Adulteration detection of plant protein beverages by UPLC-MS/MS based on signature peptide of allergen

Plant protein beverage adulteration occurs frequently,which may cause health problems for consumers due to the hidden allergens.Hence,a novel method was developed for authentication by ultra-performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS).Almond,peanut,walnut and soybean were hydrolyzed,followed by separation by NanoLC-Triple TOF MS.The obtained fingerprints were identified by ProteinPilotTM combined with Uniprot,and 16 signature peptides were selected.Afterwards,plant protein beverages treated by trypsin hydrolysis were analyzed with UPLC-MS/MS.This method showed a good linear relationship with R2>0.99403.The limit of quantification(LOQ)were 0.015,0.01,0.5 and 0.05 g/L for almond,peanut,walnut and soybean,respectively.Mean recoveries ranged from 84.77%to 110.44%with RSDs<15%.The developed method was successfully applied to the adulteration detection of 31 plant protein beverages to reveal adulteration and false labeling.Conclusively,this method could provide technical support for authentication of plant protein beverages to protect the rights and health of consumers.

Estimation of Digestible Energy Values of Plant Protein Supplement in Pig

[Objective] The aim of the study was to establish the effective and accurate formulas for estimating the digestible energy （DE） values of plant protein supplement in pig. [Method] By difference method with different amount of alternative feeds （20% -50%）, two4 x4 Latin- square-designed trials were taken on eight castrated male pigs [ Yorkshire x Landrace x Neijiang pig, initial body-weight： （46 ±2） kg ] to deter- mine the apparent digestible energy （ADE） of the eight kinds of plant protein supplement commonly used in China, that is, corn gluten meal （sol.）, soybean meal （ sol. ）, fababean, pea, rapeseed meal （ sol. ）, sesame meal （ sol. ）, rapeseed meal （ exp. ） and cotton seed meal （sol.）. [Resultl （1） Fiber was the most important factor to estimate the ADE of plant protein supplement in pigs, and ADF was the best one. （2） The most effective equations were as below： （ 1 ） OE （kJ/kg DM） = 14 741.86 - 185.01ADF＋54.01SCHO＋22.45CP （ R =0.988,RSD= 67.9,P〈0.01 ） ; （2） DE （kJ/kg DM） =22 223.26 -209.58ADF＋26.79SCHO-1.09GE （ Ff =0.989,RSD=66.9, P〈0.01 ） . [Conclusion] The accurate, practical and specific regression equations were established for DE prediction of plant protein supplement in pig.

Gelling Behavior of Plant Proteins and Polysaccharides in Food Systems

Biological macromolecules, such as proteins and polysaccharides, are widely used in food systems because their interactions impart a desirable texture to food products. Plant proteins interact with food components via protein-protein and protein-polysaccharide associations, and the formation of a matrix, which can entrap other food components such as water, lipids and flavors. These networks provide structural integrity to food products and can serve as important functional ingredients in processed foods. Intermolecular interactions of typical polysaccharides result either in simple associations or in the form of a double or triple helix. The linear double helical segments may then interact to form a super junction and a three-dimensional gel network. The formation of these structural networks takes place during processing and involves the transformation from a liquid or viscous sol into a solid material with elastic properties. Interests in the behavior of mixed gels center on the prospects of enhanced flexibility in their mechanical and structural properties compared to those of pure gels. Findings on molecular interactions between plant proteins （e.g., soy, canola and pea proteins） and polysaccharides （e.g., guar gum, carrageenan, and pectin） allow for the modification of physical and textural characteristics of mixed biopolymers to meet desired functional property.

pLoc_Deep-mPlant: Predict Subcellular Localization of Plant Proteins by Deep Learning

Current coronavirus pandemic has endangered mankind life. The reported cases are increasing exponentially. Information of plant protein subcellular localization can provide useful clues to develop antiviral drugs. To cope with such a catastrophe, a CNN based plant protein subcellular localization predictor called “pLoc_Deep-mPlant” was developed. The predictor is particularly useful in dealing with the multi-sites systems in which some proteins may simultaneously occur in two or more different organelles that are the current focus of pharmaceutical industry. The global absolute true rate achieved by the new predictor is over 95% and its local accuracy is about 90%?-?100%. Both have substantially exceeded the?other existing state-of-the-art predictors. To maximize the convenience for most?experimental scientists, a user-friendly web-server for the new predictor has been established?at?http://www.jci-bioinfo.cn/pLoc_Deep-mPlant/, by which the majority of experimental?scientists can easily obtain their desired data without the need to go through the?mathematical details.

