Recovering Ancient Grapevine Cultivars in the Balearic Islands: Sanitary Status Evaluation and Virus Elimination.

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.

Leaf physiological traits of plants from the Qinghai-Tibet Plateau and other arid sites in China: Identifying susceptible species and well-adapted extremophiles.

Extreme environments, such as deserts and high-elevation ecosystems, are very important from biodiversity and ecological perspectives. However, plant physiology at those sites has been scarcely studied, likely due to logistic difficulties. In the present study, leaf physiological traits in native plants were analyzed from arid zones across an elevational transect in Western China, from Turpan Basin to the Qinghai-Tibet Plateau (QTP) at Delingha. The aim of this study was to use leaf physiological traits to help identifying potentially threatened species and true extremophiles. Physiological measurements in the field, and particularly in situ measurements of gas exchange and chlorophyll fluorescence, have been determined to be useful to determine the current state of plants at a given environment. Using this approach plus a combination of leaf traits, several species performing particularly well at the QTP were identified, e.g. Hedysarum multijugum, as well as at Manas drylands, e.g. Peganum harmala and Setaria viridis. On the other hand, several species showed marked signs of severe stress, in particular a very low photosynthetic rate over its potential maximum, as well as other negative traits, like low water and/or nitrogen-use-efficiency, which should be considered in conservation plans. Interestingly, all C4 species studied except Setaria viridis were among the most stressed species. Despite their higher water use efficiency and drought-tolerance reputation, they presented a much larger photosynthesis depression than most C3 species. This is an intriguing and interesting observation that deserves further studies.

Mildly toxic shrubs as indicators of goats herbivory give information for the management of natural landscapes on Mediterranean islands.

Herbivory of insular plant communities by introduced animals has been widely studied for decades. Though their diet mainly includes palatable and highly nutritive species, goats will also eat plants that are toxic to other animals. Thus, severe affection of toxic species may indicate high herbivore pressure or a low quality of vegetative food. To evaluate whether herbivory damage to low-palatability shrubs could give us information about feral goat pressure on vegetation, we assessed the predation impact of feral goats on the shrub Euphorbia dendroides (Euphorbiaceae) on Mallorca Island (Spain). We aimed to investigate whether goats consume juvenile E. dendroides and affect their population structure and determine if the plants increase the concentrations of toxic compounds as an adaptation to herbivory. Overall, two experimental plots and analysis of eleven natural populations indicated E. dendroides is affected by ungulates and that the population structure change with the presence of feral goats. Euphorbia dendroides could be used as an ecological indicator to determine the extent of ungulate damage to vegetation or indicate poor food availability, and thus inform the maintenance of optimal animal populations. Depending on the management objective for the territory, E. dendroides could be used as an ecological indicator to determine the extent of ungulate damage to vegetation or indicate poor food availability for animals, and thus inform the maintenance of optimal animal populations.

Historic exposure to herbivores, not constitutive traits, explains plant tolerance to herbivory in the case of two Medicago species (Fabaceae).

Mechanisms that allow plants to survive and reproduce after herbivory are considered to play a key role in plant evolution. In this study, we evaluated how tolerance varies in species with different historic exposure to herbivores considering ontogeny. We exposed the range-restricted species Medicago citrina and its closely related and widespread species M. arborea to one and two herbivory simulations (80 % aerial biomass loss). Physiological and growth parameters related to tolerance capacity were assessed to evaluate constitutive values (without herbivory) and induced tolerance after damage. Constitutive traits were not always related to greater tolerance, and each species compensated for herbivory through different traits. Herbivory damage only led to mortality in M. citrina; adults exhibited root biomass loss and increased oxidative stress after damage, but also compensated aerial biomass. Despite seedlings showed a lower death percentage than adults after herbivory in M. citrina, they showed less capacity to recover control values than adults. Moderate tolerance to M. arborea herbivory and low tolerance to M. citrina is found. Thus, although the constitutive characteristics are maintained in the lineage, the tolerance of plants decreases in M. citrina. That represents how plants respond to the lack of pressure from herbivores in their habitat.

Space and Vine Cultivar Interact to Determine the Arbuscular Mycorrhizal Fungal Community Composition.

