Percorrer por autor "Saibo, Nelson"
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- Coping with abiotic stress: Proteome changes for crop improvementPublication . Abreu, Isabel A.; Farinha, Ana Paula; Negrão, Sónia; Gonçalves, Nuno; Fonseca, Cátia; Rodrigues, Mafalda; Batista, Rita; Saibo, Nelson; Oliveira, M. MargaridaPlant breeders need new and more precise tools to accelerate breeding programs that address the increasing needs for food, feed, energy and raw materials, while facing a changing environment in which high salinity and drought have major impacts on crop losses worldwide. This review covers the achievements and bottlenecks in the identification and validation of proteins with relevance in abiotic stress tolerance, also mentioning the unexpected consequences of the stress in allergen expression. While addressing the key pathways regulating abiotic stress plant adaptation, comprehensive data is presented on the proteins confirmed as relevant to confer tolerance. Promising candidates still to be confirmed are also highlighted, as well as the specific protein families and protein modifications for which detection and characterization is still a challenge. This article is part of a Special Issue entitled: Translational Plant Proteomics.
- In vitro culture is the major contributing factor for transgenic vs. non-transgenic proteomic plant differencesPublication . Fonseca, Cátia; Planchon, Sébastien; Serra, Tânia; Chander, Subhash; Saibo, Nelson; Renaut, Jenny; Oliveira, M.Margarida; Batista, RitaThe identification of similarities and differences between genetically modified plants and derived food/feed and their comparators plays a central role in risk assessment strategy. Our main goal was to better understand the relevance of transgene presence, genetic and epigenetic changes promoted by transgene insertion and in vitro culture in the potential unintended effects/differences between transgenic and conventional counterparts. In order to achieve this goal we have used Multiplex fluorescence 2D gel electrophoresis technology coupled with MS to characterize the proteome of three different rice lines (Oryza sativa L. ssp. japonica cv. Nipponbare): a control conventional counterpart, an Agrobacterium-transformed transgenic line (Ta) and a negative segregant (NSb), progeny of a different transgenic line. We have observed that Ta and NSb plant lines grouped together (only 1 differentially regulated spot - fold difference ≥ 1.5), separated from the control (49 spots with fold difference ≥1.5, in both Ta and NSb lines comparing to control line). Since the only feature in common between the tested transgenic and negative segregant lines is that they have both suffered in vitro culture procedures we hypothesised that stress caused by in vitro culture was, in this case, the most relevant factor contributing for the encountered proteomic differences. MS identifications of differentially regulated spots supported our hypothesis, demonstrating that Ta and NSb rice lines present several adjusted metabolic pathways and several proteins with altered expression that were previously associated with plant stress response.
- Inducible and constitutive expression of HvCBF4 in rice leads to differential gene expression and drought tolerancePublication . Lourenço, Tiago; Saibo, Nelson; Batista, Rita; Pinto Ricardo, Cândido; Oliveira, Maria MargaridaThe effects of the ectopic expression of a barley transcription factor (HvCBF4) under the control of a constitutive (maize Ubi1) or a stress-inducible (Arabidopsis RD29A) promoter in the abiotic stress response in rice (Oryza sativa L.) was investigated. The transformed plants were analyzed both at molecular and physiological level and the AtRD29A::HvCBF4 plants were further analyzed using the GeneChip® rice genome array under control conditions. Only the plants constitutively expressing HvCBF4 have shown increased survival to drought stress, but not to cold or high-salinity. These plants have also shown better photosynthetic capacity, as determined by chlorophyll fluorescence. Plants expressing AtRD29A::HvCBF4 did not show increased survival to any of the stresses applied. However in the GeneChip® microarray, these plants have shown up-regulation of many stress-responsive genes (> 400) as compared to non-transformed plants. Interestingly, RT-PCR analysis revealed not only differential gene expression between roots and shoots, but also between transgenic lines with the different promoters. Our results indicate that different HvCBF4 expression levels resulted in different transcriptomes and drought tolerance. Given that AtRD29A::HvCBF4 plants did not show increased tolerance to any of the imposed stresses, we may conclude that this promoter may be inappropriate for rice transformation aiming for enhanced abiotic stress tolerance.
- Microarray analyses reveal that plant mutagenesis may induce more transcriptomic changes than transgene insertionPublication . Batista, Rita; Saibo, Nelson; Lourenço, Tiago; Oliveira, Maria MargaridaControversy regarding genetically modified (GM) plants and their potential impact on human health contrasts with the tacit acceptance of other plants that were also modified, but not considered as GM products (e.g., varieties raised through conventional breeding such as mutagenesis). What is beyond the phenotype of these improved plants? Should mutagenized plants be treated differently from transgenics? We have evaluated the extent of transcriptome modification occurring during rice improvement through transgenesis versus mutation breeding. We used oligonucleotide microarrays to analyze gene expression in four different pools of four types of rice plants and respective controls: (i) a gamma-irradiated stable mutant, (ii) the M1 generation of a 100-Gy gamma-irradiated plant, (iii) a stable transgenic plant obtained for production of an anticancer antibody, and (iv) the T1 generation of a transgenic plant produced aiming for abiotic stress improvement, and all of the unmodified original genotypes as controls. We found that the improvement of a plant variety through the acquisition of a new desired trait, using either mutagenesis or transgenesis, may cause stress and thus lead to an altered expression of untargeted genes. In all of the cases studied, the observed alteration was more extensive in mutagenized than in transgenic plants. We propose that the safety assessment of improved plant varieties should be carried out on a case-by-case basis and not simply restricted to foods obtained through genetic engineering.
- Selection of the best comparator for the risk assessment of GM plants- conventional counterpart vs. negative segregantPublication . Fonseca, Cátia; Planchon, Sébastien; Serra, Tânia; Chandler, Subhash; Saibo, Nelson; Renaut, Jenny; Oliveira, Margarida; Batista, RitaAbstract for 12th international Symposium on biosafety of genetically modified organisms The identification of similarities and differences between GM plants and derived food/feed and their comparators plays a central role in risk assessment strategy. Therefore, selecting the right comparators must be one of the top priorities. The question is which control would allow us to better evaluate the potential unintended effects related directly to the transgene and/or DNA rearrangements, discounting the potential effects caused by in vitro culture procedures; since, these are non-controversial procedures also used in conventional breeding. Aiming to answer the previous question we have used Multiplex fluorescence 2D gel electrophoresis technology (DyeAGNOSTICS Refraction-2D) coupled with MS to characterize the proteome of three different rice lines (Oriza sativa L. ssp. Japonica cv Nipponbare): A control conventional counterpart. An Agrobacterium transformed transgenic line. A negative segregant (homozygous negative progeny) from a different transgenic line. We have observed that transgenic and negative segregant plant lines grouped together (only 1 differentially regulated spot - fold difference > 1.5, ANOVA, P<0.05,) and apart from control (49 spots with fold difference >1.5, ANOVA, P<0.05, in both transgenic and negative segregant lines comparing to control line). Additionally, the 35 proteins identified (using MS) in this study, were already associated with stress response by other authors. The only feature in common between the transgenic and negative segregant lines is that they have both suffered in vitro culture procedures. Hence, the results obtained indicate that, in this study, different gene disruption and/or DNA rearrangements and the presence/absence of transgene were factors with less impact on rice proteome than the proteomic promoted differences caused by in vitro culture, and eventually the stress caused by this process. This work highlights the importance of continuous revision and upgrade of the guidance criteria to be followed for the selection of suitable comparators in GMO risk assessment.