Enhancing resistance in Pinus radiata seedlings to terminal crook (Colletotrichum acutatum) using methyl jasmonate and ultraviolet‐C radiation

Colletotrichum acutatum is a fungal pathogen that causes terminal crook disease in radiata pine (Pinus radiata) seedlings in New Zealand forest nurseries. Symptoms of infection include malformation or death of the growing tip and a stiffening and thickening of the stem. Although the disease can be managed effectively using fungicides, the New Zealand forest industry is interested in alternative control options such as induced resistance. The aim of this study was to evaluate spray application of chitosan (1.4 g/l) or 2.25 mm methyl jasmonate (MeJA) and irradiation with UV‐C (2.16 kJ/m²) for their potential to induce resistance to terminal crook. The treatments were applied to 4‐month‐old seedlings at 1 week before pathogen inoculation. By the end of the experimental period (42 days after inoculation), there was 80% disease incidence in the controls, with 48% of seedlings exhibiting severe terminal crook symptoms. The most effective treatment (p < 0.05) was MeJA with 16% disease incidence and none with severe symptoms. UV‐C also significantly (p < 0.05) reduced infection with 52% incidence and 20% of seedlings exhibiting severe symptoms. Chitosan did not reduce disease incidence (72%) compared with the control (80%) but did significantly reduce (p < 0.05) disease severity with 28% exhibiting severe symptoms. MeJA was the only treatment that significantly (p < 0.05) reduced the detrimental effects of infection on seedling apical growth and stem diameter. To our knowledge, this is the first report demonstrating the potential for MeJA and UV‐C to control terminal crook in radiata pine.     

Genome classification of banana cultivars from South India using IRAP markers

Summary The banana cultivars are originated from the intra- and inter-specific hybridization of two wild diploid species, Musa acuminata Colla and Musa balbisiana Colla, contributing the A and B genomes, respectively. They are classified into genomic groups by scoring morphological features. Molecular markers provide a quick and reliable system of genome characterization and manipulation in breeding lines. In the present study a PCR based molecular marker specific for B genomes is been reported. The IRAP primer, designed based on the LTR sequence of banana Ty3-gypsy-like retroelement (Musa acuminata Monkey retrotransposon, AF 143332), was used to identify the B genome in the banana cultivars. Further a primer pair designed from B specific bands of Musa balbisiana `Pisang Gala' was used to classify AAB and ABB cultivars in the collection. Among the 36 cultivars tested with this primer, the B specific band was absent in the AA and AAA cultivars (except in one AAA and AAB cultivar) but present in all other AB, AAB and ABB cultivars. Among the triploid AAB/ABB, the PCR products with B specific primers showed restriction pattern polymorphism with AluI. In ABB genomes the band intensity was high whereas low intensity band observed in AAB genomes. Four cultivars reported to have the ABB genome showed a pattern similar to AAB, and one cultivar reported to have AAA genome showed a pattern similar to ABB genome, suggesting missampling or misidentification. The primers used in this study are useful to identify the presence of B genome in banana cultivars, and band intensity may be a preliminary indicator of ploidy level of the B genome but needs further studies with competitive PCR for clarification. These authors contributed equally in this paper.     

Functional links between Aβ toxicity, endocytic trafficking, and Alzheimer's disease risk factors in yeast

Aβ (beta-amyloid peptide) is an important contributor to Alzheimer's disease (AD). We modeled Aβ toxicity in yeast by directing the peptide to the secretory pathway. A genome-wide screen for toxicity modifiers identified the yeast homolog of phosphatidylinositol binding clathrin assembly protein (PICALM) and other endocytic factors connected to AD whose relationship to Aβ was previously unknown. The factors identified in yeast modified Aβ toxicity in glutamatergic neurons of Caenorhabditis elegans and in primary rat cortical neurons. In yeast, Aβ impaired the endocytic trafficking of a plasma membrane receptor, which was ameliorated by endocytic pathway factors identified in the yeast screen. Thus, links between Aβ, endocytosis, and human AD risk factors can be ascertained with yeast as a model system.     

Agricultural practices alter sex ratios in a reptile with environmental sex determination

Anthropogenic changes to the environment have the opportunity to impact natural systems, particularly in organisms that exhibit phenotypic plasticity. Species with environmental sex determination (ESD) are uniquely susceptible to changes in the stimuli that affect sexual development, potentially leading to maladaptive sex ratios. We studied the factors affecting sex determination and sex ratios in the common snapping turtle, Chelydra serpentina, in an area heavily impacted by agricultural practices. We investigated the effects of soybean, corn, and sunflower planting on incubation temperatures, sex ratios, and depredation in naturally laid nests. We also identified and analyzed a novel mitochondrial microsatellite in order to examine the presence of natal homing and determine the likelihood that nest sites impacted by agricultural practices could be transmitted across generations. Females frequently chose to nest in agricultural fields over sand prairie sites, and offspring sex ratios and depredation rates were significantly influenced by crop planting. Despite detecting considerable genetic variation in our population, we found no relationship between relatedness and nesting location, suggesting that females are not transmitting nesting sites across generations. Our results suggest that agricultural practices can directly impact populations of animals with ESD, and will need to be considered in management decisions.     

