Characterization and Functional Implications of the Nonexpressor of Pathogenesis-Related Genes 1 (NPR1) in Saccharum

Sugarcane (Saccharum spp.) is an important sugar and energy crop worldwide. As a core regulator of the salicylic acid (SA) signaling pathway, nonexpressor of pathogenesis-related genes 1 (NPR1) plays a significant role in the response of the plant to biotic and abiotic stresses. However, there is currently no report on the NPR1-like gene family in sugarcane. In this study, a total of 18 NPR1-like genes were identified in Saccharum spontaneum and classified into three clades (clade I, II, and III). The cis-elements predicted in the promotors revealed that the sugarcane NPR1-like genes may be involved in various phytohormones and stress responses. RNA sequencing and quantitative real-time PCR analysis demonstrated that NPR1-like genes were differentially expressed in sugarcane tissues and under Sporisorium scitamineum stress. In addition, a novel ShNPR1 gene from Saccharum spp. hybrid ROC22 was isolated by homologous cloning and validated to be a nuclear-localized clade II member. The ShNPR1 gene was constitutively expressed in all the sugarcane tissues, with the highest expression level in the leaf and the lowest in the bud. The expression level of ShNPR1 was decreased by the plant hormones salicylic acid (SA) and abscisic acid (ABA). Additionally, the transient expression showed that the ShNPR1 gene plays a positive role in Nicotiana benthamiana plants’ defense response to Ralstonia solanacearum and Fusarium solani var. coeruleum. This study provided comprehensive information for the NPR1-like family in sugarcane, which should be helpful for functional characterization of sugarcane NPR1-like genes in the future.     

Ubiquitination of Receptorsomes,Frontline of Plant Immunity

Sessile plants are constantly exposed to myriads of unfavorable invading organisms with different lifestyles. To survive, plants have evolved plasma membrane-resident pattern recognition receptors (PRRs) and intracellular nucleotide-binding domain leucine-rich repeat receptors (NLRs) to initiate sophisticated downstream immune responses. Ubiquitination serves as one of the most important and prevalent posttranslational modifications (PTMs) to fine-tune plant immune responses. Over the last decade, remarkable progress has been made in delineating the critical roles of ubiquitination in plant immunity. In this review, we highlight recent advances in the understanding of ubiquitination in the modulation of plant immunity, with a particular focus on ubiquitination in the regulation of receptorsomes, and discuss how ubiquitination and other PTMs act in concert to ensure rapid, proper, and robust immune responses.     

Lack of NPR1 Increases Vascular Endothelial Adhesion through Induction of Integrin Beta 4

Natriuretic peptide receptor 1 (NPR1) serves as a modulator of vascular endothelial homeostasis. Interactions between monocytes and endothelial cells may initiate endothelium dysfunction, which is known as an early hallmark of atherosclerosis. In this study, we performed RNA-sequencing analysis for the aorta of Npr1 knockout (Npr1^+/−) mice and found that differentially expressed genes were significantly related to cell adhesion. This result was supported by an increased expression of intercellular adhesion molecule 1 (ICAM-1) in the aortic endothelium of Npr1^+/− mice. Moreover, we observed that the knockdown of NPR1 increased ICAM-1 expression and promoted THP-1 monocyte adhesion to human umbilical vein endothelial cells (HUVECs). NPR1 overexpression decreased ICAM-1 expression and inhibited the adhesion of monocytes to HUVECs treated by TNF-α (a cell adhesion inducer). Further analysis showed that adhesion-related genes were enriched in the focal adhesion signaling pathway, in which integrin beta 4 (Itgb4) was determined as a key gene. Notably, ITGB4 expression increased in vascular endothelium of Npr1^+/− mice and in NPR1-knockdown HUVECs. The deficiency of ITGB4 decreased ICAM-1 expression and attenuated monocyte adhesion to NPR1-knockdown endothelial cells. Additionally, a reduced NPR1 and an increased ITGB4 expression level were found in an atherosclerosis mouse model. In conclusion, our findings demonstrate that NPR1 deficiency increases vascular endothelial cell adhesion by stimulating ITGB4 expression, which may contribute to the development of atherosclerosis.     

Sulfur-Containing Secondary Metabolites from Arabidopsis thaliana and other Brassicaceae with Function in Plant Immunity

Biosynthesis of antimicrobial secondary metabolites in response to microbial infection is one of the features of the plant immune system. Particular classes of plant secondary metabolites involved in plant defence are often produced only by species belonging to certain phylogenetic clades. Brassicaceae plants have evolved the ability to synthesise a wide range of sulfur-containing secondary metabolites, including glucosinolates and indole-type phytoalexins. A subset of these compounds is produced by the model plant Arabidopsis thaliana. Genetic tools available for this species enabled verification of immune functions of glucosinolates and camalexin (A. thaliana phytoalexin), as well as characterisation of their respective biosynthetic pathways. Current knowledge of the biosynthesis of Brassicaceae sulfur-containing metabolites suggests that the key event in the evolution of these compounds is the acquisition of biochemical mechanisms originating from detoxification pathways into secondary metabolite biosynthesis. Moreover, it is likely that glucosinolates and Brassicaceae phytoalexins, traditionally considered as separate groups of compounds, have a common evolutionary origin and are interconnected on the biosynthetic level. This suggests that the diversity of Brassicaceae sulfur-containing phytochemicals reflect phylogenetic clade-specific branches of an ancient biosynthetic pathway.     