The interest in the use of microbes as biofertilizers is increasing in recent years as the demands for sustainable cropping systems become more pressing. Although very widely used as biofertilizers, arbuscular mycorrhizal (AM) fungal associations with specific crops have received little attention and knowledge is limited, especially in the case of vineyards. In this study, the AM fungal community associated with soil and roots of a vineyard on Mallorca Island, Spain was characterized by DNA sequencing to resolve the relative importance of grape variety on their diversity and composition. Overall, soil contained a wider AM fungal diversity than plant roots, and this was found at both taxonomic and phylogenetic levels. The major effect on community composition was associated with sample type, either root or soil material, with a significant effect for the variety of the grape. This effect interacted with the spatial distribution of the plants. Such an interaction revealed a hierarchical effect of abiotic and biotic factors in shaping the composition of AM fungal communities. Our results have direct implications for the understanding of plant-fungal assemblages and the potential functional differences across plants in vineyard cropping.

Salt Marsh Elevation Drives Root Microbial Composition of the Native Invasive Grass Elytrigia atherica.

Elytrigia atherica is a native invasive plant species whose expansion on salt marshes is attributed to genotypic and phenotypic adaptations to non-ideal environmental conditions, forming two ecotypes. It is unknown how E. atherica-microbiome interactions are contributing to its adaptation. Here we investigated the effect of sea-water flooding frequency and associated soil (a)biotic conditions on plant traits and root-associated microbial community composition and potential functions of two E. atherica ecotypes. We observed higher endomycorrhizal colonization in high-elevation ecotypes (HE, low inundation frequency), whereas low-elevation ecotypes (LE, high inundation frequency) had higher specific leaf area. Similarly, rhizosphere and endosphere bacterial communities grouped according to ecotypes. Soil ammonium content and elevation explained rhizosphere bacterial composition. Around 60% the endosphere amplicon sequence variants (ASVs) were also found in soil and around 30% of the ASVs were ecotype-specific. The endosphere of HE-ecotype harbored more unique sequences than the LE-ecotype, the latter being abundant in halophylic bacterial species. The composition of the endosphere may explain salinity and drought tolerance in relation to the local environmental needs of each ecotype. Overall, these results suggest that E. atherica is flexible in its association with soil bacteria and ecotype-specific dissimilar, which may enhance its competitive strength in salt marshes.

Preference by Donkeys and Goats among Five Mediterranean Forest Species: Implications for Reducing Fire Hazard.

During the second half of the 20th century, European countries experienced an increase in their forest area due to the global change. Consequently, there has been an increase in large forest fires, mainly in the Mediterranean basin, and this has forced the development of several types of prevention programs. One of them is the control of the understory by livestock. In this sense, browsing with a combination of donkeys and goats could be a good option, as both animals usually feed on forest species. However, little is known about their preferences for the key species of the Mediterranean forest. Using a cafeteria test, the preferences and consumption of both animals have been determined for five typical species of the Mediterranean forest, such as Quercus ilex, Pinus halepensis, Phillyrea latifolia, Rubus ulmifolius, and Brachypodium retusum. Results showed that donkeys and goats could act complementarily in the reduction of the fuel biomass of forests. Donkeys appear to act more on fine fuel, such as B. retusum, and goats on the more pyrophyte species, in this case P. halepensis. In addition, given that donkeys are at severe risk of extinction in Europe, this role of providing ecosystem services could contribute to their conservation. Despite this study only showing that goats and donkeys would consume all five presented plant species and that there are some differences in consumption during a short-term test, it constitutes a useful first step for conservation and fire prevention in the Mediterranean forests.

Arbuscular Mycorrhizal Fungi Confer Salt Tolerance in Giant Reed (Arundo donax L.) Plants Grown Under Low Phosphorus by Reducing Leaf Na+ Concentration and Improving Phosphorus Use Efficiency.

Salinization is one of the major causes of agricultural soil degradation worldwide. In arid and semi-arid regions with calcareous soils, phosphorus (P) deficiency further worsens the quality of salinized soils. Nonetheless, nutrient poor soils could be suitable of producing second-generation energy crops. Due to its high biomass production, Arundo donax L. (giant reed) is one of the most promising species for energy and second-generation biofuel production. A. donax can be propagated by micropropagation, an in vitro technique that produces high number of homogeneous plantlets. However, crop establishment is often compromised due to poor plantlet acclimatization to the soil environment. Arbuscular mycorrhizal fungi (AM) are components of soil-plant systems able to increase root phosphorus uptake and to confer the plant an increase tolerance to salinity with a consequent enhancement effect of plant growth and yield. In the present study, the relative importance of the early symbiosis establishment between AM fungi and A. donax micropropagated plantlets in the response to salt stress under low phosphorus availability was determined. A commercial inoculum which contained two different AM fungi species: Rhizophagus intraradices and Funneliformis mosseae was used. AM-symbionts (AM) and non-symbionts plants were grown at two phosphorus [2.5 µM (C) and 0.5 mM (P)] and three NaCl (1, 75 and 150 mM) concentrations in a room chamber under controlled conditions. After 5 weeks, AM root colonization was 60, 26 and 15% in 1, 75 and 150 mM NaCl-treated plants, respectively. At 1 and 75 mM NaCl, AM plants showed increased growth. In all saline treatments, AM plants had decreased Na+ uptake, Na+ root-to-shoot translocation, Na+/K+ ratio and increased P and K use efficiencies with respect to C and P plants. AM improved the nutritional status of A. donax plants by enhancing nutrient use efficiency rather than nutrient uptake. Increased phosphorus use efficiency in AM plants could have benefited ion (Na+ and K+) uptake and/or allocation and ultimately ameliorate the plant's response to saline conditions.

