Factors Affecting the Radiosensitivity of Hexaploid Wheat to γ-Irradiation: Radiosensitivity of Hexaploid Wheat (Triticum aestivum L.)

Understanding the radiosensitivity of plants, an important factor in crop mutation breeding programs, requires a thorough investigation of the factors that contribute to this trait. In this study, we used the highly radiosensitive wheat (Triticum aestivum L.) variety HY1 and J411, a γ-irradiation-insensitive control, which were screened from a natural population, to examine the factors affecting radiosensitivity, including free radical content and total antioxidant capacity, as well as the expression of TaKu70 and TaKu80 (DNA repair-related genes) as measured by real-time PCR. We also investigated the alternative splicing of this gene in the wild-type wheat ecotype by sequence analysis. Free radical contents and total antioxidant capacity significantly increased upon exposure of HY1 wheat to γ-irradiation in a dose-dependent manner. By contrast, in J411, the free radical contents exhibited a similar trend, but the total antioxidant capacity exhibited a downward trend upon increasing γ-irradiation. Additionally, we detected dose-dependent increases in TaKu70 and TaKu80 expression levels in γ-irradiated HY1, while in J411, TaKu70 expression levels increased, followed by a decline. We also detected alternative splicing of TaKu70 mRNA, namely, intron retention, in HY1 but not in J411. Our findings indicate that γ-irradiation induces oxidative stress and DNA damage in hexaploid wheat, resulting in growth retardation of seedlings, and they suggest that TaKu70 may play a causal role in radiosensitivity in HY1. Further studies are required to exploit these factors to improve radiosensitivity in other wheat varieties.     

γ-Aminobutyric Acid (GABA) Imparts Partial Protection from Heat Stress Injury to Rice Seedlings by Improving Leaf Turgor and Upregulating Osmoprotectants and Antioxidants

Four-day-old rice (Oryza sativa L.) seedlings were subjected to varying temperatures of 30/20, 35/25, and 42/37 °C [light/dark (15/9 h); light intensity: 350 μmol m^?2 s^?1, RH 65–70 %] in glass Petri dishes for 10 days in the absence (control) or the presence of γ-aminobutyric acid (GABA) 1 mM under the controlled conditions of a growth chamber. With rise in temperature, the length of both shoots and roots was inhibited severely and there was a marked decrease in survival, especially at 42/37 °C. Endogenous GABA content increased more than twofold in moderately stressed (MS) 35/25 °C plants, whereas it decreased sevenfold in severely stressed (SS) 42/37 °C plants compared to MS plants, and this decrease was associated with marked reduction in growth and survival. Exogenous application of GABA to the heat-stressed plants significantly improved growth as well as survival. It was linked to reduction in damage to membranes, improvement in cellular reducing ability, chlorophyll content, and photochemical efficiency in shoots. Relative leaf water content and stomatal conductance were also improved with the application of GABA and their improvement was related to increased accumulation of the osmolytes proline and trehalose. In the presence of GABA, the shoots suffered less oxidative damage in terms of malondialdehyde and hydrogen peroxide contents. The activities of enzymatic antioxidants such as superoxide dismutase, catalase, ascorbate peroxidase, and glutathione reductase were severely inhibited in plants growing at 42/37 °C compared to those growing at 35/25 °C. The nonenzymatic antioxidants like ascorbate and glutathione followed a similar pattern. GABA-treated SS plants showed enhanced levels of enzymatic and nonenzymatic antioxidants compared to untreated controls. Thus, GABA appears to impart partial protection from heat stress to rice plants by elevating leaf turgor due to increased accumulation of osmolytes and reduction of oxidative damage by stimulation of antioxidants. These findings provided evidence about the involvement of GABA in governing heat sensitivity in rice.     

Did the house mouse (Mus musculus L.) shape the evolutionary trajectory of wheat (Triticum aestivum L.)?

