Pasting characteristics and in vitro digestibility of γ-irradiated RS4 waxy maize starches

The effect of γ-irradiation on the physicochemical properties of cross-linked waxy maize resistant starches was examined. The cross-linked waxy maize starches contained resistant starch (RS) of 56.1 and 63.5%, respectively for 5 and 10% sodium trimetaphosphate (STMP)/sodium tripolyphosphate (STPP) cross-linking, and the RS contents slightly decreased as the irradiation dose increased whereas the RS content in unmodified waxy maize starch increased with an increase in irradiation dose. For both native and cross-linked starches, the rapidly digestible starch (RDS) content increased and the slowly digestible starch (SDS) content decreased by the irradiation. The solubility of the native and cross-linked starches increased as the irradiation dose increased. The cross-linked starches did not swell in boiling water without showing pasting viscosity. However, the starches became swellable, forming pastes by irradiation, and the pasting viscosity gradually increased with an increase in irradiation dose. The crystallinity as determined by an X-ray diffraction analysis remained unchanged upon cross-linking and γ-irradiation. However, the gelatinization enthalpy of the cross-linked starches decreased in proportion with irradiation dose. The melting temperatures of cross-linked starches gradually decreased and the temperature range for melting increased with an increase in irradiation dose.     

Studies on bioactivities of tea (Camellia sinensis L.) fruit peel extracts: Antioxidant activity and inhibitory potential against α-glucosidase and α-amylase in vitro

Tea fruit peel is the main byproduct during manufacture of tea seed oil. The great increase in tea seed oil production in recent years brings the challenge of finding application for tea fruit peel. The aims of this study were to obtain tea fruit peel extracts enriched with bioactive compounds by several solvent extraction methods and to evaluate their antioxidant activity and inhibitory potential against α-glucosidase and α-amylase in vitro. Flavonoids and phenolics were accumulated in ethyl acetate, butanol, and chloroform fractions, and these fractions possessed much better antioxidant activities, including scavenging effect on 1,1-diphenyl-2-picrylhydrazyl radicals (DPPH) and 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) cation radicals (ABTS⁺), and reducing activity, compared with those of the 75% ethanol extract and water fraction. Moreover, the ethyl acetate, butanol, and chloroform fractions exhibited excellent inhibitory activity against α-glucosidase, much stronger than that of the positive control (acarbose). These fractions also showed mild inhibition on α-amylase activity.     

Are insensitivities of Venturia inaequalis to myclobutanil and fenbuconazole correlated?

In the UK, two demethylation inhibitor (DMI) fungicides, myclobutanil and fenbuconazole, are recommended for controlling apple scab. Experiments were conducted to determine whether the sensitivity of V. inaequalis to myclobutanil was correlated with that to fenbuconazole. There was a marked reduction in the sensitivity of V. inaequalis to myclobutanil; averaged ED₅₀ values increased from 0.338 mg L⁻¹ in the baseline population to 2.945 mg L⁻¹ for isolates from a commercial orchard. Overall, the average ED₅₀ value for fenbuconazole was only about 20% of that for myclobutanil for the baseline population. There was an overall significant positive correlation in the fungal sensitivities to myclobutanil and fenbuconazole, but such correlation only accounted for 40% of the total observed variability. In addition, the magnitude of this cross-resistance varied among orchards. The finding is discussed in the context of fungicide deposition in relation to disease control.     

Identification and characterization by PCR–RFLP analysis of the genetic variation for the Glu-A1x and Glu-B1x genes in rivet wheat (Triticum turgidum L. ssp. turgidum)

Many studies have suggested that the true variation of high-molecular-weight (HMW) glutenin subunits in wheat could be under-estimated due to the anomalous mobility of these proteins in one-dimensional electrophoresis (SDS-PAGE). An alternative technique used is the specific PCR amplification of these genes, however the scarce variation in size among the different alleles could also under-estimate the true variability. In this study, the variability of HMW glutenin subunits found in one Spanish collection of rivet wheat (Triticum turgidum L. ssp. turgidum) was evaluated by a combination of two techniques (PCR amplification and digestion with endonucleases). The data allowed detection of allelic variations that were not clearly detected by SDS-PAGE or PCR analysis alone. The approach used in the current study could allow identification of alleles contributing to achieve desirable quality in modern wheat.     

Are plant cell wall hydrolysing enzymes of saprobe fungi implicated in the biological control of the Verticillium dahliae pathogenesis?

We studied the possibility that the antagonistic saprobe fungi Coriolopsis rigida, Trametes versicolor, Fusarium lateritium, Penicillium chrysogenum and Verticillium dahliae-2379 may control V. dahliae disease through the inhibition of the activity of hydrolytic enzymes produced by the pathogen. These saprobe fungi were able to decrease the growth in vitro of V. dahliae. The exudates produced by these fungi seemed to be the main factor responsible for their antagonistic effect. The exudates of all the fungi tested had endopolymethylgalacturonase, endoglucanase and endoxyloglucanase activities. Exudates of P. chrysogenum and V. dahliae-2379 had higher hydrolytic activities than those of V. dahliae. The saprobe V. dahliae-2379 did not decrease the growth of the pathogen V. dahliae but decreased its harmful effect on the growth of tomato. However, no inhibition of the activities of the hydrolytic enzyme of the pathogenic V. dahliae by the no pathogenic V. dahliae-2379 or by the other saprobe fungi was observed. Nevertheless, the protection of tomato by the five antagonistic saprobe fungi against V. dahliae disease could be carried out by the induction of plant defense by the hydrolytic enzymes produced by these fungi.     

