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International audience; Les communautés bactériennes associées aux racines dePanicum turgide, exposés à des conditions arides, ont été investis-associée à une combinaison d'approches culturelles et métataxonomiques. Technologie traditionnelle basée sur la culture-ont été utilisées et 32 ​​isolats de racines irradiées ont été identifiés comme appartenant àActinobactéries, Bacteroidetes, Firmicutes et Proteobacteria embranchements. Quatre souches actinobactériennes ont étéRésistant aux rayonnements ionisants (IR) :Microbactériesp. PT8 (4,8 kGy (kGy)),Microcoquesp.PT11 (4,4 kGy),Kocuria rhizophilaPT10 (2,9 kGy) etPromicromonospora paniciPT9T(2,6 kGy), basésur le Ddixdose nécessaire pour une réduction de 90 % des unités formant colonies (UFC). Concernant l'enquêtedes communautés microbiennesin situ, analyses métataxonomiques de la diversité des microorganismes résistants aux IRassociée aux racines irradiées a révélé une dominance marquée des Actinobactéries (46,6%) etProtéobactéries (31,5%) par rapport aux Bacteroidetes (4,6%) et Firmicutes (3,2%). Irradiation gamma nonn'ont fait que modifier la structure des communautés bactériennes, mais ont également affecté leurs propriétés fonctionnelles.Des analyses comparatives des profils métaboliques ont indiqué l'induction de plusieurs voies liées à l'adaptation.au stress oxydatif dans les racines irradiées, comme la réparation de l'ADN, la synthèse de métabolites secondaires, la réactionenzymes atténuant les espèces oxygénées (ROS),etc. P. turgidumest emblématique des plantes adaptées au désert.Jusqu'à présent, aucun autre travail n'a porté sur le profil microbien des racines irradiées de cexérophyte.

In the context of the absence of any prior art on the vermicomposting of any xerophyte—presumably because xerophytes, in general, are structurally tough and have attributes which help them resist biodegradation—the present work has been undertaken. It has led to a procedure which makes even the highly toxic leaves of prosopis amenable to vermicomposting. Two years long and continuous operation of vermireactors with six different species of earthworms, has shown that the earthworms gradually adapted to prosopis as their exclusive feed, showing a consistently increasing rate of vermicast production while remaining healthy and displaying good fecundity throughout. The work provides an avenue of utilizing prosopis leaves which are generated in very large quantities across the tropical and sub-tropical world. At present no process exists which can make use of prosopis leaves even as the wood of its trees is utilizable. Besides valorizing an otherwise wasted phytomass the present work will also prevent falling of prosopis leaves on soil and their very slow biodegradation during which they toxify the soil with allelochemicals and emit global warming gases.

Balanites aegyptiaca has been identified as a source of seed oil for biodiesel feedstock. Diversity in its population based on morphological descriptors and seed oil yield has been studied in order to evaluate the variation, association of morphological descriptors with oil yield and inheritance of the traits to facilitate the plans for genetic improvement and its conservation. From seven agro-climatic regions, 56 accessions of B. aegyptiaca were studied to evaluate variability based on morphological descriptors, viz. height, girth, leaf, fruit, pericarp, mesocarp, nut and kernel. The data were subjected to ANOVA, simple measures of variation and D2 statistics. Genetic variability among morphological descriptors was recorded. High heritability (> 0.8) and genetic advance (~ 360%) make kernel weight a suitable marker for genetic improvement of B. aegyptiaca for oil yield. Cluster analysis revealed that cluster V (Jaipur, Sikar, Jodhpur, Dungarpur, Alwar and Kota regions) had high oil. Cluster II with the highest intracluster distance (10,239) was found to be the most suitable for genetic improvement. The population of B. aegyptiaca in Udaipur, Jaipur, Sikar, Jodhpur, Alwar and Dungarpur may be protected for in situ conservation. The study helps in designing strategy to get enhanced oil from B. aegyptiaca and its conservation.

