Recuperation and genetic diversity preservation of local cultivars have acquired a huge interest in viticulture areas worldwide. In the Balearic Islands, most of the old cultivars are only preserved in grapevine germplasm banks, and so far, the sanitary status of these local cultivars has remained unexplored. The aim of this study was to survey and detect the virus incidence of all conserved cultivars in the government Grapevine Germplasm Bank of the Balearic Islands and to promote the sanitary recovery of two important minor cultivars, Argamussa and Gorgollassa. Enzyme-linked immunosorbent assay (ELISA) screenings were performed on 315 vines of 33 local cultivars. It was shown that the local cultivars were highly infected with simple (39.7%) and mixed infections (52.1%) and only 8.25% of them were free from the viruses tested. Grapevine leafroll-associated virus 3 (GLRaV-3) infection was the most common (82%). Moreover, Grapevine fanleaf virus (GFLV) and Grapevine fleck virus (GFkV) were also present with considerable incidence (25.4% and 43.5%, respectively). In addition, two sanitation protocols were used: shoot tip culture (ST) and thermotherapy in combination with shoot tip culture (CT). Virus elimination using only ST was effective to obtain "healthy" vines of cvs. Argamussa and Gorgollassa. It is important to emphasize that the methods described in the current study were rapid and effective in eliminating both GLRaV-3 and GFLV, also in combination.

Agriculture water resources are limited in several Mediterranean regions. In this context, the current study was conducted to examine the response of mychorrizal olive plants to two water-saving irrigation techniques, namely partial-root zone drying (PRD) and regulated deficit irrigation (RDI). Young olive (Olea europaea L., cv Picholine marocaine) trees were grown with (+AMF) or without (-AMF) Rhizophagus irregularis using a split-root experiment, which consists in dividing the root system of the plant in two parts placed in separate pots. The pots were exposed simultaneously to three different water regimes: Control, with both root compartments well irrigated; RDI, with both compartments irrigated (50% of the control); and PRD, with one compartment irrigated (50% of the control), while the other compartment was kept dry switching every 10 days. Stomatal conductance (gs), leaf relative water content (RWC), vegetative growth (shoot length, total leaf area and leaf number), proline and sugar contents and leaf carbon isotope discrimination (delta 13C) were measured in order to evaluate the influence of arbuscular mycorrhizal (AM) symbiosis on the tolerance of the olive tree to water stress induced by RDI and PRD. The low soil moisture under this two water treatments have a negative effect on all studied parameters. However, the olive plants inoculated with the AM fungi (AMF) generally have significant great growth indices in comparison with the non-inoculated ones. Furthermore, at physiological (gs and RWC) and biochemical (proline, sugar and delta 13C) level, +AMF olive plants exhibit better performance under drought than -AMF ones. These responses were mostly, earlier under PRD treatment. AM olive plants can tolerate better the water deficit stress of RDI and PRD treatments saving up to 50% of the irrigation water. (C) 2022 SAAB. Published by Elsevier B.V. All rights reserved.

The main objective of the present study was to evaluate the responses to water deficit stress and recovery capacity of young potted trees from two olive cultivars, Empeltre cv. and the widely planted Arbequina cv. The experiment was carried out under semiarid environmental conditions at the experimental field of the University of Balearic Islands in Mallorca, Spain. Two-year-old plants in 22 L pots were exposed to three water availability regimes (full capacity [FC]; 50% FC; 30% FC). Growth, gas exchange, intrinsic water use efficiency, C 13 discrimination and biochemical parameters (total soluble sugars, proline, starch, total soluble protein, pigments and phenolic fraction) were evaluated. Plants were rewetted and assessed again after the re-watering period. Drought stress reduced photosynthesis, mainly by regulating stomatal conductance (g s ). Arbequina cv. exhibited a more conservative water use strategy than Empeltre, with greater reductions in g s , accompanied by significant reductions in vegetative growth. Non-significant differences in intrinsic water use efficiency were observed between cultivars and treatments. However, C 13 discrimination analysis showed better water use efficiency in Empeltre than Arbequina in all treatments. Water deficit stress caused an increase of proline and total soluble solids and a reduction of starch, total soluble protein and chlorophylls concentrations of both cultivars. Empeltre showed a higher total phenol concentration than Arbequina during non-water deficit stress conditions. Cultivar-specific differences in the mechanisms to deal with drought were observed. Empeltre cv. exhibits a higher capacity to tolerate drought and it continues growing under water stress and recovery.

