Recent Progress in Elucidating the Structure, Function and Evolution of Disease Resistance Genes in Plants

Plants employ multifaceted mechanisms to fight with numerous pathogens in nature. Resistance （R） genes are the most effective weapons against pathogen invasion since they can specifically recognize the corresponding pathogen effectors or associated protein（s） to activate plant immune responses at the site of infection. Up to date, over 70 R genes have been isolated from various plant species. Most R proteins contain conserved motifs such as nucleotide-binding site （NBS）, leucine-rich repeat （LRR）, Toll-interleukin-1 receptor domain （TIR, homologous to cytoplasmic domains of the Drosophila Toll protein and the manamalian intefleukin-1 receptor）, coiled-coil （CC） or leucine zipper （LZ） structure and protein kinase domain （PK）. Recent results indicate that these domains play significant roles in R protein interactions with effector proteins from pathogens and in activating signal transduction pathways involved in innate immunity. This review highlights an overview of the recent progress in elucidating the structure, function and evolution of the isolated R genes in different plant-pathogen interaction systems.

Expression of Fusion Lytic Peptides Promotes Fungal Disease Resistance in Transgenic Plants

Many organisms produce small proteins which exhibit antimicrobial activities. In recent decades, the biological role of antimicrobial peptides (AMP) has been recognized as the main factor in the defense mechanisms against a broad range of pathogenic microbes. The increased worldwide incidence of microbial resistance to antibiotics makes AMPs promising alternative for the control of microbial disease. Exploring the potential of AMPs in transgenic crops could lead to the development of new and improved cultivars which are resistant to various economically important diseases. In the present study, two fusion lytic peptide gene constructs coding for antimicrobial peptides were expressed in Nicotiana benthamiana tobacco plants and tested against three fungal pathogens, Sclerotinia sclerotiorum, Rhizoctonia solani, and Pythium sp. Detached-leaf bioassay was employed for the transgenic plants carrying the fusion lytic peptide constructs (ORF13 and RSA1), transgenic vector only control plants (1234), and wild-type control plants (WT) against the three fungal pathogens. Symptom area of each leaf was measured with high accuracy and data were recorded and processed by statistical analyses. The results showed that transgenic plant lines ORF13 and RSL1 have substantial resistance to Sclerotinia sclerotiorum infection, producing significantly smaller lesion areas compared to vector only plant line 1234 and wild type plants. These transgenic lines also provided resistance against Rhizoctonia solani, however, these lines were not effective against the other fungal pathogen Pythium sp.

Problems, challenges and future of plant disease management: from an ecological point of view

Plant disease management faces ever-growing challenges due to： （i） increasing demands for total, safe and diverse foods to support the booming global population and its improving living standards; （ii） reducing production potential in agriculture due to competition for land in fertile areas and exhaustion of marginal arable lands; （iii） deteriorating ecology of agro-ecosystems and depletion of natural resources; and （iv） increased risk of disease epidemics resulting from agricultural intensification and monocultures. Future plant disease management should aim to strengthen food security for a stable society while simultaneously safeguarding the health of associated ecosystems and reducing dependency on natural resources. To achieve these multiple functionalities, sustainable plant disease management should place emphases on rational adaptation of resistance, avoidance, elimination and remediation strategies individually and collectively, guided by traits of specific host-pathogen associations using evolutionary ecology principles to create environmental （biotic and abiotic） conditions favorable for host growth and development while adverse to pathogen reproduction and evolution.

Identification of stably expressed QTL for resistance to black shank disease in tobacco(Nicotiana tabacum L.) line Beinhart 1000-1

Cigar line Beinhart 1000-1 has effective durable resistance to black shank(BS) and is considered one of the most resistant sources in tobacco(Nicotiana tabacum L.). To investigate the inheritance and identification of stable quantitative trait loci(QTL) for BS response, F2,BC1 F2 individuals and BC1 F2:3 lines were produced from a cross between Beinhart 1000-1 and Xiaohuangjin 1025. Two major quantitative trait loci(M-QTL) named qBS7 and qBS17 were repeatedly detected under different conditions. QTL qBS7 was mapped to the region between PT30174 and PT60621 and explained 17.40%–25.60% of the phenotypic variance under different conditions. The other QTL qBS17 in interval PT61564–PT61538 of linkage group 17 was detected in a BC1 F2 population in the field and in BC1 F2:3 in both the field and at the seedling stage, explaining 6.90% to 11.60% of the phenotypic variance. The results improve our understanding of the inheritance of resistance to BS and provide information that can be used in marker-assisted breeding.