Made available in DSpace on 2022-04-29T08:32:33Z (GMT). No. of bitstreams: 0 Previous issue date: 2022-01-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) The indiscriminate use of fertilizers and chemical pesticides can lead to boron contamination of the soil. Decontamination in general is expensive and results in other impacts. Phytoremediation is a sustainable alternative for soil restoration. Astronium fraxinifolium Schott (Anacardiaceae) is a tree species native to the Cerrado that is considered to be a pioneer species and a selective xerophyte, and it has been widely used in the reforestation and restoration of degraded areas. This study set out to characterize the physiology and anatomy of A. fraxinifolium under different boron concentrations and to assess the tolerance and phytoremediation potential of the species. An experiment with a completely randomized design was conducted in a greenhouse. The carbon allocation and chlorophyll content of leaves of A. fraxinifolium were determined. Boron concentration and the species’ tolerance index were calculated from root and shoot samples. Levels of amino acids, proteins, total carbohydrates, starch, phenolic compounds, and anatomical analysis were also measured. A. fraxinifolium showed tolerance to boron concentrations in the substrate and accumulated a greater amount of the element in the aerial part, showing its phytoextraction ability. No significant differences were found in the physiology of A. fraxinifolium; however, some anatomical changes were observed. In the leaves, there were changes in the thickness of the abaxial surface of the epidermis and palisade and spongy parenchyma, and total leaf thickness, and in the roots, there were changes in the thickness of the phloem, diameter of vessel elements, and number of vessel elements per square millimeter. However, boron did not interfere in the development and survival of A. fraxinifolium, which points to the possibility that the species has phytoremediation potential. Faculdade de Engenharia de Ilha Solteira Department of Biology and Animal Science Universidade Estadual Paulista “Júlio de Mesquita Filho”, São Paulo Faculdade de Engenharia de Ilha Solteira Department of Biology and Animal Science Universidade Estadual Paulista “Júlio de Mesquita Filho”, São Paulo CNPq: 130355/2018-6 FAPESP: 2018/01498-6

Myricaria laxiflora (Tamaricaceae) is an endangered plant that is narrowly distributed in the riparian zone of the Three Gorges, along the Yangtze River, China. Using bright-field and epifluorescence microscopy, we investigated the anatomical and histochemical features that allow this species to tolerate both submerged and terrestrial environments. The adventitious roots of Myr. laxiflora had an endodermis with Casparian bands and suberin lamellae; the cortex and hypodermal walls had lignified thickenings in the primary structure. In the mature roots, the secondary structure had cork. The apoplastic barriers in stems consisted of a lignified fiber ring and a cuticle at the young stage and cork at the mature stage. The leaves had two layers of palisade tissue, a hyaline epidermis, sunken stomata, and a thick, papillose cuticle. Aerenchyma presented in the roots and shoots. Several Myr. laxiflora structures, including aerenchyma, apoplastic barriers in the roots and shoots, were adapted to riparian habitats. In addition, shoots had typical xerophyte features, including small leaves, bilayer palisade tissues, sunken stomata, a thick, papillose cuticle, and a hyaline epidermis. Thus, our study identified several anatomical features that may permit Myr. laxiflora to thrive in the riparian zone of the Three Gorges, China.

This study aimed to investigate the leaf anatomy of Jacquinia armillaris plants in two different Venezuelan xeric shrublands to evaluate possible variations caused by the environments, which differ in rainfall and soil salinity. Leaf samples were collected in two sites: La Tortuga Island, a dryer and salty environment than the other collecting site, Turpialito, a coastal location in the mainland. The epidermis and the mesophylls were observed with a light microscope and measured with an ocular micrometer inserted in one of the eyepieces. The results show that J. armillaris has many characteristic anatomical traits of xerophytes, among them: thick cuticles and thick epidermis in both leaf surfaces, stomata only in the abaxial side and epidermal depressions lodging a glandular trichome. Leaves are bifacial and present multistratified palisade parenchyma facing the adaxial epidermis and abaxial spongy parenchyma with abundant intercellular spaces. Furthermore, the hypodermis is composed of one or two cell layers below the upper epidermis. Leaf lamina dimension, petiole, cuticles, epidermis and hypodermis cells, as well as the stomatal occlusive cells and number of trichomes, had differences in size and number when the plants of both sites were compared, being higher in plants from La Tortuga. On the other hand, palisade parenchyma and stomatal density were higher in Turpialito plants. Plants collected in La Tortuga Island showed characteristics that suggest adaptation to the island’s saline and more arid conditions in comparison to plants from Turpialito, which presented more leaf traits related to adaptations to water deficit. These results demonstrate the phenotypic plasticity of J. armillaris plants that grow in two different xeric shrublands.