Wheat (Triticum aestivum L.) is one of the most successful domesticated plant species in the world. The majority of wheat carries mutations in the Puroindoline genes that result in a hard kernel phenotype. An evolutionary explanation, or selective advantage, for the spread and persistence of these hard kernel mutations has yet to be established. Here, we demonstrate that the house mouse (Mus musculus L.) exerts a pronounced feeding preference for soft over hard kernels. When allele frequencies ranged from 0.5 to 0.009, mouse predation increased the hard allele frequency as much as 10‐fold. Studies involving a single hard kernel mixed with ~1000 soft kernels failed to recover the mutant kernel. Nevertheless, the study clearly demonstrates that the house mouse could have played a role in the evolution of wheat, and therefore the cultural trajectory of humankind.     

The Uptake of NO3?, NO2?, and NH4+ by Intact Wheat (Triticum aestivum) Seedlings : I. Induction and Kinetics of Transport Systems

The inducibility and kinetics of the NO₃⁻, NO₂⁻, and NH₄⁺ transporters in roots of wheat seedlings (Triticum aestivum cv Yercora Rojo) were characterized using precise methods approaching constant analysis of the substrate solutions. A microcomputer-controlled automated high performance liquid chromatography system was used to determine the depletion of each N species (initially at 1 millimolar) from complete nutrient solutions. Uptake rate analyses were performed using computerized curve-fitting techniques. More precise estimates were obtained for the time required for and the extent of the induction of each transporter. Up to 10 and 6 hours, respectively, were required to achieve apparent full induction of the NO₃⁻ and NO₂⁻ transporters. Evidence for substrate inducibility of the NH₄⁺ transporters requiring 5 hours is presented. The transport of NO₃⁻ was mediated by a dual system (or dual phasic), whereas only single systems were found for transport of NO₂⁻ and NH₄⁺. The K_m values for NO₃⁻, NO₂⁻, and NH₄⁺ were, respectively, 0.027, 0.054, and 0.05 millimolar. The K_m for mechanism II of NO₃⁻ transport could not be defined in this study as it exhibited only apparent first order kinetics up to 1 millimolar.     

Purification and characterization of a hydroxamic acid glucoside β-glucosidase from wheat (Triticum aestivum L.) seedlings

A beta-glucosidase (EC 3.2.1.21) with a high affinity for cyclic hydroxamic acid beta-D-glucosides was purified from 48-h-old wheat (Triticum aestivum L.) seedlings. The activity occurred transiently at a high level during the non-autotrophic stage of growth, and the nature of the transient occurrence was correlated with that of 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one glucoside (DIMBOA-Glc). The glucosidase had maximum activity at an acidic pH (pH 5.5) and the purified enzyme showed a high affinity for DIMBOA-Glc, Vmax and Km being 4100 nkat/mg protein and 0.27 mM, respectively. It also hydrolyzed p-nitrophenol beta-glycosides, as well as flavone and isoflavone glucosides, but to a lesser extent. The results indicated that the primary natural substrate for the glucosidase is DIMBOA-Glc and that the enzyme is involved in defense against pathogens and herbivores in non-autotrophic wheat. The glucosidase was found to be present as oligomeric forms with a molecular mass of 260-300 kDa comprising 60- and 58-kDa monomers. The N-terminal 12-amino-acid sequences of the two monomers were identical (Gly-Thr-Pro-(Ser?)-Lys-Pro-Ala-Glu-Pro-Ile-Gly-Pro), and showed no similarity to those of other plant glucosidases. Polyacrylamide gel electrophoresis under nondenaturing condition indicated the existence of at least eight isozymes. Three cultivars of Triticum aestivum had the same zone of glucosidase activity on zymograms, but the activity zones of the Triticum species, T. aestivum L., T. spelta L. and T. turgidum L., had different mobilities.     