国内外153份小麦种质条锈病抗性鉴定与评价

【目的】条锈病是威胁小麦安全生产的重要真菌病害,了解国内外育种材料抗性水平和抗病基因的分布,发掘新的抗性资源,为提高抗病基因利用效率提供依据。【方法】利用中国当前条锈菌优势生理小种CYR33和CYR34对153份国内外小麦育种材料进行苗期抗性鉴定,于2018—2019、2019—2020和2020—2021年,在湖北鄂州,利用这两个小种对供试材料进行成株期抗性鉴定;结合已知抗性基因Yr5、Yr9、Yr10、Yr15、Yr17、Yr18、Yr26、Yr29和YrSP等功能标记或紧密连锁分子标记进行基因型检测。【结果】苗期结果显示,10份材料对CYR33表现免疫(反应型IT为0),包括7份国内材料(即山农28、漯麦163、石麦13、中意6号、郯麦98-2、中麦175和泰山21)和3份国际玉米小麦改良中心(CIMMYT)材料(CIM-53、CIM-60和CIM-71);仅2份国内材料在苗期对CYR34小种表现免疫(郯麦98-1和山农102)。此外,成株期条锈病田间鉴定显示,64份材料在田间3年均表现出稳定抗性(最终严重度≤5%),包括7份国内材料和57份CIMMYT材料。利用抗病基因功能标记或紧密连锁分子标记检测显示,153份材料中携带Yr9、Yr10、Yr17、Yr18、Yr26、Yr29和YrSP抗性基因的材料分别有31、23、73、2、4、50和2份,未检测到含有Yr5和Yr15的材料。综合苗期和成株期表型,仅CIM-53对2个生理小种在苗期和成株期均表现为免疫(IT=0,严重度为0),分子标记检测显示,该材料可能含有已知抗病基因Yr17和Yr29。【结论】国内外153份小麦种质对当前条锈菌流行生理小种的抗性主要以成株抗性为主,其中国内小麦品种主要携带Yr9、Yr10和Yr26抗性基因,而CIMMYT小麦品系则携带Yr17、Yr18和Yr29为主,表明通过聚合1—2个非免疫苗期抗性基因和2—3个成株抗性基因,在成株期多个环境条件下均表现出近免疫抗性水平,是CIMMYT小麦品系保持持久抗性的主要原因。亟待广泛挖掘抗源,发掘新的抗病基因,充分利用现代生物技术手段快速培育具有持久抗性且农艺性状优良的小麦新品种,进一步提高中国麦区条锈病整体抗性水平。

植物促生菌暹罗芽孢杆菌37402-1的功能特性及对大蒜的促生效果

大蒜(Allium sativum L.)是我国的重要经济作物,主产地连作障碍严重,其种植生产的持续性受到制约。植物根际促生菌(PGPR)能够促进植物生长、防治病害且对环境友好。研制高效防控大蒜土传病害的微生物肥料对我国大蒜产业可持续发展和绿色发展有着重要的生态学和现实意义。以实验室前期从山东省金乡县连作大蒜根部分离的细菌为供试菌株,筛选获得对大蒜根腐病病原真菌尖刀镰孢菌(Fusarium oxysporum)ACCC37402和拟枝孢镰刀菌(Fusarium sporotrichioides)ACCC36464具有较好拮抗效果的菌株37402-1。菌株37402-1的PGPR功能特性研究结果显示:对大蒜根腐病病原真菌ACCC37402和ACCC36464的抑菌率分别为52.70%和37.98%;经16S rDNA基因序列同源性分析,确定为暹罗芽孢杆菌(Bacillus siamensis);具有水解蛋白能力、产铁载体能力、溶解有机磷和无机磷的能力。温室盆栽试验显示,接种暹罗芽孢杆菌37402-1菌悬液能够促进大蒜幼苗的生长。田间试验表明,接种暹罗芽孢杆菌37402-1菌剂使大蒜增产12.78%,并改变土壤酶活性(提高土壤蔗糖酶和土壤脲酶活性,降低土壤过氧化氢酶活性)。菌株暹罗芽孢杆菌37402-1兼具多种功能特性,对大蒜根腐病具有较好的拮抗效果,同时可以显著促进大蒜幼苗生长,并可在大田条件下促进大蒜的单产,有望开发成为高效的微生物肥料生产菌种。