A Putative Effector CcSp84 of Cytospora chrysosperma Localizes to the Plant Nucleus to Trigger Plant Immunity

Cytospora chrysosperma is the main causal agent of poplar canker disease in China, especially in some areas with poor site conditions. Pathogens secrete a large number of effectors to interfere the plant immunity and promote their infection and colonization. Nevertheless, the roles of effectors in C. chrysosperma remain poorly understood. In this study, we identified and functionally characterized a candidate effector CcSp84 from C. chrysosperma, which contained a nuclear localization signal motif at the C-terminal and was highly induced during infection stages. Transient expression of CcSp84 in Nicotiana benthamiana leaves could trigger cell death. Additionally, deletion of CcSp84 significantly reduced fungal virulence to the polar twigs, while no obvious defects were observed in fungal growth and sensitivity to H₂O₂. Confocal microscopy revealed that CcSp84 labeled with a green fluorescent protein (GFP) was mainly accumulated in the plant nucleus. Further analysis revealed that the plant nucleus localization of CcSp84 was necessary to trigger plant immune responses, including ROS accumulation, callose deposition, and induced expression of jasmonic acid and ethylene defense-related genes. Collectively, our results suggest that CcSp84 is a virulence-related effector, and plant nucleus localization is required for its functions.     

Candidate Effectors from Botryosphaeria dothidea Suppress Plant Immunity and Contribute to Virulence

Fungal effectors play important roles in host–pathogen interactions. Botryosphaeria dothidea is an ascomycetous fungus that is responsible for the diseases of hundreds of woody plant species, including apple ring rot, which seriously affects apples worldwide. However, little is known about the effectors of B. dothidea. In this study, we analyzed the B. dothidea genome and predicted 320 candidate effector genes, 124 of which were successfully amplified and cloned. We investigated the effects of these genes on plant cell death in Nicotiana benthamiana while using a transient expression system. Twenty-four hours after initial inoculation with Agrobacterium tumefaciens cells carrying candidate effectors, the infiltrated leaves were challenged with A. tumefaciens cells carrying the BAX gene. In total, 116 candidate effectors completely inhibited, while one partially inhibited, the programmed cell death (PCD) of N. benthamiana induced by BAX, whereas seven candidate effectors had no effect. We then further tested seven candidate effectors able to suppress BAX-triggered PCD (BT-PCD) and found that they all completely inhibited PCD triggered by the elicitors INF1, MKK1, and NPK1. This result suggests that these effectors were activated in order to suppress pathogen-associated molecular pattern-triggered immunity. The signal peptides of these candidate effectors exhibited secretory activity in yeast (pSUC2 vector). Moreover, the respective deletion of Bdo_11198 and Bdo_12090 significantly reduced the virulence of B. dothidea. These results suggest that these effectors play important roles in the interaction of B. dothidea with its hosts.     

土壤中植物根际促生菌研究进展

植物根际促生菌(Plant growth-promoting rhizobacteria,PGPR)借助其代谢过程或代谢产物来改善植物生长条件及营养环境。如固定空气中的游离氮,参与土壤中养分的转化,增加有效养分,分泌激素,刺激植物根系发育,抑制有害微生物活动,更重要的是有些PGPR能够诱导植物产生系统抗性。本文主要介绍了共生、非共生固氮菌和溶磷菌的功能以及应用,强调应在基础理论研究的基础上加大其产业化进展。     

植物源农药研究进展

综述了植物源农药的资源研究状况、作用机制、施用方式及范围,剂型加工和稳定性。     

红树林植物抗氧化活性研究进展

近年来,国内外学者在对红树林植物抗氧化活性成分方面的研究有了很大进展,其中含多酚类化合物的糖苷、单宁是抗氧化活性的主要成分;很多有效成分效果好于标准对照物.本文以清除DPPH自由基、清除羟基自由基、清除亚硝基阴离子、清除超氧阴离子自由基、脂质过氧化抑制、清除过氧化氢、FRAP法、还原能力测定、ABTS法对近年来红树林抗...     

