多肽在凯特芒果上的应用效果

以9龄生凯特芒果树为试材,施用不同浓度(常规施肥+多肽500倍液、常规施肥+多肽1 000倍液、常规施肥+多肽1 500倍液、常规施肥+1 000倍多肽叶喷施、常规施肥+清水对照)的多肽,研究其对芒果吸收部分矿质营养和品质的影响.结果表明:多肽能促进芒果果实吸收N、P、K素营养和改善果实品质.施用多肽500倍液,果实中N、P、K素营养含量分别比对照高12.1%、34.7%、17.2%,可滴定酸降低44.3%,可溶性总糖提高24.6%,抗坏血酸提高59.5%.     

农用聚天门冬氨酸同源多肽研究进展

聚天门冬氨酸同源多肽是一种水溶性多肽,可生物降解,属于环境友好型代谢仿生型产品。本文综述了农用聚天门冬氨酸同源多肽的开发历程、主要作用原理、农用产品开发、在农业上的应用效果、应用前景和发展建议,以期对农用聚天门冬氨酸同源多肽有全面的了解,推动农用聚天门冬氨酸同源多肽的开发应用。     

New Kunitz-Type HCRG Polypeptides from the Sea Anemone Heteractis crispa

Sea anemones are a rich source of Kunitz-type polypeptides that possess not only protease inhibitor activity, but also Kv channels toxicity, analgesic, antihistamine, and anti-inflammatory activities. Two Kunitz-type inhibitors belonging to a new Heteractis crispa RG (HCRG) polypeptide subfamily have been isolated from the sea anemone Heteractis crispa. The amino acid sequences of HCRG1 and HCRG2 identified using the Edman degradation method share up to 95% of their identity with the representatives of the HCGS polypeptide multigene subfamily derived from H. crispa cDNA. Polypeptides are characterized by positively charged Arg at the N-terminus as well as P1 Lys residue at their canonical binding loop, identical to those of bovine pancreatic trypsin inhibitor (BPTI). These polypeptides are shown by our current evidence to be more potent inhibitors of trypsin than the known representatives of the HCGS subfamily with P1Thr. The kinetic and thermodynamic characteristics of the intermolecular interactions between inhibitors and serine proteases were determined by the surface plasmon resonance (SPR) method. Residues functionally important for polypeptide binding to trypsin were revealed using molecular modeling methods. Furthermore, HCRG1 and HCRG2 possess anti-inflammatory activity, reducing tumor necrosis factor-α (TNF-α) and interleukin 6 (IL-6) secretions, as well as proIL-1β expression in lipopolysaccharide (LPS)-activated macrophages. However, there was no effect on nitric oxide (NO) generation.     

聚天门冬氨酸同源多肽对西红柿生长发育和抗病性的影响

以夏红1号和长葫芦柿为试材,采用田间小区试验和田间调查试验,研究聚天门冬氨酸同源多肽对西红柿生物学性状和产量的影响。结果表明：聚天门冬氨酸同源多肽可增强西红柿生长势,使西红柿提早进入结果期,聚天门冬氨酸同源多肽对西红柿的增产作用达极显著水平,单位面积产量比对照增加9.33%;其销售量比对照增加37.52%,以销售收入核算的产出投入比达10.91,可显著提高西红柿的经济收益。田间试验调查发现：聚天门冬氨酸同源多肽对培育西红柿壮苗效果显著,对西红柿的大田长势及抗病方面也有显著的积极作用,并且病虫害的发生比对照     

多肽对香蕉幼苗生长及根系活力的影响

以巴西蕉组织培养苗为试材,研究不同多肽浓度(600、800、1 000、1 200倍液)对巴西蕉幼苗生长及根系活力的影响。结果表明,外源多肽处理能促进巴西蕉幼苗的生长,增加根重、苗高、叶片长度和宽度,同时还能提高巴西蕉幼苗根系活力,但是对根长影响不显著。在试验的各个浓度中,以600倍液的处理效果最好。     

Variation in Friabilin Composition as Determined by A-PAGE Fractionation and PCR Amplification, and its Relationship to Grain Hardness in Bread Wheat