Effects of High Plant Protein and High Soluble Fiber Beverages on Satiety, Appetite Control and Subsequent Food Intake in Healthy Men

Plant based proteins and fibers are attractive ingredients for weight management-dietary preventive strategies due to their positive satiety enhancement effects. The objective of this study was to evaluate the effect of beverages high in plant-protein and soluble fiber on satiety, appetite, hunger and subsequent food intake in healthy young men. This was a randomized crossover study with 30 normal weight male participants, BMI 23.6 ± 1.6 and age 22 ± 1.4. Volunteers consumed one high carbohydrates control (B) and 3 treatments on different days with 3-day washout period. Beverages had similar viscosity and energy content (238 ± 3.8 Kcal). The blank contained (B)-0 g protein/2g fiber), High protein (HP)-30 g protein/2g fiber, High Fiber (HF)-0 g protein/11g fiber and High protein high fiber beverage (HPHF)-30g protein/11g fiber. Visual Analogue Scales VAS were used for subjective satiety, hunger and appetite. Subsequent energy and macronutrient intake was measured by difference after consuming lunch ad libitum. Beverages HP, HF and HPHF showed higher satiety effect than B after 2 and 3 hours post consumption (P = 0.02). HP showed the most prolonged effect on satiety (4 h) compared to the control (P = 0.02). Appetite control was not different between treatments but significant differences were observed against the control after 2 h of consumption (P = 0.01). No differences on hunger perception, subsequent energy or macronutrient intake were observed among all beverages (P > 0.05). The current study demonstrates that HPHF, HP and HF beverages led to improved satiety over high carbohydrate beverages. In conclusion, beverages formulated with plant-based proteins, soluble corn fiber or both may be an effective strategy to promote satiety as part of an overall weight management plan.

Research Progress on Plant Anti-Freeze Proteins

Plant antifreeze proteins(AFPs)are special proteins that can protect plant cells from ice crystal damage in low-temperature environments,and they play a crucial role in the process of plants adapting to cold environ-ments.Proteins with these characteristics have been found infish living in cold regions,as well as many plants and insects.Although research on plant AFPs started relatively late,their application prospects are broad,leading to the attention of many researchers to the isolation,cloning,and genetic improvement of plant AFP genes.Studies have found that the distribution of AFPs in different species seems to be the result of independent evolu-tionary events.Unlike the AFPs found infish and insects,plant AFPs have multiple hydrophilic ice-binding domains,and their recrystallization inhibition activity is about 10–100 times that offish and insect AFPs.Although different plant AFPs have the characteristics of low TH and high RI,their DNA and amino acid sequences are completely different,with small homology.With in-depth research and analysis of the character-istics and mechanisms of plant AFPs,not only has our understanding of plant antifreeze mechanisms been enriched,but it can also be used to improve crop varieties and enhance their freezing tolerance,yield,and quality through genetic engineering.In addition,the study of plant AFPs also contributes to our understanding of freezing resistance mechanisms in other organisms and provides new research directions for thefield of biotech-nology.Therefore,based on the analysis of relevant literature,this article will delve into the concepts,character-istics,research methods,and mechanisms of plant AFPs,summarize the latest research progress and application prospects of AFPs in plant,and provide prospects for the future development of AFP gene research.

The meat of the matter: plant-based meat analogue versus traditional meat product nutritional quality

Plant-based meat analogues(PBMA)are formulated to mimic the sensory characteristics of traditional meat products(TMP)using vegetarian ingredients and are increasingly popular with the trend towards plantbased diets,even among meat-eating consumers.This narrative review compared the nutritional quality of PBMA and TMP to broaden the discussion on the suitability of simulated meat products to substitute TMP,while exploring other attributes for their comparison.The complexity of PBMA and TMP means they are not entirely interchangeable.Importantly,PBMA health effects extend beyond their basic nutrient content and quality.Postprandial metabolism and satiety,for example,can be affected by product formulation,ingredient interactions,and thermomechanical processing involved in producing organoleptically acceptable PBMA.There are specific opportunities for low-sodium PBMA products to contribute to a healthy shift toward plantbased diets.In conclusion,PBMA cannot be assumed to be healthier than TMP.They should be designed with comprehensive consideration of composition and processing to ensure they support consumers who are adopting plant-based diets in realizing the theoretical health benefits.

