| 1. |
- Johansson Jänkänpää, Hanna, 1981-, et al.
(författare)
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Arabidopsis thaliana with reduced capacity for non-photochemical quenching show altered herbivore preference
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Under natural conditions, plants have to cope with a multitude of stresses, two of those are light-stress and herbivory. Plants have evolved several mechanisms to avoid the damage done by strong and fluctuating light and one important photoprotection mechanism is the qE-type of non-photochemical quenching (NPQ) where the PsbS protein is involved. We have compared Arabidopsis thaliana wild type and two "photoprotection genotypes", npq4 and oePsbS that, respectively, lack and overexpress PsbS. In dual-choice feeding experiments on field-grown plants with a specialist (Plutella xylostella) and a generalist (Spodoptera littoralis) insect herbivore, both herbivores preferred the plants with higher expression of PsbS. Also both herbivores survived equally well on the different genotypes but for oviposition, female adults of Plutella xylostella preferred plants with lower expression of PsbS. No difference in the amount and composition of the ten most prominent glucosinolates — the most important substances in the Arabidopsis chemical warfare against herbivores — were found between the genotypes. When leaves of the three genotypes, after transfer from a growth chamber to the field, were profiled for changes in composition of metabolites using GC-MS, we found significant differences in metabolite composition. This suggests that differences in herbivore preferences were rather a consequence of changes in the primary metabolism of the plant rather than differences in the composition of typical "defence compounds". In npq4, superoxide accumulated under high light conditions and is likely to directly, or indirectly after dismutation to H2O2, trigger the metabolic change.
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| 2. |
- Johansson Jänkänpää, Hanna, et al.
(författare)
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Non-photochemical quenching capacity in arabidopsis thaliana affects herbivore behaviour
- 2013
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:1, s. e53232-
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Tidskriftsartikel (refereegranskat)abstract
- Under natural conditions, plants have to cope with numerous stresses, including light-stress and herbivory. This raises intriguing questions regarding possible trade-offs between stress defences and growth. As part of a program designed to address these questions we have compared herbivory defences and damage in wild type Arabidopsis thaliana and two "photoprotection genotypes", npq4 and oePsbS, which respectively lack and overexpress PsbS (a protein that plays a key role in qE-type non-photochemical quenching). In dual-choice feeding experiments both a specialist (Plutella xylostella) and a generalist (Spodoptera littoralis) insect herbivore preferred plants that expressed PsbS most strongly. In contrast, although both herbivores survived equally well on each of the genotypes, for oviposition female P. xylostella adults preferred plants that expressed PsbS least strongly. However, there were no significant differences between the genotypes in levels of the 10 most prominent glucosinolates; key substances in the Arabidopsis anti-herbivore chemical defence arsenal. After transfer from a growth chamber to the field we detected significant differences in the genotypes' metabolomic profiles at all tested time points, using GC-MS, but no consistent "metabolic signature'' for the lack of PsbS. These findings suggest that the observed differences in herbivore preferences were due to differences in the primary metabolism of the plants rather than their contents of typical "defence compounds". A potentially significant factor is that superoxide accumulated most rapidly and to the highest levels under high light conditions in npq4 mutants. This could trigger changes in planta that are sensed by herbivores either directly or indirectly, following its dismutation to H2O2.
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| 3. |
- Zulfugarov, Ismayil S., et al.
(författare)
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Enhanced resistance of PsbS-deficient rice (Oryza sativa L.) to fungal and bacterial pathogens
- 2016
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Ingår i: Journal of Plant Biology. - : Springer Berlin/Heidelberg. - 1226-9239 .- 1867-0725. ; 59:6, s. 616-626
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Tidskriftsartikel (refereegranskat)abstract
- The 22-kDa PsbS protein of Photosystem II is involved in nonphotochemical quenching (NPQ) of chlorophyll fluorescence. Genome-wide analysis of the expression pattern in PsbS knockout (KO) rice plants showed that a lack of this protein led to changes in the transcript levels of 406 genes, presumably a result of superoxide produced in the chloroplasts. The top Gene Ontology categories, in which expression was the most differential, included 'Immune response', 'Response to jasmonic acid', and 'MAPK cascade'. From those genes, we randomly selected nine that were up-regulated. Our microarray results were confirmed by quantitative RT-PCR analysis. The KO and PsbS RNAi (knockdown) plants were more resistant to pathogens Magnaporthe oryzae PO6-6 and Xanthomonas oryzae pv. oryzae than either the wild-type plants or PsbS-overexpressing transgenic line. These findings suggest that superoxide production might be the reason that these plants have greater pathogen resistance to fungal and bacterial pathogens in the absence of energy-dependent NPQ. For example, a high level of cell wall lignification in the KO mutants was possibly due to enhanced superoxide production. Our data indicate that certain abiotic stress-induced reactive oxygen species can promote specific signaling pathways, which then activate a defense mechanism against biotic stress in PsbS-KO rice plants.
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| 4. |
- Zulfugarov, Ismayil S., et al.
(författare)
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Production of superoxide from Photosystem II in a rice (Oryza sativa L.) mutant lacking PsbS
- 2014
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Ingår i: BMC Plant Biology. - : Springer Science and Business Media LLC. - 1471-2229. ; 14, s. 242-
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Tidskriftsartikel (refereegranskat)abstract
- Background: PsbS is a 22-kDa Photosystem (PS) II protein involved in non-photochemical quenching (NPQ) of chlorophyll fluorescence. Rice (Oryza sativa L.) has two PsbS genes, PsbS1 and PsbS2. However, only inactivation of PsbS1, through a knockout (PsbS1-KO) or in RNAi transgenic plants, results in plants deficient in qE, the energy-dependent component of NPQ. Results: In studies presented here, under fluctuating high light, growth of young seedlings lacking PsbS is retarded, and PSII in detached leaves of the mutants is more sensitive to photoinhibitory illumination compared with the wild type. Using both histochemical and fluorescent probes, we determined the levels of reactive oxygen species, including singlet oxygen, superoxide, and hydrogen peroxide, in leaves and thylakoids. The PsbS-deficient plants generated more superoxide and hydrogen peroxide in their chloroplasts. PSII complexes isolated from them produced more superoxide compared with the wild type, and PSII-driven superoxide production was higher in the mutants. However, we could not observe such differences either in isolated PSI complexes or through PSI-driven electron transport. Time-course experiments using isolated thylakoids showed that superoxide production was the initial event, and that production of hydrogen peroxide proceeded from that. Conclusion: These results indicate that at least some of the photoprotection provided by PsbS and qE is mediated by preventing production of superoxide released from PSII under conditions of excess excitation energy.
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