A-PAGE fractionation of starch granule proteins from 63 bread wheat cultivars with contrasting grain texture characteristics revealed two prominent polypeptides and three minor ones, approximately 15 kDa in size. These proteins were found to be encoded by genes on the short arm of chromosome 5D. The two major friabilin components were assumed to correspond to puroindolines a and b (pinA and pinB), as suggested by PCR amplification of genes coding for pinA, glycine-type or serine-type pinB. Two electrophoretic patterns for pinA (presence vs absence) and three patterns for pinB were obtained by A-PAGE. In cultivars with pinA (allele Pina-D1a), pinB was found to be encoded by wild-type Pinb-D1a, serine-type Pinb-D1b or by the novel glycine-type b1 allele. Cultivars lacking pinA (allele Pina-D1b) were shown to contain eitherPinb-D1a or the novel b2 allele, both alleles coding for glycine-type pinB. The intensity of pinB in A-PAGE gels was found to be associated with grain hardness as determined by the SKCS method. Cultivars lacking pinA had the highest SKCS values, suggesting that both pinA and pinB may affect grain texture. In the presence of pinA, cultivars with wild-type allelePinb-D1a had soft grain texture, whereas those with alleles Pinb-D1b or b1 showed increased grain hardness. It is suggested that allele b1 affects the interaction of pinB with starch granules because of a sequence mutation different from the glycine-to-serine change.     

水稻中对不亲和白叶枯病菌株专一识别的多肽

 经蛋白质双向电泳分析，发现水稻IR26、IR1545及TN1各有一个多肽能与不亲和的白叶枯病菌株产生特异性作用而消失，但与亲和菌株相互不发生作用。成株期抗病品种南粳l5在成株期有与不亲和菌株作用的多肽存在．而在苗期则未观察到这一多肽。对全期抗病品种IR26分析表明，它无论在成株期还是苗期均出现一个与不亲和菌株专一作用的多肽。经典遗传学分析认为有三个抗白叶枯病基因的DV85，则观察到DV85有两个以上的菌株特异性多肽。由于选些多肽表现出菌株的专一性及其它表达生理时期均与该品种的田间抗病表型一致，同时多肽的数目也与经典遗传学分析结果类似，推测这些多肽可能是抗病基因的产物。     

Isolation and Characterisation of Single Chain Amylose

Five amylose preparations of different origins (cassava, potato, smooth seeded pea, wheat and maize), obtained from native starch granules by thymol complexation, were ultracentrifuged as the final decontamination step to remove a high molecular weight population contaminating the amylose solutions. The efficiency of this ultracentrifugation procedure was assessed by dynamic light scattering (DLS): decreases in apparent hydrodynamic radii,R?_H, from 46·1–72·6 nm before ultracentrifugation to 16·1–29·3 nm after were observed. Amylose solutions were then characterised by size exclusion chromatography coupled on-line to multi-angle laser light scattering (SEC–MALLS). Under these conditionsM?_wof cassava, potato, smooth seeded pea, wheat and maize amyloses were, respectively, 1·05×10⁶, 7×10⁵, 6·2×10⁵, 5·1×10⁵and 3·4×10⁵g/mol. Using a specific optimisation algorithm, experimental molecular weight distributions (MWD) were fitted by two mathematical models of ‘Most Probable’ distribution and ‘log-normal’ distribution. The best fit was obtained for the second model, but fittedM?_wwere higher than experimentalM?_w. When a ‘Most Probable’ model was used, the fittedM?_wwere consistent with experimentalM?_wbut with a lower quality of fit. Exponentscin the power lawR_G=KM^cwere between 0·6 and 0·7, indicating an extended linear random coil in the range of MW analysed (3×10⁵–9×10⁶g/mol). This procedure was also applied to the characterisation of different commercial amylose products.     

