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Enhancing the biocontrol potential of the predator Nesidiocoris tenuis through genetic selection
Full text linkThe zoophytophagous Nesidiocoris tenuis has proven to be a highly effective natural enemy against tomato key pests. It can enhance tomato plants' defenses due to its phytophagous behavior. However, its plant feeding can result in severe plant damage when prey is scarce. Previous studies using an isofemale line demonstrated the dietary habits of N. tenuis are genetically regulated, specifically with regard to phytophagy and zoophagy. In this study, we assessed the life-history traits of the IVIA strain, selected for over 50 generations for its zoophagy and phytophagy, compared to a commercial strain. The IVIA strain developed 3.5% faster, had 34% more offspring, preyed on 34% more Ephestia kuehniella eggs, and caused 50% fewer necrotic rings on tomato plants than the commercial strain. The IVIA strain controlled B. tabaci and T. absoluta in greenhouse experiments at the same level as the commercial strain but produced less damage to the plant. We also studied the capacity of the IVIA strain to induce plant defenses. The IVIA strain increased plant defenses compared to the control, although to a lesser extent than the commercial strain. This finding confirms the reduced phytophagy of the IVIA strain. Interestingly, the use of microsatellite markers revealed genetic differentiation between the IVIA strain and the commercial strain. Our results highlight the potential of selective breeding for improving biocontrol traits of interest in N. tenuis and open the door to differentiating selected races of N. tenuis using molecular techniques
Differential response to calcium-labelled (44Ca) uptake and allocation in two peach rootstocks in relation to transpiration under in vitro conditions
Full text linkCalcium-labelled (44Ca) uptake and transport under in vitro GreenTray® temporary immersion bioreactor conditions have been studied related to aeration conditions. For this aim, Rootpac®-20 (RP-20) and Garnem® (G × N) were selected as two main rootstocks used in peach production. Two transpiration conditions, aerated and unaerated, were established for each plant material. 44Ca location, plant development and foliar stomata surface were measured after the in vitro culture period. The results showed that aeration improved Ca transport within the shoot, but it did not enhance Ca uptake by the roots. Regarding plant material, G × N presented a better Ca uptake capacity and concentration. The findings suggest that Ca uptake in the roots is a precise process that is influenced by transpiration. However, it was observed that transpiration and thus the water flux is not the only force promoting Ca uptake by roots. Furthermore, the transport of Ca to the shoot was primarily determined by transpiration, indicating that water flux plays a crucial role in the aboveground movement of Ca. The study also revealed distinct behaviors in Ca uptake and allocation between the different peach rootstocks, emphasizing the importance of considering these factors in the selection process of rootstocks. These findings contribute to our understanding of the mechanisms involved in Ca uptake and transport in peach rootstocks under in vitro conditions. They provide valuable insights for rootstock selection processes and highlight the need for further research in this area
Distinctive acidity in citrus fruit is linked to loss of proanthocyanidin biosynthesis
Full text linkThe distinctive acidity of citrus fruit is determined by a regulatory complex of MYB and bHLH transcription
factors together with a WDR protein (MBW complex) which operates in the unique juice vesicles of the
fruit. We describe a mutation affecting the MYB protein, named Nicole, in sweet orange and identify
its target genes that determine hyperacidification, specifically. We propose that the acidity, typical of citrus
fruits, was the result of a loss of the ability of Nicole to activate the gene encoding anthocyanidin
reductase, an enzyme essential for the synthesis of proanthocyanidins, which are absent in citrus fruit
NITIRSOIL: A model that balances complexity with prediction uncertainty for improving nitrogen fertilization in agriculture
No full textMismanagement of the nitrogen (N) fertilization in agriculture leads to low N use efficiency (NUE) and therefore
pollution of waters and atmosphere due to NO3 leaching, and N2O and NH3 emissions. The use of N simulation
models of the soil-plant system can help improve the N fertilizer management increasing NUE and decreasing N
