Rick Davis

Arbuscular mycorrhiza (AM) are soil-borne fungi that form intimate symbiotic associations with the roots of most land plants. AM fungi act as extensions of the root system, increasing the root ����������������uptake area��������������� more than 1000-fold and considerably improving the plant's ability to acquire water and nutrients from the soil. AM fungi therefore substantially improve the host plant������������������s access to macronutrients including phosphorous (P), potassium (K) and nitrogen (N), and micronutrients. This proposal describes a project to understand the genetics controlling the association between corn and AM fungi. If successful, this will facilitate the increased used of AM fungi in corn cultivation and help reduce the expensive and ecologically-damaging use of fertilizers.

The North Carolina Biotechnology Center������������������s Crop Commercialization Program (CCP) will coordinate and manage research efforts related to assessing weeds and diseases damaging to stevia production and evaluating the efficacy of biocontrol agents and products in greenhouse and field trials. The research will result in an organic disease and weed management strategy for stevia and preliminary data that will be submitted to the IR4 program for product labeling. Current and future stevia growers, as well as stevia processing companies, will directly benefit from the research, as the outcomes will help ease production management and financial hurdles for growing organic stevia in North Carolina.

The Guava root-knot nematode (GRKN), Meloidogyne enterolobii, is an invasive and highly aggressive soilborne pathogen. GRKN overcomes all known crop resistance genes that are effective in controlling other RKN species, and thus represents a significant threat to agricultural production in NC. The threat of GRKN to the NC sweetpotato industry and the communities reliant upon the industry is estimated at 95,000 harvested acres worth $342 million. Multifaceted research of chemical control and screening for cultivar resistance is needed to investigate solutions to this problem. However, a significant hindrance to such research lies in identifying suitable field locations with sufficient GRKN populations to perform the work. This project aims to establish a contained research farm infested with GRKN. The proposed farm would allow for management studies and the ability to screen sweetpotato, soybean, tobacco, and vegetable cultivars under field conditions. To reduce the risk of accidental movement of GRKN to other sites, the farm will be enclosed in fencing, with dedicated equipment and storage building, and a decontamination station.

Smallholder farming practices in sub-Saharan Africa (SSA) include land-raised seed (piece) use, continuous cultivation (often monoculture) with limited inputs, and virtually non-existent seed (piece) treatment techniques. Yam (Dioscorea spp.) is the primary example of this cropping system and is an extremely important and valuable crop for smallholder farmers in SSA. These practices result in nutrient-depleted soils, nematode infestation, and ultimately low crop yields. Reducing the nematode population in crop soil will dramatically increase crop yield and quality. In many cases, smallholder farmers in SSA lose greater than 50% of their crop to plant-parasitic nematodes, primarily due to lack of available and affordable control options. For this BMG GCE Phase III proposal, we will build upon our promising results from Phase II trials, including increased yields and higher tuber quality and storability for both yam and potato, and use our expertise and connections for pulping banana fiber to validate and prepare for commercialization a developing-world transferable product platform enabling a field deployable paper-like seed (piece) treatment to combat plant pathogenic nematodes. In addition, this platform will be amenable to delivering other crop production moieties, including natural products and oils, necessary minerals and nutrients, or insecticides and fungicides, with its application. Our laboratories������������������ expertise in nematology and lignocellulosic fibrous materials enables us to target the delivery of beneficial small molecules during seed (piece) germination and plant establishment. Importantly the incorporation of active ingredients into a lignocellulose matrix, such as banana tissue paper, allows for widespread distribution of crop protection agents without interfering in smallholder farming practices. The shelf-stable light-weight banana tissue paper can be applied at the point of seed (piece) planting where farmers can use the concept of ����������������wrap and plant��������������� with their own seeds/pieces. Our ���������������wrap and plant������������������ product will be an ����������������active��������������� paper sheet pretreated with ultralow concentrations of active nematicidal ingredient to simply wrap and protect the seed (piece) at planting. The localization of active ingredients carried directly within the paper targets specific plant pathogenic nematodes versus beneficial organisms. Nematodes are primarily a seedling disease, so protection early is critical to the success of the crop, although post harvest losses do occur in yam due to the yam nematode (Scutellonema bradys). Reduction in nematode populations by deploying the ���������������wrap and plant������������������ product protects yam from significant infections that may lead to these post-harvest losses. Our ultimate goal is to validate the ���������������wrap and plant������������������ product in Phase III and to translate the product manufacture to a regional African company for commercialization and distribution.

Pathogens that are spread by insects or wind pose a community wide threat to cotton production. Methods to forecast inoculum exposure would allow growers to take timely preventative actions such as: delayed planting, resistant varieties, selective fungicides, crop growth regulators, irrigation management, targeted rotations and only where necessary - limited tillage. The NMPTI is foundational for leveraging existing human and animal infectious decision support tools for agriculture. Adaptation of these tools for key diseases of cotton will facilitate disease management and preventive/mitigative actions and planning for disease prevention. These tools offer decision support at varying temporal and spatial scales and individual tools can be used at different points along the spectrum of crop disease surveillance, from early detection to outbreak management to post harvest investigations.

The invasive guava root-knot nematode (GRKN), Meloidogyne enterolobii, was discovered in NC cotton fields in late 2011 and has now been detected in soybean, cotton, tobacco, and sweetpotato fields in eight eastern NC counties. GRKN is more aggressive than other RKN species, it overcomes all known crop resistances to RKN, and few options to reduce the damage in NC crops are currently known. The threat to NC sweetpotato industries and the communities they serve, currently estimated at 95,000 harvested acres worth $342 million, is of particular concern because of potential crop damage and interstate commerce restrictions imposed by recent state GRKN quarantines. The proposed project seeks relatively rapid solutions to limit GRKN damage in NC sweetpotatoes by field evaluation of potential nematicides for GRKN control while more long-term integrative management options are explored. An extension to the current GRKN detection survey into NC soybean and tobacco crops will also be implemented.

This proposal describes the preliminary steps in a project to identify and characterize genes conferring resistance to the bull-whip phenotype associated with calcium deficiency. Calcium uptake is affected by a number of factors including water availability and uptake, pH, salt levels and the presence of cations such as magnesium and aluminum. While bull-whip symptoms are rarely seen in the field in North Carolina, it is likely that the genes associated with bull-whip resistance play fundamental roles in nutrient and water uptake in the plant. So by using the bull-whip phenotype as a convenient indicator of nutrient or water stress we hope to identify genes that play a role in important agronomic traits such as drought resistance, salt and aluminum tolerance and nutrient uptake.

The Micropropagation and Repository Unit (MPRU) at North Carolina State University (NCSU) is currently the National Clean Plant Network center that produces, maintains and distributes pathogen-tested G1 material of berry crops (strawberry, blackberry, raspberry and blueberry), sweetpotato to industry and researchers in the U.S., and additionally proposes to develop capacity in muscadine grapes. This project will ensure that high quality plant material will be developed and distributed under the standards established by NCPN.

We have created a set of maize populations designed for the identification of maize disease resistance genes. We have characterized these populations for resistance to three fungal disease and have identified resistance genes which confer resistance to more than one disease. During 2018 we will confirm the effects of these genes and refine our knowledge of their genomic positions. We expect these genes to be of particular utility in the southeastern US.

We have created a set of corn populations, consisting of 1749 lines, designed for the identification of maize disease resistance genes. We have characterized these populations for resistance to three fungal diseases and have identified resistance genes which confer resistance to more than one disease. We are requesting funding to enable the deposition of these lines in the maize genetic stock center so they will be available for use by other scientists interested in characterizing disease resistance in corn.