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ABA Treatment (aba + treatment)
Selected AbstractsAbscisic acid deficiency leads to rapid activation of tomato defence responses upon infection with Erwinia chrysanthemiMOLECULAR PLANT PATHOLOGY, Issue 1 2008BOB ASSELBERGH SUMMARY In addition to the important role of abscisic acid (ABA) in abiotic stress signalling, basal and high ABA levels appear to have a negative effect on disease resistance. Using the ABA-deficient sitiens tomato (Solanum lycopersicum) mutant and different application methods of exogenous ABA, we demonstrated the influence of this plant hormone on disease progression of Erwinia chrysanthemi. This necrotrophic plant pathogenic bacterium is responsible for soft rot disease on many plant species, causing maceration symptoms mainly due to the production and secretion of pectinolytic enzymes. On wild-type (WT) tomato cv. Moneymaker E. chrysanthemi leaf inoculation resulted in maceration both within and beyond the infiltrated zone of the leaf, but sitiens showed a very low occurrence of tissue maceration, which never extended the infiltrated zone. A single ABA treatment prior to infection eliminated the effect of pathogen restriction in sitiens, while repeated ABA spraying during plant development rendered both WT and sitiens very susceptible. Quantification of E. chrysanthemi populations inside the leaf did not reveal differences in bacterial growth between sitiens and WT. Sitiens was not more resistant to pectinolytic cell-wall degradation, but upon infection it showed a faster and stronger activation of defence responses than WT, such as hydrogen peroxide accumulation, peroxidase activation and cell-wall fortifications. Moreover, the rapid activation of sitiens peroxidases was also observed after application of bacteria-free culture filtrate containing E. chrysanthemi cell-wall-degrading enzymes and was absent during infection with an out E. chrysanthemi mutant impaired in secretion of these extracellular enzymes. [source] Overexpression of rice isoflavone reductase-like gene (OsIRL) confers tolerance to reactive oxygen speciesPHYSIOLOGIA PLANTARUM, Issue 1 2010Sang Gon Kim Isoflavone reductase is an enzyme involved in isoflavonoid biosynthesis in plants. However, rice isoflavone reductase-like gene (OsIRL, accession no. AY071920) has not been unraveled so far. Here, we have characterized its behavior in response to oxidizing agents. Using Northern and Western blot analyses, the OsIRL gene and protein were shown to be down-regulated in young seedling roots treated with reduced glutathione (GSH) and diphenyleneiodonium (DPI), known quenchers of reactive oxygen species (ROS). The OsIRL transcript level in rice suspension-cultured cells was also found to be induced by oxidants such as hydrogen peroxide (H2O2), ferric chloride (FeCl3), methyl viologen (MV) and glucose/glucose oxidase (G/GO), but down-regulated when co-treated with GSH. Furthermore, to investigate whether overexpression of OsIRL in transgenic rice plants promotes resistance to ROS, we generated transgenic rice lines overexpressing the OsIRL gene under an abscisic acid (ABA) inducible promoter. Results showed that the OsIRL transgenic rice line activated by ABA treatment was tolerant against MV and G/GO-induced stress in rice leave and suspension-cultured cells. Our results strongly suggest the involvement of OsIRL in homeostasis of ROS. [source] Biochemical and molecular responses to water stress in resurrection plantsPHYSIOLOGIA PLANTARUM, Issue 2 2004Giovanni Bernacchia A small group of angiosperms, known as resurrection plants, can tolerate extreme dehydration. They survive in arid environments because they are able to dehydrate, remain quiescent during long periods of drought, and then resurrect upon rehydration. Dehydration induces the expression of a large number of transcripts in resurrection plants. Gene products with a putative protective function such as LEA proteins have been identified; they are expressed at high levels in the cytoplasm or in chloroplasts upon dehydration and/or ABA treatment of vegetative tissue. An increase in sugar concentration is usually