根系分泌物介导的植物对土传病害的抗性机制

根系分泌物作为地下防御物质越来越受到关注。近年来,研究逐渐揭示了植物在病原胁迫下根系分泌物的表达特征及其在植物抗病性中的作用,一些由根分泌物介导的抗性调节机制也已被模拟。鉴于土传病害造成的损失日益增加,了解根系分泌物如何抵抗各种病原菌已成为研究热点。本文全面综述了土壤病原胁迫下根系分泌物介导的植物抗性机制,研究病原胁迫下根系分泌物的表达特征,根系分泌物在植物抗病过程中的作用,以及抗性根介导的分泌物和植物抗性的功能。讨论了当前植物病害条件下根系分泌物对植物抗性的影响,旨在为今后土传病害抗性机制的研究提供思路。

大豆高产栽培技术研究进展及展望

我国大豆单产较美国有很大差距,为打破我国大豆生产的困境,提高单产是关键因素之一。本文对我国与美国典型高产大豆进行整理、比较、分析。发现美国大豆单产高于我国大豆单产的原因是大豆品种具有抗草甘膦、高耐密、抗病性好和适应性广等特性,且还具有自然地理条件优异、灌溉技术与管理和田间管理较好等优势。通过分析影响我国与美国大豆单产的原因,提出我国大豆品种育种的未来方向应该注重耐密性和抗草甘膦等。在大豆栽培技术,如在合理密植与施肥技术、科学灌溉与排水、病虫害综合防控、化学调控、农业机械化与智能化等方面应特别关注。未来大豆高产研究还应关注基因编辑技术的应用、精准农业与智慧农业的创新与应用,加强国际合作与交流,从而为我国大豆高产研究与单产的提升提供理论指导。

Engineering disease-resistant plants with alternative translation efficiency by switching uORF types through CRISPR

Engineering disease-resistant plants can be a powerful solution to the issue of food security.However,it requires addressing two fundamental questions:what genes to express and how to control their expressions.To find a solution,we screen CRISPR-edited upstream open reading frame(uORF)variants in rice,aiming to optimize translational control of disease-related genes.By switching uORF types of the 5′-leader from Arabidopsis TBF1,we modulate the ribosome accessibility to the downstream firefly luciferase.We assume that by switching uORF types using CRISPR,we could generate uORF variants with alternative translation efficiency(CRISPR-aTrE-uORF).These variants,capable of boosting translation for resistance-associated genes and dampening it for susceptible ones,can help pinpoint previously unidentified genes with optimal expression levels.To test the assumption,we screened edited uORF variants and found that enhanced translational suppression of the plastic glutamine synthetase 2 can provide broad-spectrum disease resistance in rice with minimal fitness costs.This strategy,which involves modifying uORFs from none to some,or from some to none or different ones,demonstrates how translational agriculture can speed up the development of disease-resistant crops.This is vital for tackling the food security challenges we face due to growing populations and changing climates.

2种免疫诱抗剂和常规药剂在小麦上的应用比较

为了验证免疫诱抗剂对小麦具有促生、防病、增产和提质的效果,本研究通过对比维大力、氨基寡糖素、常规化学药剂和空白对照在小麦拌种及叶面喷施应用的效果,研究其对小麦秧苗素质、纹枯病防治效果、赤霉病防治效果、产量及呕吐毒素的影响。结果显示,利用维大力进行小麦拌种处理能显著增加小麦根长,促进次生根产生;在小麦拔节期喷施免疫诱抗剂对纹枯病防治效果达83.33%,显著优于常规药剂;在小麦抽穗扬花期喷施免疫诱抗剂对赤霉病防治效果达96.45%~98.05%,显著降低了呕吐毒素产生;利用免疫诱抗剂在拔节期和扬花期与常规药剂配合使用,可显著提高小麦籽粒实粒数,较单用常规药剂增产12.1%~13.7%。免疫诱抗剂在小麦应用上具有较高价值。

拟禾本科根结线虫种群密度与旱稻产量损失的关系

本研究旨在探讨土壤中拟禾本科根结线虫(Meloidogyne graminicola)的初始种群密度对旱稻产量损失的影响。通过室外网室盆栽试验,在旱种旱管模式下测定了土壤不同初始种群密度对旱稻产量和线虫繁殖的影响。研究结果表明,在2~200个卵和二龄幼虫/100 cm^(3)土的初始种群密度下,旱稻根长、根重、株高、分蘖数、穗长、千粒重和单盆谷粒重与土壤线虫初始种群密度呈极显著负相关,符合一元回归方程;旱稻产量随着土壤初始种群密度的增加,其损失率增加,在初始密度为2个卵和二龄幼虫/100 cm^(3)土时,旱稻产量损失率为28.4%,接种密度为200个卵和二龄幼虫/100 cm^(3)土时,损失率最大,为67.8%;随着线虫初始种群密度的增加,线虫的繁殖系数呈现降低的趋势。利用Seinhorst模型,初始线虫种群密度与相对产量的关系式为Y=0.24+0.76(0.3252)(Pi)。在旱种旱管模式下,拟禾本科根结线虫在2~200个卵和二龄幼虫/100 cm^(3)土的初始种群密度下与旱稻产量损失呈极显著正相关,表明拟禾本科根结线虫对旱稻的危害风险性较高。