Size Characterisation of Glutenin Polymers by HPSEC-MALLS

The use of an on-line coupling of a new high-performance size exclusion chromatography (HPSEC) phase characterised by a very high exclusion limit and a multiangle laser light scattering detection (MALLS) for the size characterisation of wheat glutenin polymer was examined. Flour glutenin polymers which were extracted and purified by differential solubility in aqueous 50 and 70% propan-1-ol were solubilised with or without sonication in combination with a surfactant, 2% SDS. The glutenin polymers of the two genotypes studied, Soissons (5+10, Glu-1D) and Thésée (2+12, Glu-1D), were characterised by large polydispersity and by significant differences of size distribution of total polymers. The molecular size distribution of the total polymers, which can be used to differentiate the two genotypes, was highly correlated with the percentage of high-molecular glutenin subunits (HMW-GS) in glutenins. Furthermore, the results obtained for both the SDS-soluble and SDS-insoluble glutenin polymers from the two varieties revealed significant differences in size distribution, and also in molecular conformation (dependence of size upon mass). The molecular dimensions of SDS-insoluble polymers increased more slowly with the molecular weight than SDS-soluble polymers, which suggested a more compact structure. To conclude, the method appears to be a viable procedure to obtain rapid size characterisation of unreduced glutenin.     

Preliminary Characterisation of Endogenous Wheat Arabinoxylan-degrading Enzymic Extracts

Endogenous arabinoxylan-degrading enzymes in wheat were investigated in extracts of whole grains and tissues. Crude enzymes from two European cultivars were observed to hydrolyse various substrates, such aso-nitrophenyl β-d-xylopyranoside,p-nitrophenyl α-l-arabinofuranoside, xylan, and water-extractable and water-unextractable wheat arabinoxylans. Viscosity measurements and gel permeation chromatography of digests of arabinoxylans by crude extracts indicated the presence of endo-acting enzymes. Moreover, high-performance anion-exchange chromatography showed that monomers (arabinose, xylose) and small xylooligosaccharides were also released. Wheat variety and harvest year were shown to have little influence on the level of activity. Grains were fractionated on a laboratory mill and assays of the crude extracts obtained from the different fractions showed that the inner tissues were less active towards arabinoxylans and model substrates than the outer.     

Spectroscopic Characterisation of the Lipid-binding Properties of Wheat Puroindolines

The lipid-binding properties of wheat puroindolines (PINs) make these proteins likely candidates to play an important role in the stability of lipid films in the gas cells of bread dough, an important aspect of bread making. Therefore, the interaction between PINs and water-soluble model lipids was investigated by fluorescence emission and circular dichroism (CD) spectroscopy. The secondary structure of PIN-a and PIN-b in solution, as determined by far-UV CD measurements, resembled that of plant non-specific lipid transfer protein (LTP). However, PINs contain a tryptophan-rich loop located at the exterior of the protein. It was shown by fluorescence emission spectroscopy and near-UV CD spectroscopy that this domain is involved in the lipid binding. Fluorescence titration experiments of PIN and its synthetic tryptophan-rich domains with the zwitterionic lipidn-hexadecylphosphocholine (C16PN) revealed that the binding was cooperative. For the binding of the charged lipids,n-hexadecacylphosphoglycol (C16PG) and hexadecyl-trimethylammoniumbromide (CTAB), a clear effect of ionic strength of the solution was obtained. Organisation of lipids into micelles was not a prerequisite for binding to PINs. Most likely, wheat PIN binds to monomeric lipid molecules via its tryptophan-rich domain, rendering the protein more hydrophobic. The overall secondary structure of wheat PINs did not change significantly upon binding to lipids.     

Characterisation and functional properties of Australian rice protein isolates

Albumin, globulin, glutelin and prolamin fractions were isolated from an Australian rice variety (cv. Langi) and characterised by yield, protein content and molecular weight profile using both capillary electrophoresis (SDS-CE) and sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). The influence of pre-extraction enzymatic hydrolysis of starch and heating to 70 °C was also investigated, as was the extraction of the glutelin fraction without prior removal of the albumin and globulin fractions. Pre-extraction treatment affected mainly the albumin fraction, increasing dry matter yield but reducing protein content. SDS-CE was able to separate the protein fractions over a wider molecular weight range than SDS-PAGE, and the peaks from SDS-CE showed slightly higher molecular weight compared to equivalent bands from SDS-PAGE. The glutelin fraction extracted without prior removal of albumin and globulin fractions had different characteristics compared to those obtained by conventional extraction methods. Pre-extraction hydrolysis of starch did not significantly affect the emulsifying, foaming and gelling properties of extracted protein. Although rice glutelin had poor solubility, emulsifying and foaming properties in aqueous systems, it had good gelling properties which could be important for food applications.     