Phosphorus concentration coordinates a respiratory bypass, synthesis and exudation of citrate, and the expression of high-affinity phosphorus transporters in Solanum lycopersicum.

Plants exhibit respiratory bypasses (e.g., the alternative oxidase [AOX]) and increase the synthesis of carboxylates in their organs (leaves and roots) in response to phosphorus (P) deficiency, which increases P uptake capacity. They also show differential expression of high-affinity inorganic phosphorus (Pi) transporters, thus avoiding P toxicity at a high P availability. The association between AOX and carboxylate synthesis was tested in Solanum lycopersicum plants grown at different soil P availability, by using plants grown under P-sufficient and P-limiting conditions and by applying a short-term (24 hr) P-sufficient pulse to plants grown under P limitation. Tests were also performed with plants colonized with arbuscular mycorrhizal fungi, which increased plant P concentration under reduced P availability. The in vivo activities of AOX and cytochrome oxidase were measured together with the concentration of carboxylates and the P concentration in plant organs. Gene transcription of Pi transporters (LePT1 and LePT2) was also studied. A coordinated response between plant P concentration with these traits was observed, indicating that a sufficient P availability in soil led to a suppression of both AOX activity and synthesis of citrate and a downregulation of the transcription of genes encoding high-affinity Pi transporters, presumably to avoid P toxicity.

Respiratory ATP cost and benefit of arbuscular mycorrhizal symbiosis with Nicotiana tabacum at different growth stages and under salinity.

Growth and maintenance partly depend on both respiration and ATP production during oxidative phosphorylation in leaves. Under stress, ATP is needed to maintain the accumulated biomass. ATP production mostly proceeds from the cytochrome oxidase pathway (COP), while respiration via the alternative oxidase pathway (AOP) may decrease the production of ATP per oxygen consumed, especially under phosphorus (P) limitation and salinity conditions. Symbiosis with arbuscular mycorrhizal (AM) fungi is reputed by their positive effect on plant growth under stress at mature stages of colonization; however, fungal colonization may decrease plant growth at early stages. Thus, the present research is based on the hypothesis that AM fungus colonization will increase both foliar respiration and ATP production at mature stages of plant growth while decreasing them both at early stages. We used the oxygen-isotope-fractionation technique to study the in vivo respiratory activities and ATP production of the COP and AOP in AM and non-AM (NM) tobacco plants grown under P-limiting and saline conditions in sand at different growth stages (14, 28 and 49days). Our results suggest that AM symbiosis represents an ATP cost detrimental for shoot growth at early stages, whilst it represents a benefit on ATP allowing for faster rates of growth at mature stages, even under salinity conditions.

Arbuscular Mycorrhizal Symbiosis with Arundo donax Decreases Root Respiration and Increases Both Photosynthesis and Plant Biomass Accumulation.

The effect of arbuscular mycorrhiza (AM) symbiosis on plant growth is associated with the balance between costs and benefits. A feedback regulation loop has been described in which the higher carbohydrate cost to plants for AM symbiosis is compensated by increases in their photosynthetic rates. Nevertheless, plant carbon balance depends both on photosynthetic carbon uptake and respiratory carbon consumption. The hypothesis behind this research was that the role of respiration in plant growth under AM symbiosis may be as important as that of photosynthesis. This hypothesis was tested in Arundo donax L. plantlets inoculated with Rhizophagus irregularis and Funneliformis mosseae. We tested the effects of AM inoculation on both photosynthetic capacity and in vivo leaf and root respiration. Additionally, analyses of the primary metabolism and ion content were performed in both leaves and roots. AM inoculation increased photosynthesis through increased CO2 diffusion and electron transport in the chloroplast. Moreover, respiration decreased only in AM roots via the cytochrome oxidase pathway (COP) as measured by the oxygen isotope technique. This decline in the COP can be related to the reduced respiratory metabolism and substrates (sugars and tricarboxylic acid cycle intermediates) observed in roots.

