Identification of several new classes of low-molecular-weight wheat gliadin-related proteins and genes

During the initial phases of a wheat endosperm Expressed-Sequence-Tag (EST) project, several clones were determined to be related to wheat gliadin sequences, but not similar enough to be classified into any of the traditional gliadin families [α-, γ-, and ω-gliadins, low-molecular-weight (LMW) glutenins]. Complete sequences of these cDNA clones revealed four new classes of gliadin-related endosperm proteins, but lacking a prominent repeat domain which until now has been characteristic of the gliadins. Two of these classes are related to different minimally described groups of Triticeae endosperm proteins. One class of proteins, which has N-terminal amino-acid sequences matching members of a reported 25-kDa globulin family from wheat, is shown by amino-acid sequencing to match to a family of 25-kDa endosperm proteins, is encoded by a multigene family, and is most similar to the LMW-glutenins. A second new class shows N-terminal homologies to LMW secalins from rye, and has an amino-acid composition similar to wheat and barley LMW proteins with extraction properties similar to prolamins. The third class is most similar to α-gliadins, and the fourth class has no close association to previously described wheat endosperm proteins. Received: 20 October 2000 / Accepted: 20 November 2000     

Molecular and agro-morphological characterization of ancient wheat landraces of turkey

Background

Turkey is one of the important gene centers for many crop species. In this research, some ancient wheats such as tetraploid and diploid hulled wheats together with hexaploid tir wheats (Triticum aestivum ssp. leucospermum Korn.) landraces mainly adapted to harsh winter conditions of Eastern Anatolian region of Turkey were characterized at agro-morphological and molecular level. Totally 50 hulled wheat population from Kastamonu, Konya and Kayseri provinces and 15 tir wheats from Kars provinces of Turkey were in-situ collected for characterization in 2013. Some quantitative and qualitative traits of each population were determined.

Results

Twenty three hulled wheat population collected from Kastamonu province were distinguished into nine emmer and 14 einkorn wheats at morphological level. Additionally, Konya, Kayseri and Kars population were characterized as einkorn, emmer and tir wheat, respectively. Among the evaluated traits, protein ratios of hulled wheats were strikingly higher than registered cultivars. All the populations were also examined by molecular level by using fluorescently labelled 11 polymorphic SSRs primers. The primers exhibited 104 bands, ranging from 6 to 16 with a mean value 9.45 per loci. The clustering analysis separated the germplasm into two clusters which were also divided into two subclusters based on genetic similarity coefficient. Sixty-five population and five checks were analyzed to estimate mean number of alleles (N), expected and observed heterozygoties (He and Ho), polymorphism information content (PIC), Wright fix index (F), genetic deviation from Hardy-Weinberg expectation (Fit-Fis) and genetic variation (Fst) were determined as 9.45, 0.71, 0.07, 0.67, 0.90, 0.39, 0.87 and 0.39, respectively. A clear genetic deviation from Hardy – Weinberg expectation was observed among population in particular. These results showed considerable genetic variation among landraces rather than within population.

Conclusions

These molecular information has revealed genetically diverse einkorn, emmer wheat and tir wheat population could be used as parents for further breeding studies in both Turkey and abroad. Furthermore, the molecular analysis has also generally discriminated the germplasm into ploidy level.

     

A paradigm shift towards low-nitrifying production systems: the role of biological nitrification inhibition (BNI)

Background

Agriculture is the single largest geo-engineering initiative that humans have initiated on planet Earth, largely through the introduction of unprecedented amounts of reactive nitrogen (N) into ecosystems. A major portion of this reactive N applied as fertilizer leaks into the environment in massive amounts, with cascading negative effects on ecosystem health and function. Natural ecosystems utilize many of the multiple pathways in the N cycle to regulate N flow. In contrast, the massive amounts of N currently applied to agricultural systems cycle primarily through the nitrification pathway, a single inefficient route that channels much of this reactive N into the environment. This is largely due to the rapid nitrifying soil environment of present-day agricultural systems.

