Efecto del estrés abiótico sobre la fisiología y regulación hormonal en citrange Carrizo

[ES] La sequía y el encharcamiento del sustrato son dos factores ambientales que afectan negativamente al cultivo de los cítricos. Este efecto negativo se puede manifestar de forma similar, aunque existan diferencias a nivel bioquímico y hormonal. Para estudiar estas diferencias en distintos órganos, en este trabajo se ha estudiado y comparado la respuesta fisiológica, bioquímica y hormonal de plantas de citrange Carrizo (Citrus sinensis (L.) Osb. x Poncirus trifoliata L.) a estas condiciones ambientales. En ambos casos la respuesta fisiológica de la parte aérea es similar, afectando de forma negativa a la actividad fotosintética así como a la eficiencia carboxilativa. El patrón de acumulación de prolina foliar y radicular difiere en función de la condición ambiental incidente, actuando como mecanismo de ajuste del balance osmótico foliar y pudiendo relacionarse con el órgano sensor del estrés. El contenido de MDA foliar incrementa en ambas situaciones, activándose a su vez la maquinaria antioxidante en hojas correspondiente al enzima APX, reduciendo la incidencia del daño. Respecto a la regulación hormonal, el JA y el ABA presentan un comportamiento paralelo incrementando su concentración en la parte aérea en respuesta a las dos condiciones de estrés. En raíces, por el contrario, se comportaron de forma opuesta presentando una respuesta específica para cada situación ambiental. En estas condiciones el JA podría actuar como mediador entre la percepción del estrés y la inducción del ABA, que actuaría como modulador de la respuesta fisiológica.[EN] Drought and waterlogging are two environmental factors that negatively affect citrus. Although both environmental conditions induce similar physiological disturbances, there might be important differences at the biochemical and hormonal levels. To study these differences, in in this work we have studied and compared physiological, biochemical and hormonal response of leaves and roots of Carrizo citrange plants (Citrus sinensis (L.) Osb. x Poncirus trifoliata L.) to these environmental conditions. The physiological response of the aerial part is similar under both adverse environmental conditions, negatively affecting the photosynthetic activity and carboxylative efficiency. The pattern of proline accumulation in leaves and roots differs depending on the environmental condition considered and was associated to leaf osmotic balance adjustment. In addition, it could be an indicator of the stress sensing organ. Leaf MDA content increased in both situations and, at the same time, the antioxidant machinery, corresponding to the APX enzyme, was activated reducing the incidence of damage. Regarding hormonal regulation, JA and ABA showed parallel behaviour increasing their concentration in leaves in response to both stress conditions. On the contrary, in roots the response appeared to be specific for each environmental condition. In these conditions JA could act as a mediator between the perception of stress and induction of ABA, which would act as a modulator of the physiological response.Pitarch Bielsa, M. (2013). Efecto del estrés abiótico sobre la fisiología y regulación hormonal en citrange Carrizo. http://hdl.handle.net/10251/37994Archivo delegad

Optimising grapevine summer stress responses and hormonal balance by applying kaolin in two Portuguese Demarcated Regions

In Mediterranean-like climate areas, field-grown grapevines are typically exposed to severe environmental conditions during the summer season, which can negatively impact the sustainability of viticulture. Despite the short-term mitigation strategies available nowadays to cope with climate change, little is known regarding their effectiveness in different demarcated winegrowing regions with differing climate features. Hence, we applied a kaolin suspension (5 %) to Touriga-Franca (TF) and Touriga-Nacional (TN) grapevine varieties located in two Portuguese demarcated regions (Alentejo and Douro) with different mesoclimates to study its effect on the physiological performance, hormonal balance and ABA-related grapevine leaf gene expression during the 2017 and 2018 growing seasons. Data show that 2017 was warmer than 2018 due to the occurrence of two heatwaves in both locations, highlighting the protective effect of kaolin application under severe environmental conditions. In the first study year, at midday, kaolin enhanced water use efficiency (23 % in Douro and 13 % in Alentejo), carbon assimilation rates (PN; 72 % in Douro and 25 % in Alentejo), and the soluble sugar content of grapevine leaves, while decreasing the accumulation of plant growth regulators (ABA, IAA, and SA) during the ripening stage. The results show an up-regulation of ABA biosynthesis-related genes (VvNCED) in TF treated vines from the Douro vineyard mainly in 2017, suggesting an increased stress response under severe summer conditions. Additionally, kaolin triggered the expression of ABA-responsive genes (VvHVA22a and VvSnRK2.6) mainly in TF, indicating different varietal responses to kaolin application under fluctuating periods of summer stress

