Physiologia plantarum最新文献

Soil salinization is a major environmental threat to the entire terrestrial ecosystem. Lichens arose from the symbiosis of fungi and algae or cyanobacteria. They have a high tolerance to various extreme environments, including adaptation to saline-alkali habitats. Thus, lichens are pioneer species on saline-alkali soil. However, the separate resilience of the two symbiotic partners under saline-alkali conditions remains insufficiently understood. In this study, two representative symbiotic algae, Diplosphaera chodatii and Trebouxia jamesii, were studied for their physiological response to the saline-alkali stress by adjusting different concentrations of NaHCO₃, together with their respective symbiotic fungi Endocarpon pusillum (terricolous lichen) and Umbilicaria muhlenbergii (saxicolous lichen). The results indicate that cell growth rate and biomass in all four cultures decreased in alkali-alkaline substrate, while cellular activities and ultrastructure were affected to a distinct extent. Compared with the symbiotic fungi, the algae were found to be more active in coordinating oxidative stress and lipid peroxidation damage under the saline-alkali stress. The antioxidant system of the alga was especially shown as a key adaptive trait and it provides an important strategy for species survival and persistence in arid saline-alkali desert. The specific survival ability of the lichen symbiosis relies on the stress resilience advantages of the symbiotic partners in combination. Our study provided new insights into understanding the adaptation of lichen symbiosis to desert saline-alkali soil, and the potential of lichen symbiotic algae in the future desert ecological restoration.

As a commonly used medicinal plant, the flavonoid metabolites of Blumea balsamifera and their association with genes are still elusive. In this study, the total flavonoid content (TFC), flavonoid metabolites and biosynthetic gene expression patterns of B. balsamifera after application of exogenous methyl jasmonate (MeJA) were scrutinized. The different concentrations of exogenous MeJA increased the TFC of B. balsamifera leaves after 48 h of exposure, and there was a positive correlation between TFC and the elicitor concentration. A total of 48 flavonoid metabolites, falling into 10 structural classes, were identified, among which flavones and flavanones were predominant. After screening candidate genes by transcriptome mining, the comprehensive analysis of gene expression level and TFC suggested that FLS and MYB may be key genes that regulate the TFC in B. balsamifera leaves under exogenous MeJA treatment. This study lays a foundation for elucidating flavonoids of B. balsamifera, and navigates the breeding of flavonoid-rich B. balsamifera varieties.

Climate change severely affects crop production. Cotton is one of the primary fiber crops in the world and its production is susceptible to various environmental stresses, especially drought and salinity. Development of stress tolerant genotypes is the only way to escape from these environmental constraints. We identified sixteen homologs of the Arabidopsis JUB1 gene in cotton. Expression of GhJUB1_3-At was significantly induced in the temporal expression analysis of GhJUB1 genes in the roots of drought tolerant (H177) and susceptible (S9612) cotton genotypes under drought. The silencing of the GhJUB1_3-At gene alone and together with its paralogue GhJUB1_3-Dt reduced the drought tolerance in cotton plants. The transgenic lines exhibited tolerance to the drought and salt stress as compared to the wildtype (WT). The chlorophyll and relative water contents of wildtype decreased under drought as compared to the transgenic lines. The transgenic lines showed decreased H₂O₂ and increased proline levels under drought and salt stress, as compared to the WT, indicating that the transgenic lines have drought and salt stress tolerance. The expression analysis of the transgenic lines and WT revealed that GAI was upregulated in the transgenic lines in normal conditions as compared to the WT. Under drought and salt treatment, RAB18 and RD29A were strongly upregulated in the transgenic lines as compared to the WT. Conclusively, GhJUB1_3-At is not an auto activator and it is regulated by the crosstalk of GhHB7, GhRAP2-3 and GhRAV1. GhRAV1, a negative regulator of abiotic stress tolerance and positive regulator of leaf senescence, suppresses the expression of GhJUB1_3-At under severe circumstances leading to plant death.