A Truncated TIR-NBS Protein TN10 Pairs with Two Clustered TIR-NBS-LRR Immune Receptors and Contributes to Plant Immunity in Arabidopsis

The encoding genes of plant intracellular nucleotide-binding site (NBS) and leucine-rich repeat (LRR) domain receptors (NLRs) often exist in the form of a gene cluster. Several recent studies demonstrated that the truncated Toll/interleukin-1 receptor-NBS (TIR-NBS) proteins play important roles in immunity. In this study, we identified a large TN gene cluster on Arabidopsis ecotype Col-0 chromosome 1, which included nine TN genes, TN4 to TN12. Interestingly, this cluster also contained two typical TIR-NBS-LRR genes: At1g72840 and At1g72860 (hereinafter referred to as TNL40 and TNL60, respectively), which formed head-to-head genomic arrangement with TN4 to TN12. However, the functions of these TN and TNL genes in this cluster are still unknown. Here, we showed that the TIR domains of both TNL40 and TNL60 associated with TN10 specifically. Furthermore, both TNL40TIR and TNL60TIR induced cell death in Nicotiana tabacum leaves. Subcellular localization showed that TNL40 mainly localized in the cytoplasm, whereas TNL60 and TN10 localized in both the cytoplasm and nucleus. Additionally, the expression of TNL40, TNL60, and TN10 were co-regulated after inoculated with bacterial pathogens. Taken together, our study indicates that the truncated TIR-NBS protein TN10 associates with two clustered TNL immune receptors, and may work together in plant disease resistance     

超声波辅助萃取天然植物香料研究进展

超声波辅助萃取技术近年已经在天然植物香料萃取方面得到越来越广泛的应用。对超声波（溶剂法）萃取、超声强化超临界CO2萃取和超声-微波协同萃取在天然植物香料提取方面的最新应用及研究进展进行了总结,同时对超声波辅助萃取天然植物香料前景进行了展望。     

植物纤维增强混凝土研究进展

随着我国“双碳”战略的持续推进,绿色低碳环保的天然纤维在水泥基材料中的应用已成为建筑行业的研究热点,得到了广泛关注。但植物纤维的力学性能差,同时存在老化和粘结力减弱等问题,很难直接应用于混凝土基体。本文综述了植物纤维的微观结构和性能,植物纤维对混凝土力学性能、耐久性和热物理性能等宏观性能的影响,植物纤维增强混凝土凝结时间、界面粘结和内养护的微观演变机制。讨论了植物纤维增强混凝土中基体改性和纤维改性的方法,深入了解不同方法的作用机理,寻求更加有效地改善性能的途径。剑麻纤维和竹纤维对混凝土性能有良好的提升作用,应用最为广泛。最后展望了植物纤维的可持续发展方向,为今后进一步研究植物纤维增强混凝土提出参考建议。     

植物油基多元醇的合成研究进展

介绍了植物油基多元醇的合成方法:过渡金属催化羰基化法、氧化法、酯交换法、醇解法、氨解法、环氧开环法,其中环氧开环法是最为成熟的一种方法,并概述了国内外近年来在植物油基多元醇工业化方面的情况。     

吸附法去除电厂汞的研究进展

重金属汞是电厂烟气中的主要污染物。主要介绍了活性炭、飞灰、钙基、矿物类及金属、生物质等吸附剂应用于烟气中脱汞的研究进展,评价了各种吸附剂的应用特点,并对今后需要开展的工作提出建议,为我国燃烧电厂汞排放控制提供参考。     

Rhamnolipid Biosurfactants as New Players in Animal and Plant Defense against Microbes

Rhamnolipids are known as very efficient biosurfactant molecules. They are used in a wide range of industrial applications including food, cosmetics, pharmaceutical formulations and bioremediation of pollutants. The present review provides an overview of the effect of rhamnolipids in animal and plant defense responses. We describe the current knowledge on the stimulation of plant and animal immunity by these molecules, as well as on their direct antimicrobial properties. Given their ecological acceptance owing to their low toxicity and biodegradability, rhamnolipids have the potential to be useful molecules in medicine and to be part of alternative strategies in order to reduce or replace pesticides in agriculture.     

植物内生菌及其次生代谢活性物质多样性的研究进展

植物内生菌是一种新型的微生物资源,具有重大的研究意义和潜在的应用价值,近年来已成为微生物资源研究的热点之一.对植物内生菌及其次生代谢活性物质多样性的研究进展进行了综述.     

植物纤维原料水解生产乙醇的研究进展

本文对以植物纤维原料生产乙醇的国内外发展趋势和研究进展进行了综述,对该领域今后的研究重点进行了展望,并认为植物纤维原料生产乙醇将逐步形成一个重要的产业,要加强植物原料预处理研究,加强对纤维素降解机理、现代生物技术以及水解新方法等的研究,强化对植物资源的高效利用。     

植物提取物延缓皮肤光老化作用的研究进展

紫外线是导致皮肤光老化的主要因素,寻找和开发能够有效防护皮肤老化的天然产物已被广泛重视。本文从紫外线对皮肤的损伤以及光老化发生的机理入手,通过吸收紫外线、抗皮肤光氧化、调节细胞外基质合成与降解、抑制色素沉着、缓解皮肤炎症、调节细胞自噬等多种途径,对不同来源的植物提取物及其特征化合物延缓皮肤光老化的作用进行了归纳分析,以期为天然产物在功能性化妆品的开发和应用提供参考。