Differential mRNA stability to endogenous ribonucleases of the coding region and 3′ untranslated regions of wheat (Triticum aestivum L.) manganese superoxide dismutase genes

The sequences of the 3′ untranslated region (UTR) of the manganese superoxide dismutase (MnSOD) genes in wheat (Triticum aestivum) were found to be quite variable with different predicted thermostabilities. The degradation rates of the 3′ UTR variants and the coding region were measured following exposure to endogenous nucleases. The degradation rates of the 3′ UTR variants for 15 min were not significantly different, meaning the degradation rates of the 3′ UTR variants were not directly related to the thermostabilities. However, the degradation rate of the coding region was significantly faster than those of the 3’ UTR variants. Further investigation revealed the coding region seemed to have specific sites for degradation, indicating a possibility of increasing MnSOD expression by the degradation site alteration.     

Experimental and modelling studies of drought‐adaptive root architectural traits in wheat (Triticum aestivum L.)

Abstract

This paper presents an interdisciplinary approach to crop improvement that links physiology with plant breeding and simulation modelling to enhance the selection of high‐yielding, drought‐tolerant varieties. In a series of field experiments in Queensland, Australia, we found that the yield of CIMMYT wheat line SeriM82 ranged from 6% to 28% greater than the current cultivar Hartog. Physiological studies on the adaptive traits revealed that SeriM82 had a narrower root architecture and extracted more soil moisture, particularly deep in the profile. Results of a simulation analysis of these adaptive root traits with the cropping system model APSIM for a range of rain‐fed environments in southern Queensland indicated a mean relative yield benefit of 14.5% in water‐deficit seasons. Furthermore, each additional millimetre of water extracted during grain filling generated an extra 55 kg ha^?1 of grain yield. Further root studies of a large number of wheat genotypes revealed that wheat root architecture is closely linked to the angle of seminal roots at the seedling stage – a trait which is suitable for large‐scale and cost‐effective screening programmes. Overall, our results suggest that an interdisciplinary approach to crop improvement is likely to enhance the rate of yield improvement in rain‐fed crops.     

Monosomic analysis of heading date and spikelet number in the common wheat (Triticum aestivum L.) multispikelet line ‘Noa’

Summary Genetic analysis of heading date and spikelet number was carried out in the common wheat (Triticum aestivum L.) multispikelet line Noa, by using the monosomic series of the regular line Mara. Noa's high number of spikelets was found to be controlled by a recessive major gene on chromosome 2D; a slight reduction in spikelet number was induced by another recessive gene on Noa's 7A chromosome. Noa's late heading date was found to be controlled by two recessive genes, located on chromosome 2D (a major effect) and 6B (a minor effect). The nature of the genes located on Noa's 2D chromosome and the relationship between spikelet number and heading date are discussed.     

Effects of Conservation Tillage on Topsoil Microbial Metabolic Characteristics and Organic Carbon within Aggregates under a Rice (Oryza sativa L.) –Wheat (Triticum aestivum L.) Cropping System in Central China

Investigating microbial metabolic characteristics and soil organic carbon (SOC) within aggregates and their relationships under conservation tillage may be useful in revealing the mechanism of SOC sequestration in conservation tillage systems. However, limited studies have been conducted to investigate the relationship between SOC and microbial metabolic characteristics within aggregate fractions under conservation tillage. We hypothesized that close relationships can exist between SOC and microbial metabolic characteristics within aggregates under conservation tillage. In this study, a field experiment was conducted from June 2011 to June 2013 following a split-plot design of a randomized complete block with tillage practices [conventional intensive tillage (CT) and no tillage (NT)] as main plots and straw returning methods [preceding crop residue returning (S, 2100−2500 kg C ha⁻¹) and removal (NS, 0 kg C ha^-1)] as subplots with three replications. The objective of this study was to reveal the effects of tillage practices and residue-returning methods on topsoil microbial metabolic characteristics and organic carbon (SOC) fractions within aggregates and their relationships under a rice–wheat cropping system in central China. Microbial metabolic characteristics investigated using the Biolog system was examined within two aggregate fractions (>0.25 and <0.25 mm). NT treatments significantly increased SOC concentration of bulk soil, >0.25 aggregate, and <0.25 mm aggregate in the 0−5 cm soil layer by 5.8%, 6.8% and 7.9% relative to CT treatments, respectively. S treatments had higher SOC concentration of bulk soil (12.9%), >0.25 mm aggregate (11.3%), and <0.25 mm aggregate (14.1%) than NS treatments. Compared with CT treatments, NT treatments increased MBC by 11.2%, 11.5%, and 20%, and dissolved organic carbon (DOC) concentration by 15.5%, 29.5%, and 14.1% of bulk soil, >0.25 mm aggregate, and <0.25 mm aggregate in the 0−5 cm soil layer, respectively. Compared with NS treatments, S treatments significantly increased MBC by 29.8%, 30.2%, and 24.1%, and DOC concentration by 23.2%, 25.0%, and 37.5% of bulk soil, >0.25 mm aggregate, and <0.25 mm aggregate in the 0−5 cm soil layer, respectively. Conservation tillage (NT and S) increased microbial metabolic activities and Shannon index in >0.25 and <0.25 mm aggregates in the 0−5 cm soil layer. Redundancy analysis showed that the SOC and its fractions (DOC and MBC) were closely correlated with microbial metabolic activities. Structural equation modelling showed that the increase in microbial metabolic activities directly improved SOC by promoting DOC in >0.25 mm aggregate in the upper (0−5 cm) soil layer under conservation tillage systems, as well as directly and indirectly by promoting DOC and MBC in <0.25 mm aggregate. Our results suggested that conservation tillage increased SOC in aggregates in the topsoil by improving microbial metabolic activities.     

