Genetic data confirms field evidence for natural breeding in a wild taro population (Colocasia esculenta) in northern Queensland, Australia

Taro (Colocasia esculenta) is a vegetatively propagated, starchy root crop cultivated in tropical to temperate regions of the world. Wild forms of taro are distributed from India to southern China, Australia and Melanesia. They are widely known wild food or fodder sources, including in Aboriginal Australia, so it is unclear to what extent wild populations have been dispersed by humans, or naturally via insect-borne pollen and seed dispersal by birds or other animals. In Australia, pollinators and seedlings of taro have not been reported, and a key question is whether or not the wild taro there can breed naturally. Here we report field observations of flowering, fruit set, and an insect pollinator (Colocasiomyia, pupal stage), in a historically significant wild taro population at Hopevale in northern Queensland. The observed pupa is congeneric with two pollinating fly species that have a highly specialised, probably coevolutionary, relationship with taro in neighbouring Papua New Guinea. The field observations suggested the possibility of natural breeding at Hopevale. By analyzing microsatellite diversity within the Hopevale taro population, we found high genetic variation overall, indicative of multiple founding individuals. Two sublocations showed low genetic diversity and strongly negative inbreeding coefficients, consistent with predominantly clonal (vegetative) reproduction. A third sublocation showed high genetic diversity and a weakly negative inbreeding coefficient, indicative of sexual reproduction. This difference between sublocations may relate to microenvironmental conditions that favour seedling establishment in some parts of the site. The data constitute the first demonstration that natural breeding and population spread occurs in Australian wild taro.     

Should farmers apply fertilizer according to when their daffodils are in flower? Utilizing a “farmer‐science” approach to understanding the impact of soil temperature on spring N fertilizer application in Wales

Perennial ryegrass starts growing when soil temperatures reach 5.5°C for five consecutive days; applying N fertilizer before this risks environmental losses. To test whether daffodil flowering signified when to apply N fertilizer, farmers volunteered to take part in a citizen science study. The PROSOIL project used a “citizen science”, participatory approach to create farmer‐informed science, aiming to increase awareness of the importance of soil health. In 2014, over 300 farmers completed a “How do you manage your soil” survey. The survey included a question on the use of daffodils (Narcissus spp.) to indicate the best time to apply the first nitrogen fertilizer of the season, based on anecdotal feedback from farmers involved in the PROSOIL project. The survey recorded 7% of farmers based their first fertilizer application on when daffodils flowered. To increase farmer awareness of soil temperatures, we provided them with soil thermometers, held workshops and hosted interactive stands at agricultural events in 2014. In autumn 2014, farmers planted daffodil bulbs of the same variety, across Wales, and monitored soil temperatures. Farmers returned postcards once their daffodils were in flower, noting the soil temperature. An assessment of whether daffodil flowering date could indicate when to apply N fertilizer was made. Overall, in spring 2015, daffodils flowered when soil temperature was 6.4(±0.35)°C, suggesting daffodil flowering date is a more reliable indicator for fertilizer application, than first hypothesized. Findings show a scientific validation of local knowledge, regarding the use of daffodils to indicate the “not‐before” date for the first N fertilizer application.     

Design of stable nanocrystalline alloys

Nanostructured metals are generally unstable; their grains grow rapidly even at low temperatures, rendering them difficult to process and often unsuitable for usage. Alloying has been found to improve stability, but only in a few empirically discovered systems. We have developed a theoretical framework with which stable nanostructured alloys can be designed. A nanostructure stability map based on a thermodynamic model is applied to design stable nanostructured tungsten alloys. We identify a candidate alloy, W-Ti, and demonstrate substantially enhanced stability for the high-temperature, long-duration conditions amenable to powder-route production of bulk nanostructured tungsten. This nanostructured alloy adopts a heterogeneous chemical distribution that is anticipated by the present theoretical framework but unexpected on the basis of conventional bulk thermodynamics.     

Chickpea molecular breeding: New tools and concepts

Summary Chickpea is a cool season grain legume of exceptionally high nutritive value and most versatile food use. It is mostly grown under rain fed conditions in arid and semi-arid areas around the world. Despite growing demand and high yield potential, chickpea yield is unstable and productivity is stagnant at unacceptably low levels. Major yield increases could be achieved by development and use of cultivars that resist/tolerate abiotic and biotic stresses. In recent years the wide use of early maturing cultivars that escape drought stress led to significant increases in chickpea productivity. In the Mediterranean region, yield could be increased by shifting the sowing date from spring to winter. However, this is hampered by the sensitivity of the crop to low temperatures and the fungal pathogen Ascochyta rabiei. Drought, pod borer (Helicoverpa spp.) and the fungus Fusarium oxysporum additionally reduce harvests there and in other parts of the world. Tolerance to rising salinity will be a future advantage in many regions. Therefore, chickpea breeding focuses on increasing yield by pyramiding genes for resistance/tolerance to the fungi, to pod borer, salinity, cold and drought into elite germplasm. Progress in breeding necessitates a better understanding of the genetics underlying these traits. Marker-assisted selection (MAS) would allow a better targeting of the desired genes. Genetic mapping in chickpea, for a long time hampered by the little variability in chickpea’s genome, is today facilitated by highly polymorphic, co-dominant microsatellite-based markers. Their application for the genetic mapping of traits led to inter-laboratory comparable maps. This paper reviews the current situation of chickpea genome mapping, tagging of genes for ascochyta blight, fusarium wilt resistance and other traits, and requirements for MAS. Conventional breeding strategies to tolerate/avoid drought and chilling effects at flowering time, essential for changing from spring to winter sowing, are described. Recent approaches and future prospects for functional genomics of chickpea are discussed.     

The great Sumatra-Andaman earthquake of 26 December 2004

The two largest earthquakes of the past 40 years ruptured a 1600-kilometer-long portion of the fault boundary between the Indo-Australian and southeastern Eurasian plates on 26 December 2004 [seismic moment magnitude (Mw) = 9.1 to 9.3] and 28 March 2005 (Mw = 8.6). The first event generated a tsunami that caused more than 283,000 deaths. Fault slip of up to 15 meters occurred near Banda Aceh, Sumatra, but to the north, along the Nicobar and Andaman Islands, rapid slip was much smaller. Tsunami and geodetic observations indicate that additional slow slip occurred in the north over a time scale of 50 minutes or longer.     

Low-field magnetic separation of monodisperse Fe3O4 nanocrystals

Magnetic separations at very low magnetic field gradients (<100 tesla per meter) can now be applied to diverse problems, such as point-of-use water purification and the simultaneous separation of complex mixtures. High-surface area and monodisperse magnetite (Fe3O4) nanocrystals (NCs) were shown to respond to low fields in a size-dependent fashion. The particles apparently do not act independently in the separation but rather reversibly aggregate through the resulting high-field gradients present at their surfaces. Using the high specific surface area of Fe3O4 NCs that were 12 nanometers in diameter, we reduced the mass of waste associated with arsenic removal from water by orders of magnitude. Additionally, the size dependence of magnetic separation permitted mixtures of 4- and 12-nanometer-sized Fe3O4 NCs to be separated by the application of different magnetic fields.     

GENETICS. The Human Variome Project

An ambitious plan to collect, curate, and make accessible information on genetic variations affecting human health is beginning to be realized.