CsaV3_1G012520 (an ethylene-responsive transcription factor) and CsaV3_1G013060 (a RING/U-box superfamily protein) in gLTT1.1, and two RING-type E3 ubiquitin transferases at CsaV3_3G018440 and CsaV3_3G017700 in gLTT3.1 that may regulate LT-tolerance in adult cucumber. Interestingly, the accessions in which the LT-tolerant haplotypes for two loci were pyramided, displayed maximally high tolerance for LT. These findings therefore provide a solid foundation for the identification of LT-tolerant genes and the molecular breeding of cucumber with LT-tolerance.

Drought and salinity stress pose threats to agricultural production in drylands. Although breeding and genetic modification techniques have been employed to develop drought- and salt-tolerant crops, these methods are costly and risky. Hence, the potential application of endophytic fungi in dryland agriculture is being explored as a novel approach in improving plant tolerance to environmental stress. In this study, endophytic fungi with growth-promoting effects were isolated, characterized, and evaluated in terms of their ability to confer drought and stress tolerance to their host plants. Seventy-seven growth-promoting endophytic fungi belonging to 20 genera were isolated from barley roots; of these, strain T-2 elicited remarkable effects on plant growth parameters. Phylogenetic analysis revealed that strain T-2 belongs to genus Leptosphaeria, whose members are generally known as plant pathogens. Thus, Leptosphaeria sp. strain T-2 is a novel endophytic fungus that promotes plant growth. Moreover, it alleviated growth inhibition caused drought and salinity stress, as evidenced by the survival and maintained health of lettuce plants inoculated with strain T-2. The results of this study suggest that strain T-2 can be applied as a biofertilizer to improve agricultural production in drylands.

Drought is a prevalent abiotic stress that commonly affects the quality and yield of tea. Although numerous studies have shown that lignin accumulation holds significant importance in conferring drought tolerance to tea plants, the underlying molecular regulatory mechanisms governing the tea plant's response to drought remain largely elusive. LACCASEs (LACs), which belong to the class of plant copper-containing polyphenol oxidases, have been widely reported to participate in lignin biosynthesis in plants and are implicated in numerous plant life processes, especially in the context of adverse conditions. In this study, we detected the upregulation of CsLAC4 in response to drought induction. Remarkably, the overexpression of CsLAC4 not only substantially increased the lignin content of transgenic Arabidopsis thaliana but also simulated the development of vascular tissues, consequently leading to a significant enhancement in drought tolerance. Moreover, via dual-luciferase assays and transient overexpression in tea leaves, we revealed that CsLAC4 was negatively regulated by the upstream CsmiR397a. Interestingly, the expression of CsmiR397a was downregulated during drought stress in tea plants. Arabidopsis thaliana overexpressing CsmiR397a showed increased sensitivity to drought stress. By transient overexpression of CsmiR397a and CsLAC4 in tea plant leaves, we verified that CsLAC4, which is regulated by CsmiR397a, conferred drought tolerance to tea plants by enhancing lignin biosynthesis. These findings enhance our understanding of the molecular regulatory mechanisms underlying the response of tea plants to drought stress.

Developmental plasticity is critical for plants to adapt to constantly changing environments. Plant root hairs display dramatic plasticity under different environments and therefore play crucial roles in defense against environmental stressors. Here, we report the isolation of an Arabidopsis mutant, salinity over-sensitive mutant 1-1 (som1-1), also exhibiting root hair developmental defects. Map-based cloning and allelic analyses confirmed that som1-1 is a new mutant allele of SPIRRIG (SPI), which encodes a Beige and Chediak Higashi (BEACH) domain-containing protein. SPI has been reported to facilitate actin dependent root hair development by temporally and spatially regulating the expression of BRICK1 (BRK1), a subunit of the SCAR/WAVE actin nucleating promoting complex. Our living cell imaging examinations revealed that salt stress induces an altered actin organization in root hair that mimics those in the spi mutant, implying SPI may respond to salt stress induced root hair plasticity by modulating actin cytoskeleton organization. Furthermore, we found BRK1 is also involved in root hair developmental change under salt stress, and overexpression of BRK1 resulted in root hairs over-sensitive to salt stress as those in spi mutant. Moreover, based on biochemical analyses, we found BRK1 is unstable and SPI mediates BRK1 stability. Functional loss of SPI results in the accumulation of steady-state of BRK1.

Salt bladders, specialized structures on the surface of quinoa leaves, secrete Na⁺ to mitigate the effects of the plant from abiotic stresses, particularly salt exposure. Understanding the development of these structures is crucial for elucidating quinoa's salt tolerance mechanisms. In this study, we employed transmission electron microscopy to detail cellular differentiation across the developmental stages of quinoa salt bladders. To further explore the developmental trajectory and underlying molecular mechanisms, we conducted single-cell RNA sequencing on quinoa protoplasts derived from young leaves. This allowed us to construct a cellular atlas, identifying 13 distinct cell clusters. Through pseudotime analysis, we mapped the developmental pathways of salt bladders and identified regulatory factors involved in cell fate decisions. GO and KEGG enrichment analyses, as well as experimental results, revealed the impacts of salt stress and the deprivation of sulfur and nitrogen on the development of quinoa salt bladders. Analysis of the transcription factor interaction network in pre-stalk cells (pre-SC), stalk cells (SC), and epidermal bladder cells (EBCs) indicated that TCP5, YAB5, NAC078, SCL8, GT-3B, and T1P17.40 play crucial roles in EBC development. Based on our findings, we developed an informative model elucidating salt bladder formation. This study provides a vital resource for mapping quinoa leaf cells and contributes to our understanding of its salt tolerance mechanisms.