Salinity causes physiological, morphological, and anatomical modifications in Mediterranean saltbush Atriplex halimus and giant saltbush Atriplex nummularia. Both species, which belong to Chenopodiaceae, are true xerophyte as shown from Kranz-anatomy and salt storage trichromes. Response of both species to salinity were differed according to genetic structures. Atriplex species leaves characteristic by presence of salt accumulating cells on upper and lower leaf epidermis, which have ecological significance. Increasing of salinity had negative effect on anatomical measurements of A. halimus leaves. However, low level of salinity had positive effect in A. nummularia leaves, but high level of had negative effect on leaves.

Despite the abundance of studies on the interactions between dark septate endophytes (DSEs) and host plants, little is known about the effects elicited by different DSE species and inoculum levels, especially in desert plants. Here, we examined the colonization status and species composition of DSEs in roots of Hedysarum scoparium, a xerophyte plant endemic to arid desert, northwest China. Subsequently, we assessed the performance of host plants inoculated with Paraphoma chlamydocopiosa and Alternaria doliconidium under different inoculum levels. DSE colonization was characterized by spatial and interannual variability, and hyphal colonization was dominant (17.2%–76.7%). Alternaria doliconidium, Edenia gomezpompae, Paraphoma pye, Subramaniula flavipila and Herpotrichia striatispora are reported here in desert ecosystems for the first time. Both P. chlamydocopiosa and A. doliconidium established positive symbiosis with H. scoparium, however, the growth-promoting effects differed significantly depending on the DSE species and inoculum level (P

The Plant Vigour Hypothesis states that herbivores preferentially feed on the most vigorous plants within a plant population and/or the most vigorous modules within a plant. The goal of this study was to evaluate how shoot size (as an indication of module vigour) affects leaf herbivory in the host plant Calotropis procera, an exotic xerophyte perennial milkweed shrub. We predicted that the proportion of leaf area removed by insect herbivores would be positively related to shoot size. Eight patches were selected containing a varied number of C. procera individuals (5, 8, 29, 31, 55, 79, 116, and 172 individuals/patch) in the Brazilian seasonally dry vegetation (Caatinga), of which five individuals were randomly selected for further analysis. From each individual, three to six shoots were randomly selected, measured and had their leaves collected, for a total of approximately 200 leaves per patch. At the regional scale, the proportion of leaf area removed was positively affected by shoot size. In addition, this pattern was also found for the majority of the studied patches (29, 31, 55, 116, and 172 individuals/patch). Among the insect herbivores associated with C. procera, larvae of Danaus spp. (Lepidoptera: Nymphalidae) were commonly observed feeding on all patches. These herbivores present a specialized behaviour to circumvent the presence of latex in the host leaves. Although more vigorous plant modules should be better defended compared with the less vigorous modules, Danaus species were able to bypass host defences, and feed on healthy, rapidly growing and vigorous plant modules of C. procera, hence causing more damage to these modules.

Plant growth and productivity are adversely affected by various abiotic (high temperature, moisture stress and salinity) and biotic stresses (Pest and Disease). To overcome this problem various strategies are followed viz., modified cultivation practices, improved breeding methods and application of stress tolerant/resistant microorganisms. Present investigation was designed with the view to address the moisture stress by exploring autochthonous microflora of xerophyte Prosopis juliflora (Sw). Ten different isolates were obtained from southern agro-climatic zone of Tamil Nadu and screened in vitro by artificial induction of drought in solution using PEG 6000. Of which two potential isolates (MLSB 2 & MLSB 6) were obtained from the rhizosphere of Prosopis juliflora collected based on significant anount of IAA and proline produced during moisture stress condition and withstand upto (-1.03 M Pa) osmotic potential.