Scope

In this Viewpoint paper, the importance of regulating nitrification as a strategy to minimize N leakage and to improve N-use efficiency (NUE) in agricultural systems is highlighted. The ability to suppress soil nitrification by the release of nitrification inhibitors from plant roots is termed ‘biological nitrification inhibition’ (BNI), an active plant-mediated natural function that can limit the amount of N cycling via the nitrification pathway. The development of a bioassay using luminescent Nitrosomonas to quantify nitrification inhibitory activity from roots has facilitated the characterization of BNI function. Release of BNIs from roots is a tightly regulated physiological process, with extensive genetic variability found in selected crops and pasture grasses. Here, the current status of understanding of the BNI function is reviewed using Brachiaria forage grasses, wheat and sorghum to illustrate how BNI function can be utilized for achieving low-nitrifying agricultural systems. A fundamental shift towards ammonium (NH₄⁺)-dominated agricultural systems could be achieved by using crops and pastures with high BNI capacities. When viewed from an agricultural and environmental perspective, the BNI function in plants could potentially have a large influence on biogeochemical cycling and closure of the N loop in crop–livestock systems.     

Effect of water stress on germination of some Hungarian wheat landraces varieties

In order to examine germination characters, seedling parameters, water relative content, tolerance index and enzyme activities of seven Hungarian wheat landraces varieties (Tiszadadai, Riscsei, Komloi, Leweucei, Mateteleki, Mikebudai and Nyiradi) under five concentrations of water stress (0, 6, 12, 18, and 24%) of polyethylene glycol (PEG-6000). A laboratory experiment has been conducted through Factorial Experiment in Randomized Complete Block Design (RCBD) with four repetitions at Research Institute of Nyiregyhaza, Hungary. From the obtained results, Leweucei variety was surpassed other studied verities under study and recorded the highest values of all studied characters followed by Mateteleki, Komloi, Nyiradi, Riscsei, Tiszadadai and Mikebudai. Increasing water stress (PEG-6000) from 0 to 6, 12, 18 and 24% significantly reduced germination characters, seedlings parameters, water relative content (WRC), tolerance index and α and β-amylases activities. Generally, under water stress condition, Leweucei and Mateteleki varieties were recorded the highest values of water relative content (WRC), tolerance index (TI) and α and β-amylases activities as well as able to prompt better drought tolerance and could be suggested as a good resource for breeding programs and cultivation under drought stress conditions compared with other wheat landraces varieties.     

Antioxidant inhibition of oxygen radicals for measurement of total antioxidant capacity in biological samples

Few methods for assessing total antioxidant capacity (TAC) include both the percentage of inhibition and the length of inhibition in the measurement. Available methods require above ambient constant temperature incubation, reaction preheating, and/or separate assays for testing hydrophilic and hydrophobic samples. We describe a high-throughput method, antioxidant inhibition of oxygen radicals (AIOR), that overcomes these difficulties. AIOR uses peroxyl radicals to trigger a decrease in fluorescence of the indicator molecule, uroporphyrin I, which is delayed by the presence of antioxidants. The area under the curve is measured by a fluorescence spectrophotometer in a 96-well microplate format, and TAC results are expressed as millimole/liter Trolox equivalents. AIOR is performed at ambient temperature and is applicable to samples in either aqueous or common organic solvents. The reaction between uroporphyrin I and the peroxyl radicals generated from 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH) was found to be of first-order kinetics with a mean rate constant (k) of 0.0254. Applications to measure antioxidant capacity are demonstrated on individual chemicals and biological samples. The method has good linearity, within- and between-assay precision, and recovery.     