Investigation of morphogenesis of inflorescence and determination of the nature of inheritance of “supernumerary spikelets” trait of bread wheat (Triticum aestivum L.) mutant line

Using C-banding and FISH methods, the karyotype of MC1611 induced mutant of bread wheat, which develop additional spikelets at a rachis node (trait “supernumerary spikelets”) was characterized. It was determined that the mutant phenotype is not associated with aneuploidy and major chromosomal rearrangements. The results of genetic analysis showed that supernumerary spikelets of the line are caused by a mutation of the single Bh-D.1 gene, influenced by the genetic background. The mutation causes abnormalities of inflorescence morphogenesis associated with the development of ectopic spikelet meristems in place of floral meristems in the basal part of the spikelets, causing the appearance of additional spikes at a rachis node. The mutant phenotype suggests that the Bh-D gene determines the fate of the lateral meristems in ear, which develops as floral meristem and gives rise to floral organs in wild-type inflorescences. In the bh-D.1 mutant, the floral meristem identity is impaired. The characterized mutant can be used in further studies on molecular genetic basis of development of wheat inflorescence.     

Plant water uptake by hard red winter wheat (Triticum aestivum L.) genotypes at 2°C and low light intensity

Background

The moss Physcomitrella patens is an attractive model system for plant biology and functional genome analysis. It shares many biological features with higher plants but has the unique advantage of an efficient homologous recombination system for its nuclear DNA. This allows precise genetic manipulations and targeted knockouts to study gene function, an approach that due to the very low frequency of targeted recombination events is not routinely possible in any higher plant.

Results

As an important prerequisite for a large-scale gene/function correlation study in this plant, we are establishing a collection of Physcomitrella patens transformants with insertion mutations in most expressed genes. A low-redundancy moss cDNA library was mutagenised in E. coli using a derivative of the transposon Tn1000. The resulting gene-disruption library was then used to transform Physcomitrella. Homologous recombination of the mutagenised cDNA with genomic coding sequences is expected to target insertion events preferentially to expressed genes. An immediate phenotypic analysis of transformants is made possible by the predominance of the haploid gametophytic state in the life cycle of the moss. Among the first 16,203 transformants analysed so far, we observed 2636 plants ( = 16.2%) that differed from the wild-type in a variety of developmental, morphological and physiological characteristics.

Conclusions

The high proportion of phenotypic deviations and the wide range of abnormalities observed among the transformants suggests that mutagenesis by gene-disruption library transformation is a useful strategy to establish a highly diverse population of Physcomitrella patens mutants for functional genome analysis.     

Molecular characterization of the celiac disease epitope domains in α-gliadin genes in Aegilops tauschii and hexaploid wheats (Triticum aestivum L.)

