The primary goal of this proposal is to develop novel regeneration technologies needed to engineer walnut rootstocks for pest and disease resistance. The productivity of the walnut industry of California is dependent the availability of superior rootstocks to combat soil disease and pest problems. Individual selections displaying resistance to either Phytophthora crown and root rots or to root ...

BACKGROUND Allergic reactions to walnut can be life-threatening. Although IgE epitopes of walnut have been studied, CD4(+) T cell-specific epitopes for walnut remain uncharacterized. In particular, the relationship of both phenotype and frequency of walnut-specific T cells to the disease have not been examined. OBJECTIVES We sought to provide a thorough phenotypic analysis for walnut-reactive...

What is thousand cankers disease of walnut? Thousand caners disease (TCD) is a newly recognized disease (2008) of certain walnut species (Juglans) caused by a fungus (Geosmithia morbida) that is vectored by a bark beetle (Pityophthorus juglandis, the “walnut twig beetle”). Thousand cankers disease has produced widespread death of walnuts in many western states during the past decade. In recent ...

The health, sustainability, and commercial viability of eastern black walnut (Juglans nigra) are currently under threat from thousand cankers disease. The disease is caused by an invasive bark beetle species, the walnut twig beetle (Pityophthorus juglandis), and its associated fungal pathogen (Geosmithia morbida). Range expansion of the beetle and pathogen has likely been facilitated by transpo...

Since 2001, widespread mortality of black walnut (Juglans nigra) has been reported in Colorado, USA. Affected trees initially show a yellowing and thinning of leaves in the upper crown, followed by twig and branch dieback and ultimately tree death. We report that this mortality is the result of a combination of an expanded geographic range of the walnut twig beetle (Pityophthorus juglandis), it...

As a by-product of oil production, walnut proteins are considered as an additional source of plant protein for human food. To make full use of the protein resource, a comprehensive understanding of composition and characteristics of walnut proteins are required. Walnut proteins have been fractionated and characterized in this study. Amino acid composition, molecular weight distribution and gel ...

Plant parasitic nematodes can devastate walnut orchards and may remain dormant deep in the soil profile for several years, beyond reach of traditional pesticides. Nematicides are often very toxic to beneficial organisms and detrimental to the environment; several of the most effective are being phased out. Developing novel methods of diagnosis and control requires characterizing pathogens and t...

Juglans L. (walnuts and butternuts) is an economically and ecologically important genus in the family Juglandaceae. All Juglans are important nut and timber trees. Juglans regia (Common walnut), J. sigillata (Iron walnut), J. cathayensis (Chinese walnut), J. hopeiensis (Ma walnut), and J. mandshurica (Manchurian walnut) are native to or naturalized in China. A strongly supported phylogeny of th...

The content of walnut metabolites is related to its nutritive value and physiological characteristics, however, comprehensive information concerning the metabolome of walnut kernels is limited. In this study we analyzed the metabolites of walnut kernels at five developmental stages from filling to ripening using GC-MS-based untargeted metabolomics; of a total 252 peaks identified, 85 metabolite...

Acidithiobacillus ferrooxidans is a Gram-negative bacterium that obtains energy by oxidizing Fe(2+) or reduced sulfur compounds. This bacterium contributes to the formation of acid mine drainage (AMD). This study determined whether walnut shell powder inhibits the growth of A. ferrooxidans. First, the effects of walnut shell powder on Fe(2+) oxidization and H⁺ production were evaluated. Second,...