Explorando el potencial bioestimulante del alga invasora Rugulopterix okamurae en vid

Trabajo presentado en las IV Jornadas del Grupo de Viticultura de la Sociedad Española de Ciencias Hortícolas, celebradas en Pamplona (España), del 26 al 28 de octubre de 202

Holistic understanding of the response of grapevines to foliar application of seaweed extracts

Viticulture is highly dependent on phytochemicals to maintain good vineyard health. However, to reduce their accumulation in the environment, green regulations are driving the development of eco-friendly strategies. In this respect, seaweeds have proven to be one of the marine resources with the highest potential as plant protective agents, representing an environmentally-friendly alternative approach for sustainable wine production. The current work follows an interdisciplinary framework to evaluate the capacity of Ulva ohnoi and Rugulopteryx okamurae seaweeds to induce defense mechanisms in grapevine plants. To our knowledge, this is the first study to evaluate Rugulopteryx okamurae as a biostimulator . This macroalgae is relevant since it is an invasive species on the Atlantic and Mediterranean coast causing incalculable economic and environmental burdens. Four extracts (UL1, UL2, RU1 and RU2 developed from Ulva and Rugulopteryx, respectively) were foliar applied to Tempranillo plants cultivated under greenhouse conditions. UL1 and RU2 stood out for their capacity to induce defense genes, such as a PR10, PAL, STS48 and GST1, mainly 24 hours after the first application. The increased expression level of these genes agreed with i) an increase in trans-piceid and trans-resveratrol content, mainly in the RU2 treated leaves, and, ii) an increase in jasmonic acid and decrease in salicylic acid. Moreover, an induction of the activity of the antioxidant enzymes was observed at the end of the experiment, with an increase in superoxide dismutase and catalase in the RU2-treated leaves in particular. Interestingly, while foliar fungal diversity was not influenced by the treatments, alga extract amendment modified fungal composition, RU2 application enriching the content of various groups known for their biocontrol activity. Overall, the results evidenced the capacity of Rugulopteryx okamurae for grapevine biostimulation, inducing the activation of several secondary metabolite pathways and promoting the abundance of beneficial microbiota involved in grapevine protection. While further studies are needed to unravel the bioactive compound(s) involved, including conducting field experiments etc., the current findings are the first steps towards the inclusion of Rugulopteryx okamurae in a circular scheme that would reduce its accumulation on the coast and benefit the viticulture sector at the same time

SEAWINES: Use of macroalgae as biostimulants against fungal diseases in grapevines

The outlook for climate change foresees major impacts on vineyards worldwide, shifting pathogens distribution and dynamics demanding more intense plant protection measures in certain regions, increasing viticulture's dependence on phytochemicals and pesticides. However, the European Commission is applying restrictions on their use, encouraging the development of more sustainable strategies efficient for disease control. Seaweeds represent an ecological alternative for a more sustainable production. Previous studies have shown that algae extracts contain compounds capable of reducing the abundance of plant fungal pathogens. Despite it, little is known about the molecular mechanism underlying this response. SEAWINES project is evaluating the efficacy of the foliar application of Ulva ohnoi and Rugulopteryx okamurae extracts to control powdery and downy mildew, in addition to testing their effect on grape and wine quality. To our knowledge, this is the first study evaluating R. okamurae biostimulant capacity and fungicidal effect in viticulture. This macroalgae is relevant since it is an invasive species in our coasts, causing incalculable economic and environmental burdens. We aim to 1- Reduce the usage of chemicals in grapevines; 2- Reduce fungal diseases in viticulture; 3- Valorize polysaccharides from seaweeds; 4- Increase the added-value to wines (ecological and quality); and 5- Provide an alternative use to seaweed biomass, contributing to bio-circular economy and reducing its accumulation in our coasts

Effect of storage conditions on post planting water status and performance of Pinus radiata D. Don stock-types