Epigenetic regulation of plant immunity:from chromatin codes to plant disease resistance

Facing a deteriorating natural environment and an increasing serious food crisis,bioengineering-based breeding is increasing in importance.To defend against pathogen infection,plants have evolved multiple defense mechanisms,including pathogen-associated molecular pattern(PAMP)-triggered immunity(PTI)and effector-triggered immunity(ETI).A complex regulatory network acts downstream of these PTI and ETI pathways,including hormone signal transduction and transcriptional reprogramming.In recent years,increasing lines of evidence show that epigenetic factors act,as key regulators involved in the transcriptional reprogramming,to modulate plant immune responses.Here,we summarize current progress on the regulatory mechanism of DNA methylation and histone modifications in plant defense responses.In addition,we also discuss the application of epigenetic mechanism-based resistance strategies in plant disease breeding.

桑椹菌核病研究进展

桑椹是一种营养丰富的果实,富含花青素等抗氧化物质,不仅可以直接食用,还可用于制作果酱、酿造果酒和饮料,具有极高的经济价值。然而,近年来由于缺乏有效的抗性品种,我国果桑种植地区的桑椹菌核病发生日益严重,已严重影响到了桑椹的产量和品质。已确认桑椹菌核病的病原真菌有4种,不同地区的优势菌株不尽相同,可能由单一种类组成,也可能是由2种及以上的菌株复合侵染。由于桑椹菌核病的发病机制复杂,防治难度大,因此,本文主要从桑椹菌核病的类型、特征和侵染循环过程,桑树与病原菌相互作用的分子机制以及防治措施3个方面对该病的研究进展进行综述,以期为今后桑椹菌核病的研究重点以及科学防治提供理论指导。

工程纳米材料抵抗作物病害的研究进展

纳米技术有望在一定程度上缓解因人口增长带来的粮食危机,纳米级农化品(纳米肥料和纳米农药)展现出的缓释和高效低剂量特性减少了传统农用化学品带来的不利环境影响。该研究着重介绍了工程纳米材料(ENMs)通过直接和间接方式防治作物病害的内在机理,重点阐述了ENMs通过调控植物营养、诱导抗氧化酶活性和改善植物光合作用的方式来抵抗病原入侵对植物造成的氧化胁迫;同时,研究亦指出ENMs能够通过诱导植物产生系统获得抗性(SAR)的方式增强植物的抗病能力。对ENMs抗病机理的深入探究能够有效提高植物病害管理,实现作物产量和质量的增加,并极大程度减轻传统农药化学品对农业生态环境的负面影响。

贵州茶树4种常见真菌病害的发生规律及抗病机理研究进展

贵州省是世界茶树原产地和茶文化发祥地之一,其独特的气候条件和地理位置利于茶树生长,但阴湿的生长环境易使病害发生,致茶叶的产量与品质大幅下降,因此,茶树病害的致病规律以及茶树与病原菌互作的分子机理研究,是病害防控的重要理论基础。本文对贵州茶树的4种常见真菌病害发生规律以及茶树抗病分子免疫机理进行综述,并对未来研究进行展望,旨在为茶树分子育种以及新型病害防治策略的研发提供参考。

Quantitative disease resistance:Multifaceted players in plant defense

In contrast to large-effect qualitative disease resistance,quantitative disease resistance(QDR)exhibits partial and generally durable resistance and has been extensively utilized in crop breeding.The molecular mechanisms underlying QDR remain largely unknown but considerable progress has been made in this area in recent years.In this review,we summarize the genes that have been associated with plant QDR and their biological functions.Many QDR genes belong to the canonical resistance gene categories with predicted functions in pathogen perception,signal transduction,phytohormone homeostasis,metabolite transport and biosynthesis,and epigenetic regulation.However,other"atypical"QDR genes are predicted to be involved in processes that are not commonly associated with disease resistance,such as vesicle trafficking,molecular chaperones,and others.This diversity of function for QDR genes contrasts with qualitative resistance,which is often based on the actions of nucleotidebinding leucine-rich repeat(NLR)resistance proteins.An understanding of the diversity of QDR mechanisms and of which mechanisms are effective against which classes of pathogens will enable the more effective deployment of QDR to produce more durably resistant,resilient crops.