Lush jungle flagship species, woody bamboos (Poaceae–Bambusoideae) are famed for their synchronous flowering as well as the extensive “bamboo forests” some species can form in tropical or temperate environments. In portions of their natural distribution, Bambusoideae members developed various adaptations to seasonality in environmental parameters, such as frost or seasonal drought. A new taxon, Laobambos calcareus, described here, is extremely novel in showing the first documented case of succulence in bamboos, with its ability to seasonally vary the volume of its stem depending on the quantity of water stored. Anatomical studies presented in this paper document this specificity at the cellular level. Though no flowers or fruits are known yet, unique morphological characteristics along with an investigation of its phylogenetic affinities using molecular data show that this new taxon should belong to a new genus herein described.

The aim of the study was to investigate the effects of a special organic fertilizer (SOF, with common organic fertilizer (COF) as the carrier and Na+ as well) on the growth performance of Haloxylon ammodendron, and soil properties in desert regions of China. All fertilization treatments were applied to seedlings in the nursery in open field in Alashan Right Banner (ARB, severe arid area) and Hangjin Banner (HB, mild arid area) of Inner Mongolia (plants were not used for afforestation), and unfertilized 1-year-old plants cultivated in Minqin (MQ, moderate arid area) of Gansu province were selected and applied SOF for afforestation in ARB, HB, and MQ, respectively. The results (take ARB for example) indicated that SOF significantly increased plant height (PH) by 52.2 and 37.6%, main root length (MRL) by 42.6 and 22.8%, and dry weight (DW) of whole plant by 142.4 and 104.6%, respectively, over the CK and COF treatments in the nursery. SOF also significantly mitigated deleterious impacts of drought stress on the growth of H. ammodendron and enhanced soil properties in afforestation, where it increased survival rate (SR) by 50.6% and 28.9%, PH by 17.2% and 12.1%, MRL by 43.5% and 44.8%, and DW by 110.3% and 54.7%, respectively, compared with CK and COF treatments. Furthermore, soil organic matter (SOM) in SOF treatment was significantly increased by 210 and 6%, and no significant effect on Na+ content in root zone soil was observed in afforestation. The effects of SOF on H. ammodendron and soil properties were more remarkable in MQ and HB than in ARB. We conclude that SOF provide efficient nutrients for H. ammodendron, and the Na+ released by SOF can be utilized by H. ammodendron in time, and will not be released to soil in large quantities, which initiates a new method to restore degraded vegetations in desert regions of China.

Plant root variations and their relations with soil moisture and nutrient supply have been well documented for many species, while effects of drought, combined with extreme poor soil nutrients, on plant roots remain unclear.Herein, we addressed root vertical distributions of two typical xerophyte semishrub species, Artemisia sphaerocephala and A. intramongolica, and their relations with soil moisture, total soil nitrogen and carbon contents in arid Hunshandake desert, China. The two species experienced similar light regimes and precipitation, but differed in soil moisture and soil nutrients.Root vertical distribution patterns (e.g., coarse root diameter, root depth and root biomass) differed considerable for the two species due to high heterogeneity of soil environments. Coarse and fine root biomasses for A. intramongolica, distributed in relatively moist fixed dunes, mainly focused on surface layers (94%); but those for A. sphaerocephala dropped gradually from the surface to 140 cm depth. Relations between root traits (e.g., diameter, root biomass) and soil moisture were positive for A. intramongolica, but those for A. sphaerocephala were negative.In general, the root traits for both species positively correlated with total soil nitrogen and carbon contents. These findings suggest that both soil moisture and poor soil nutrients were the limiting resources for growth and settlement of these two species., The root traits for Artemisia sphaerocephala and A. intramongolica were positively correlated with total soil nitrogen and carbon contents. These findings indicate that both soil moisture and poor soil nutrients were the limiting resources for growth in these two species.