We examined the post-planting effect of storage on the plant quality and initial survival potential of bare-root (BR) and soil-plugged root (PR) of radiata pine seedlings outplanted in wet and dry soils. Seedlings were subjected to planting shock even under well-watered conditions. Although the transpiration rate declined, indicating closure of stomata, water stress occurred as evidenced by the decline in relative water content (RWC) and in the leaf water potential. More than 80% of the PR seedlings and only 20% of BR seedlings transplanted in well-watered regimen survived. Regardless of storage conditions and duration, seedlings planted under water shortage with a RWC < 50% did not survive. According to these results, it is not advisable to store radiata pine seedlings for more than 1 week when planting is under drought conditions even if the seedlings have soil around roots (PR seedlings).Effet des conditions de stockage sur l’état hydrique et l’établissement de plantules de Pinus radiata D. Don avec motte et à racines nues. L’étude a porté sur l’effet du stockage sur la qualité du plant et sur les potentialités de survie initiale de plantules de Pinus radiata D. Don à racine nue (BR) et avec motte (PR), replantées dans des sols humides et secs. Les plantules ont subi un stress de transplantation, même dans des conditions hydriques optimales. Malgré la diminution de la transpiration, signe d’une fermeture stomatique, un stress hydrique est intervenu, comme en témoigne la baisse tant du contenu hydrique relatif (RWC) que du potentiel hydrique. Plus de 80 % des plantules PR et uniquement 20 % des plantules BR ont survécu à leur transplantation dans des conditions hydriques optimales. Indépendamment des conditions de stockage et de la durée de celui-ci, les plantules mises en place sous déficit hydrique, avec un RWC inférieur à 50 %, n’ont pas survécu. Conformément à ces résultats, le stockage de plantules de Pinus radiata pour des périodes supérieures à une semaine est déconseillé lorsque la transplantation se fait sous déficit hydrique, même lorsqu’il s’agit de plantules avec motte (PR)

Lipoic acid and redox status in barley plants subjected to salinity and elevated CO2

Future environmental conditions will include elevated concentrations of salt in the soil and an elevated concentration of CO2 in the atmosphere. Because these environmental changes will likely affect reactive oxygen species (ROS) formation and cellular antioxidant metabolism in opposite ways, we analyzed changes in cellular H2O2 and non-enzymatic antioxidant metabolite [lipoic acid (LA), ascorbate (ASA), glutathione (GSH)] content induced by salt stress (0, 80, 160 or 240 mM NaCl) under ambient (350 μmolmol−1) or elevated (700 μmolmol−1) CO2 concentrations in two barley cultivars (Hordeum vulgare L.) that differ in sensitivity to salinity (cv. Alpha is more sensitive than cv. Iranis). Under non-salinized conditions, elevated CO2 increased LA content, while ASA and GSH content decreased. Under salinized conditions and ambient CO2, ASA increased, while GSH and LA decreased. At 240 mM NaCl, H2O2 increased in Alpha and decreased in Iranis. When salt stress was imposed at elevated CO2, less oxidative stress and lower increases in ASA were detected, while LA was constitutively higher. The decrease in oxidative stress could have been because of less ROS formation or to a higher constitutive LA level, which might have improved regulation of ASA and GSH reductions. Iranis had a greater capacity to synthesize ASA de novo and had higher constitutive LA content than did Alpha. Therefore, we conclude that elevated CO2 protects barley cultivars against oxidative damage. However, the magnitude of the positive effect is cultivar specific

Concentration of phenolic compounds is increased in lettuce grown under high light intensity and elevated CO2

The present study was focused on lettuce, a widely consumed leafy vegetable for the large number of healthy phenolic compounds. Two differently-pigmented lettuce cultivars, i.e. an acyanic-green leaf cv. and an anthocyanic-red one, were grown under high light intensity or elevated CO2 or both in order to evaluate how environmental conditions may affect the production of secondary phenolic metabolites and, thus, lettuce quality. Mild light stress imposed for a short time under ambient or elevated CO2 concentration increased phenolics compounds as well as antioxidant capacity in both lettuce cvs, indicating how the cultivation practice could enhance the health-promoting benefits of lettuce. The phenolic profile depended on pigmentation and the anthocyanic-red cv. always maintained a higher phenolic amount as well as antioxidant capacity than the acyanicgreen one. In particular, quercetin, quercetin-3-O-glucuronide, kaempferol, quercitrin and rutin accumulated under high light or high CO2 in the anthocyanic-red cv., whereas cyanidin derivatives were responsive to mild light stress, both at ambient and elevated CO2. In both cvs total free and conjugated phenolic acids maintained higher values under all altered environmental conditions, whereas luteolin reached significant amounts when both stresses were administered together, indicating, in this last case, that the enzymatic regulation of the flavonoid synthesis could be differently affected, the synthesis of flavones being favored

