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Projeto de investigação
GREEN-IT "Bioresources for Sustainability"
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Autores
Publicações
Stromal Ascorbate Peroxidase (OsAPX7) Modulates Drought Stress Tolerance in Rice (Oryza sativa)
Publication . Jardim-Messeder, Douglas; Caverzan, Andreia; Balbinott, Natalia; Menguer, Paloma; Paiva, Ana L. S.; Lemos, Moaciria; Cunha, Juliana R.; Gaeta, Marcos L.; Costa, Miguel; Zamocky, Marcel; Saibo, Nelson J. M.; Silveira, Joaquim A. G.; Margis, Rogério; Margis-Pinheiro, Márcia
Chloroplast ascorbate peroxidases exert an important role in the maintenance of hydrogen
peroxide levels in chloroplasts by using ascorbate as the specific electron donor. In this work, we
performed a functional study of the stromal APX in rice (OsAPX7) and demonstrated that silencing
of OsAPX7 did not impact plant growth, redox state, or photosynthesis parameters. Nevertheless,
when subjected to drought stress, silenced plants (APX7i) show a higher capacity to maintain stomata
aperture and photosynthesis performance, resulting in a higher tolerance when compared to nontransformed
plants. RNA-seq analyses indicate that the silencing of OsAPX7 did not lead to changes
in the global expression of genes related to reactive oxygen species metabolism. In addition, the
drought-mediated induction of several genes related to the proteasome pathway and the downregulation
of genes related to nitrogen and carotenoid metabolism was impaired in APX7i plants.
During drought stress, APX7i showed an up-regulation of genes encoding flavonoid and tyrosine
metabolism enzymes and a down-regulation of genes related to phytohormones signal transduction
and nicotinate and nicotinamide metabolism. Our results demonstrate that OsAPX7 might be
involved in signaling transduction pathways related to drought stress response, contributing to the
understanding of the physiological role of chloroplast APX isoforms in rice.
Population structure in Quercus suber L. revealed by nuclear microsatellite markers
Publication . Sousa, Filipe; Costa, Joana; Ribeiro, Carla; Varandas, Marta; Pina-Martins, Francisco; Simões, Fernanda; Matos, José; Glushkova, Maria; Miguel, Célia; Veloso, Maria Manuela; Oliveira, Margarida; Ricardo, Cândido Pinto; Batista, Dora; Paulo, Octávio S.
Quercus suber L. is a sclerophyllous tree species native to the western Mediterranean,
a region that is considered highly vulnerable to increased temperatures and severe dry
conditions due to environmental changes. Understanding the population structure
and demographics of Q. suber is essential in order to anticipate whether populations at
greater risk and the species as a whole have the genetic background and reproductive
dynamics to enable rapid adaptation. The genetic diversity of Q. suber has been subject
to different studies using both chloroplast and nuclear data, but population structure
patterns remain unclear. Here, we perform genetic analyses on Q. suber using 13
nuclear microsatellite markers, and analysed 17 distinct locations across the entire
range of the species. Structure analyses revealed that Q. suber may contain three major
genetic clusters that likely result from isolation in refugia combined with posterior
admixture and putative introgression from other Quercus species. Our results show a
more complex structure scenario than previously inferred for Q. suber using nuclear
markers and suggest that different southern populations contain high levels of genetic
variation that may contribute to the resilience of Q. suber in a context of environmental
change and adaptive pressure.
Haplotype diversity patterns in Quercus suber (Fagaceae) inferred from cpDNA sequence data
Publication . Sousa, Filipe; Viegas, Mariana Bray; Costa, Joana; Marques, Isabel; Pina‑Martins, Francisco; Simões, Fernanda; Matos, José; Glushkova, Maria; Miguel, Célia; Veloso, Maria Manuela; Oliveira, M. Margarida; Ricardo, Cândido Pinto; Batista, Dora; Paulo, Octávio S.
Chloroplast genome diversity in cork oak (Quercus suber) is characterised by the occurrence of haplotypes that are akin
to those found in other Mediterranean oak species, particularly in Q. ilex and Q. rotundifolia, suggesting the possible presence
of an introgressed chloroplast lineage. To further investigate this pattern, we reconstructed chloroplast haplotypes by
sequencing four chloroplast markers (cpDNA), sampled across 181 individuals and 10 taxa. Our analyses resulted in the
identification of two diversified chloroplast haplogroups in Q. suber, corresponding to a geographically widespread lineage
and an Afro-Iberian lineage. Time-calibrated phylogenetic analyses of cpDNA point to a Miocene origin of the two haplogroups
in Q. suber, suggesting that the Afro-Iberian lineage was present in cork oak before the onset of glaciation periods.
The persistence of the two haplogroups in the western part of the species distribution range may be a consequence of either
ancient introgression events or chloroplast lineage sorting, combined with different fixation in refugia through glaciation
periods. Our results provide a comprehensive insight on the origins of chloroplast diversity in these ecologically and economically
important Mediterranean oaks.
Primary Metabolite Adjustments Associated With Pinewood Nematode Resistance in Pinus pinaster
Publication . Rodrigues, Ana M.; Carrasquinho, Isabel; António, Carla
The pinewood nematode (PWN) Bursaphelenchus xylophilus is the causal agent of the
pine wilt disease (PWD) and represents one of the major threats to conifer forests.
The detection of the PWN in Portugal, associated with Pinus pinaster, increased the
concern of its spread to European forests. Despite its susceptibility to PWD, genetic
variability found among P. pinaster populations has been associated with heritable
PWD resistance. Understanding the mechanisms underlying tree resistance constitutes
a valuable resource for breeding programs toward more resilient forest plantations.
This study investigated changes in anatomy, chlorophyll a fluorescence (ChlF), and
primary metabolism in susceptible and resistant P. pinaster half-sib plants, after PWN
inoculation. Susceptible plants showed a general shutdown of central metabolism,
osmolyte accumulation, photosynthetic inhibition, and a decrease in the plant water
status. The ChlF transient rise (OJIP curve) revealed the appearance of L- and K-bands,
indicators of environmental stress. In contrast, resistant plants revealed a regulated
defense response and were able to restrict PWN migration and cellular damage.
Furthermore, the accumulation of g-aminobutyric acid (GABA) and succinate suggested
a role of these metabolites in PWD resistance and the possible activation of the GABA
shunt. Altogether, these results provide new insights to the role of primary metabolism
in PWD resistance and in the selection of resistant phenotypes for disease mitigation
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Financiadores
Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
6817 - DCRRNI ID
Número da atribuição
UIDB/04551/2020