Paul B Larsen

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Aluminum (Al) toxicity in acid soils is a worldwide agricultural problem that severely limits crop productivity through inhibition of root growth. Previously, Arabidopsis mutants with increased Al sensitivity were isolated in order to identify genes important for Al tolerance in plants. One mutant, als3, exhibited extreme root growth inhibition in the(More)
Aluminum toxicity in acid soils severely limits crop productivity through inhibition of root growth and, consequently, shoot development. Several Arabidopsis mutants were previously identified as having roots with Al hypersensitivity, suggesting that these represent deleterious mutations affecting genes required for either Al tolerance or resistance(More)
The senescence of carnation (Dianthus caryophyllus L.) flower petals is regulated by the phytohormone ethylene and is associated with considerable catabolic activity including the loss of protein. In this paper we present the molecular cloning of a cysteine proteinase and show that its expression is regulated by ethylene and associated with petal(More)
Ethylene signaling in Arabidopsis begins at a family of five ethylene receptors that regulate activity of a downstream mitogen-activated protein kinase kinase kinase, CTR1. Triple and quadruple loss-of-function ethylene receptor mutants display a constitutive ethylene response phenotype, indicating they function as negative regulators in this pathway. No(More)
Ethylene signaling is a complex pathway that has been intensively analyzed partly due to its importance to the manifestation of horticultural phenomena, including fruit ripening and tissue senescence. In order to further our understanding of how this pathway is regulated, a screen for Arabidopsis mutants with increased ethylene response was conducted. From(More)
Aluminium (Al) toxicity is a global agricultural problem that occurs in acid soil environments and severely limits root growth and crop productivity. The isolation and characterization of a gene, ALS3, which is absolutely required by Arabidopsis seedlings for growth in an Al-toxic environment was reported previously. Since the als3-1 loss-of-function mutant(More)
Phosphatidic acid (PA) has only recently been identified as an important eukaryotic lipid-signalling molecule. In plants, PA formation is triggered by various biotic and abiotic stresses, including wounding, pathogen attack, drought, salinity, cold, and freezing. However, few molecular targets of PA have been identified so far. One of the best characterized(More)
The eer3-1 loss-of-function mutant, which was identified by screening for Arabidopsis mutant seedlings with an enhanced ethylene response, has both increased sensitivity and profound exaggeration of response to ethylene when visually assessed, yet exhibits partial ethylene insensitivity at the molecular level. The eer3-1 mutation represents a conditional(More)
By screening etiolated Arabidopsis seedlings for mutants with aberrant ethylene-related phenotypes, we identified a mutant that displays features of the ethylene-mediated triple response even in the absence of ethylene. Further characterization showed that the phenotype observed for the dark-grown seedlings of this mutant is reversible by prevention of(More)
An Arabidopsis mutant, eer5-1, which has an enhanced ethylene response in etiolated seedlings, including hypersensitivity and extreme exaggeration of response to ethylene, was isolated and characterized. As with other identified eer mutants, the enhanced response phenotype of eer5-1 was correlated with failure to induce appropriately a subset of(More)