Changes in environmental CO2 concentration can modify Rhizobium-soybean specificity and condition plant fitness and productivity

Over the past 10 years, it has been demonstrated in the literature that legume responses to elevated [CO2], whether positive, negative, or null, are in part dependent on the Rhizobium species and genotypes that establish symbiosis with the plant. However, all the strains used in these past experiments were isolated in field conditions at ambient [CO2]. We studied for first time the fitness response of soybean inoculated with a Rhizobium strain that has been previously isolated from nodules of plants grown at elevated [CO2] in field conditions at a FACE site. In experiments developed in controlled growth chambers, and in the field under ambient [CO2], the plants inoculated with the strain isolated at elevated [CO2] showed similar response as plants without inoculation. We hypothesize that deficient nodulation may be associated with a change in root exudates caused by the change in [CO2]. This study showed that the strains isolated in nodules at elevated [CO2] are not capable of properly nodulating soybean plants grown at ambient [CO2] and that the origin of strains do not ensure the performance of plants under the same conditions. However, more research is needed in order to understand how changes in environmental conditions can affect the symbiotic relationship and ultimately how we can improve plant fitness in a changeable world.A. Sanz-Sáez was the recipient of a post-doctoral fellowship granted by the Education, Linguistic Policy, and Education Department of the Basque Country, Spain. This research was financially supported by the following grant: GRUPO GobiernoVasco-IT1022-16.Peer reviewe

Soybean Inoculated With One Bradyrhizobium Strain Isolated at Elevated [CO2] Show an Impaired C and N Metabolism When Grown at Ambient [CO2]

Soybean (Glycine max L.) future response to elevated [CO] has been shown to differ when inoculated with B. japonicum strains isolated at ambient or elevated [CO]. Plants, inoculated with three Bradyrhizobium strains isolated at different [CO], were grown in chambers at current and elevated [CO] (400 vs. 700 ppm). Together with nodule and leaf metabolomic profile, characterization of nodule N-fixation and exchange between organs were tested through N-labeling analysis. Soybeans inoculated with SFJ14-36 strain (isolated at elevated [CO]) showed a strong metabolic imbalance, at nodule and leaf levels when grown at ambient [CO], probably due to an insufficient supply of N by nodules, as shown by N-labeling. In nodules, due to shortage of photoassimilate, C may be diverted to aspartic acid instead of malate in order to improve the efficiency of the C source sustaining N-fixation. In leaves, photorespiration and respiration were boosted at ambient [CO] in plants inoculated with this strain. Additionally, free phytol, antioxidants, and fatty acid content could be indicate induced senescence due to oxidative stress and lack of nitrogen. Therefore, plants inoculated with Bradyrhizobium strain isolated at elevated [CO] may have lost their capacity to form effective symbiosis at ambient [CO] and that was translated at whole plant level through metabolic impairment.This work was financially supported by the following grants: GRUPO Gobierno Vasco IT1022-16 and projects 32-2016-00043, 37-2017-00047, and 000049-IDA2019-38 from the Economic Development and Infrastructures Department of the Basque Country, Spain. DS was a recipient of a Ph.D. grant supported by the Public University of Navarra. AS-S was partially supported by a postdoctoral fellowship granted by the Education, and Linguistic Policy Department of the Basque Country, Spain and the Alabama Agricultural Experiment Station and the Hatch Program of the National Institute of Food and Agriculture, United States Department of Agriculture. Technical support by Azucena González, Phytotron Service, SGIker (UPV/EHU) is gratefully acknowledged