Structural Characterisation of Water-extractable and Water-unextractable Arabinoxylans in Wheat Bran

Water-extractable arabinoxylan (WE-AX) in wheat bran, of which only a minority originates from adherent endosperm, amounted to 6% of the total arabinoxylan (AX) content in such bran. WE-AX had an arabinose to xylose (A/X)-ratio of 0·45. Graded ethanol precipitation (20–80% range) yielded AX with an A/X-ratio increasing from 0·31 to 0·85. A population of molecular weight (MW) of 50 kDa precipitated between 0 and 40% ethanol and one with much lower apparent MW precipitated at higher ethanol concentrations. Wheat bran unextractable cell wall material (UCM) was obtained as the residue withstanding thermostable α-amylase and protease treatments and consisted mainly of AX (ca 45%) and cellulose (30–35%). Two consecutive extractions of UCM with alkaline hydrogen peroxide (AHP; 2·0%, pH 11·5, 4 h, 60 °C) resulted in a cellulose rich residue (CRR) containing 33% of the AX originally present in UCM. The average A/X-ratio of AX in CRR was lower than that in UCM. The extracted AX polymers (ca 45% of the AX originally present in UCM) had a high A/X-ratio (0·82). Their elution profiles showed two polydisperse peaks with apparent MW of respectively 100–120 kDa and 5–10 kDa. Graded ethanol precipitation resulted in a lowly substituted fraction (A/X=0·40; 0–40% ethanol) of high MW and a fraction of highly substituted AX (A/X>0·95; 40–70% ethanol) containing both low molecular weight (LMW-) as well as high molecular weight (HMW-) AX. At an ethanol concentration of 70% or more, only LMW-AX precipitated.     

Characterisation of Sorghum Kafirins in Relation to their Cross-linking Behaviour

Sorghum storage proteins (kafirins) were extracted with 60% 2-methyl-propan-2-ol (t-butanol) and analysed in the unreduced form by sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS–PAGE). The pattern obtained showed the presence of various protein oligomers of differentM_rs, in addition to γ-, α₁-, α₂- and β-kafirin. These oligomers comprised γ-, α₁- and α₂-kafirin linked together by disulphide (SS) bonds, as demonstrated by SDS–PAGE analysis after reduction. In contrast, β-kafirin was present only in its monomeric form and not as a component of the oligomers. Size-exclusion high-performance liquid chromatography (SE-HPLC) analysis confirmed these results, and indicated that about 70% of the total protein in the extract was in the form of SS-linked oligomers. Sonication of the residue allowed the extraction of additional protein, which, when analysed by SDS–PAGE (in both the unreduced and reduced forms) and SE-HPLC, was shown to comprise mainly polymers of high molecular size, representing 90% of the total protein extracted by sonication. In this case, some monomers and dimers of γ- and α₁-kafirin were also detected, whereas monomeric β-kafirin was absent. The polymers comprised γ-, α₁-, and β-kafirin, but α₂-kafirin was not detected. From these results, we suggest that the degree of polymerisation of kafirin proteins is determined by the competitive linkage through SS bonds to γ- and α₁-kafirin of α₂- (a «chain terminator») and β-kafirin (a «chain extender»).     

