@article{bartz_glassbrook_danehower_cubeta_2013, title={Modulation of the phenylacetic acid metabolic complex by quinic acid alters the disease-causing activity of Rhizoctonia solani on tomato}, volume={89}, ISSN={0031-9422}, url={http://dx.doi.org/10.1016/j.phytochem.2012.09.018}, DOI={10.1016/j.phytochem.2012.09.018}, abstractNote={The metabolic control of plant growth regulator production by the plant pathogenic fungus Rhizoctonia solani Kühn (teleomorph = Thanatephorus cucumeris (A.B. Frank) Donk) and consequences associated with the parasitic and saprobic activity of the fungus were investigated. Fourteen genetically distinct isolates of the fungus belonging to anastomosis groups (AG) AG-3, AG-4, and AG-1-IA were grown on Vogel's minimal medium N with and without the addition of a 25 mM quinic acid (QA) source of carbon. The effect of QA on fungal biomass was determined by measuring the dry wt of mycelia produced under each growth condition. QA stimulated growth of 13 of 14 isolates of R. solani examined. The production of phenylacetic acid (PAA) and the chemically related derivatives 2-hydroxy-PAA, 3-hydroxy-PAA, 4-hydroxy-PAA, and 3-methoxy-PAA on the two different media was compared by gas chromatography coupled with mass spectrometry (GC–MS). The presence of QA in the growth medium of R. solani altered the PAA production profile, limiting the conversion of PAA to derivative forms. The effect of QA on the ability of R. solani to cause disease was examined by inoculating tomato (Solanum lycopersicum L.) plants with 11 isolates of R. solani AG-3 grown on media with and without the addition of 25 mM QA. Mean percent survival of tomato plants inoculated with R. solani was significantly higher when the fungal inoculum was generated on growth medium containing QA. The results of this study support the hypotheses that utilization of QA by R. solani leads to reduced production of the plant growth regulators belonging to the PAA metabolic complex which can suppress plant disease development.}, journal={Phytochemistry}, publisher={Elsevier BV}, author={Bartz, Faith E. and Glassbrook, Norman J. and Danehower, David A. and Cubeta, Marc A.}, year={2013}, month={May}, pages={47–52} }
 @article{bartz_glassbrook_danehower_cubeta_2012, title={Elucidating the role of the phenylacetic acid metabolic complex in the pathogenic activity of Rhizoctonia solani anastomosis group 3}, volume={104}, ISSN={["0027-5514"]}, DOI={10.3852/11-084}, abstractNote={The soil fungus Rhizoctonia solani produces phytotoxic phenylacetic acid (PAA) and hydroxy (OH-) and methoxy (MeO-) derivatives of PAA. However, limited information is available on the specific role that these compounds play in the development of Rhizoctonia disease symptoms and concentration(s) required to induce a host response. Reports that PAA inhibits the growth of R. solani conflict with the established ability of the fungus to produce and metabolize PAA. Experiments were conducted to clarify the role of the PAA metabolic complex in Rhizoctonia disease. In this study the concentration of PAA and derivatives required to induce tomato root necrosis and stem canker, in the absence of the fungus, and the concentration that inhibits mycelial growth of R. solani were determined. The effect of exogenous PAA and derivatives of PAA on tomato seedling growth also was investigated. Growth of tomato seedlings in medium containing 0.1–7.5 mM PAA and derivatives induced necrosis of up to 85% of root system. Canker development resulted from injection of tomato seedling stems with 7.5 mM PAA, 3-OH-PAA, or 3-MeO-PAA. PAA in the growth medium reduced R. solani biomass, with 50% reduction observed at 7.5 mM. PAA, and derivatives were quantified from the culture medium of 14 isolates of R. solani belonging to three distinct anastomosis groups by GC-MS. The quantities ranged from below the limit of detection to 678 nM, below the concentrations experimentally determined to be phytotoxic. Correlation analyses revealed that isolates of R. solani that produced high PAA and derivatives in vitro also caused high mortality on tomato seedlings. The results of this investigation add to the body of evidence that the PAA metabolic complex is involved in Rhizoctonia disease development but do not indicate that production of these compounds is the primary or the only determinant of pathogenicity.}, number={4}, journal={MYCOLOGIA}, author={Bartz, Faith E. and Glassbrook, Norman J. and Danehower, David A. and Cubeta, Marc A.}, year={2012}, pages={793–803} }