Disposable sensor for measuring the biochemical oxygen demand for nitrification and inhibition of nitrification in wastewater

A disposable-type microbial sensor was developed for the determination of both the biochemical oxygen demand for nitrification (N-BOD) and inhibiting effects on nitrifying bacteria. The sensor was based on the respiratory activity of nitrifying bacteria immobilized on a miniature oxygen electrode. Typical response times for measuring N-BOD of ammonium standard solutions as well as of wastewater samples were in the range of 6–12 min. A dynamic evaluation of the signals after a measuring time of 120 s also resulted in good reproducibility and sensitivity. A daily profile of a municipal sewage plant was recorded, comparing the biosensor data with two standard methods. For the measurement of nitrification-inhibiting effects a 120-s dynamic signal evaluation was preferred to a steady-state method because of the long recovery times resulting from extended exposure to inhibitors. However, steady-state measurement techniques allowed allylthiourea detection with a ten times higher sensitivity. Because of the advantages of this miniaturized electrode, e.g. short response time, simple measuring procedure and low costs of production, this sensor system is considered to be suitable for commercial application in environmental analysis. Received: 30 April 1998 / Received revision: 4 September 1998 / Accepted: 13 September 1998     

Identification and mapping of a tiller inhibition gene (tin3) in wheat

Tillering is one of the most important agronomic traits in cereal crops because tiller number per plant determines the number of spikes or panicles per plant, a key component of grain yield and/or biomass. In order to characterize the underlying genetic variation for tillering, we have isolated mutants that are compromised in tillering ability using ethyl methanesulphonate (EMS)-based mutagenesis in diploid wheat (Triticum monococcum subsp. monococcum). The tillering mutant, tiller inhibition (tin3) produces only one main culm compared to the wild type with many tillers. The monoculm phenotype of tin3 is due to a single recessive mutation. Genetic and molecular mapping in an F₂ population of diploid wheat located the tin3 gene on the long arm of chromosome 3A^m. One codominant RFLP marker Xpsr1205 cosegregated with tin3 in the F₂ population. Physical mapping of PSR1205 in a set of Chinese Spring deletion lines of group-3 chromosomes placed the tin3 gene in the distal 10% of the long arm of chromosome 3A, which is a recombination-rich region in wheat. The implications of the mapping of tin3 on chromosome arm 3A^mL are discussed with respect to putative orthologs of tin3 in the 3L colinear regions across various cereal genomes and other tillering traits in grasses.     

Alpha-amylase activity of Rhyzopertha dominica (Coleoptera: Bostrichidae) reared on several wheat varieties and its inhibition with kernel extracts

Total progeny of Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae) reared on 10 wheat, Triticum aestivum L., varieties was evaluated. Higher amylase activities were detected in populations with few individuals, whereas the opposite was observed in higher populations. As protein ingested increased, reproductive success increased. However, consumption of wheat protein was inversely correlated with amylase activity levels (r = -0.66). Amylase activity in homogenates of R. dominica populations showed variable inhibition by wheat extracts prepared from wheat varieties on which they were reared. Insect populations with lowest amylase activities were inhibited more by wheat extracts than those with higher amylase activity (r = -0.77). An electrophoretic analysis revealed four phenotypes showing combinations of three isoamylases (Rm 0.70, 0.79, and 0.90) in different populations of R. dominica. Some of the insect progeny that emerged from resistant wheat varieties contained the three isoamylases, whereas progeny that emerged from the most susceptible varieties showed reduced activity of isoamylases 0.70 or 0.90. These results suggest that the alpha-amylase activity levels and the composition of isoamylases in R. dominica populations are modulated by diet and that the alpha-amylase inhibitory activity of the wheat kernels influences these variations.     

Biological nitrification inhibition in sorghum: the role of sorgoleone production

Aims

Organically-certified orchard floor management was assessed for its ability to improve soil fertility and biological activity and apple orchard performance.

Methods

‘Ambrosia’/B9 apple was maintained for the first six growing seasons with four orchard floor treatments, including 1) annual compost application; 2) in-row application of mown alfalfa grown between the rows; 3) bark mulch plus in-row application of mown hay; and 4) black plastic mulch.