pollution issues. However, many N simulation models lack balance between complexity and uncertainty with the
result that they are not applied in actual practice. The NITIRSOIL is a one-dimensional transient-state model with
a monthly time step that aims at addressing this lack in the estimation of, mainly, dry matter yield (DMY), crop N
uptake (Nupt), soil mineral N (Nmin), and NO3 leaching in agricultural fields. According to its global sensitivity
analysis for horticulture, the NITIRSOIL simulations of the aforementioned outputs mostly depend on the critical
N dilution curve, harvest index, dry matter fraction, potential fresh yield and nitrification coefficients. According
to its validation for 35 nitrogen fertilization trials with 11 vegetables under semi-arid Mediterranean climate in
Eastern Spain, the NITIRSOIL presents indices of agreement between 0.87 and 0.97 for the prediction of total dry
matter, DMY, Nupt, NO3 leaching and soil Nmin at crop season end. Therefore, the NITIRSOIL model can be used
in actual practice to improve the sustainability of the N management in, particularly horticulture, due to the
balance it features between complexity and prediction uncertainty. For this aim, the NITRISOIL can be used
either on its own, or in combination with “Nmin” on-site N fertilization recommendation methods, or even could
be implemented as the calculation core of decision support system
A hydroxypropyl methylcellulose (HPMC)-based coating inhibits ethylene-dependent quality changes and reduces superficial scald incidence and blue mould severity during postharvest handling of two apple varieties
No full textThe search of new alternatives to substitute postharvest treatments based on synthetic chemicals has gained
attention on recent years due to social pressure and stricter legislative policies. Consequently, edible coatings
from natural sources have risen as potential solutions to retain postharvest fruit quality. Among these, coatings
based on hydroxypropyl methylcellulose (HPMC) have shown potential in preserving fruit quality after harvest.
However, scarce studies have explored into their effects on the physiology of climacteric fruits. In this context,
the effect of a novel HPMC-based edible coating on fruit postharvest physiology and quality was evaluated in two
apple cultivars: ‘Golden Reinders’ and ‘Granny Smith’. In both cultivars, the HPMC-based coating was able to
preserve some initial quality attributes, such as firmness and colour, while reducing superficial scald and the
severity of blue mould caused by Penicillium expansum. Coated fruit showed reduced ACS activity and ethylene
production, delaying changes in ethylene-dependent parameters such as colour and firmness during two different
postharvest scenarios: shelf life after harvest and after 3 months of cold storage. Other ripening-associated traits
such as starch index, soluble solids content (SSC), and total titratable acidity (TTA) were not affected by the
coating application. The coating altered the levels and composition of volatile organic compounds (VOCs), yet
without affecting the overall consumer acceptance in most of the studied scenarios. Changes in fruit physiology
promoted by the coating, including the decrease of α-farnesene levels and its oxidation products, together with
enhanced accumulation of ethanol may reduce the superficial scald incidence in ‘Granny Smith’ and the severity
of blue mould rot in the two studied cultivars. Overall, the use of the HPMC-based coating in apples could be
useful for maintaining fruit quality and reducing postharvest losses related to mould development and physiological
disorders without compromising taste perceptio
Análisis multivariante de recubrimientos comestibles antifúngicos para mantener la calidad de ciruela ‘Angeleno’ durante frigoconservación
Full text linkLos recubrimientos comestibles antifúngicos (RCs) son una alternativa segura y sostenible para
mantener la calidad poscosecha de ciruelas. La efectividad de los RCs depende principalmente
de la composición, tipo de fruto y condiciones de almacenamiento. El objetivo de este trabajo
fue evaluar el efecto de dos ingredientes naturales con carácter antifúngico (extracto de
hueso de aguacate (AVS) y geraniol (GE)) incorporados a dos RCs (hidroxipropil metilcelulosa
(HPMC) o goma arábiga (GA) y cera de abeja) en la calidad de ciruelas ‘Angeleno’ durante
frigoconservación mediante un Análisis de Componentes Principales (ACP). Los frutos control
(sin recubrir) y recubiertos con los RCs con y sin los agentes antifúngicos se almacenaron
durante 5 y 8 semanas a 1 °C (S1 y S2), seguidas de 3 días a 7 °C y 5 días a 20 °C. Tras ambos