Classification and Nomenclature of Plant Metallothionein-like Proteins Based on Their Cysteine Arrangement Patterns

随着植物基因组研究的进展 ,在基因文库和蛋白文库登录的植物类金属硫蛋白基因已超过 5 0个 ,接近金属硫蛋白总数的 1/ 3,而且有不断上升的趋势。鉴于目前植物类金属硫蛋白命名与分类随意性太大 ,很有必要建立一个统一合理的命名与分类法。对植物类金属硫蛋白一级结构进行详细分析后 ,发现该蛋白两端富含半胱氨酸的区域内半胱氨酸的排列方式颇具规律性 ,进而提出了以半胱氨酸排列方式为基础的分类及命名法 ,并阐述了采用这种方法的理由及其可行性。

An automatically progressed computer-controlled simulated digestion system to predict digestible and metabolizable energy of unconventional plant protein meals for growing pigs

The objective of this experimentwas to develop a new computer-controlled simulated digestion system to predict the digestible energy(DE)and metabolizable energy(ME)of unconventional plant protein meals for growing pigs.Nine meals tested included 1 source of rapeseed meal,4 sources of cottonseed meal,2 sources of sunflower meal,and 2 sources of peanut meal.Twenty growing pigs(Duroc[LandraceLarge White])with an initial body weight(BW)of 41.7±2.6 kg were allotted to a replicated 103 incomplete Latin square design to determine the DE and ME of 1 basal diet and 9 experimental diets formulated with 9 unconventional plant protein meals.The DE andMEvalues of unconventional plant protein meals were calculated by the difference method.The in vitro digestible energy(IVDE)of 1 basal diet,9 experimental diets,and 9 unconventional plant protein meals were determined with 5 replicates of each sample in a complete randomized arrangement.The IVDE/DE or IVDE/ME ranged from 0.96 to 0.98 or 1.00 to 1.01,and the correlation coefficient between IVDE and DE or MEwas 0.97 or 0.98 in 10 experimental diets.Accordingly,the IVDE/DE or IVDE/ME ranged from 0.86 to 1.05 or 0.96 to 1.20,and the correlation coefficient between IVDE and DE orME was 0.92 or 0.91 in 9 unconventional plant protein meals.The coefficient of variation(CV)of IVDE was less than that of DE and ME in the experimental diets(0.43%,0.80%,and 0.97%for CV of IVDE,DE and ME,respectively)and unconventional plant protein meals(0.92%,4.84%,and 6.33%for CV of IVDE,DE and ME,respectively).The regression equations to predict DE from IVDE in 10 experimental diets and 9 unconventional plant protein meals were DE=0.8851IVDE t539(R^(2)=0.9411,residual standard deviation[RSD]=23 kcal/kg DM,P<0.01)and DE=0.9880IVDE t 166(R^(2)=0.8428,RSD=182 kcal/kg DM,P<0.01),respectively.Therewas no statistical difference in the slopes(P=0.82)or intercepts(P=1.00)of these 2 equations.Thus,10 diets and 9 unconventional plant protein meals were pooled to establish the regression equation of DE on IVDE as:DE=0.9813IVDE t187(R^(2)=0.9120,RSD=118 kcal/kg DM,P<0.01).The regression equations to predictME from IVDE in 10 experimental diets and 9 unconventional plant protein meals were ME=0.9559IVDE t146(R^(2)=0.9697,RSD=18 kcal/kg DM,P<0.01)and ME=0.9388IVDEt3(R^(2)=0.8282,RSD=182 kcal/kg DM,P<0.01),respectively.Therewas no statistical difference in slopes(P=0.97)but significant difference between the intercepts(P=0.02)of these 2 equations.Our results indicate IVDE has similar response to the DE but different response to the ME in 10 experimental diets and 9 unconventional plant protein meals.Therefore,IVDE is moresuitable to predict DE than ME of diets and unconventional plant protein meals for growing pigs.

Higher Plant Proteins of Cyanobacterial Origin:Are They or Are They Not Preferentially Targeted to Chloroplasts?