The predicted climate change conditions are forcing crop improvement researchers to find drought tolerant genotypes. The aim of this experiment was to screen a large tomato (Solanum lycopersicum L.) collection cultivated under well-watered and water deficit conditions, in order to identify those genotypes with the best performance under water shortage. Thus, 165 tomato genotypes including different cultivars (landraces and modern genotypes) and fruit types (processing, big size, long shelf-life and cherry) were grown in open field under two different cultivation regimes: well-watered (WW, covering 100% crop evapotranspiration demands) and water deficit (WD, irrigation stopped one month after field transplantation). Several leaf-level traits, yield and fruit quality were measured. Large variability was found under WW, with 20-fold variations in yield among genotypes. No differences in yield or fruit quality traits were found between modern genotypes and landraces, while differences in these parameters were observed based on the fruit type. Water deficit affected the observed variability, with a general decrease of yield and increases of fruit quality. Cluster analysis based on fruit traits placed several landraces in the same cluster that the most productive modern genotypes, irrespective of the water treatment. Variable responses to WD were observed, depending on the fruit or cultivar type. Carbon isotope composition was positively correlated with leaf nitrogen content, and determined the yield limit under both treatments. The results of this study highlight the potential of landraces for minimizing yield reduction under WD and increasing fruit quality, having similar or even better performance as compared to modern improved genotypes.

In the Mediterranean region, grapevines usually deal with drought during their summer growth season. Concurrently, grapevines are hosts to a large number of viruses from which grapevine leafroll associated virus-3 is one of the most widespread and provokes considerable economic losses in many vineyards. However, information concerning grapevine metabolic responses to the combination of drought and viral infection is scarce. Gas-chromatography coupled to mass-spectrometry based metabolite profiling was used in combination with growth analysis, viral loads and gas exchange data to perform an integrative study of the effects of individual and combined stress in two Majorcan grapevine varieties at two experimental years. Metabolic responses of both varieties to the combination of water stress and virus infection were specific and not predicted from the sum of single stress responses. Correlations between respiration, biomass and key metabolites highlight specific adjustments of respiratory and amino acid metabolism possibly underlying the maintenance of carbon balance and growth in grapevines under stress combination.

Trabajo presentado en el 40th World Congress of Vine and Wine: Science and Economy, Culture and Education, celebrado en Sofia (Bulgaria), del 29 de mayo al 2 de junio (2017)

The low recruitment success of some endemic species under Mediterranean environmental conditions is primarily the result of a low ability to create an efficient (highly conductive) and safe (able to maintain an intact water column under negative pressure) hydraulic system. Consequently, their lower resistance to drought-induced cavitation may induce mortality in seedlings and, during summer droughts, in mature individuals. In this study, the hydraulic safety (water potential at 50% loss of conductivity, P50), hydraulic efficiency (specific conductivity, Ks) and xylem anatomy were compared between Rhamnus ludovicisalvatoris, an endemic species of the Balearic Islands whose distribution area is being reduced, and two populations of Rhamnus alaternus, which is widely distributed along the Mediterranean basin. R. ludovicisalvatoris was found to be more susceptible to drought-induced cavitation and less efficient at conducting water in comparison with R. alaternus. Moreover, R. ludovici-salvatoris demonstrated a lower vessel area, wood density and inter-vessel wall strength than R. alaternus. These results are in accordance with the lower ability of R. ludovici-salvatoris to recruit seedlings under Mediterranean conditions in comparison with R. alaternus; this may partially explain the reduction in the distribution area of R. ludovici-salvatoris. (C) 2017 Elsevier GmbH. All rights reserved.

Water limitation is one of the major threats affecting grapevine production. Thus, improving water-use efficiency (WUE) is crucial for a sustainable viticulture industry in Mediterranean regions. Under field conditions, water stress (WS) is often combined with viral infections as those are present in major grape-growing areas worldwide. Grapevine leafroll-associated virus 3 (GLRaV-3) is one of the most important viruses affecting grapevines. Indeed, the optimization of water use in a real context of virus infection is an important topic that needs to be understood. In this work, we have focused our attention on determining the interaction of biotic and abiotic stresses on WUE and hydraulic conductance (Kh ) parameters in two white grapevine cultivars (Malvasia de Banyalbufar and Giró Ros). Under well-watered (WW) conditions, virus infection provokes a strong reduction (P < 0.001) in Kpetiole in both cultivars; however, Kleaf was only reduced in Malvasia de Banyalbufar. Moreover, the presence of virus also reduced whole-plant hydraulic conductance (Khplant ) in 2013 and 2014 for Malvasia de Banyalbufar and in 2014 for Giró Ros. Thus, the effect of virus infection on water flow might explain the imposed stomatal limitation. Under WS conditions, the virus effect on Kplant was negligible, because of the bigger effect of WS than virus infection. Whole-plant WUE (WUEWP ) was not affected by the presence of virus neither under WW nor under WS conditions, indicating that plants may adjust their physiology to counteract the virus infection by maintaining a tight stomatal control and by sustaining a balanced carbon change.

