Lack of release of bound anthocyanins and phenolic acids from carrot plant cell walls and model composites during simulated gastric and small intestinal digestion

Separately, polyphenols and plant cell walls (PCW) are important contributors to the health benefits associated with fruits and vegetables. However, interactions with PCW which occur either during food preparation or mastication may affect bioaccessibility and hence bioavailability of polyphenols. Binding interactions between anthocyanins, phenolic acids (PAs) and PCW components, were evaluated using both a bacterial cellulose-pectin model system and a black carrot puree system. The majority of available polyphenols bound to PCW material with 60-70% of available anthocyanins and PAs respectively binding to black carrot puree PCW matter. Once bound, release of polyphenols using acidified methanol is low with only similar to 20% of total anthocyanins to similar to 30% of PAs being released. Less than 2% of bound polyphenol was released after in vitro gastric and small intestinal (S.I.) digestion for both the model system and the black carrot puree PCW matter. Confocal laser scanning microscopy shows localised binding of anthocyanins to PCW. Very similar patterns of binding for anthocyanins and PAs suggest that PAs form complexes with anthocyanins and polysaccharides. Time dependent changes in extractability with acidified methanol but not the total bound fraction suggests that initial nonspecific deposition on cellulose surfaces is followed by rearrangement of the bound molecules. Minimal release of anthocyanins and PAs after simulated gastric and S.I. digestion indicates that polyphenols in fruits and vegetables which bind to the PCW will be transported to the colon where they would be expected to be released by the action of cell wall degrading bacteria.

Binding of polyphenols to plant cell wall analogues - Part 2: Phenolic acids

Bacterial cellulose and cellulose-pectin composites were used as well-defined model plant cell wall (PCW) systems to study the interaction between phenolic acids (PA) derived from purple carrot juice concentrate (PCJC) and PCW components. Significant PA depletion from solution occurred, with pure cellulose initially (30 s-1 h) absorbing more than cellulose-pectin composites in the first hour (ca 20% cf 10-15%), but with all composites absorbing similar levels (ca 30%) after several days. Individual PAs bound to different relative extents with caffeic acid > chlorogenic acid > ferulic acid. Extrapolation of data for these model systems to carrot puree suggests that nutritionally-significant amounts of PAs could bind to cell walls, potentially restricting bioavailability in the small intestine and, as a consequence, delivering PAs to the large intestine for fermentation and metabolism by gut bacteria. (C) 2012 Elsevier Ltd. All rights reserved.

Potential Distribution and Risk Assessment of an Invasive Plant Species: A Case Study of Hymenachne amplexicaulis in Australia

Given the limited resources available for weed management, a strategic approach is required to give the best bang for your buck. The current study incorporates: (1) a model ensemble approach to identify areas of uncertainty and commonality regarding a species invasive potential, (2) current distribution of the invaded species, and (3) connectivity of systems to identify target regions and focus efforts for more effective management. Uncertainty in the prediction of suitable habitat for H. amplexicaulis (study species) in Australia was addressed in an ensemble-forecasting approach to compare distributional scenarios from four models (CLIMATCH; CLIMEX; boosted regression trees [BRT]; maximum entropy [Maxent]). Models were built using subsets of occurrence and environmental data. Catchment risk was determined through incorporating habitat suitability, the current abundance and distribution of H. amplexicaulis, and catchment connectivity. Our results indicate geographic differences between predictions of different approaches. Despite these differences a number of catchments in northern, central, and southern Australia were identified as high risk of invasion or further spread by all models suggesting they should be given priority for the management of H. amplexicaulis. The study also highlighted the utility of ensemble approaches in indentifying areas of uncertainty and commonality regarding the species invasive potential.