Dear Editor, What does the evolutionary origin of a plant protein tell about its subcellular localization？ Naively thinking, one would assume that plant proteins that were originally encoded in the endosymbiont genome are targeted to the chloroplast. However, published data seem to support only a loose link between evolutionary origin and subcel- lular localization. About half of the Arabidopsis proteins with a detectable cyanobacterial ortholog are targeted to subcellular compartments other than the chloroplast （Martin et al., 2002）. H

Modeling the Cysteine Rich Domain of Plant Metallothionein-like Protein

With the progress of plant genome research, more than 50 plant metallothionein_like (MT_L) genes have been found, but only several MT_L proteins have been detected and no experimental structural information for MT_L proteins has been reported so far. Since detailed knowledge of the protein tertiary structure is required to understand its biological function, a method is needed to determine the structure of these proteins. In this study, the structural data of known mammal MT was used to determine the interatomic distance constraints of the CXC and CXXC motifs and the metal_sulfur chelating cluster. Then several possible MT conformations were predicted using a distance geometry algorithm. The statistical analysis was used to select those with much lower target function values and lower conformation energies as the predicted tertiary structural models of the cysteine_rich (CR) domains of these proteins. A suitable prediction method for modeling the CR domain of the plant MT_L protein was constructed. The accurately predicted result for the known structure of an MT protein from blue crab suggests that this method is practicable. The tertiary structures of CR domains of rape MT_L protein LSC54 was then modeled with this method.

Protein Extraction Methods for Two-Dimensional Electrophoresis from Baphicacanthus cusia(Nees)Bremek Leaves-A Medicinal Plant with High Contents of Interfering Compounds

Protein extraction is a critical step for two-dimensional electrophoresis （2-DE）. Different plant samples require different and adaptive protein extraction protocols. The leaves of medicinal plant, Baphicacanthus cusia （Nees） Bremek are notoriously recalcitrant to common protein extraction methods due to high levels of interfering compounds （especially the secondary metabolites and pigments）. This study was aimed to establish a routine procedure for the proteomic analysis ofB. cusia leaves, and a new protocol for the protein extraction was developed by optimizing trichloroacetic acid （TCA）/ acetone extraction method. The efficiency of this protocol was demonstrated by comparison with 3 published protein extraction methods （chloroform/acetone, Mg/NP-40, Tris-base/acetone）. The results showed that the optimized TCA/ acetone precipitation extraction method gave a relatively high protein yield （9.263 mg g^-1 fresh weight）, high-resolution separation, clear protein profiles, the highest proteins spots （1 31 t protein spots）, and displayed less contamination in 2- DE gels. Therefore, the results suggested that the optimized TCA/acetone method was the most effective among the 4 methods for B. cusia leaves.

An Evaluation on the Ratio of Plant to Animal Protein in the Diet of Juvenile Sea Cucumber(Apostichopus japonicus):Growth,Nutrient Digestibility and Nonspecific Immunity

This study was conducted to evaluate the effects of plant/animal(P/A) protein ratios(viz.1:4, 1:3, 1:2, 1:1,2:1, 3:1, 4:1) on growth performance, body composition, apparent digestibility of diets, and nonspecific immunity of juvenile sea cucumber(Apostichopus japonicus). Sea cucumbers were divided into 21 plastic tanks, and each tank was stocked with 15 individuals(initial weight: about 23.73 g). Each feed was allocated to three replicates of sea cucumbers. The feeding experiment lasted for 50 days. Results indicated that weight gain rate(WGR) and body wall weight(BWW) significantly increased as dietary ratio of P/A increased from 1:4 to 3:1, and then decreased significantly with further increase of this ratio(P < 0.05). The body wall coefficient(BWC) showed a similar tendency to WGR and BWW, but no significance was detected among dietary treatments(P > 0.05). The apparent digestibility of dry matter, protein and lipid increased with ratio of P/A increasing from 1:4 to 2:1(P < 0.05), and then decreased with further increase of this ratio. Correspondingly, activities of trypsin and amylase were significantly increased as P/A increased from 1:4 to 2:1(P < 0.05). The activities of SOD and CAT showed a similar trend with WGR, with the highest value observed in the ratio of 1:2 and 1:1, respectively. Results above showed that moderate or relatively higher ratio of P/A protein(1:1-3:1) significantly increased the growth performance, apparent digestibility, and nonspecific immunity of sea cucumber. This will contribute to improving the feed formulation for juvenile cucumbers.