Nineteen novel full-ORF α-gliadin genes and 32 pseudogenes containing at least one stop codon were cloned and sequenced from three Aegilops tauschii accessions (T15, T43 and T26) and two bread wheat cultivars (Gaocheng 8901 and Zhongyou 9507). Analysis of three typical α-gliadin genes (Gli-At4, Gli-G1 and Gli-Z4) revealed some InDels and a considerable number of SNPs among them. Most of the pseudogenes were resulted from C to T change, leading to the generation of TAG or TAA in-frame stop codon. The putative proteins of both Gli-At3 and Gli-Z7 genes contained an extra cysteine residue in the unique domain II. Analysis of toxic epitodes among 19 deduced α-gliadins demonstrated that 14 of these contained 1–5 T cell stimulatory toxic epitopes while the other 5 did not contain any toxic epitopes. The glutamine residues in two specific ployglutamine domains ranged from 7 to 27, indicating a high variation in length. According to the numbers of 4 T cell stimulatory toxic epitopes and glutamine residues in the two ployglutamine domains among the 19 α-gliadin genes, 2 were assigned to chromosome 6A, 5 to chromosome 6B and 12 to chromosome 6D. These results were consistent with those from wheat cv. Chinese Spring nulli-tetrasomic and phylogenetic analysis. Secondary structure prediction showed that all α-gliadins had high content of β-strands and most of the α-helixes and β-strands were present in two unique domains. Phylogenetic analysis demonstrated that α-gliadin genes had a high homology with γ-gliadin, B-hordein, and LMW-GS genes and they diverged at approximate 39 MYA. Finally, the five α-gliadin genes were successfully expressed in E. coli, and their expression amount reached to the maximum after 4 h induced by IPTG, indicating that the α-gliadin genes can express in a high level under the control of T₇ promoter.     

Differential Sensitivity of Macrocarpa and Microcarpa Types of Chickpea （Cicer arietinum L.） to Water Stress： Association of Contrasting Stress Response with Oxidative Injury

Chickpea (Cicer arietinum L.) is particularly sensitive to water stress at its reproductive phase and, under conditions of water stress, will abort flowers and pods, thus reducing yield potential. There are two types of chickpea: (i) Macrocarpa (“Kabuli”), which has large, rams head‐shaped, light brown seeds; and (ii) Microcarpa (“Desi”), which has small, angular and dark‐brown seeds. Relatively speaking, “Kabuli” has been reported to be more sensitive to water stress than “Desi”. The underlying mechanisms associated with contrasting sensitivity to water stress at the metabolic level are not well understood. We hypothesized that one of the reasons for contrasting water stress sensitivity in the two types of chickpea may be a variation in oxidative injury. In the present study, plants of both types were water stressed at the reproductive stage for 14 d. As a result of the stress, the “Kabuli” type exhibited an 80% reduction in seed yield over control compared with a 64% reduction observed for the “Desi” type. The decrease in leaf water potential (Ψ_w) was faster in the “Kabuli” compared with the “Desi” type. At the end of the water stress period, Ψ_w was reduced to ?2.9 and ?3.1 MPa in the “Desi” and “Kabuli” types, respectively, without any significant difference between them. On the last day of stress, “Kabuli” experienced 20% more membrane injury than “Desi”. The chlorophyll content and photosynthetic rate were significantly greater in “Desi” compared with “Kabuli”. The malondialdehyde and H₂O₂ content were markedly higher at the end of the water stress in “Kabuli” compared with “Desi”, indicating greater oxidative stress in the former. Levels of anti‐oxidants, such as ascorbic acid and glutathione, were significantly higher in “Desi” than “Kabuli”. Superoxide dismutase and catalase activity did not differ significantly between the two types of chickpea, whereas on the 10th day, the activities of ascorbate peroxidase, dehydroascorbate reductase, and glutathione reductase were higher in “Desi”. These findings indicate that the greater stress tolerance in the “Desi” type may be ascribed to its superior ability to maintain better water status, which results in less oxidative damage. In addition, laboratory studies conducted by subjecting both types of chickpea to similar levels of polyethylene glycol‐induced water stress and to 10 μ.mol/L abscisic acid indicated a greater capacity of the “Desi” type to deal with oxidative stress than the “Kabuli” type. (Managing editor: Ping He)     