Among several biotic and abiotic stress combinations, interaction between drought and pathogen is one of the most studied combinations in some crops but still not in grapevine. In the present work, we focused on the interaction effects of biotic (GLRaV-3) and abiotic (drought) stresses on grapevine photosynthetic metabolism on two cultivars (cvs. 'Malvasia de Banyalbufar and Giro-Ros'). Non-infected and GLRaV-3 infected potted plants were compared under water stress conditions (WS) and well-watered (WW) conditions. Under WW condition, the results showed that photosynthesis (AN) in both cultivars was decreased by the presence of GLRaV-3. The stomatal conductance (gs) was the main factor for decreasing AN in Malvasia, meanwhile reductions in Giro-Ros were closely related to decreases in gm. The observed differences in gm between both cultivars might result from variation in their leaf anatomical, Giro-Ros having higher values of gm and leaf porosity (in all treatments). Moderate water deficit resulted in a closure of stomata and a decrease in gm accompanied by a decrease in AN in both cultivars. The maximum velocity of carboxylation (Vcmax) and electron transport rate (Jmax) were also reduced under water stress. Moreover, the combined stress resulted in a reduction of most physiological parameters compared to healthy irrigated plants. However, no considerable differences were found between non-infected and virus infected (GLRaV-3) plants under water stress. Most of the results could be explained by the difference of virus concentration between cultivars and treatments.

Rhamnus alaternus and R. ludovici-salvatoris, two Mediterranean shrubs with different geographic distributions, have shown important differences in seedling recruitment capacity. The objectives of this work were to determine the ability of these species to germinate seeds under different temperature ranges, as well as the capacity of seedlings to emerge from different burial depths, in order to better understand their regeneration processes. Two different experiments were performed. In the first one, seed germination was studied in Petri dishes and in the dark at different temperature regimes: a) 5–15°C, b) 10–20°C and c) 15–25°C (12h/12h). In the second experiment, seedling emergence capacity from different burial depths (0.5, 2 and 5 cm) was tested. R. ludovici-salvatoris showed a significantly higher final germination rates, a lower dormancy period, and average time response at 10–20°C than at other temperature ranges, although differences were much greater when seeds were subjected to the 5–15°C temperature regime. By contrast, R. alaternus did not show significant differences between treatments (5–15°C and 10–20°C) in germination behavior. Seedling emergence of both species was lower and slower when seeds were buried at 5 cm. However, R. ludovici-salvatoris always showed a lower seedling emergence capacity than R. alaternus at any burial depth. The low ability of R. ludovici-salvatoris to germinate seeds and emerge between 5–15°C, even from shallow depths, is discussed in relation to its low regeneration capacity and declining geographic distribution.

Plants may exhibit some degree of acclimation after experiencing drought, but physiological adjustments to consecutive cycles of drought and re-watering (recovery) have scarcely been studied. The Mediterranean evergreen holm oak (Q. ilex) and the semi-deciduous rockrose (C. albidus) showed some degree of acclimation after the first of three drought cycles (S1, S2, and S3). For instance, during S2 and S3 both species retained higher relative leaf water contents than during S1, despite reaching similar leaf water potentials. However, both species showed remarkable differences in their photosynthetic acclimation to repeated drought cycles. Both species decreased photosynthesis to a similar extent during the three cycles (20-40% of control values). However, after S1 and S2, photosynthesis recovered only to 80% of control values in holm oak, due to persistently low stomatal (g(s)) and mesophyll (g(m)) conductances to CO(2). Moreover, leaf intrinsic water use efficiency (WUE) was kept almost constant in this species during the entire experiment. By contrast, photosynthesis of rockrose recovered almost completely after each drought cycle (90-100% of control values), while the WUE was largely and permanently increased (by 50-150%, depending on the day) after S1. This was due to a regulation which consisted in keeping g(s) low (recovering to 50-60% of control values after re-watering) while maintaining a high g(m) (even exceeding control values during re-watering). While the mechanisms to achieve such particular regulation of water and CO(2) diffusion in leaves are unknown, it clearly represents a unique acclimation feature of this species after a drought cycle, which allows it a much better performance during successive drought events. Thus, differences in the photosynthetic acclimation to repeated drought cycles can have important consequences on the relative fitness of different Mediterranean species or growth forms within the frame of climate change scenarios.