Wheat root protection from cereal cyst nematode (Heterodera avenae) by fluopyram seed treatment

Cereal cyst nematode (Heterodera avenae), an important plant-parasitic nematode causing yield losses on wheat, has been found in many provinces in China. It is urgent to develop an effective method to protect wheat from H. avenae damage. With a novel mode of action, fluopyram has been registered for controlling root-knot nematodes on cucumber and tomato in China. However, the bioactivity of fluopyram against H. avenae and whether seed treatment is effective in controlling H. avenae on wheat remains unknown. In this study, a bioactivity assay revealed that fluopyram increased the mortality of H. avenae second stage juveniles (J2), with LC50 and LC90 values of 0.92 mg L-1 and 2.92 mg L-1, respectively. Hatching tests showed that H. avenae egg hatching percent decreased 35.2-69.2% with fluopyram at the rate of 1.6-6.4 mg L-1, and the egg hatching period was delayed by 3-9 days compared with the control. In pot and field trials, fluopyram seed treatment significantly reduced H. avenae population density and increased wheat yield by 3.0-13.7%. Therefore, fluopyram seed treatment is an effective approach for the management of H. avenae on wheat in China.

A new Bacillus thuringiensis protein for Western corn rootworm control

The Western corn rootworm (WCR) Diabrotica virgifera virgifera LeConte is one of the most economically important insect pests in North America. Since 2003, transgenic maize expressing WCR-active proteins from Bacillus thuringiensis (Bt) have been widely adopted as the main approach to controlling WCR in the U.S. However, the emergence of field resistance to the Bt proteins in current commercial products has been documented in recent years, highlighting the need to develop additional tools for controlling this devasting pest. Here we report the discovery of Vpb4Da2 (initially assigned as Vip4Da2), a new insecticidal protein highly selective against WCR, through high-throughput genome sequencing of a Bt strain sourced from grain dust samples collected in the eastern and central regions of the US. Vpb4Da2 contains a sequence and domain signature distinct from families of other WCR-active proteins. Under field conditions, transgenic maize expressing Vpb4Da2 demonstrates commercial-level (at or below NIS 0.25) root protection against WCR, and reduces WCR beetle emergence by ≥ 97%. Our studies also conclude that Vpb4Da2 controls WCR populations that are resistant to WCR-active transgenic maize expressing Cry3Bb1, Cry34Ab1/Cry35Ab1 (reassigned as Gpp34Ab1/Tpp35Ab1), or DvSnf7 RNA. Based on these findings, Vpb4Da2 represents a valuable new tool for protecting maize against WCR.

Shedding the Last Layer: Mechanisms of Root Cap Cell Release

The root cap, a small tissue at the tip of the root, protects the root from environmental stress and functions in gravity perception. To perform its functions, the position and size of the root cap remains stable throughout root growth. This occurs due to constant root cap cell turnover, in which the last layer of the root cap is released, and new root cap cells are produced. Cells in the last root cap layer are known as border cells or border-like cells, and have important functions in root protection against bacterial and fungal pathogens. Despite the importance of root cap cell release to root health and plant growth, the mechanisms regulating this phenomenon are not well understood. Recent work identified several factors including transcription factors, auxin, and small peptides with roles in the production and release of root cap cells. Here, we review the involvement of the known players in root cap cell release, compare the release of border-like cells and border cells, and discuss the importance of root cap cell release to root health and survival.

Biocides used in building materials and their leaching behavior to sewer systems

There is increasing concern about diffuse pollution of aquatic systems by biocides used in urban areas. We investigated sources and pathways of biocides significant for the pollution of storm water runoff. Main sources seem to be building envelopes, i.e. facades (paints, plasters) and roof sealing membranes. First results from a defined urban catchment drained by a separated sewer system without any agricultural activities reveal a substantial occurrence. Even after the first flush, concentrations of terbutryn, carbendazim, mecoprop as well as Irgarol 1051® and its metabolite exceeded the Swiss water quality standard of 0.1 μg/L. In laboratory experiments, leaching of mecoprop used as a root protection agent in bitumen sheets for roof waterproofing was determined. The concentrations differed in 16 different sheets two orders of magnitude, depending on the product composition. Using optimized products, it is expected to be the most efficient and sustainable way to reduce the environmental impact. To understand transport dynamics and environmental risk, further storm water events will be analyzed. Based on the ongoing project URBIC, first measures will be proposed to limit the release to surface and ground water.