The xerophyte Pugionium cornutum can accumulate large amounts of Cl– in its shoots for osmotic adjustment, and this is linked with improved hydration status and photosynthesis under salt and drought conditions., Chloride (Cl–) is pervasive in saline soils, and research on its influence on plants has mainly focused on its role as an essential nutrient and its toxicity when excessive accumulation occurs. However, the possible functions of Cl– in plants adapting to abiotic stresses have not been well documented. Previous studies have shown that the salt tolerance of the xerophytic species Pugionium cornutum might be related to high Cl– accumulation. In this study, we investigated the Cl–-tolerant characteristics and possible physiological functions of Cl– in the salt tolerance and drought resistance of P. cornutum. We found that P. cornutum can accumulate a large amount of Cl– in its shoots, facilitating osmotic adjustment and turgor generation under saline conditions. Application of DIDS (4,4´-diisothiocyanostilbene-2,2´-disulfonic acid), a blocker of anion channels, significantly inhibited Cl– uptake, and decreased both the Cl– content and its contribution to leaf osmotic adjustment, resulting in the exacerbation of growth inhibition in response to NaCl. Unlike glycophytes, P. cornutum was able to maintain NO3– homeostasis in its shoots when large amounts of Cl– were absorbed and accumulated. The addition of NaCl mitigated the deleterious effects of osmotic stress on P. cornutum because Cl– accumulation elicited a strong osmotic adjustment capacity. These findings suggest that P. cornutum is a Cl–-tolerant species that can absorb and accumulate Cl– to improve growth under salt and drought stresses.

Drought and soil salinity are the main environmental stress factors affecting plant growth and development. A certain appropriate concentration of NaCl in the soil has been suggested to show a beneficial effect on halophyte and xerophyte growth, while drought could cause severe damage to plants. Thus, under drought conditions, whether the moderate soil salinity could still stimulate all plant growth and productivity is curious. In this study, three plants with different salt tolerance, including arrowleaf saltbush (Atriplex tr-iangularis Willd.), cotton (Gossypium hirsutum L.) and soybean [Glycine max (Linn.) Merr.], were sown in soils containing different concentrations of NaCl and exposed to drought and non-drought conditions for 30 days. The shoot biomass, water potential, osmotic potential, Na+ and K+ concentrations in seedlings were measured. Both drought and salt stress could inhibit the growth of arrowleaf saltbush, cotton and soybean, but the decreases in plant height and shoot biomass under drought conditions were attenuated with the increase of NaCl concentration. The Na+ concentration in the leaves subjected to combined drought and salt stresses was significantly higher than that in leaves subjected only to drought stress. Meanwhile, the osmotic potential of the leaves was significantly lower in the former than the latter, and the RWC and cell turgor pressure in the leaves were significantly higher in the former than the latter. Our results prove that the appropriate soil salinity could alleviate the detrimental effects of drought stress on the water status and plant growth, no matter they are salt-tolerant or salt-sensitive plants.

A salt-tolerant, Gram-negative, rod-shaped and yellow-pigmented bacterium, designated strain AY-3RT, was isolated from rhizosphere soil of a desert xerophyte, Haloxylon ammodendron, sampled at Badain Jaran Desert, Alxa region, Inner Mongolia, PR China. Growth of this strain was observed at 20–42 °C (optimum, 28–30 °C), at pH 6.0–9.0 (optimum, pH 6.0–7.0) and at 0–8 % (w/v) NaCl (optimum, 3 %). Results of phylogenetic analysis based on 16S rRNA gene sequences showed that strain AY-3RT was a member of the genus Altererythrobacter , with the highest similarity to Altererythrobacter aerophilus Ery1T (97.6 %), followed by Altererythrobacter xinjiangensis S3-63T (96.9 %). The predominant fatty acids (>10.0 %) were C18 : 1ω7c, C17 : 1ω6c and summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c). The major polar lipids were diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, sphingoglycolipid and one unknown polar lipid. The predominant respiratory quinone was ubiquinone-10. The G+C content of the genomic DNA of strain AY-3RT was 66.3 mol%. On the basis of the data from this polyphasic taxonomic study, strain AY-3RT represents a novel species of the genus Altererythrobacter , named Altererythrobacter rhizovicinus sp. nov. (=MCCC 1K03572T=KCTC 72280T).

