Ethylene Responses (ethylene + response)

Distribution by Scientific Domains


Selected Abstracts


Calcium requirement for ethylene-dependent responses involving 1-aminocyclopropane-1-carboxylic acid oxidase in radicle tissues of germinated pea seeds,

PLANT CELL & ENVIRONMENT, Issue 5 2003
L. PETRUZZELLI
ABSTRACT The Ca2+ requirements of ethylene-dependent responses were investigated in germinating seeds of Pisum sativum L. using 1-aminocyclopropane-1-carboxylic acid (ACC) oxidase (Ps-ACO1), ACC synthase (Ps-ACS2) and class I , -1,3-glucanase as molecular markers. Ethylene biosynthesis and responsiveness are localized to the elongation and differentiation zones of the pea radicle. Ethylene treatment induced ectopic root hair formation in the cell elongation zone and promoted root hair elongation growth in the radicles of germinated seeds. Characterized Ca2+ antagonists, including EGTA, lanthanum, verapamil, ruthenium red, W-7, lithium and neomycin, were used to test for the involvement of the apoplastic and the intracellular Ca2+ -pool, the Ca2+/calmodulin complex and the phoshoinositide (PI) cycle in the ethylene responses. Ca2+ release from internal pools, but no appreciabe apoplastic Ca2+, is involved in the transcriptional induction by ethylene of Ps-ACO1 and in ectopic root hair formation in the radicle elongation zone of germinated pea seeds. Furthermore, the Ca2+/calmodulin complex and the PI cycle seem to be involved in these ethylene responses. In contrast, both the intracellular and the apoplastic Ca2+ -pools are required for the negative and positive ethylene responses to the gene expression of PS-ACS2 and class I , -1,3-glucanase, respectively; and, apoplastic Ca2+ also promotes root hair elongation growth. Tissues from adult plants and germinating seeds exhibit temporal and spatial differences in the signal/response coupling by Ca2+ of ethylene-regulated processes. [source]


Genetic dissection of the role of ethylene in regulating auxin-dependent lateral and adventitious root formation in tomato

THE PLANT JOURNAL, Issue 1 2010
Sangeeta Negi
Summary In this study we investigated the role of ethylene in the formation of lateral and adventitious roots in tomato (Solanum lycopersicum) using mutants isolated for altered ethylene signaling and fruit ripening. Mutations that block ethylene responses and delay ripening ,Nr (Never ripe), gr (green ripe), nor (non ripening), and rin (ripening inhibitor) , have enhanced lateral root formation. In contrast, the epi (epinastic) mutant, which has elevated ethylene and constitutive ethylene signaling in some tissues, or treatment with the ethylene precursor 1-aminocyclopropane carboxylic acid (ACC), reduces lateral root formation. Treatment with ACC inhibits the initiation and elongation of lateral roots, except in the Nr genotype. Root basipetal and acropetal indole-3-acetic acid (IAA) transport increase with ACC treatments or in the epi mutant, while in the Nr mutant there is less auxin transport than in the wild type and transport is insensitive to ACC. In contrast, the process of adventitious root formation shows the opposite response to ethylene, with ACC treatment and the epi mutation increasing adventitious root formation and the Nr mutation reducing the number of adventitious roots. In hypocotyls, ACC treatment negatively regulated IAA transport while the Nr mutant showed increased IAA transport in hypocotyls. Ethylene significantly reduces free IAA content in roots, but only subtly changes free IAA content in tomato hypocotyls. These results indicate a negative role for ethylene in lateral root formation and a positive role in adventitious root formation with modulation of auxin transport as a central point of ethylene,auxin crosstalk. [source]


Ethylene regulates lateral root formation and auxin transport in Arabidopsis thaliana

THE PLANT JOURNAL, Issue 2 2008
Sangeeta Negi
Summary Lateral root branching is a genetically defined and environmentally regulated process. Auxin is required for lateral root formation, and mutants that are altered in auxin synthesis, transport or signaling often have lateral root defects. Crosstalk between auxin and ethylene in root elongation has been demonstrated, but interactions between these hormones in the regulation of Arabidopsis lateral root formation are not well characterized. This study utilized Arabidopsis mutants altered in ethylene signaling and synthesis to explore the role of ethylene in lateral root formation. We find that enhanced ethylene synthesis or signaling, through the eto1-1 and ctr1-1 mutations, or through the application of 1-aminocyclopropane-1-carboxylic acid (ACC), negatively impacts lateral root formation, and is reversible by treatment with the ethylene antagonist, silver nitrate. In contrast, mutations that block ethylene responses, etr1-3 and ein2-5, enhance root formation and render it insensitive to the effect of ACC, even though these mutants have reduced root elongation at high ACC doses. ACC treatments or the eto1-1 mutation significantly enhance radiolabeled indole-3-acetic acid (IAA) transport in both the acropetal and the basipetal directions. ein2-5 and etr1-3 have less acropetal IAA transport, and transport is no longer regulated by ACC. DR5-GUS reporter expression is also altered by ACC treatment, which is consistent with transport differences. The aux1-7 mutant, which has a defect in an IAA influx protein, is insensitive to the ethylene inhibition of root formation. aux1-7 also has ACC-insensitive acropetal and basipetal IAA transport, as well as altered DR5-GUS expression, which is consistent with ethylene altering AUX1-mediated IAA uptake, and thereby blocking lateral root formation. [source]


Host and non-host pathogens elicit different jasmonate/ethylene responses in Arabidopsis

THE PLANT JOURNAL, Issue 5 2004
Laurent Zimmerli
Summary Arabidopsis does not support the growth and asexual reproduction of the barley pathogen, Blumeria graminis f. sp. hordei Bgh). A majority of germlings fail to penetrate the epidermal cell wall and papillae. To gain additional insight into this interaction, we determined whether the salicylic acid (SA) or jasmonate (JA)/ethylene (ET) defence pathways played a role in blocking barley powdery mildew infections. Only the eds1 mutant and NahG transgenics supported a modest increase in penetration success by the barley powdery mildew. We also compared the global gene expression patterns of Arabidopsis inoculated with the non-host barley powdery mildew to those inoculated with a virulent, host powdery mildew, Erysiphe cichoracearum. Genes repressed by inoculations with non-host and host powdery mildews relative to non-inoculated control plants accounted for two-thirds of the differentially expressed genes. A majority of these genes encoded components of photosynthesis and general metabolism. Consistent with this observation, Arabidopsis growth was inhibited following inoculation with Bgh, suggesting a shift in resource allocation from growth to defence. A number of defence-associated genes were induced during both interactions. These genes likely are components of basal defence responses, which do not effectively block host powdery mildew infections. In addition, genes encoding defensins, anti-microbial peptides whose expression is under the control of the JA/ET signalling pathway, were induced exclusively by non-host pathogens. Ectopic activation of JA/ET signalling protected Arabidopsis against two biotrophic host pathogens. Taken together, these data suggest that biotrophic host pathogens must either suppress or fail to elicit the JA/ET signal transduction pathway. [source]