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Funding: J.F.S. acknowledges the financial support of the Strategic Priority Research Program of the Chinese Academy of Sciences (grant number XDB07030200). Erasable electrical conductive domain walls in an insulating ferroelectric matrix provide novel functionalities for applications in logic and memory devices. The crux of such success requires sufficiently high wall currents to drive high‐speed and high‐power nanodevices. This work provides an appealing strategy to increase the current by two orders of magnitude through the careful selection of current flowing paths along the charged walls. The dense walls come into form through the hierarchical evolution of the 71°, 109°, and 180° domains of epitaxial BiFeO3 films in a planar‐geometry ferroelectric resistance‐switching memory cell. The engineered films grown on SrTiO3 and GdScO3 substrates allow the observation of detailed local configurations and the evolution of the different domain types using vector piezo‐force microscopy. The higher local electrical conductivity near the charged domain walls is identified by conductive atomic‐force microscopy. It is shown that 180° domain reversal proceeds by three‐step 71° rotations of the pristine domains. Surprisingly, a maximum current of ≈300 nA is observed for current paths along charge‐uncompensated head‐to‐head hierarchical domain walls connecting the two electrodes on the film surface. Furthermore, the achievable current level can be conveniently controlled by varying the relative directions of the initial polarization and the applied field. Postprint

Sugar beet (Beta vulgaris) is an important arable crop, traditionally used for sugar extraction, but more recently, for biofuel production. A wide range of pests, including beet cyst nematode (Heterodera schachtii), root-knot nematodes (Meloidogyne spp.), green peach aphids (Myzus persicae) and beet root maggot (Tetanops myopaeformis), infest the roots or leaves of sugar beet, which leads to yield loss directly or through transmission of beet pathogens such as viruses. Conventional pest control approaches based on chemical application have led to high economic costs. Development of pest-resistant sugar beet varieties could play an important role towards sustainable crop production while minimising environmental impact. Intensive Beta germplasm screening has been fruitful, and genetic lines resistant to nematodes, aphids and root maggot have been identified and integrated into sugar beet breeding programmes. A small number of genes responding to pest attack have been cloned from sugar beet and wild Beta species. This trend will continue towards a detailed understanding of the molecular mechanism of insect-host plant interactions and host resistance. Molecular biotechnological techniques have shown promise in developing transgenic pest resistance varieties at an accelerated speed with high accuracy. The use of transgenic technology is discussed with regard to biodiversity and food safety.

Summary A number of stably transformed wheat cell lines were obtained using two different direct gene transfer techniques. When integration of the foreign genes was investigated in DNA samples taken at 10 months post-selection, complicated profiles of transgene bands were observed in Southern blot analysis. Among these, a number of common bands were identified showing similar hybridization patterns between independently transformed cell lines. This type of hybridization pattern has been a common observation and is usually interpreted as concatameric rearrangement of integrated DNA. However, when integration was reinvestigated with DNA samples taken at 30 months postselection, the hybridization pattern changed and most of the common bands had disappeared. Further analysis using a set of methylation-sensitive enzymes revealed that the DNA represented by the common bands was N6-adenine methylated (m6A DNA), and there was even m6A DNA in some 30 month samples. Although the source of m6A DNA in the wheat cultures was not clearly established, the data indicate that transformation of an endophyte (e.g. a mycoplasma-like organism) may have occurred at the same time as the transformation of wheat cells. The integration pattern of undermethylated transgenes in the transformed cells became simpler and clearer after treating the DNA preparations with Dpnl, which only cuts m6A DNA. The implications of these data for other methods of inoculating cereals with DNA are discussed.