Despite desert ecosystem being crucial to our understanding of natural geography, species evolution and global climate change, there is limited information on the dynamics of their composition and the diversity of endophytic fungi communities driven by plant identity and organ differentiation. Here, an extensive investigation of endophytic fungal microbiome in root, stem, and leaf organs associated with five xerophyte shrubs in an extremely arid desert, Northwest China, were examined. The fungal community dominated by Dothideomycetes and Pleosporales. Shrub species strongly drive the niche-based processes of endophytic fungi across the root, stem and leaf compartments. The diversity and composition of endophytic fungi in stem showed higher variability among plant species than leaf and root. The fungal communities in root libraries were more diverse and exhibited a remarkable differentiation of community composition. We further demonstrated the significant host preferences and tissue specificity of desert endophytic fungi, and unique specific taxa were also observed. The co-occurrence network revealed the coexistence of fungal endophytes in arid desert, and the root fungal network harbored the highest interspecies connectivity. Members of Pleosporales were the most common keystone species in the root fungal network. This is the first report of mycobiota in both plant species and organ differentiation in an extremely arid desert ecosystem.

Scabiosa hymettia Boiss. & Spruner (syn. Lomelosia hymettia, fam. Dipsacaceae) is an endemic xerophyte of central and southern Greece, and of the northern Aegean region. It is a small shrub of the macchia zone, very attractive from May to mid-July when it bears blue-purple flowers on elongated flower peduncles. In the present study its vegetative propagation by stem cuttings was investigated, in order to introduce the species as an ornamental plant in urban and suburban areas and historical Mediterranean landscapes. Cuttings derived from the apical part of shoots, 15 cm long, bearing two to four lateral shoots, were collected from a wild population at mount Parnitha (prefecture of Attiki, Greece), in spring (March), summer (August), autumn (October) and winter (January) for two consecutive years. The base of the cuttings was immersed either in powder indole-3-butyric acid (IBA) for herbaceous/softwood or for hardwood cuttings, or in IBA ethanol-water (1:1, v/v) solutions, at four different concentrations: 0 (control), 1000, 2000 and 3000 mg L(‑1), for two dipping times, 1 or 5 min, and were put for rooting on a mix of 1 peat:1 perlite (v/v) in a mist system for two weeks and then on a heated-glasshouse bench for further six weeks. Almost all cuttings (92.5-100%) collected in autumn and winter rooted when treated with powder IBA for hardwood cuttings, or with 1000 mg L(‑1) IBA ethanol-water solution for 1 min, while the controls rooted at 45-65%. In spring and particularly in summer, cuttings rooted at lower rates compared to autumn and winter. Best response in spring was achieved with the use of powder IBA for hardwood cuttings (50% rooting), or with 5 min dipping in IBA solutions (50-67.5% rooting). In summer highest rooting was induced either with powder IBA for hardwood cuttings (45.0%) or with 1000 mg L(‑1) IBA for 1 min dipping time (37.5%).

Reaumuria soongorica, a salt-secreting xerophytic shrub, is a dominant species in arid desert regions of northwest China. To investigate whether NaCl could stimulate the growth and alleviate drought stress in R. soongorica, the seedlings were treated with a range of different concentrations of 0–1.17 g kg−1 NaCl, and also were withheld water for drought stress under without or supplementary 0.59 g kg-1 NaCl. The results showed that 0.59 g kg-1 NaCl (moderate NaCl) significantly stimulated the growth of R. soongorica, and also effectively alleviated deleterious impacts of drought stress on its growth and leaf morphological structure. Further analysis showed that moderate NaCl significantly improved photosynthetic capacity and mitigated light suppression of drought stress on photosystem II in R. soongorica, concomitantly, decreased osmotic potential, enlarged turgor pressure as well as increased the relative water content in leaves under drought stress. Furthermore, moderate NaCl induced an obvious increase of Na+ accumulation in tissues of R. soongorica, which resulted in a significant increase of the contribution of Na+ to leaf osmotic potential from13 to 22% under drought stress. Additionally, moderate NaCl also promoted Na+ secretion via salt glands of leaf. These results suggest that the positive roles of NaCl on the growth and drought resistance of R. soongorica is due to the increase of Na+ accumulating in leaf tissues, facilitating plant to maintain higher photosynthetic activity and better water status in arid environment, simultaneously, salt secretion of salt glands protects plant from excess Na+ toxicity.