Plant-environment interactions, particularly biotic stress, are increasingly essential for global food security due to crop losses in the dynamic environment. Therefore, understanding plant responses to biotic stress is vital to mitigate damage. Beneficial microorganisms and their association with plants can reduce the damage associated with plant pathogens. One such group is PGPR (Plant growth-promoting rhizobacteria), which influences plant immunity significantly by interacting with biotic stress factors and plant signalling compounds. This review explores the types, metabolism, and mechanisms of action of PGPR, including their enzyme pathways and the signalling compounds secreted by PGPR that modulate gene and protein expression during plant defence. Furthermore, the review will delve into the crosstalk between PGPR and other plant growth regulators and signalling compounds, elucidating the physiological, biochemical, and molecular insights into PGPR's impact on plants under multiple biotic stresses, including interactions with fungi, bacteria, and viruses. Overall, the review comprehensively adds to our knowledge about PGPR's role in plant immunity and its application for agricultural resilience and food security.

Lichens are important components of high-latitude boreal and Arctic habitats. While stress tolerant, they are among the most sensitive ecosystem components to climate change, in particular, an increase in ultraviolet light (UV) arising from polar ozone depletion and deforestation. This study is the first to explore the effects of UV-B on gene expression in lichens to predict metabolic pathways involved in tolerance. Using transcriptome profiling and bioinformatic analyses, here we studied the effects of UV-B on gene expression in lichens using Lobaria pulmonaria (L.) Hoff. as a model species. UV-B exposure causes significant browning of the upper cortex of the thallus, which correlates to an increased expression of biosynthetic gene clusters involved in the synthesis of eu- and allomelanins and melanin precursors. Based on transcriptome analyses, we suggest that the biosynthesis of melanins and other secondary metabolites, such as naphthalene derivates, tropolones, anthraquinones, and xanthones, is a trade-off that lichens pay to protect essential metabolic processes such as photosynthesis and respiration. Expression profiles of general stress-associated genes, in particular, related to reactive oxygen species scavenging, protection of proteins, and DNA repair, clearly indicate that the mycobiont is the more UV-B-responsive and susceptible partner in lichen symbiosis. Our findings demonstrate that UV-B stress activates an intricate gene network involved in tolerance mechanisms of lichen symbionts. Knowledge obtained here may enable the prediction of likely effects on lichen biodiversity caused by climate change and pollution.

The precise regulation of stem cells in the shoot apical meristems (SAMs) involves the function of the homeodomain transcription factor (TF)-WUSCHEL (WUS). WUS has been shown to move from the site of production-the rib-meristem (RM), into overlaying cells of the central zone (CZ), where it specifies stem cells and also regulates the transcription of CLAVATA3 (CLV3). The secreted signalling peptide CLV3 activates a receptor kinase signalling that restricts WUS transcription and also regulates the nuclear gradient of WUS by offsetting nuclear export. WUS has been shown to regulate both CLV3 levels and spatial activation, restricting its expression to a few cells in the CZ. The HAIRY MERISTEM (HAM), a GRASS-domain class of TFs expressed in the RM, has been shown to physically interact with WUS and regulate CLV3 expression. However, the mechanisms by which this interaction regulates CLV3 expression non-cell autonomously remain unclear. Here, we show that HAM function is required for regulating the WUS protein stability, and the CLV3 expression responds to altered WUS protein levels in ham mutants. Thus, HAM proteins non-cell autonomously regulates CLV3 expression.

This study focused on two aspects: to develop a selected functionally competent bacterial community, and its integrated with biostimulant humic acid and seaweed extract which was validated to enhance wheat growth and nutrient content. Wheat and maize-associated bacterial isolates (92) were screened for Plant Growth-Promoting traits (PGPts-72) and Community-Forming traits (CFts-66). 46 isolates possessed both kinds of traits, of which 20 isolates were chosen based on high Bonitur scale ratings. Based on metabolic diversity, growth rate, and compatibility, 11 isolates were grouped to make a synthetic microbial community (SM). Non-microbial biostimulants, humic acid (HA) and seaweed extract (SWE) were used, and 0.2% HA and 1% SWE were found to be optimal for bacterial and plant growth. SM integrated each with 0.2% HA and 1% SWE, leading to products SynBio1 (SM + HA) and SynBio2 (SM + SWE). Under microcosm study, SynBio1 and SynBio2 improved germination by 90.10% and 83.80%, respectively. SynBio1 increased chlorophyll content by 40.5 SPAD units, root length by 15.7%, and shoot length by 18.4%. Field level validations revealed that SynBio1 increased plant height by 15.76%, root length by 27.16%, and flag leaf length by 21.35% compared to the control. The grain yield with SynBio1 was 40.41% higher than that of the control. Macro and micronutrient analysis of seeds treated with SynBio1 showed significant improvements. These findings demonstrate the potential of integrating microbial communities with biostimulants, and they pave the way for developing novel bioinoculants for sustainable agriculture and promoting a healthier environment.

