@article {1049, title = {Programmed cell death activated by Rose Bengal in Arabidopsis thaliana cell suspension cultures requires functional chloroplasts.}, journal = {Journal of experimental botany}, year = {2014}, month = {2014 Apr 10}, abstract = {Light-grown Arabidopsis thaliana cell suspension culture (ACSC) were subjected to mild photooxidative damage with Rose Bengal (RB) with the aim of gaining a better understanding of singlet oxygen-mediated defence responses in plants. Additionally, ACSC were treated with H2O2 at concentrations that induced comparable levels of protein oxidation damage. Under low to medium light conditions, both RB and H2O2 treatments activated transcriptional defence responses and inhibited photosynthetic activity, but they differed in that programmed cell death (PCD) was only observed in cells treated with RB. When dark-grown ACSC were subjected to RB in the light, PCD was suppressed, indicating that the singlet oxygen-mediated signalling pathway in ACSC requires functional chloroplasts. Analysis of up-regulated transcripts in light-grown ACSC, treated with RB in the light, showed that both singlet oxygen-responsive transcripts and transcripts with a key role in hormone-activated PCD (i.e. ethylene and jasmonic acid) were present. A co-regulation analysis proved that ACSC treated with RB exhibited higher correlation with the conditional fluorescence (flu) mutant than with other singlet oxygen-producing mutants or wild-type plants subjected to high light. However, there was no evidence for the up-regulation of EDS1, suggesting that activation of PCD was not associated with the EXECUTER- and EDS1-dependent signalling pathway described in the flu mutant. Indigo Carmine and Methylene Violet, two photosensitizers unable to enter chloroplasts, did not activate transcriptional defence responses in ACSC; however, whether this was due to their location or to their inherently low singlet oxygen quantum efficiencies was not determined.}, issn = {1460-2431}, doi = {10.1093/jxb/eru151}, url = {http://jxb.oxfordjournals.org/content/early/2014/04/09/jxb.eru151.long}, author = {Guti{\'e}rrez, Jorge and Gonz{\'a}lez-P{\'e}rez, Sergio and Garcia-Garcia, Francisco and Daly, Cara T and Lorenzo, Oscar and Revuelta, Jos{\'e} L and McCabe, Paul F and Arellano, Juan B} } @article {22112448, title = {Does singlet oxygen activate cell death in Arabidopsis cell suspension cultures? Analysis of the early transcriptional defence responses to high light stress.}, journal = {Plant signaling \& behavior}, volume = {6}, year = {2011}, month = {2011 Dec 1}, abstract = {

Can Arabidopsis cell suspension cultures (ACSC) provide a useful working model to investigate genetically-controlled defence responses with signalling cascades starting in chloroplasts? In order to provide a convincing answer, we analysed the early transcriptional profile of Arabidopsis cells at high light (HL). The results showed that ACSC respond to HL in a manner that resembles the singlet oxygen ( ( 1) O 2)-mediated defence responses described for the conditional fluorescent (flu) mutant of Arabidopsis thaliana. The flu mutant is characterized by the accumulation of free protochlorophyllide (Pchlide) in plastids when put into darkness and the subsequent production of ( 1) O 2 when the light is on. In ACSC, ( 1) O 2 is produced in chloroplasts at HL when excess excitation energy flows into photosystem II (PSII). Other reactive oxygen species are also produced in ACSC at HL, but to a lesser extent. When the HL stress ceases, ACSC recovers the initial rate of oxygen evolution and cell growth continues. We can conclude that chloroplasts of ACSC are both photosynthetically active and capable of initiating ( 1) O 2-mediated signalling cascades that activate a broad range of genetically-controlled defence responses. The up-regulation of transcripts associated with the biosynthesis and signalling pathways of OPDA (12-oxophytodienoic acid) and ethylene (ET) suggests that the activated defence responses at HL are governed by these two hormones. In contrast to the flu mutant, the ( 1) O 2-mediated defence responses were independent of the up-regulation of EDS1 (enhanced disease susceptibility) required for the accumulation of salicylic acid (SA) and genetically-controlled cell death.\ 

}, author = {Guti{\'e}rrez, Jorge and Gonz{\'a}lez-P{\'e}rez, Sergio and Garcia-Garcia, Francisco and Lorenzo, Oscar and Arellano, Juan B} } @article {21531897, title = {Early transcriptional defence responses in Arabidopsis cell suspension culture under high light conditions.}, journal = {Plant physiology}, volume = {156}, number = {3}, year = {2011}, month = {2011 Apr 29}, pages = {1439-56}, abstract = {