Effect of elevated carbon dioxide (CO2) on phenolic acids,flavonoids, tocopherols,tocotrienols, γ-oryzanol and antioxidant capacities of rice (Oryza sativa L.)

There have been no studies conducted with the objective of investigating the effect of elevated CO₂ concentrations ([CO₂]) on antioxidants in grains. Therefore, a two-year field experiment was conducted using open-top chambers with two levels of atmospheric CO₂ (375 and 550 μmol/mol) to evaluate their effects on rice grain antioxidants. Following exposure to high [CO₂], the total phenolic content of all rice milling fractions decreased (3%–18%), with the highest reduction in the brown rice for sinapic acid (167%), and in the white rice for p-hydroxybenzoic acid (100%). The total flavonoid content also decreased under elevated [CO₂] in all rice milling fractions (8%–14%), with apigenin (25%) being highly affected in the white rice, and tricin (12%) in the bran. The same trend was found for γ-oryzanol, with decreases of 35%, 32%, 25%, and 2% in the white rice, brown rice, husk, and bran, respectively. In the white and brown rices, tocopherols and tocotrienols were all lower under elevated [CO₂], with reductions larger for α-tocotrienol (69%), γ-tocotrienol (46%), and α-tocopherol (38%). Good correlations between antioxidant contents and DPPH radical scavenging capacities indicated that these decreases may be meaningful in the preventive ability of rice against free radical-mediated degenerative diseases.     

Interpreting the Possible Ecological Role(s) of Cyanotoxins: Compounds for Competitive Advantage and/or Physiological Aide?

To date, most research on freshwater cyanotoxin(s) has focused on understanding the dynamics of toxin production and decomposition, as well as evaluating the environmental conditions that trigger toxin production, all with the objective of informing management strategies and options for risk reduction. Comparatively few research studies have considered how this information can be used to understand the broader ecological role of cyanotoxin(s), and the possible applications of this knowledge to the management of toxic blooms. This paper explores the ecological, toxicological, and genetic evidence for cyanotoxin production in natural environments. The possible evolutionary advantages of toxin production are grouped into two main themes: That of “competitive advantage” or “physiological aide”. The first grouping illustrates how compounds produced by cyanobacteria may have originated from the need for a cellular defence mechanism, in response to grazing pressure and/or resource competition. The second grouping considers the contribution that secondary metabolites make to improved cellular physiology, through benefits to homeostasis, photosynthetic efficiencies, and accelerated growth rates. The discussion also includes other factors in the debate about possible evolutionary roles for toxins, such as different modes of exposures and effects on non-target (i.e., non-competitive) species. The paper demonstrates that complex and multiple factors are at play in driving evolutionary processes in aquatic environments. This information may provide a fresh perspective on managing toxic blooms, including the need to use a “systems approach” to understand how physico-chemical conditions, as well biological stressors, interact to trigger toxin production.     

Indirect changes associated with a selection program for increased seed-yield in wild species of Lesquerella (Brassicaceae): Are we developing a phenotype opposite to the expected ideotype?

Seed-yield stability, frequently associated with drought-tolerance strategies, is one of the main breeding objectives for the development of crops for semi-arid mediterranean-type environments. Since breeding of new industrial crops targeted for arid lands is not appreciably different from that of traditional crops, higher yield is achieved by increased harvest-index, at the cost of losing traits associated with drought-tolerance and reduced seed-yield stability. Using Lesquerella as a model we compared selected and unselected accessions of annual (L. gracilis and L. angustifolia) and perennial (L. pinetorum and L. mendocina) genotypes grown in field experiments in Patagonia, Argentina. Our objective was to assess the effects of breeding for increased seed-yield on traits related to the main characteristics that define the most common ideotype for mediterranean-type environments: early vigor, conservative growth strategy post-anthesis and reserves storage. Our specific question was: Have any of the attributes associated with seed-yield stability been indirectly selected during the domestication process? Our results show that these characteristics were reduced or lost, in selected lines compared to their wild relatives. Early vigor was lower in selected accessions and was associated mainly with reduced relative growth rate and CO₂ assimilation. During the reproductive period the growth strategy was changed by selection towards a non-conservative and more acquisitive resource use strategy. Traits associated with this strategy were linked to higher water use efficiency and growth capacity (higher CO₂ assimilation rate, specific leaf area, and leaf allocation), but also with loss of structural adaptation to low resource environments (i.e. low specific leaf area), an increase in nutrient and water demands, and reduced nutrient use efficiency. Carbohydrates accumulation pre-anthesis was lower in selected accessions of all four species, and also, just in perennials we found lower reserves storage post-anthesis. These changes in the pattern of carbohydrates accumulation could be associated to lower seed-yield stability due to the loss of buffer capacity linked with the use of pre-anthesis reserves for seed filling. On the other hand, in perennial species lower reserves storage after seed harvest could reduce plant longevity and survival. We conclude that indirect changes occurred during the preliminary domestication of both annual and perennial species of Lesquerella used in our experiment. These changes were against those required if these species were to be developed as crops for semi-arid, mediterranean environments and should result in low seed-yield stability.