Production,morphology, and cytogenetics of Triticum aestivum (L.) Thell × Elymus scabrus (R. Br.) Love intergeneric hybrids obtained by in ovulo embryo culture

Summary Intergeneric hybrids were produced between common wheat, Triticum aestivum (2n=6x=42, AABBDD), and an apomictic Triticeae species, Elymus scabrus (syn. Agropyron scabrum) (2n=6x=42, HHSSSS), the first successful report of this cross. Nine tiny, underdeveloped, and structureless embryos were obtained in vitro only by in ovulo embryo culture at 4 days after pollination, which gave rise to five mature hybrid plants. All the hybrid plants were vigorous and possessed a phenotype intermediate to the two parents. There were 2n=6x=42 (ABDHSS) somatic chromosomes in the hybrids. There was little or no homology between the parental genomes, as shown by an overall meiotic chromosome association of 32.83 I + 4.08 rod II + 0.21 ring II + 0.18 III + 0.02 IV. The hybrids were completely sterile and so far backcrosses to wheat parent have not been successful. Alternate approaches to induce gene transfer(s) from E. scabrus to wheat are being attempted.Agriculture Canada Contribution No. 398.     

Identification of ‘Amigo’ and ‘Kavkaz’ translocations in Ohio soft red winter wheats (Triticum aestivum L.)

One cultivar (GR876) and two advanced Ohio soft red winter wheat lines (OH413 and OH414), with Kavkaz in their pedigrees, were examined for the presence of the Kavkaz, 1RS/1BL rye/wheat chromosome translocation. Another advanced line (OH416), with Amigo in its pedigree, was examined for the presence of the Amigo, 1RS/1AL translocation. Only two satellited chromosomes were observed in most mitotic root-tip cells from GR876, OH413, and OH414, compared to four in most cells from OH416. Heteromorphic bivalents were observed in most PMCs from hybrids produced by crossing GR876, OH413, and OH414 as females to Chinese Spring. No heteromorphic bivalents were observed in PMCs from OH416 x Chinese Spring hybrids. When GR876 and the Ohio lines were hybridized with Chinese Spring dimonotelosomic-1B, telosomic trivalents, consisting of the short- and longarm telosomes paired with chromosome 1B, were only observed in PMCs from 43-chromosome hybrids involving OH416. The long-arm telosome paired with the translocation chromosome, while the short-arm telosome remained unpaired in all other 43-chromosome hybrids. Separation of gliadin proteins from GR876 and the Ohio lines by PAGE revealed that secalin bands for GR876, OH413, and OH414, migrated similarly to the secalins for Kavkaz. Bands for OH416, identified as possible secalins, migrated similarly to those for Amigo. Cultivar GR876 and advanced Ohio soft red winter wheat lines OH413 and OH414 carry the Kavkaz translocation, while OH416 carries the Amigo translocation.Communicated by K. Tsunewaki     

Two-Dimensional Electrophoretic Analysis of Soluble Leaf Proteins of a Salt-sensitive （Triticum aestivum） and a Salt-tolerant （T. durum） Cultivar in Response to NaCI Stress

