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Research Project
Bioresources 4 Sustainability
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Publications
Will Casuarina glauca Stress Resilience Be Maintained in the Face of Climate Change?
Publication . Jorge, Tiago F.; Ramalho, José C.; Alseekh, Saleh; Pais, Isabel P.; Leitão, António E.; Rodrigues, Ana P.; Scotti-Campos, Paula; Ribeiro-Barros, Ana I.; Fernie, Alisdair R.
Actinorhizal plants have been regarded as promising species in the current climate change
context due to their high tolerance to a multitude of abiotic stresses. While combined salt-heat stress
effects have been studied in crop species, their impact on the model actinorhizal plant, Casuarina
glauca, has not yet been fully addressed. The effect of single salt (400 mM NaCl) and heat (control at
26/22 C, supra optimal temperatures at 35/22 C and 45/22 C day/night) conditions on C. glauca
branchlets was characterised at the physiological level, and stress-induced metabolite changes
were characterised by mass spectrometry-based metabolomics. C. glauca could withstand single
salt and heat conditions. However, the harshest stress condition (400 mM NaCl, 45 C) revealed
photosynthetic impairments due to mesophyll and membrane permeability limitations as well
as major stress-specific differential responses in C and N metabolism. The increased activity of
enzymatic ROS scavengers was, however, revealed to be sufficient to control the plant oxidative
status. Although C. glauca could tolerate single salt and heat stresses, their negative interaction
enhanced the effects of salt stress. Results demonstrated that C. glauca responses to combined
salt-heat stress could be explained as a sum of the responses from each single applied stress
SNP Detection in Pinus pinaster Transcriptome and Association with Resistance to Pinewood Nematode
Publication . Modesto, Inês; Inácio, Vera; Novikova, Polina; Carrasquinho, Isabel; Van de Peer, Yves; Miguel, Célia M.
Pinewood nematode (PWN, Bursaphelenchus xylophilus) is the causal agent of pine wilt
disease (PWD), which severely affects Pinus pinaster stands in southwestern Europe. Despite the high
susceptibility of P. pinaster, individuals of selected half-sib families have shown genetic variability in
survival after PWN inoculation, indicating that breeding for resistance can be a valuable strategy
to control PWD. In this work, RNA-seq data from susceptible and resistant plants inoculated with
PWN were used for SNP discovery and analysis. A total of 186,506 SNPs were identified, of which
31 were highly differentiated between resistant and susceptible plants, including SNPs in genes
involved in cell wall lignification, a process previously linked to PWN resistance. Fifteen of these
SNPs were selected for validation through Sanger sequencing and 14 were validated. To evaluate
SNP-phenotype associations, 40 half-sib plants were genotyped for six validated SNPs. Associations
with phenotype after PWN inoculation were found for two SNPs in two different genes (MEE12
and PCMP-E91), as well as two haplotypes of HIPP41, although significance was not maintained
following Bonferroni correction. SNPs here detected may be useful for the development of molecular
markers for PWD resistance and should be further investigated in future association studies
Carry-over effects on bud fertility makes early defoliation a risky crop-regulating practice in Mediterranean vineyards
Publication . Lopes, C.M.; Egipto, R.; Zarrouk, O.; Chaves, M.M.
Background and Aims: Recently, early defoliation (ED) has been used widely to regulate yield and reduce bunch compactness
to improve tolerance to bunch rot. The aim of this study was to test ED, as an alternative to the conventional crop
thinning (CT), to regulate yield and improve tolerance to bunch rot of the Vitis vinifera L. cv. Aragonez.
Methods and Results: Early defoliation and CT were compared with an untreated Control over three consecutive seasons
in a commercial vineyard in Portugal. Early defoliation had little effect on tolerance to bunch rot and led to progressive loss
of yield reducing fruitset, bunch number, berry number and mass, compared to Control vines. Reduced bunch number is
likely to be a function of reduced bud fertility. Crop thinning also reduced yield but, unlike ED, the yield reduction was less
and remained constant over the seasons studied. Both ED and CT had little effect on berry composition.
Conclusions: Among the two crop-regulating techniques, CT appears more suitable than ED to control grape yields in
regions where yield limitations are imposed. The progressive yield decline caused by ED is likely to be not economically viable
in the region studied.
Significance of the Study: Early defoliation reduces bud fertility in unirrigated vineyards under Mediterranean conditions.
Therefore, this practice should be avoided under those conditions
Molecular Defense Response of Pine Trees (Pinus spp.) to the Parasitic Nematode Bursaphelenchus xylophilus
Publication . Modesto, Inês; Mendes, André; Carrasquinho, Isabel; Miguel, Célia M.
Pine wilt disease (PWD) is a severe environmental problem in Eastern Asia andWestern
Europe, devastating large forest areas and causing significant economic losses. This disease is caused
by the pine wood nematode (PWN), Bursaphelenchus xylophilus, a parasitic migratory nematode
that infects the stem of conifer trees. Here we review what is currently known about the molecular
defense response in pine trees after infection with PWN, focusing on common responses in different
species. By giving particular emphasis to resistance mechanisms reported for selected varieties
and families, we identified shared genes and pathways associated with resistance, including the
activation of oxidative stress response, cell wall lignification, and biosynthesis of terpenoids and
phenylpropanoids. The role of post-transcriptional regulation by small RNAs in pine response
to PWN infection is also discussed, as well as the possible implementation of innovative RNAinterference
technologies, with a focus on trans-kingdom small RNAs. Finally, the defense response
induced by elicitors applied to pine plants before PWN infection to prompt resistance is reviewed.
Perspectives about the impact of these findings and future research approaches are discussed
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Funders
Funding agency
Fundação para a Ciência e a Tecnologia
Funding programme
6817 - DCRRNI ID
Funding Award Number
UID/Multi/04551/2013