2007 Annual Report 1a.Objectives (from AD-416) Investigate basic aspects of weed biology with an emphasis on the areas of herbicide-resistant weeds and weedy vines, in an effort to provide more effective control practices. Determine the way in which weedy vine species are able to vine and use supplementary structures as tendrils and holdfasts in their ability to climb on other plants and surfaces. Establish structural and biochemical differences between vines and, including touch sensitivity responses. Develop in vitro assays to determine which compounds might effectively inhibit twining responses. Discover mechanisms of herbicide resistance to existing weed biotypes, especially in terms of resistance to glyphosate, paraquat and quinclorac. Develop systems to monitor risk of herbicide development to existing weeds. Determine pathways for herbicide metabolism and herbicide mode of action relative to resistance. 1b.Approach (from AD-416) Much of the approach of this project will involve microscopic approaches such as light microscopy, fluorescence and standard microscopy, scanning and transmission electron microcopy. These will serve as first indicators as to the effects of herbicides, possible differences in herbicide-tolerant/ resistant biotypes, and changes that occur in vining weeds such as touch sensitivity and ability to climb. Basic growth analyses will determine major changes that occur in the resistant biotypes or vining weeds as a consequence of either herbicide resistance or vining. Subsequent biochemical and immunochemical techniques will identify more specifically the changes, using techniques of immunocytochemistry and proteomics. Specific probes will be developed to determine especially recalcitrant aspects of the project. 3.Progress Report None 4.Accomplishments In our previous studies, we found that gelatinous fibers were the structure that elicited the coiling in redvine tendrils. To further these studies, we examined a number of species that either have twining stems or tendrils that coil. In all cases we found gelatinous fibers, but the arrangement and occurrence of the fibers differed significantly between species. In tendrils that are sensitive to touch on all surfaces, the gelatinous fibers were also present on all surfaces. However, in species with tendrils that are sensitive only on one surface, the gelatinous fibers were only present on that touch-sensitive surface. In the twining stems of vines, the gelatinous fibers occur dispersed in between the vascular tissue and the epidermis and increase in number with an increasing diameter of the support on which the vine is ascending. Gelatinous fibers seem to lock the vine into position on the support. Thus, all vines that use tendrils or twining stems use gelatinous fibers to cause the coiling or twining motion. A biotype of bindweed resistant to glyphosate was selected by repeated spraying of glyphosate over a field infested with these weeds. After spraying with glyphosate, bindweed plants had an unusual symptomatology. Areas away from the veins were bright green, like untreated controls, but areas near the veins had significantly less chlorophyll. In contrast, susceptible plants were more uniformly affected. Structural studies revealed that in the resistant biotype, chloroplasts near the vein exhibited ultrastructure typical of glyphosate treatment (thylakoids organized into magnograna) whereas chloroplasts away from the vein were no different than untreated controls. In the susceptible biotype, all chloroplasts were affected. These data indicate that a restricted movement away from the veins in the resistant biotype is responsible for the glyphosate resistance. 5.Significant Activities that Support Special Target Populations None 6.Technology Transfer Number of web sites managed 1 Number of non-peer reviewed presentations and proceedings 2 Number of newspaper articles and other presentations for non-science audiences 1 Review Publications Meloche, C.G., Knox, J.P., Vaughn, K.C. 2007. A cortical band of gelatinous fibers causes the coiling of redvine tendrils: a model based upon structural and immunocytochemical studies. Planta 225:485-498. Vaughn, K.C., Talbot, M.J., Offler, C.E., Mccurdy, D.W. 2007. Wall ingrowths in epidermal transfer cell of Vica faba Cotyledons are modified primary walls marked by localized accumulations of Arabinogalactan proteins. Journal of Plant Cell Physiology 48(1):159-168. Vaughn, K.C. 2007. Conversion of the searching hyphae of dodder into xylic and phloic hyphae: a cytochemical and immunocytochemical investigation. International Journal of Plant Science 167(6):1099-1114. Turley, R.B., Scheffler, J.A., Vaughn, K.C. 2007. Line Development and Properties of Fifteen Fuzzless Seed Lines of Upland Cotton (Gossypium hirsutum L.). Euphytica. (2007) 156:57-65