Clarence A. Ryan

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Inducible defensive responses in plants are known to be activated locally and systemically by signaling molecules that are produced at sites of pathogen or insect attacks, but only one chemical signal, ethylene, is known to travel through the atmosphere to activate plant defensive genes. Methyl jasmonate, a common plant secondary compound, when applied to(More)
Systemin, an 18-amino-acid polypeptide released from wound sites on tomato leaves caused by insects or other mechanical damage, systemically regulates the activation of over 20 defensive genes in tomato plants in response to herbivore and pathogen attacks. Systemin is processed from a larger prohormone protein, called prosystemin, by proteolytic cleavages.(More)
Innate immunity is initiated in animals and plants through the recognition of a variety of pathogen-associated molecules that in animals are called pathogen-associated molecular patterns and in plants are called elicitors. Some plant pathogen-derived elicitors have been identified as peptides, but peptide elicitors derived from the plant itself that(More)
Hydrogen peroxide (H2O2) generated in response to wounding can be detected at wound sites and in distal leaf veins within 1 hr after wounding. The response is systemic and maximizes at about 4-6 hr in both wounded and unwounded leaves, and then declines. The timing of the response corresponds with an increase in wound-inducible polygalacturonase (PG) mRNA(More)
A 5-kDa polypeptide was isolated from tobacco leaves that induced a rapid alkalinization of the culture medium of tobacco suspension-cultured cells and a concomitant activation of an intracellular mitogen-activated protein kinase. An N-terminal sequence was obtained, and a cDNA coding for the 49-aa polypeptide was isolated from a tobacco cDNA library. The(More)
Defensive genes in plants can be activated by several different types of nonpeptide signaling molecules. An endogenous polypeptide, consisting of 18 amino acids, was isolated from tomato leaves and was able at very low concentrations to induce the synthesis of two wound-inducible proteinase inhibitor proteins when supplied to young tomato plants. The(More)
The systemic accumulation of both hydrogen peroxide (H(2)O(2)) and proteinase inhibitor proteins in tomato leaves in response to wounding was inhibited by the NADPH oxidase inhibitors diphenylene iodonium (DPI), imidazole, and pyridine. The expression of several defense genes in response to wounding, systemin, oligosaccharides, and methyl jasmonate also was(More)
AtPep1 is a 23-aa endogenous peptide elicitor from Arabidopsis leaves that signals the activation of components of the innate immune response against pathogens. Here, we report the isolation of an AtPep1 receptor from the surface of Arabidopsis suspension-cultured cells. An (125)I-labeled AtPep1 analog interacted with suspension-cultured Arabidopsis with a(More)
Some animal and yeast hormone genes produce prohormone polypeptides that are proteolytically processed to produce multiple copies of hormones with the same or different functions. In plants, four polypeptides have been identified that can be classed as hormones (intercellular chemical messengers) but none are known to be produced as multiple copies from a(More)
The activation of defense genes in tomato plants has been shown to be mediated by an octadecanoic acid-based signaling pathway in response to herbivore attack or other mechanical wounding. We report here that a tomato mutant (JL5) deficient in the activation of would-inducible defense genes is also compromised in resistance toward the lepidopteran predator(More)