Heterogeneous three-dimensional electronics by use of printed semiconductor nanomaterials

We developed a simple approach to combine broad classes of dissimilar materials into heterogeneously integrated electronic systems with two- or three-dimensional layouts. The process begins with the synthesis of different semiconductor nanomaterials, such as single-walled carbon nanotubes and single-crystal micro- and nanoscale wires and ribbons of gallium nitride, silicon, and gallium arsenide on separate substrates. Repeated application of an additive, transfer printing process that uses soft stamps with these substrates as donors, followed by device and interconnect formation, yields high-performance heterogeneously integrated electronics that incorporate any combination of semiconductor nanomaterials on rigid or flexible device substrates. This versatile methodology can produce a wide range of unusual electronic systems that would be impossible to achieve with other techniques.     

Trichoderma atroviride promotes growth and enhances systemic resistance to Diplodia pinea in radiata pine (Pinus radiata) seedlings

Root drench application of Trichoderma atroviride isolates R32, R33, R40 and R84 promoted the growth of potted radiata pine seedlings. After 6 weeks, seedlings treated with R33 and R84 had thicker stems and greater stem and root biomass (p < 0.05) than untreated controls. Treatment with R32 increased seedling root biomass whilst R40 increased stem diameter. None of the isolates affected seedling height. One isolate, R33, induced systemic resistance to stem inoculation with Diplodia pinea and reduced dieback incidence by 20% compared with untreated controls. To our knowledge, this is the first report of systemic induced resistance by Trichoderma in a pine species. Furthermore, seedlings that were treated with R33 (root drench) plus foliar application of methyl jasmonate (MeJA) expressed elevated peroxidase activity in their stems 2 weeks later, compared with seedlings treated only with MeJA. Because R33 itself did not affect peroxidase activity, this may be indicative of treatment synergy or defence potentiation by R33. Curiously, R33 + MeJA induced terpenoids but suppressed phenylalanine ammonia‐lyase activity suggesting possible trade‐offs between phenolic and terpenoid defence pathways in the treated seedlings.     

Survival of hypoxic human mesenchymal stem cells is enhanced by a positive feedback loop involving miR-210 and hypoxia-inducible factor 1

The use of mesenchymal stem cells (MSCs) has emerged as a potential new treatment for myocardial infarction. However, the poor viability of MSCs after transplantation critically limits the efficacy of this new strategy. The expression of microRNA-210 (miR-210) is induced by hypoxia and is important for cell survival under hypoxic conditions. Hypoxia increases the levels of hypoxia inducible factor-1 (HIF-1) protein and miR-210 in human MSCs (hMSCs). miR-210 positively regulates HIF-1α activity. Furthermore, miR-210 expression is also induced by hypoxia through the regulation of HIF-1α. To investigate the effect of miR-210 on hMSC survival under hypoxic conditions, survival rates along with signaling related to cell survival were evaluated in hMSCs over-expressing miR-210 or ones that lacked HIF-1α expression. Elevated miR-210 expression increased survival rates along with Akt and ERK activity in hMSCs with hypoxia. These data demonstrated that a positive feedback loop involving miR-210 and HIF-1α was important for MSC survival under hypoxic conditions.     

Infection criteria,inoculum sources and splash dispersal pattern of <Emphasis Type="Italic">Colletotrichum acutatum</Emphasis> causing bitter rot of apple in New Zealand

Infection of Malus x domestica cv. Royal Gala fruit by Colletotrichum acutatum causing bitter rot was studied in the temperate climate of New Zealand. Temperatures above 15 °C were required for lesions to develop on detached apple wound-inoculated or inoculated without wounding with C. acutatum spores, regardless of maturity. A wetness period of 72 h was required for infection of mature detached apple fruit without wounding. On wound-inoculated detached apple fruits, sporulation was related to temperature and followed a similar pattern. In the field, a mean temperature above 15 °C for 72 h after wound-inoculation was required for lesions to develop. Buds were a more important source of inoculum than twigs, and it was shown that C. acutatum could be isolated more frequently from outer bud scales than from inner scales. Asymptomatic infection of vegetative and reproductive buds was detected. C. acutatum was detected on asymptomic surface-sterilised petals and fruit, more commonly during summer than spring. Symptomless sterilised leaves generally yielded C. acutatum throughout the season, but isolations were more frequent in summer. Recovery of inoculum using a splash meter to detect vertical dispersal showed that in summer inoculum was primarily splashed up from the ground. In spring, inoculum was recovered in similar quantities from all heights up to a metre, suggesting that splash dispersal occurs from the canopy as well as from the ground. A disease cycle for C. acutatum infecting apples and causing bitter rot in New Zealand is suggested.