The early transcriptional defence responses and ROS production in Arabidopsis cell suspension culture (ACSC), containing functional chloroplasts, were examined at high light (HL). The transcriptional analysis revealed that most of the ROS markers identified among the 449 transcripts with significant differential expression were transcripts specifically up-regulated by singlet oxygen (1O2). On the contrary, minimal correlation was established with transcripts specifically up-regulated by superoxide radical (O2\•) or hydrogen peroxide (H2O2). The transcriptional analysis was supported by fluorescence microscopy experiments. The incubation of ACSC with the 1O2 sensor green reagent and 2{\textquoteright},7{\textquoteright}-dichlorofluorescein diacetate showed that the 30-min-HL-treated cultures emitted fluorescence that corresponded with the production of 1O2, but not of H2O2. Furthermore, the in vivo photodamage of the D1 protein of photosystem II (PSII) indicated that the photogeneration of 1O2 took place within the PSII reaction centre. Functional enrichment analyses identified transcripts that are key components of the ROS signalling transduction pathway in plants as well as others encoding transcription factors that regulate both ROS scavenging and water deficit stress. A meta-analysis examining the transcriptional profiles of mutants and hormone treatments in Arabidopsis showed a high correlation between ACSC at HL and the flu mutant family of Arabidopsis, a producer of 1O2 in plastids. Intriguingly, a high correlation was also observed with aba1 and max4, two mutants with defects in the biosynthesis pathways of two key (apo)carotenoid-derived plant hormones (i.e. ABA and strigolactones, respectively). ACSC has proven to be a valuable system for studying early transcriptional responses to HL stress.

}, url = {http://www.plantphysiol.org/content/early/2011/04/29/pp.111.177766.short?keytype=ref\&ijkey=ph5B6J2khjnqwzN}, author = {Gonz{\'a}lez-P{\'e}rez, Sergio and Guti{\'e}rrez, Jorge and Garcia-Garcia, Francisco and Osuna, Daniel and Joaqu{\'\i}n Dopazo and Lorenzo, Oscar and Revuelta, Jos{\'e} L and Arellano, Juan B} } @article {532, title = {Early transcriptional defense responses in Arabidopsis cell suspension culture under high-light conditions.}, journal = {Plant Physiol}, volume = {156}, year = {2011}, month = {2011 Jul}, pages = {1439-56}, abstract = {

The early transcriptional defense responses and reactive oxygen species (ROS) production in Arabidopsis (Arabidopsis thaliana) cell suspension culture (ACSC), containing functional chloroplasts, were examined at high light (HL). The transcriptional analysis revealed that most of the ROS markers identified among the 449 transcripts with significant differential expression were transcripts specifically up-regulated by singlet oxygen ((1)O(2)). On the contrary, minimal correlation was established with transcripts specifically up-regulated by superoxide radical or hydrogen peroxide. The transcriptional analysis was supported by fluorescence microscopy experiments. The incubation of ACSC with the (1)O(2) sensor green reagent and 2{\textquoteright},7{\textquoteright}-dichlorofluorescein diacetate showed that the 30-min-HL-treated cultures emitted fluorescence that corresponded with the production of (1)O(2) but not of hydrogen peroxide. Furthermore, the in vivo photodamage of the D1 protein of photosystem II indicated that the photogeneration of (1)O(2) took place within the photosystem II reaction center. Functional enrichment analyses identified transcripts that are key components of the ROS signaling transduction pathway in plants as well as others encoding transcription factors that regulate both ROS scavenging and water deficit stress. A meta-analysis examining the transcriptional profiles of mutants and hormone treatments in Arabidopsis showed a high correlation between ACSC at HL and the fluorescent mutant family of Arabidopsis, a producer of (1)O(2) in plastids. Intriguingly, a high correlation was also observed with ABA deficient1 and more axillary growth4, two mutants with defects in the biosynthesis pathways of two key (apo)carotenoid-derived plant hormones (i.e. abscisic acid and strigolactones, respectively). ACSC has proven to be a valuable system for studying early transcriptional responses to HL stress.

}, keywords = {Arabidopsis, Blotting, Western, Cell Culture Techniques, Cells, Cultured, Chloroplasts, Cluster Analysis, Gene Expression Profiling, Gene Expression Regulation, Plant, Hydrogen Peroxide, Light, mutation, Oligonucleotide Array Sequence Analysis, Photosystem II Protein Complex, Plant Growth Regulators, Reproducibility of Results, Reverse Transcriptase Polymerase Chain Reaction, RNA, Messenger, Signal Transduction, Stress, Physiological, Transcription, Genetic}, issn = {1532-2548}, doi = {10.1104/pp.111.177766}, author = {Gonz{\'a}lez-P{\'e}rez, Sergio and Guti{\'e}rrez, Jorge and Garcia-Garcia, Francisco and Osuna, Daniel and Dopazo, Joaquin and Lorenzo, Oscar and Revuelta, Jos{\'e} L and Arellano, Juan B} }