Host selection and parasitism behavior of lysiphlebus testaceipes: Role of plant, aphid species and instar

The aphid parasitoid Lysiphlebus testaceipes is a potentially valuable biological control agent of Aphis gossypii a major worldwide pest of cotton. One means of increasing the abundance of a biological control agent is to provide an alternative host habitat adjacent to cropping, from which they can provide pest control services in the crop. Host selection and parasitism rate of an alternative host aphid, Aphis craccivora by L. testaceipes were studied in a series of experiments that tested its host suitability relative to A. gossypii on cotton, hibiscus and mungbean. Host acceptance, as measured by number of ovipositions was much greater in A. craccivora compared to A. gossypii, while more host aphids were accepted on mungbean than cotton. When given a choice L. testaceipes attacks more 4th instar and adult stages (63% and 70%, respectively) of both hosts than 2nd instar nymphs (47%). In a switching (host choice) experiment, L. testaceipes preferentially attacked A. craccivora on mungbean over A. gossypii on cotton. Observations of parasitoid contact with A. gossypii cornicle secretion suggest it provides a useful deterrent against parasitoid attack. From these experiments it appears L. testaceipes has a preference for A. craccivora and mungbean compared to A. gossypii and cotton, in this respect using A. craccivora and mungbean as alternative habitat may not work as the parasitoid is unlikely to switch away from its preferred host. © 2012.

Lexicon for the Sensory Description of Australian Native Plant Foods and Ingredients

Understanding and describing Australian flavor has proved to be a challenge for marketers of native foods because of the diversity of unique flavor signatures exhibited. Descriptive analysis techniques were applied, using a panel of 11 experienced judges, to define and articulate the sensory properties of 18 key commercial Australian native plant foods and ingredients including fruits, herbs and spices. Quantitative descriptive data were transformed into concise and accurate verbal descriptions for each of the species. The sensory language developed during the vocabulary development panel sessions was combined, categorized and ordered to develop a sensory lexicon specific for the genre. The language developed to describe the foods and ingredients was diverse and distinctly Australian including aromas such as musk, rosella, citrus and spiced tea to eucalypt, bush scrub, fresh beetroot and wheat biscuit. Practical Applications This work provides a clear, useful means of characterizing and accurately describing the flavors of Australian native plant foods and ingredients. This information has been communicated to the native food industry, chefs, formulators, food technologists and flavor experts, and provides knowledge that will assist the wider food industry to successfully develop flavor blends and produce food products from native food ingredients. It is anticipated that extension of this information to both the local and international food markets will stimulate a renewed interest in Australian native ingredients and open new market opportunities for the industry. The data developed by this research have also formed the basis of quality control targets for emerging native foods and ingredients.

Production of cuttings in response to stock plant temperature in the subtropical eucalypts, Corymbia citriodora and Eucalyptus dunnii

Propagation of subtropical eucalypts is often limited by low production of rooted cuttings in winter. This study tested whether changing the temperature of Corymbia citriodora and Eucalyptus dunnii stock plants from 28/23A degrees C (day/night) to 18/13A degrees C, 23/18A degrees C or 33/28A degrees C affected the production of cuttings by stock plants, the concentrations of Ca and other nutrients in cuttings, and the subsequent percentages of cuttings that formed roots. Optimal temperatures for shoot production were 33/28A degrees C and 28/23A degrees C, with lower temperatures reducing the number of harvested cuttings. Stock plant temperature regulated production of rooted cuttings, firstly by controlling shoot production and, secondly, by affecting the ensuing rooting percentage. Shoot production was the primary factor regulating rooted cutting production by C. citriodora, but both shoot production and root production were key determinants of rooted cutting production in E. dunnii. Effects of lower stock plant temperatures on rooting were not the result of reduced Ca concentration, but consistent relationships were found between adventitious root formation and B concentration. Average rooting percentages were low (1-15% for C. citriodora and 2-22% for E. dunnii) but rooted cutting production per stock plant (e.g. 25 for C. citriodora and 52 for E. dunnii over 14 weeks at 33/28A degrees C) was sufficient to establish clonal field tests for plantation forestry.