浚单系列玉米品种耐密性与抗病性研究

本研究以浚单系列玉米品种中较为畅销的浚单29、浚单3136、浚单658、浚单1618为试验材料,设置不同种植密度,对其耐密性及抗病性进行评价。结果表明:随着密度的增加,浚单系列玉米品种株高、重心高明显增高;茎腐病、穗腐病、南方锈病随密度的增加表现出加重趋势,以浚单658综合抗病性最好;随着密度的增加,产量构成因素中穗行数、行粒数、千粒重、单株籽粒干重等逐渐降低;产量以7.50万株/hm^(2)密度处理下的浚单658为最高,达到13243.8 kg/hm^(2)。

常见植物精油在反刍动物疾病防治中的应用

[目的]总结几种常见植物精油的来源、组分、种类、生物学活性及其在反刍动物疾病防治中的应用。[方法]通过查阅相关文献,对植物精油相关内容进行概述和分析。[结果]植物精油是一种天然低毒、低残留、高生物活性的芳香气味混合物,如牛至精油、百里香精油、肉桂精油等,主要生物活性物质为百里香酚、香芹酚、肉桂醛等。植物精油具有抗菌、抗氧化、驱虫和杀虫等作用,对反刍动物奶牛乳房炎、繁殖障碍性疾病、寄生虫以及肢蹄病具有良好的实践应用效果。[结论]植物精油来源广泛、生物活性高,可以在畜禽养殖生产、动物疾病防治中进一步推广和研究应用。

Effects of silicon amendment on the occurrence of rice insect pests and diseases in a field test

Rice is one of the most important staple foods for the world population,but it is attacked by a number of destructive pests.While evidence from greenhouse and laboratory tests has shown that silicon（Si）amendment can confer enhanced resistance to pests in rice,few studies have directly demonstrated the Si-mediated protection from pests in a field situation.In this study,field plots with silicon amendments at 0,75,150 and 300 kg SiO2 ha-1 in early-and late-season rice were employed to evaluate the effects of silicon amendment on the occurrence of major insect pests and diseases and rice yield.Compared with the control plots without silicon amendment,plant damage by stem borer and leaf folder and population size of planthopper were significantly lower in three to five of the seven monitoring observations in each season in the plots amended with 300 kg SiO2 ha-1.The disease index of rice blast in the early-season rice was lower in the plots amended with Si at 300 kg SiO2 ha-1 than in the control plots,while Si protection from rice blast in the late-season rice and from rice sheath blight in the early-season rice were not apparent.An insignificant increase of rice yield by 16.4%（604 kg ha-1）was observed in the plots amended with 300 kg SiO2 ha-1 over the control plots.Our results indicate that Si amendment at 300kg SiO2 ha-1 can provide substantial protection from some of the rice pests under field conditions.These findings support the recommendation of silicon amendment as a key component of integrated management of rice pests.

Expressing p20 hairpin RNA of Citrus tristeza virus confers Citrus aurantium with tolerance/resistance against stem pitting and seedling yellow CTV strains

The Citrus tristeza virus (CTV) uses 3 silencing suppressor genes, p20, p23 and p25, to resist the attacks from its Citrus hosts. Inactivating these genes is therefore obviously a potential defensive option in addition to the current control strat-egies including aphid management and the use of mild strain cross protection. In this study, we cloned partial DNA frag-ments from the three genes, and used them to construct vectors for expressing hairpin RNAs (hpRNAs). To facilitate the formation of hpRNAs, the constructs were introduced in a loop structure. Fol owing transformation of sour orange (Citrus aurantium) with these constructs, 8 p20 hpRNA (hp20) and 1 p25 hpRNA (hp25) expressing lines were obtained. The 7 hp20 transgenic lines were further characterized. Their reactions to CTV were tested fol owing inoculation with CT14A and/or TR-L514, both of which are severe strains. Results showed that 3 lines (hp20-5, hp20-6 and hp20-8) were completely resistant to TR-L514 under greenhouse conditions for no detectable viral load was found in their leaves by PCR. However, they exhibited only partial suppression of TR-L514 under screen house conditions since the virus was detected in their leaves, though 2 months later compared to non-transgenic controls. Further tests showed that hp20-5 was tolerant also to CT14A under screen house conditions. The growth of hp20-5 was much better than others including the controls that were concurrently chal enged with CT14A. These results showed that expressing p20 hpRNA was sufifcient to confer sour orange with CTV resistance/tolerance.