periodos, se evaluó la calidad fisicoquímica y sensorial. El ACP diferenció tres grupos en función
del tiempo de almacenamiento (cosecha, S1 y S2) y mostró que los RCs mejoraron la calidad
del fruto respecto al control sin recubrir. En S1, el color y firmeza mostraron una alta correlación
con PC1; mientras que en S2, el contenido en volátiles y la pérdida de peso contribuyeron en
PC2. En cuanto a la calidad sensorial, la apariencia visual, el sabor y la jugosidad destacaron
en PC1, mientras que el brillo y la jugosidad lo hicieron en PC2. En general, la incorporación de
los agentes antifúngicos no alteró significativamente ninguno de los parámetros de calidad en
comparación con las formulaciones sin antifúngico y los RCs con AVS presentaron una menor
variabilidad que los formulados con GE, mostrando su potencial como agente antifúngico sin
modificar las propiedades barrera de los RCs en ciruela ‘Angeleno’. Este trabajo forma parte
del proyecto StopMedWaste (Programa PRIMA; NextGenerationEU/PRTR; Agencia Estatal de
Investigación, PCI2020-112095)
Intraspecific diversity of Erwinia amylovora strains from northern Algeria
Full text linkBackground Fire blight, caused by Erwinia amylovora, is the most destructive bacterial disease affecting plants in
the Rosaceae family, leading to significant economic losses. In Algeria, this disease has been reported since 2010. This
study aimed to investigate the origin of fire blight in Algeria, in order to increase knowledge of the epidemiology of
this serious disease and contribute to its management. A comprehensive characterization of 18 E. amylovora isolates
recovered from northern Algeria between 2016 and 2021 to evaluate their phenotypical and genotypical diversity
was conducted.
Results Phenotypic differences, particularly in growth kinetics, virulence, and fatty acid profiles, allowed
differentiation of strains into five groups, possibly indicating distinct introduction events. Genetic characterization
revealed that only one strain lacked the ubiquitous plasmid pEA29, which is correlated with reduced virulence, while
none harbored the pEI70 plasmid. Phylogenetic analysis using concatenated sequences of the recA, groEL, rpoS, ams,
and hrpN genes grouped Algerian strains with those from a broadly prevalent clade. CRISPR genotyping identified a
novel CR1 pattern and three genotypes, two of them previously unreported.
Conclusions This study represents the first phenotypic, genetic, and phylogenetic investigation of E. amylovora
strains in the region, and provides valuable information on the possible pathways of the introduction of this fire blight
pathogen in northern Africa. The findings suggest one or more introduction events from a common ancestor, likely
originating in northern Italy, followed by dispersal in various regions of Algeria
Wildflower strips enhance pest regulation services in citrus orchards
Full text linkContemporary approaches to agriculture must be reimaged to include ecological techniques that maximise
ecosystem services, so that food can be produced sustainably whilst simultaneously meeting yield demands. Pest
regulation services, harnessed through the conservation of natural enemies in the agri-environment are an
economically important service degraded by conventional citrus production practices. For the first time, a sown
wildflower strip composed of native forbs and tussock-forming grasses has been investigated for its influence on
natural enemies and their pest regulation services in citrus orchards. A novel management strategy was applied,
using the predicted generation times of Aonidiella aurantii Maskell (Hemiptera: Diaspididae), a key pest in citrus,
to determine whether cutting the wildflower strips could force spill-over of natural enemies onto the adjacent
crop, enhancing pest regulation services. Three treatments applied to orange orchard alleyways were compared:
i) a control treatment, the standard orchard practice of regular cutting to 5 cm throughout the year, ii) a sown
wildflower treatment managed with cutting once a year in February to a height of 10 cm (standard management
wildflower treatment, SMWT), and iii) the same sown wildflower treatment but managed with two additional
cuts in May and June (active management wildflower treatment, AMWT). Orange tree canopies were sampled for
natural enemies, and pest regulation services were quantified using sentinel prey cards baited with Ephestia
kuehniella eggs. Natural enemy richness was greatest in canopies with SMWT, supporting a greater relative
abundance of primary parasitoids and lower relative abundances of antagonists (ants) compared to the control.