Results

Soil collected from 0 to 10 cm indicated high soil organic matter and exchangeable K were measurable for all treatments by the second year. After 6 years, highest organic matter, total-, particulate- and mineral–C were associated with soil beneath the bark mulch treatment which also had most vigorous trees, decreased leaf N and elevated leaf P and K. Addition of alfalfa and bark mulch were equally effective at maintaining high exchangeable K and soil phosphatase enzymes, high total and particulate-N by the fourth year.

Conclusions

Despite measurable improvements in soil properties among treatments, fruit yield and quality were minimally affected by management implying no limitations to adoption of any of the assessed strategies.     

An electrochemical impedance spectroscopy (EIS) assay measuring the calcification inhibition capacity in biological fluids

Pathological calcification of the cardiovascular system is one of the major causes of high mortality and morbidity in dialysis patients. The inhibition of ectopic calcification relies (I) on the formation of calciprotein particles (CPPs), nanospherical complexes of calcium phosphate mineral, fetuin-A and other acidic serum proteins, and (II) on the stabilization of calcium phosphate prenucleation clusters by fetuin-A monomers. In supersaturated serum, mineral ion aggregation leads to a change in the electrical impedance. In this work, we present a method based on electrochemical impedance spectroscopy (EIS) to establish an impedance trace of mineral ion clustering in vitro. In the presence of 20 μM of serum protein fetuin-A, a prototypic calcification inhibitor, we measured a change in impedance (Δ(R)) of 195.52 ± 27.78%Ω compared to 430.41 ± 11.36%Ω in inhibitor-free samples. We also identified a CPP-formation dependency on the actual content of ions and protein in the samples under investigation. Two-step ripening of CPP was also observed. The presented method may form the basis of a simple label-free bedside or online test to be used in routine clinical practice for estimating the calcification risk in serum.     

Studies on biological decomposition of wheat straw

Summary The incorporation of undecomposed wheat straw in the soil along-with the micro-organisms favourably increased the yield of groundnut crop. An increase of 37 per cent in yield was recorded when wheat straw was inoculated withPenicillium digitatum and the C:P ratio was adjusted to 65. Inoculated treatments of narrower C:P ratio gave a higher yield than wider C:P ratio treatments inoculated with the same cultures. An increase in nitrogen uptake by groundnut plants was recorded due to incorporation of straw alongwith the micro-organisms in soil. The organic carbon and nitrogen content of the soil increased with all the treatments except control. The highest increase in organic carbon and nitrogen of the soil was observed with a treatment of wheat straw of 65 C:P ratio inoculated withS. coccosporum. The yield of wheat crop after groundnut was significantly more with several treatments than control plots. The highest increase of 79 per cent in grain yield of wheat was observed in the plots previouslq received with wheat straw of 200 C:P ratio.This paper is based on the data presented at IV Southern Regional Conference on Microbial Inoculants, held at Parbhani during 3–4 July 1978.     

Identification of genetic loci associated with ear-emergence in bread wheat

A doubled haploid population constructed from a cross between the South Australian wheat cultivars ‘Trident’ and ‘Molineux’ was grown under winter field conditions, under field conditions over summer and under artificial light both with and without vernalisation. The duration from planting to ear-emergence was recorded and QTL associated with heading date were detected using a previously constructed genetic linkage map. Associations were shown with chromosomal regions syntenous to previously identified photoperiod (Ppd-B1) and vernalisation (Vrn-A1) sensitive loci. Additional QTL associated with time to heading were also identified on chromosomes 1A, 2A, 2B, 6D, 7A and 7B. Comparisons between the genetic associations observed under the different growing conditions allowed the majority of these loci to be classified as having either photoperiod-sensitive, vernalisation-sensitive or earliness per se actions. The identification of a photoperiod-sensitive QTL on chromosome 1A provides evidence for a wheat gene possibly homoeologous to Ppd-H2 previously identified on chromosome 1H of barley. The occurrence of a putative major gene for photoperiod sensitivity observed on chromosome 7A is presented. The combined additive effects at these loci accounted for more than half the phenotypic variance in the duration from planting to ear-emergence in this population. The possible role of these loci on the adaptation of wheat in Australia is discussed.