Angelica sinensis, a traditional Chinese medicinal plant, has been primarily reported due to its nutritional value. Pigmentation in this plant is an important appearance trait that directly affects its commercial value. To understand the mechanism controlling purpleness in A. sinensis, hormonal and transcriptomic analyses were performed in three different tissues (leave, root and stem), using two cultivars with contrasting colors. The two-dimensional data set provides dynamic hormonal and gene expression networks underpinning purpleness in A. sinensis. We found abscisic acid as a crucial hormone modulating anthocyanin biosynthesis in A. sinensis. We further identified and validated 7 key genes involved in the anthocyanin biosynthesis pathway and found a specific module containing ANS as a hub gene in WGCNA. Overexpression of a candidate pigment regulatory gene, AsANS (AS08G02092), in transgenic calli of A. sinensis resulted in increased anthocyanin production and caused purpleness. Together, these analyses provide an important understanding of the molecular networks underlying A. sinensis anthocyanin production and its correlation with plant hormones, which can provide an important source for breeding.

Canker caused by Lonsdalea populi has seriously reduced the economic and ecological benefits of poplar. MicroRNAs play vital roles in the response of plants to biotic stress. However, there is little research about the regulatory mechanism of miRNAs among different tree varieties upon pathogen infection. To dissect miRNAs involved in L. populi resistance, three poplar varieties, 2025 (susceptible), 107 (moderately resistant) and Populus. tomentosa cv 'henan' (resistant) were selected to elucidate the expression profiles of miRNAs using small RNA-seq. A total of 227 miRNAs were identified from all varieties. Intriguingly, miR160, miR169, miR171 and miR482b-5p were only identified in the resistant variety P. tomentosa upon pathogen infection, and these miRNAs might be important candidates for future investigation to improve the tolerance of poplar to L. populi. Among all identified miRNAs, 174 were differentially expressed in all varieties. Functional annotation analysis indicated that an array of miRNAs, including miR482, miR472, miR169, miR481, and miR172, should be involved in disease resistance and phytohormone signal transduction. Furthermore, correlation analysis of small RNA-seq and RNA-seq identified a handful of L. populi-responsive miRNAs and target genes, which exhibited that miR159 and miR172 played key roles in resistant variety P. tomentosa by targeting MYB and ERF, while miR6462c-5p and miR828 were related to the susceptibility of 2025 by targeting MYB. The comprehensive integration analysis in this research provides new insights into the regulatory pathways involved in the defence response of poplar to L. populi and offers crucial candidate miRNAs-target genes modules for poplar resistance improvement.

The Arabidopsis SUPERMAN (SUP) gene and its orthologs in eudicots are crucial in regulating the number of reproductive floral organs. In Medicago truncatula, in addition to this function, a novel role in controlling meristem activity during compound inflorescence development was assigned to the SUP-ortholog (MtSUP). These findings led us to investigate whether the role of SUP genes in inflorescence development was legume-specific or could be extended to other eudicots. To assess that, we used Solanum lycopersicum as a model system with a cymose complex inflorescence and Arabidopsis thaliana as the best-known example of simple inflorescence. We conducted a detailed comparative expression analysis of SlSUP and SUP from vegetative stages to flower transition. In addition, we performed an exhaustive phenotypic characterisation of two different slsup and sup mutants during the plant life cycle. Our findings reveal that SlSUP is required for precise regulation of the meristems that control shoot and inflorescence architecture in tomato. In contrast, in Arabidopsis, SUP performs no meristematic function, but we found a role of SUP in floral transition. Our findings suggest that the functional divergence of SUP-like genes contributed to the modification of inflorescence architecture during angiosperm evolution.