Zygophyllum xanthoxylum is a salt‐accumulating xerophytic species with excellent adaptability to adverse environments. Previous studies demonstrated that Z. xanthoxylum absorbs a great quantity of Na⁺ as an osmoregulatory substance under arid conditions. To investigate the nutritional status of Z. xanthoxylum in comparison with a typical glycophyte, Arabidopsis thaliana, seedlings were exposed to NaCl (50 mM for Z. xanthoxylum and 5 mM for A. thaliana), osmotic stress (–0.5 MPa), and osmotic stress combined with the NaCl treatment. Compared to the control, NaCl treatment or osmotic stress significantly increased Na⁺ concentration in leaves and roots of Z. xanthoxylum, but not of A. thaliana. Under osmotic stress, the addition of NaCl significantly increased Na⁺ concentration in leaves and roots of Z. xanthoxylum, resulting in improved biomass and tissue water content. However, such changes were not observed in A. thaliana. Compared to the control, K⁺ concentrations in leaves and roots remained unchanged in Z. xanthoxylum when exposed to osmotic stress, with or without additional 50 mM NaCl. In contrast, significant reductions in shoot K⁺ concentrations of A. thaliana were observed under osmotic stress alone or when combined with 5 mM NaCl. Moreover, NaCl alone or when combined with osmotic stress enhanced the accumulation of N, P, Fe, Si, Ca²⁺, and Mg²⁺ in Z. xanthoxylum, but did not cause such nutritional changes in A. thaliana. Compared to the glycophyte A. thaliana, Z. xanthoxylum could accumulate Na⁺ and maintain the stability of nutritional status at a relatively constant level to cope with drought stress.

Premise of the study The C3 desert shrub ocotillo (Fouquieria splendens) completely lacks xeromorphic leaves but is uncommonly both stem succulent and repetitively drought deciduous (documented to have produced many foliation-defoliation cycles during a growing season). Both adaptations conserve water in this xerophyte, but are the roles of succulence and deciduousness merely redundant? The observation that year-to-year reproductive effort was relatively consistent while vegetative growth was not offered a critical clue that, coupled with long-term precipitation data, helped answer this question. Methods At two sites in the Chihuahuan Desert in southern New Mexico, United States, 22 ocotillos were studied annually for more than two decades to explore the relationships among reproductive effort, vegetative stem growth, and patterns of precipitation. Key results Vegetative stem growth occurred in mid- to late summer (July-September), the season of maximum precipitation in the Chihuahuan Desert, and was significantly related to summer precipitation received in the year of growth. Reproductive effort occurred in early to late spring (April-June), which with winter account for minimum precipitation during the year, but was significantly related to summer precipitation received in the previous year, suggesting the importance of stem succulence and stored water. Conclusions While highly variable summer precipitation was responsible for enormous fluctuations in annual ocotillo stem growth, stem succulence insulated reproductive effort from such immense variability. Stem-stored water allowed the production of flowers and fruits to proceed relatively consistently during the driest years and during the driest time of year in the Chihuahuan Desert.

SUMMARY The effects of vesicular-arbuscular mycorrhizal inoculum and competition from non-mycorrhizal annual plants were tested on Agropyron smithii Rydb. and Agropyron dasystachyum (Hook.) Scribn. growing in an inoculum-poor soil. Mycorrhizal A. smithii decreased stomatal resistance (rs) and increased leaf water potential compared to the non-inoculated plants, but only during the driest portion of the growing season. The presence of annuals caused increased rs of A. smithii, but only of non-inoculated plants. Mycorrhizal plants had the same rs with or without annuals, indicating that mycorrhizas may alleviate the detrimental effects of competition on rs of A. smithii. By contrast, neither inoculation nor annuals significantly affected water relations of A. dasystachyum. Mycorrhizas also did not increase N and P concentrations or percentage cover of either grass, but both had delayed phenology when mycorrhizal. This research was done during a wet year when the effects of mycorrhizas may be subtle. Long-term observations are necessary to determine the importance of mycorrhizas under field conditions.