In this research, 3-day-old etiolated wheat seedlings of Triticum aestivum L. cv. Ceyhan-99 （salt-sensitive） and T. durum Desf. cv. Firat-93 （salt-tolerant） were grown in control and salt （150 mmol/L NaCl） treatments at a 15/25℃ temperature regime in the light for 12 days. Soluble proteins extracted from the first leaf tissues of two cultivars were analyzed by twodimensional （2-D） electrophoresis in order to detect NaCl-induced changes. The soluble leaf protein profiles of cultivars were observed to be similar. However, quantitative differences in 74 proteins were detected in the salt treatment group, compared to the control. Among the 74 protein spots, 14 were common for two cultivars. As a result of NaCl treatment, two low-molecular-weight （LMW） proteins （28.9 and 30.0 kDa） and one intermediate-molecular-weight （IMW） protein （44.3 kDa） in cv. Ceyhan-99 and six LMW proteins （18.6, 19.4, 25.7, 25.9, 26 and 27.6 kDa） in cv. Firat-93 were newly synthesized. The newly synthesized proteins were specific to each cultivar. In the Firat-93 cultivar, four proteins with LMW （24.8-27.9 kDa） were completely lost in NaCl treatment. Moreover, these four protein spots were not observed in both protein profiles of cv. Ceyhan-99. Most of these proteins were in acidic character （pl 〈6.0-6.9） and low molecular weight （〈31.6 kDa）. It is suggested that the newly synthesized or completely lost LMW proteins may be important for cultivars differing in sensitivity towards NaCl.     

Genes encoding α-amylase inhibitors are located in the short arms of chromosomes 3B, 3D and 6D of wheat (Triticum aestivum L.)

Summary Three -amylase inhibitors, designated Inh. I, II and III have been purified from the 70% ethanol extract of hexaploid wheat (Triticum aestivum L.) and characterized by amino acid analysis, N-terminal amino acid sequencing and enzyme inhibition tests. Inhibitors I and III have identical N-terminal sequences and inhibitory properties to those of the previously described 0.19/0.53 group of dimeric inhibitors. Inhibitor II has an N-terminal sequence which is identical to that of the previously described 0.28 monomeric inhibitor, but differs from it in that in addition to being active against -amylase from Tenebrio molitor, it is also active against mammalian salivary and pancreatic -amylases. Compensating nulli-tetrasomic and ditelosomic lines of wheat cv. Chinese Spring have been analysed by two-dimensional electrophoresis, under conditions in which there is no overlap of the inhibitors with other proteins, and the chromosomal locations of the genes encoding these inhibitors have been established: genes for Inh. I and Inh. III are in the short arms of chromosomes 3B and 3D, respectively, and that for Inh. II in the short arm of chromosome 6D.     

Structural analysis of wheat wax (Triticum aestivum, c.v. ‘Naturastar’ L.): from the molecular level to three dimensional crystals

In order to elucidate the self assembly process of plant epicuticular waxes, and the molecular arrangement within the crystals, re-crystallisation of wax platelets was studied on biological and non-biological surfaces. Wax platelets were extracted from the leaf blades of wheat (Triticum aestivum L., c.v. ‘Naturastar’, Poaceae). Waxes were analysed by gas chromatography (GC) and mass spectrometry (MS). Octacosan-1-ol was found to be the most abundant chemical component of the wax mixture (66 m%) and also the determining compound for the shape of the wax platelets. The electron diffraction pattern showed that both the wax mixture and pure octacosan-1-ol are crystalline. The re-crystallisation of the natural wax mixture and the pure octacosan-1-ol were studied by scanning tunnelling microscopy (STM), atomic force microscopy (AFM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Crystallisation of wheat waxes and pure octacosano-1-ol on the non polar highly ordered pyrolytic graphite (HOPG) led to the formation of platelet structures similar to those found on the plant surface. In contrast, irregular wax morphologies and flat lying plates were formed on glass, silicon, salt crystals (NaCl) and mica surfaces. Movement of wheat wax through isolated Convallaria majalis cuticles led to typical wax platelets of wheat, arranged in the complex patterns typical for C. majalis. STM of pure octacosan-1-ol monolayers on HOPG showed that the arrangement of the molecules strictly followed the hexagonal structure of the substrate crystal. Re-crystallisation of wheat waxes on non-polar crystalline HOPG substrate showed that technical surfaces could be used to generate microstructured, biomimetic surfaces. AFM and SEM studies proved that a template effect of the substrate determined the orientation of the re-grown crystals. These effects of the structure and polarity of the substrate on the morphology of the epicuticular waxes are relevant for understanding interactions between biological as well as technical surfaces and waxes.