Protocol for Increasing Carotenoid Levels in the Roots of Citrus Plants

Carotenoids in plants play several key functions such as acting as light-harvesters, antioxidants (Lado et al., 2016) or being precursors of strigolactones, abscisic acid, volatiles and other signaling compounds (Arbona et al., 2013). Although those functions are well-known in light-exposed tissues, information in belowground organs is limited because of reduced abundance of these pigments. In order to better understand the role of carotenoids in roots, we developed a methodology to increase the abundance of these pigments in underground tissues. We took advantage of the fact that citrus roots exposed to light develop pigmentation in order to increase the carotenoid content. Therefore, here we describe a simple method to increase carotenoids in citrus roots.This work was supported by the Ministerio de Economia (MINECO) and Universitat Jaume I through grants No. AGL2013- 42038-R and P1IB2013-23, respectively. MM was recipient of a ‘Santiago Grisolia’ fellowship from Generalitat Valenciana (Spain). This protocol is based on the methodology used in the manuscript Manzi et al. (2016)

Leaf dehydration is needed to induce abscisic acid accumulation in roots of citrus plants

The root system is the main organ involved in the water uptake and it is assumed that it perceives soil dehydration, triggering water stress responses at the entire plant level, including abscisic acid (ABA) accumulation. However, several lines of evidence demonstrate that leaves directly adjust their water status (and induce increases in ABA levels) in response to changes in the evaporative demand. To evaluate the influence of leaf water status on ABA accumulation in roots, the canopy of citrus plants was kept at high humidity while roots were dehydrated. Leaves and roots of completely dehydrated plants increased levels of ABA whereas plants with turgid leaves did not accumulate ABA either in leaves or in roots. Furthermore, in dehydrated roots, the expression of several key genes involved in carotenoid and ABA biosynthetic pathways such as CsβCHX1 and CsNCED1 was strongly affected by the water status of leaves whereas water availability in roots showed a marginal influence. Overall, results confirm that leaves are a relevant source of ABA for roots during dehydration and also demonstrate that leaf-dehydration is required to trigger ABA-induced responses in roots

La combinación de calor y salinidad genera una respuesta específica en plantas de cítricos

Las plantas cultivadas en el campo están sometidas a numerosos estreses ambientales que les afectan simultáneamente. Se prevé que un incremento de las temperaturas, debido al cambio climático, afecte a los cultivos durante los próximos años provocando importantes pérdidas económicas. En este trabajo hemos estudiado el efecto del estrés salino, habitual en los campos de la región mediterránea, junto con las altas temperaturas en el portainjerto de cítricos Citrange Carrizo (Poncirus trifoliata L. Raf. x Citrus sinensis L. Osb.). Nuestros resultados demuestran que la combinación de estas dos condiciones de estrés es más perjudicial para las plantas que los estreses aplicados individualmente. El aumento en la apertura estomática y transpiración provocado por las altas temperaturas favorece la absorción y acumulación en la planta del ion tóxico Cl- presente en el sustrato, dañando gravemente a las plantas. La acumulación de las ftohormonas ABA, JA y SA activa respuestas moleculares y fsiológicas (reducción de apertura estomática y de la transpiración). En conjunto, nuestros datos muestran la importancia de las respuestas específcas fsiológicas y hormonales de la planta para adaptarse a la combinación de salinidad y altas temperaturas. Los programas de mejora genética en cítricos deberían tener en cuenta estas respuestas específcas a la combinación de estreses para buscar nuevos patrones de cítricos o mejorar los existentes, consiguiendo una adaptación a las futuras condiciones ambientales