Pathogenesis-related protein genes involved in race-specific allstage resistance and non-race specific high-temperature adultplant resistance to Puccinia striiformis f. sp. tritici in wheat

Interactions of the stripe rust pathogen （Puccinia striiformis f. sp responses. Among various genes involved in the plant-pathogen related （PR） protein genes determine different defense responses tritici） with wheat plants activate a w^ae range OT nost nteractions, the expressions of particular pathogenesis-Different types of resistance have been recognized and utilized for developing wheat cultivars for resistance to stripe rust. All-stage resistance can be detected in seedling stage and remains at high levels throughout the plant growth stages. This type of resistance is race-specific and not durable. In contrast, plants with only high-temperature adult-plant （HTAP） resistance are susceptible in seedling stage, but become resistant when plants grow older and the weather becomes warmer. HTAP resistance controlled by a single gene is partial, but usually non-race specific and durable. The objective of this study was to analyze the expression of PR protein genes involved in different types of wheat resistance to stripe rust. The expression levels of 8 PR protein genes （PR1, PRI.2, PR2, PR3, PR4, PR5, PR9 and PRIO） were quantitatively evaluated at 0, 1, 2, 7 and 14 days after inoculation in single resistance gene lines of wheat with all-stage resistance genes YrTrl, Yr76, YrSP and YrExp2 and lines carrying HTAP resistance genes Yr52, Yr59, Yr62 and Yr7B. Races PSTv-4 and PSTv-37 for compatible and incompatible interactions were used in evaluation of PR protein gene expression in wheat lines carrying all-stage resistance genes in the seedling- stage experiment while PSTv-37 was used in the HTAP experiment. Analysis of quantitative real-time polymerase chain reaction （qRT-PCR） revealed that all of the PR protein genes were involved in the different types of resistance controlled by different Yr genes. However, these genes were upregulated at different time points and at different levels during the infection process among the wheat lines with different Yr genes for either all-stage resistance or HTAP resistance. Some of the genes were also induced in compatible interactions, but the levels were almost always higher in the incompatible interaction than in the compatible interaction at the same time point for each Yr gene. These results indicate that both salicylic acid and jasmonate signaling pathways are involved in both race-specific all-stage resistance and non-race specific HTAP resistance. Although expressing at different stages of infection and at different levels, these PR protein genes work in concert for contribution to different types of resistance controlled by different Yr genes.

Plant Antifreeze Proteins and Their Expression Regulatory Mechanism

Low temperature is one of the major limiting environmental factors which constitutes the growth, development, productivity and distribution of plants. Over the past several years, the proteins and genes associated with freezing resistance of plants have been widely studied. The recent progress of domestic and foreign research on plant antifreeze proteins and the identifica- tion and characterization of plant antifreeze protein genes, especially on expression regulatory mechanism of plant antifreeze proteins are reviewed in this paper. Finally, some unsolved problems and the trend of research in physiological functions and gene expression regulatory mechanism of plant antifreeze proteins are discussed.

Effects of inter-culture, arabinogalactan proteins, and hydrogen peroxide on the plant regeneration of wheat immature embryos

The regeneration rate of wheat immature embryo varies among genotypes, howbeit many elite agriculture wheat varieties have low regeneration rates. Optimization of tissue culture conditions and attempts of adding signal molecules are effective ways to increase plant regeneration rate. Inter-culture is one of ways that have not been investigated in plant tissue culture. Moreover, the use of arabinogalactan proteins （AGPs） and hydrogen peroxide （H202） have been reported to increase regeneration rate in a few plant species other than wheat. The current research pioneeringly uses inter-culture of immature embryos of different wheat genotypes, and also investigates impacts of AGP and H2O2 on the induction of embryogenic calli and plant regeneration. As a result, high-frequency regeneration wheat cultivars Kenong 199 （KN 199） and Xinchun 9 （XC9）, together with low-frequency regeneration wheat line Chinese Spring （CS）, presented striking increase in the induction of embryogenic calli and plant regeneration rate of CS through inter-culture strategy, up to 52.19 and 67.98%, respectively. Adding 50 to 200 mg L-1 AGP or 0.005 to 0.01‰ H2O2 to the callus induction medium, enhanced growth of embryogenic calli and plant regeneration rate in quite a few wheat genotypes. At 50 mg L-1 AGP application level in callus induction medium plant regeneration rates of 8.49,409.06 and 283.16% were achieved for Jimai 22 （JM22）, Jingdong 18 （JD18） and Yangmai 18 （YM18）, respectively; whereas at 100 mg L-1 AGP level, CS （105.44%）, Chuannong 16 （CN16） （80.60%） and Ningchun 4 （NC4） （62.87%） acted the best. Moreover CS （79.05%）, JM22 （7.55%）, CN16 （101.87%）, YM18 （365.56%）, Yangmai 20 （YM20） （10.48%）, and CB301 （187.40%） were more responsive to 0.005 %o of H2O2, and NC4 （35.37%） obtained the highest shoot regeneration rates at 0.01%o of H2O2. Overall, these two methods, inter-culture and AGP （or H2O2） application, can be further applied to wheat transgenic research.