observed at the onset of desiccation in vegetative tissue of resurrection plants. These sugars may be effective in osmotic adjustment or they may stabilize membrane structures and proteins. Regulatory genes such as a protein translation initiation factor, homeodomain-leucine zipper genes and a gene probably working as a regulatory RNA have been isolated and characterized. The knowledge of the biochemical and molecular responses that occur during the onset of drought may help to improve water stress tolerance in plants of agronomic importance. [source] AtCHIP functions as an E3 ubiquitin ligase of protein phosphatase 2A subunits and alters plant response to abscisic acid treatmentTHE PLANT JOURNAL, Issue 4 2006Jinhua Luo Summary CHIP proteins are E3 ubiquitin ligases that promote degradation of Hsp70 and Hsp90 substrate proteins through the 26S proteasome in animal systems. A CHIP-like protein in Arabidopsis, AtCHIP, also has E3 ubiquitin ligase activity and has important roles to play under conditions of abiotic stress. In an effort to study the mode of action of AtCHIP in plant cells, proteins that physically interact with it were identified. Like its animal orthologs, AtCHIP interacts with a unique class of ubiquitin-conjugating enzymes (UBC or E2) that belongs to the stress-inducible UBC4/5 class in yeast. AtCHIP also interacts with other proteins, including an A subunit of protein phosphatase 2A (PP2A). This PP2A subunit appears to be a substrate of AtCHIP, because it can be ubiquitylated by AtCHIP in vitro and because the activity of PP2A is increased in AtCHIP -overexpressing plants in the dark or under low-temperature conditions. Unlike the rcn1 mutant, that has reduced PP2A activity due to a mutation in one of the A subunit genes of PP2A, AtCHIP -overexpressing plants are more sensitive to ABA treatment. Since PP2A was previously shown to be involved in low-temperature responses in plants, the low-temperature-sensitive phenotype observed in AtCHIP -overexpressing plants might be partly due to the change in PP2A activity. These data suggest that the E3 ubiquitin ligase AtCHIP may function upstream of PP2A in stress-responsive signal transduction pathways under conditions of low temperature or in the dark. [source] The 6-phosphogluconate Dehydrogenase Genes Are Responsive to Abiotic Stresses in RiceJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 5 2007Fu-Yun Hou Abstract Glucose-6-phosphate dehydrogenase (G6PDH, E.C. 1.1.1.49) and 6-phosphogluconate dehydrogenase (6PGDH, EC 1.1.1.44) are both key enzymes of the pentose phosphate pathway (PPP). The OsG6PDH1 and Os6PGDH1 genes encoding cytosolic G6PDH and cytosolic 6PGDH were isolated from rice (Oryza sativa L.). We have shown that Os6PGDH1 gene was up-regulated by salt stress. Here we reported the isolation and characterization of Os6PGDH2 from rice, which encode the plastidic counterpart of 6PGDH. Genomic organization analysis indicated that OsG6PDH1 and OsG6PDH2 genes contain multiple introns, whereas two Os6PGDH1 and Os6PGDH2 genes have no introns in their translated regions. In a step towards understanding the functions of the pentose phosphate pathway in plants in response to various abiotic stresses, the expressions of four genes in the rice seedlings treated by drought, cold, high salinity and abscisic acid (ABA) were investigated. The results show that OsG6PDH1 and OsG6PDH2 are not markedly regulated by the abiotic stresses detected. However, the transcript levels of both Os6PGDH1 and Os6PGDH2 are up-regulated in rice seedlings under drought, cold, high salinity and ABA treatments. Meanwhile, the enzyme activities of G6PDH and 6PGDH in the rice seedlings treated by various abiotic stresses were investigated. Like the mRNA expression patterns, G6PDH activity remains constant but the 6PGDH increases steadily during the treatments. Taken together, we suggest that the pentose phosphate pathway may play an important role in rice responses to abiotic stresses and the second key enzyme of PPP, 6PGDH, may function as a regulator controlling the efficiency of the pathway under abiotic stresses. (Handling editor: Kang Chong) [source] | ||||||||||