Pathogenic Interactions of Alternaria crassa and Phenolic Metabolism in Jimsonweed (Datura stramonium L.) Varieties

Abstract

Alternaria crassa, a mycoherbicide for jimsonweed control, was tested for differential effects on growth, infectivity, and phenolic metabolism of two field-collected jimsonweed varieties. Seeds from field-grown red- and green-stemmed jimsonweed varieties were grown in the greenhouse and spores were applied in aqueous solutions. Infection studies showed no significant differences between the two weed varieties when tested at various growth stages from cotyledonary to 8–leaf stage at 2.5 × 104spores ml−1. Spore dose response tests with A. crassa spores (6.25 to 100 x103spores ml−1) showed no significant varietal differences in disease ratings. Extractable phenylalanine ammonia-lyase activity increased nearly equally (2- to 3-fold above control) in both varieties (8- to 9-leaf stage) 48 to 72 h after treatment with 5 × 104spores ml−1. The only significant differences between treated varieties occurred 72 h after treatment. Exposure to A. crassa lowered total ethanol-soluble phenolic levels in both varieties 72 h after treatment. Spectrophotometric scans (400 to 700 nm) of ethanol extracts (72 h after treatment) indicated that infection caused some absorbance increases, especially in red-stemmed jimsonweed. Anthocyanin content was about 11-fold higher in red-stemmed than green-stemmed jimsonweed, and A. crassa treatment slightly increased the anthocyanin absorption peak of the red-stemmed variety.

Interaction of Glufosinate and <i>Colletotrichum truncatum</i> on Ammonia Levels and Glutamine Synthetase Activity in Hemp Sesbania

“…PAL activity was elevated 3-fold above uninoculated plants and remained high for several days. Similar results were reported for Alternaria crassa, a fungal bioherbicide that controls jimsonweed (Datura stramonium) [65]. Many examples have been reported and summarized with respect to the correlation of PAL activity with pathogen challenge and plant defense e.g.…”

Interaction of Gibberellic Acid and Glyphosate on Growth and Phenolic Metabolism in Soybean Seedlings

“…The present study, coupled with the companion study on IAA-glyphosate interactions in soybean seedlings [41], provides a template for future studies that could provide novel information relative to herbicide behavior in plants and the action of bioherbicides in weeds. We have studied various bioherbicides (mostly phytopathogenic fungi) for the control of major weeds as outlined elsewhere [48,49] and discovered involvement with secondary metabolism (PAL) in several pathogen-weed interaction studies [50][51][52]. Secondary plant metabolism is critically involved in plant stress and defense mechanisms [30,31].…”

Chemical Interactions with Bioherbicides to Improve Efficacy

“…I{ands is a fungal pathogen with bioherbicidal potential for the control ofjilnsonweed (33). Exalnination of defense responses of red-stenllncd and grecn-stclnnled varieties of jilnsonwecd during challenge by the pathogen indicated that PAL activity was elevated 2-to 3-fold above untreated control levels in both biotypes (127). Anthocyanin content (originally about II-fold higher in red-than green-stctnnlcd plants) \vas also increased after infection" especially in rcd-stel11n1cd plants.…”