Characterisation of genes isolated from a potato swellingstolon cDNA library

Summary In screening to isolate a full-length copy of a previously isolated cDNA clone, a further three cDNAs were also isolated from a library prepared from sub-apical swelling-stolon tissue of potato (Solanum tuberosum L.). Sequence analysis showed these clones to be similar to extensin-like protein genes, acyl carrier protein thioesterase genes and high mobility group protein genes, respectively. A further cDNA, isolated by subtractive hybridisation, was similar to a tomato cDNA previously isolated on the basis of its down-regulation following nematode infection. While all the newly isolated genes were expressed in swelling stolons, for most, maximal expression was seen to be in stem tissue. Possible roles for these genes in the development of potato plants are discussed, as is the significance of gene expression in stems and stolons to the process of tuberisation.     

Resistant Starch in Wheat-based Products: Isolation and Characterisation

Resistant starch was isolated from wheat-based foods such as chapati, phulka and poori and structurally characterised. Perchloric acid digestion and size exclusion chromatography gave pure resistant starch, which was shown to be a linear 1,4-linked α-D-glucan essentially derived from retrograded amylose fraction. The latter is dependent on the severity of the processing treatments as well as the levels of gluten and damaged starch in the wheat flour.     

Characterisation and management of Phalaris paradoxa resistant to ACCase-inhibitors

Phalaris paradoxa is a competitive grass commonly found in durum wheat crops of central and southern Italy. Among the 85 populations screened from 1998 to 2008 for resistance to ACCase-inhibitors and graminicide sulfonylureas, 17 resulted as being resistant to at least one ACCase inhibitor while none of the populations showed resistance to sulfonylureas. ACCase resistance in hood canary-grass seems to be spreading rather slowly in Italy. Out of the 17 populations, seven were characterised through outdoor dose-response pot experiments to investigate resistance levels and cross-resistance patterns to ACCase-inhibitors and multiple resistance to other mode of action. Molecular bases of resistance to the recently introduced DEN herbicide pinoxaden were also investigated. Six populations were confirmed to be ACCase-resistant with various cross-resistance patterns. Two populations were resistant to all tested ACCase herbicides, with pinoxaden resistance indexes (RI) based on survival ranging from 22 to 50. The two populations have been molecularly characterised for resistance to pinoxaden. A single point-mutation in the ACCase gene was identified in each population, causing the amino-acid substitutions of Ile₁₇₈₁Val and Asp₂₀₇₈Gly in 0478L and 0025, respectively. The results suggest that resistance of P. paradoxa to pinoxaden is due to an altered target site and different mutations cause different resistance levels. The biological characteristics of the species, mainly self-pollinated, and the absence of multiple resistance allow herbicides with different modes of action to be used for controlling ACCase-resistant populations. Chemical tools should be carefully used within integrated weed management strategies.     

Purification and Characterisation of Ascorbate Oxidase from Flour and Immature Wheat Kernels

White flour from wheat was shown to contain basic-ascorbate oxidase (AOX) enzymes (pI 7·6–9·6) and acidic-AOX enzymes (pI 5·1–6·6) in a ratio of 0·4:1, based on chromatography data. Immature wheat kernels (two weeks post-anthesis) contained about 12 times more AOX activity (units/g dry weight) than flour from mature grain, and the ratio of basic- to acidic-AOX was 5:1. Acidic-AOX was purified 90-fold from flour by hydrophobic interaction, gel filtration and anion exchange chromatography. Basic-AOX was purified 20 000-fold from immature wheat by hydrophobic interaction, anion exchange, cation exchange and gel filtration chromatography in a yield of 5%. The acid-AOX had a M of 140 k, was optimally active at pH 6·3 and 40 °C, and was stable in the pH range 5–9 and at 30 °C for 0·5 h at pH 6·2. The Km values were 0·26 m for L-ascorbic acid and 0·93 m for D-iso ascorbic acid. The basic-AOX had a M of 139 k and subunit M of 72 k. The enzyme was optimally active at pH 6·2 and 50 °C, and was stable in the pH range 5–9 and at 40 °C for 0·5 h at pH 6·2. The Km values were 0·30 m for L-ascorbic acid and 0·53 m for D-iso ascorbic acid. The absorption spectrum of basic-AOX had absorption maxima at 280 nm and 607 nm of similar magnitude to those measured in AOX fromCucurbita species (squash). This indicates that wheat AOX contains protein-bound copper similar to other plant AOX.