Effect of Plant AntifreezeProteins on Porcine Embryo to Cryopreservaton

This study was to research the cryopreservation effect of plant antifieeze proteins(AFPs) on day 7 porcine expanded and hatched blastocysts that were frozen in 1.5 M glycerol by conventional slow freezing method. The developmental rates of porcine embryos frozen with 0.5 mg/ml AFPs in freeze medium and cultured for 12 and 24 hours in vitro are 25% and 0%respectively. With the concentration of AFPs increased to 5 mg/ml, the corresponding values became 80% and 40%. The hatched rates for porcine embryos frozen with 0.5 mg/ml and 5 mg/ml of AFPs and cultured for 24 hours in vitro are 0% and 20% respectively..The developmental and hatched rate of the contnrol are all 0%(0/4). These results indicate that the survival rates of porcine expanded and hatched blastocyst can be improved by supplementing freeze medium with plant AFPs.

Protein quantitation using dyes obtained from plant materials

We present a preliminary report on the use of plant dyes in the quantitation of proteins in solution. We have used ethanol, acid, alkali and water to extract dyes from some plant materials, including flowers of Jungle flame (Izora coccinea), China rose (Hibiscus rosa-sinensis) and leaves of West African Indigo (Lonchocarpus cyanescens), Mimosa (Mimosa pudica), Roselle (Hibiscus sabdarifa), Jatropha (Jatropha curcas) and Henna (Lawsonia inermis). The dyes obtained were used in the protein-dye binding studies. The colour of the protein-dye complex of the ethanolic extracts was stable and increased linearly with increase in protein concentration. The extracts achieved linearity up to the following amount of proteins in the test samples: Hibiscus rosa-sinensis (60 mg), Ixora coccinea (120 mg), Hibiscus sabdarifa (80 - 100 mg), Jatropha curcas (80 mg), and Lawsonia inermis (100 mg). The sensitivity of the dyes especially at low protein concentrations indicate that they can provide suitable alternatives to other well known standard methods of protein determination.

我国植物油料油脂加工技术新进展

植物油料油脂加工的主要内容包括油脂及蛋白的初加工和深加工技术、综合利用技术、工程装备技术及品质控制技术等,概述了我国植物油料油脂加工技术新进展。我国已初步建立起基于营养和安全为评价标准的食用植物油精准适度加工体系;突破了零反式脂肪酸专用油脂生产技术,能满足各种食品加工场景需求;功能油脂制备技术成果渐次落地,推动产业进入蓬勃发展期,多款结构脂产品进入量产,跨国公司垄断局面得以改变;新油源开发方兴未艾;植物蛋白结构功效关系基础研究促进了植物基产品开发;油料油脂综合利用规模扩大;食用油安全防控技术、绿色储油技术研究不断深入;大型浸出器和浓缩蛋白制取装备的设计和制造水平达到国际先进水平;智能化工厂建设支撑我国油料油脂加工各项经济技术指标处于世界领先地位。

NBS-LRR Proteins and Their Partners:Molecular Switches of Plant Defense

Specificity of the plant innate immune system is often conferred by resistance（R）proteins.Most plant disease resistance （R）proteins contain a series of leucine-rich repeats（LRRs）,a nucleotide-binding site（NBS）,and a putative amino-terminal signaling domain.They are termed NBS-LRR proteins.The LRRs are mainly involved in recognition,and the amino-terminal domain determines signaling specificity,whereas the NBS domain presumably functions as a molecular switch.During the past years,the most important discoveries are the role of partners in NBS-LRR gene mediated defenses,mounting support for the so-called＂guard hypothesis＂of R gene function,and providing evidence for intramolecular interactions and intermolecular interactions within NBS- LRR proteins as a mode of signaling regulation.The outcome of these interactions determines whether a plant activates its defense responses.