Nuevos recursos naturales como complemento de la dieta de caprinos durante la época seca, en el Valle de Tehuacán, México / New natural resources as diet supplement for domestic goats during the dry season, in the Tehuacán Valley, Mexico / Novos recursos naturais como complemento da dieta de caprinos durante a época seca, no Vale de Tehuacán, México

La ganadería caprina es una de las actividades más importantes para la subsistencia campesina en el Valle de Tehuacán, México Aquí, como en otras tantas zonas semiáridas del trópico, esta práctica enfrenta una marcada limitación debido a la escasez de forraje durante la época de sequía. Para evaluar las características nutricionales de la dieta del ganado caprino durante dicha época, se determinaron los principales componentes de la misma y sus características. Por otro lado, se evaluaron diferentes recursos vegetales de la zona, determinando sus propiedades bromatológicas con el objetivo de analizar su uso potencial como complemento alimenticio. Durante la época de sequía se observó una marcada limitación de forraje que obliga al ganado a consumir plantas con bajo contenido nutricional y alto contenido en metabolitos secundarios, produciendo una pérdida importante de peso. En conjunto, la dieta durante la época de sequía es deficitaria en proteína y fósforo. Los resultados indican que especies de Opuntia, Agave salmiana, los frutos de Yucca periculosa y las vainas de Prosopis laevigata y Acacia subangulata tienen un alto potencial para ser usadas, combinadas con el tradicional rastrojo de maíz, como complemento alimenticio. Estas nuevas fuentes de alimento posibilitan la estabulación o semi-estabulación del ganado durante la época de secas, como una alternativa de manejo. Ello reduciría la pérdida de energía en busca de recursos alimenticios, mejorando la productividad y disminuyendo el impacto sobre una de las vegetaciones más biodiversas de Norteamérica.

The extensive herding of goats has become the most important productive activity of subsistence for farmers at the Tehuacan Valley, Mexico. However, as in other semiarid tropical areas, the productivity of goat ranches is very low because of a very adverse period during the dry season. In order to determine the nutritional characteristics of the goats’ diet during this season, the diet was examined and the chemical characteristics of the principal species that are consumed was analyzed. On the other hand, different plant resources in the area, which can potentially be used as food supplementation, were analyzed determining their nutritional properties. A marked limitation of fodder during the dry season was found, which forces goats to eat plants with low nutritional characteristics and high content of secondary metabolites, provoking significant weight loss. Overall, grazing diet is deficient in protein and phosphorus during the dry season. The results indicate that species of Opuntia, Agave salmiana, the fruits of Yucca periculosa, and pods of Prosopis laevigata and Acacia subangulata present a high potential for use as food supplements, combined with the traditional corn stubble,. These new sources of nutrients make possible the enclosure of goats during the dry period, avoiding the high use of energy for food search, improving goat production and reducing goat impact on one of the most biodiverse area of vegetation North America.

A criação de gado caprino é uma das atividades mais importantes para a subsistência camponesa no Vale de Tehuacán, México. Aqui, como em outras tantas zonas semi-áridas do trópico, esta prática enfrenta uma marcada limitação devido à escassez de forragem durante a época de seca. Para avaliar as características nutricionais da dieta do gado caprino durante dita época, se determinaram os principais componentes da mesma e suas características. Por outro lado, se avaliaram diferentes recursos vegetais da zona, determinando suas propriedades bromatológicas com o objetivo de analisar seu uso potencial como complemento alimentício. Durante a época de seca se observou uma marcada limitação de forragem que obriga ao gado a consumir plantas com baixo conteúdo nutricional e alto conteúdo em metabólitos secundários, produzindo uma perda importante de peso. Em conjunto, a dieta durante a época de seca é deficitária em proteína e fósforo. Os resultados indicam que espécies de Opuntia, Agave salmiana, os frutos de Yucca periculosa e as vagens de Prosopis laevigata e Acacia subangulata têm um alto potencial para o uso combinado com o tradicional resíduo cultural do milho, como complemento alimentício. Estas novas fontes de alimento possibilitam a estabulação ou semi-estabulação do gado durante a época de secas, como uma alternativa de manejo. Isto reduziria a perda de energia em busca de recursos alimentícios, melhorando a produtividade e diminuindo o impacto sobre uma das vegetações mais biodiversas de Norte América.