Kaolin impacts on hormonal balance, polyphenolic composition and oenological parameters in red grapevine berries during ripening

ACKGROUND:Kaolin particle-film application is a well-known strategy to avoid fruit damage. However, its putative role in balancing berry ripening under a changing climate remains poorly explored. OBJECTIVE:We assessed kaolin treatment effect on several ripening berry components, hormonal balance and oenological parameters of the field-grown Touriga-Franca (TF) and Touriga–Nacional (TN) grapevine varieties at veraison (EL35) and ripening (EL38) during two growing seasons (2017 and 2018). RESULTS:Under the adverse summer conditions (two heatwave events) of 2017, kaolin application increased 211.2 %and 51.4 %the salicylic acid (SA) and abscisic acid (ABA) levels in TF berries at EL38, while no significant differences were observed in TN. Conversely, TF, and TN kaolin treated berries showed lower SA and ABA accumulation in 2018, respectively. Tartaric acid content increased about 17.2 %, and 24.2 %in TF and TN treated berries at stage EL35 in the 2017 growing season. Though kaolin treatment had no consistent effect on anthocyanins accumulation, flavonoids, ortho-diphenols and tannins increased in kaolin treated grapevines in 2017. CONCLUSIONS:This study highlights the key role of climate in triggering ripening related processes and fruit quality potential. Nevertheless, kaolin treated grapevines displayed an improved response to oxidative stress signals by increasing secondary metabolites accumulation in warm vintages. Kaolin application promoted different varietal responses, with a possible ripening delaying effect in TF, reinforcing its efficiency in alleviating severe summer stress impacts

Uncovering the effects of kaolin on balancing berry phytohormones and quality attributes of Vitis vinifera grown in warm-temperate climate regions

Research ArticleReceived: 22 December 2020 Revised: 6 April 2021 Accepted article published: 5 July 2021 Published online in Wiley Online Library:(wileyonlinelibrary.com) DOI 10.1002/jsfa.11413Uncovering the effects of kaolin on balancingberry phytohormones and quality attributesof Vitis vinifera grown in warm-temperateclimate regionsSara Bernardo,aLia-Tânia Dinis,aNelson Machado,bAna Barros,aMarta Pitarch-Bielsa,cAureliano C Malheiro,aAurelio Gómez-Cadenascand José Moutinho-Pereir aa*AbstractBACKGROUND: The application of kaolin particle lm is considered a short-term strategy against several environmental stres-ses in areas with a Mediterranean-like climate. However, it is known that temperature uctuations and water availability overthe season can jeopardize kaolin efciency in many Mediterranean crops. Hence, this study aims to evaluate the effects of kao-lin foliar application on berry phytohormones, antioxidant defence, and oenological parameters at veraison and harvest stagesof Touriga-Franca (TF) and Touriga-Nacional (TN) grapevines in two growing seasons (2017 and 2018). The 2017 growing sea-son was considered the driest (−147.1 dryness index) and the warmest (2705 °C growing degree days) of the study.RESULTS: In 2017, TF kaolin-treated berries showed lower salicylic acid (−26.6% compared with unsprayed vines) and abscisicacid (ABA) (−10.5%) accumulation at veraison, whereas salicylic acid increased up to 28.8% at harvest. In a less hot season, TNand TF kaolin-treated grapevines showed a twofold in ABA content and a threefold increase in the indole-3-acetic acid contentat veraison and lower ABA levels (83.8%) compared with unsprayed vines at harvest. Treated berries showed a decreased sugarcontent, without compromising malic and tartaric acid levels, and reactive oxygen species accumulation throughout berryripening.CONCLUSION: The results suggest kaolin exerts a delaying effect in triggering ripening-related processes under severe summerstress conditions. Treated berries responded with improved antioxidant defence and phytohormone balance, showing signif-icant interactions between kaolin treatment, variety, and developmental stage in both assessed years