This was associated with enhanced pest regulation services (depletion of sentinel prey from baited cards),
especially during the early summer months, which coincides with a critical period to control A. aurantii and other
key citrus pests. In contrast, AMWT did not enhance natural enemy richness, and pest regulation services were
diminished. This study suggests that leaving wildflower strips uncut throughout the season, as in SMWT, may
help to mitigate pest incidence through enhanced pest regulation services. Further studies are now required to
determine how this would influence populations of target pests
Do hydraulic pumps and filters of sprayers influence the viability of Beauveria bassiana based mycoinsecticide Botanigard®?
Full text linkEntomopathogenic fungi are promising biocontrol agents for pest management, but they could be sensitive to application methods. Sprayers, used for both fungal and chemical products, can potentially harm the fungal propagules. This study investigated the impact of common hydraulic pumps (piston and diaphragm) on the viability of Beauveria bassiana Vuillemin (Ascomycota: Hyprocreales) based mycoinsecticide Botanigard® in the spray mixture. It also aimed to determine the optimal filter mesh size for the system to prevent clogging during application. The results showed significant reduction in conidial germination percentages with increasing number of passes through both types of pumps. However, in both cases the decrease was around 4% with a 90% of conidial germination which may be high enough to control the pest. The temperature of the mixture increased with the number of passes through the pumps, but it remained within the suitable range for fungal growth. When it came to filter clogging, the 32-mesh filter did not clog, the 50-mesh had a low clogging percentage, and the 80-mesh filters had higher clogging percentages (18% for suction filter and 56% for impulsion filter) after 30 passes through the system. As a conclusion, hydraulic pumps are suitable to apply B. bassiana based mycoinsecticide Botanigard®, but temperature control should be taken into account to prevent conidia damage. Using 32-mesh filters for both suction and impulsion is recommended to prevent clogging issues when applying this product
Screening Local Sicilian Tomato Ecotypes to Evaluate the Response of Tomato Brown Rugose Fruit Virus Infection
Full text linkTomato is one of the most important crops worldwide, with a production of ≈190 million tons,
but it is constantly threatened by several viral diseases. Tomato brown rugose fruit virus (ToBRFV),
identified in 2014 on tomato plants and subsequently reported in many countries, represents one of
the major threats to tomato crops, due to production losses, different transmission modes and its rapid
spread. This work aimed to evaluate 37 local Sicilian tomato ecotypes against ToBRFV infection. After a
preliminary screening by molecular analyses for tomato mosaic virus (ToMV) and pepino mosaic virus
(PepMV), and ToBRFV detection, tomato plants were grown in a greenhouse for their morphological
characterization and for evaluating resistance and tolerance to ToBRFV. Resistance and tolerance levels
were estimated by mechanical inoculation with ToB SIC01/19 ToBRFV isolate in ten plants per ecotype
and evaluating virus accumulation by RT-qPCR and visual observation of symptoms. All ecotypes were
infected with ToBRFV, showing several symptoms with different disease severity. No tomato ecotype
showed a high level of resistance, but two ecotypes, Pop27 and Pop35, showed very moderate symptoms
and therefore a high tolerance. These Sicilian tomato ecotypes could be used in genetic breeding programs
as parental ones to obtain cultivars tolerant to ToBRFV