Origin of leaf rust adult plant resistance gene Rph20 in barley

Rph20 is the only reported, simply inherited gene conferring moderate to high levels of adult plant resistance (APR) to leaf rust (Puccinia hordei Otth) in barley (Hordeum vulgare L.). Key parental genotypes were examined to determine the origin of Rph20 in two-rowed barley. The Dutch cultivar 'Vada' (released in the 1950s) and parents, 'Hordeum laevigatum' and 'Gull' ('Gold'), along with the related cultivar 'Emir' (a derivative of 'Delta'), were assessed for APR to P. hordei in a disease screening nursery. The marker bPb-0837-PCR, co-located with Rph20 on the short arm of chromosome 5H (5HS), was used to screen genotypes for the resistance allele, Rph20.ai. Results from phenotypic assessment and DNA analysis confirmed that Rph20 originated from the landrace 'H. laevigatum' (i.e., Hordeum vulgare subsp. vulgare). Tracing back this gene through the pedigrees of two-rowed barley cultivars, indicated that Rph20 has contributed APR to P. hordei for more than 60 years. Although there have been no reports of an Rph20-virulent pathotype, the search for alternative sources of APR should continue to avoid widespread reliance upon a single resistance factor.

Rapid phenotyping for adult-plant resistance to stripe rust in wheat

Stripe or yellow rust (YR) is a significant problem in wheat crops worldwide. The deployment of adult-plant resistance (APR) genes in wheat cultivars is considered a sustainable management strategy, as these genes confer partial resistance that is usually non-race specific. Screening for APR typically involves assessment of adult plants in the field, where expression may be influenced by environmental factors. We report a high-throughput screening method for YR APR that can be used to assess fixed lines or segregating populations grown under controlled environmental conditions (CEC). Inoculation of 3-week-old wheat plants from lines with known APR responses to YR, when grown under constant light and temperature, provided disease responses typical of adult plants. Two F-2 populations ('H45' x 'ST93' and 'Wyalkatchem' x 'ST93') segregating for APR were assessed under both CEC and field conditions. These populations showed similar variation in disease response and lines assessed in both environments attained similar rankings. Phenotypic screening using CEC and continuous light provides an opportunity to accelerate the development of new wheat cultivars with durable resistance.

Effect of Time of Planting and Plant Size on the Productivity of ‘Festival’ and ‘Florida Fortuna’ Strawberry Plants in a Subtropical Environment

The effect of time of planting and plant size on the performance of ‘Festival’ and ‘Florida Fortuna’ strawberry (Fragaria ×ananassa) plants was studied at Nambour in southeastern Queensland, Australia, over 2 years. The main objective of the work was to determine whether small plants yielded proportionally less than large plants as planting was delayed. First, bare-rooted transplants of ‘Festival’ were divided into small (crown diameters ranging from 6 to 10 mm) or large plants (10 to 17 mm) and planted in late March, mid-April, or late April. Second, transplants of ‘Florida Fortuna’ were divided into small (5 to 8 mm) or large plants (8 to 17 mm) and planted in early April, mid-April, or early May. The early planting for each cultivar corresponded with the time that the transplants are first available from commercial strawberry nurseries. Yields were generally greater in plants planted in late March/early April compared with plants planted later. Differences in yield between the small and large plants were consistent across the different times of planting, with the small plants always having lower yields. Small transplants are an issue for the productivity of strawberry fields in this environment whether they are planted early or late. Producers should consider paying a premium for large transplants delivered early in the season.

A revised taxonomy for Australian Teneropsis Chapin and Cregya Leconte (Coleoptera: Cleridae: Korynetinae)

The taxonomic status of Australian species presently assigned to the genera Teneropsis Chapin and Cregya LeConte is assessed. Two new genera are erected: Gnidmus gen. nov. for Gnidmus jocosus (Schenkling) comb. nov. (transferred from Teneropsis); Hautenerus gen. nov. for Hautenerus australicus (Lea) comb. nov. (transferred from Teneropsis), Haute - nerus kioloa (Kolibáć) comb. nov. (transferred from Cregya) and Hautenerus leichhardti sp. nov. The three previously described species are redescribed. The systematic position of these taxa is discussed. Additionally, Tarsostenus hilaris (Westwood) comb. nov. is transferred from Tarsostenosis Heller and a revised key to Australian genera of Korynetinae is provided. © The State of Queensland, Queensland Museum 2013.

Papaya as a Medicinal Plant

Papaya has been used medicinally to treat an extremely broad range of ailments including intestinal worms, dengue fever, diabetes, hypertension, wound repair, and as an abortion agent. Although papaya is most commonly consumed as a ripe fruit, the plant tissues used as curatives are mainly derived from the seeds, young leaves, latex, or green immature fruit. The agents responsible for action have not been conclusively identified for all uses, but there is increasing evidence that activity may be attributable to benzyl isothiocyanate (BITC) in the case of anthelmintic and abortifacient action, and to the protease papain, and possibly chymopapain, in relation to wound repair. The location of these compounds in papaya tissues is likely to explain why different tissues are used for different ailments. Seeds, young leaves, and latex are good sources of BITC and are consequently used as a curative for intestinal worms. Immature green fruit is a good source of protease and is used as a topical application for burn wounds to accelerate tissue repair. The type of papaya tissue used may therefore provide a clue as to the active agent in ailments where papaya extracts have exhibited some activity (diabetes, hypertension, dengue fever). However, the compound(s) responsible for action remains to be identified. Modes of action of papaya extracts vary, but may include lowering blood glucose levels (diabetes), vascular muscle relaxation (hypertension), increasing blood cell count (dengue fever), stimulation of cell proliferation (wound healing), spasmodic contraction of uterine muscles (abortion), and induction of phase 2 enzymes (cancer chemoprevention). Although there has been increased study over the last decade into the physiological mode of action of papaya extracts, further increase in the knowledge of the compounds responsible for curative action will help to transfer the use of papaya from folklore remedies to mainstream medicinal use.

Plot size matters: interference from intergenotypic competition in plant phenotyping studies

Genetic and physiological studies often comprise genotypes diverse in vigour, size and flowering time. This can make the phenotyping of complex traits challenging, particularly those associated with canopy development, biomass and yield, as the environment of one genotype can be influenced by a neighbouring genotype. Limited seed and space may encourage field assessment in single, spaced rows or in small, unbordered plots, whereas the convenience of a controlled environment or greenhouse makes pot studies tempting. However, the relevance of such growing conditions to commercial field-grown crops is unclear and often doubtful. Competition for water, light and nutrients necessary for canopy growth will be variable where immediate neighbours are genetically different, particularly under stress conditions, where competition for resources and influence on productivity is greatest. Small hills and rod-rows maximise the potential for intergenotypic competition that is not relevant to a crop’s performance in monocultures. Response to resource availability will typically vary among diverse genotypes to alter genotype ranking and reduce heritability for all growth-related traits, with the possible exception of harvest index. Validation of pot experiments to performance in canopies in the field is essential, whereas the planting of multirow plots and the simple exclusion of plot borders at harvest will increase experimental precision and confidence in genotype performance in target environments.

The Myrtle Rust pathogen has arrived - and South African Myrtales are at risk : green news - plant disease alert

For many years Australian forest pathologists and other scientists have dreaded the arrival of the rust fungus, Puccinia psidii, commonly known as Myrtle Rust, in Australia. This pathogen eventually did arrive in that country and was first detected in New South Wales in 2010 on Willow Myrtle (Agonis flexuosa). It is generally accepted that it entered the country on an ornamental Myrtales* host brought in by a private nursery. Despite efforts to eradicate the invasive rust, it has already spread widely, now occurring along the east coast of Australia, from temperate areas in Victoria and southern North South Wales to tropical areas in north Queensland.