Drought and salinity can result in cell dehydration and water unbalance in plants, which seriously diminish plant growth and development. Cellular water homeostasis maintained by aquaporin is one of the important strategies for plants to cope with these two stresses. In this study, a stress-induced aquaporin, ZxPIP1;3, belonging to the PIP1 subgroup, was identified from the succulent xerophyte Zygophyllum xanthoxylum. The subcellular localization showed that ZxPIP1;3-GFP was located in the plasma membrane. The overexpression of ZxPIP1;3 in Arabidopsis prompted plant growth under favorable condition. In addition, it also conferred salt and drought tolerance with better water status as well as less ion toxicity and membrane injury, which led to more efficient photosynthesis and improved growth vigor via inducing stress-related responsive genes. This study reveals the molecular mechanisms of xerophytes’ stress tolerance and provides a valuable candidate that could be used in genetic engineering to improve crop growth and stress tolerance.

Haloxylon ammodendron, a typical xerophyte, tolerates various abiotic stresses and is widely distributed in desert areas. Two PGPR strains, Bacillus sp. WM13-24 and Pseudomonas sp. M30-35, were previously isolated from the rhizosphere of H. ammodendron in Tengger Desert, Gansu province, northwest China. The aim of this study was to investigate the role of M30-35 and WM13-24 in drought stress alleviation of ryegrass (Lolium perenne L.). Under normal condition, both M30-35 and WM13-24 increased shoot fresh and dry weight, chlorophyll content, total nitrogen and phosphorus contents and altered phytohormone distribution compared to control. Moreover, after 7 days of drought stress, WM13–24 and M30-35 enhanced photosynthetic capacity, relative water content, the activities of catalase (CAT) and peroxidase (POD) and proline content, resulted in decreased malondialdehyde (MDA) content, relative membrane permeability (RMP) and H2O2 accumulation; interestingly, the two strains decreased ABA content in leaves. This study demonstrated that the two PGPR strains promoted ryegrass growth and root development via regulating plant hormone distribution and enhanced drought tolerance of ryegrass through improving the activities of antioxidant enzymes, regulating ABA signaling and maintaining plant growth. Our results indicated that PGPR strains from rhizosphere of the desert plant species could be considered as promising bioinoculants for grass plants.

14 páginas, 5 tablas, 4 figuras, A new strain belonging to the genus Kocuria, designed PT10, was isolated from irradiated roots of the xerophyte Panicum turgidum. Isolate PT10 is a Gram-positive, coccoid, aerobic and ionizing-radiation (IR)-resistant acti-nobacterium. PT10 has shown an ability to survive under extreme conditions, such as gamma irradiation, desiccation and high concentration of hydrogen peroxide. Phenotypic, chemotaxonomic and comparative genome analyses support the assignment of strain PT10 (LMG 31102 =DSM 108617) as Kocuria rhizophila. The complete genome sequence of PT10 consists of one chromosome (2,656,287 bps), with a 70.7% G +C content and comprises 2481 protein-coding sequences. A total of 1487 proteins were identified by LC-MS/MS profiling. In silico analyses revealed that the proteome of the oxidation-tolerant PT10 possesses several features explaining its IR-resistant phenotype and many adaptive pathways implicated in response to environmental pressures — desiccation, cold, reactive oxygen species and other stressors., This work was performed under the auspices of Université Lyon 1, UMR 5557, Ecologie Microbienne (France) and the National Center for Nuclear Sciences and Technologies CNSTN (MESRS, Tunisia) and in the ambit of the BIODESERT research program of the LR11-ES31 (BVBGR, ISBST, University of Manouba (MESRS, Tunisia). The LABGeM (CEA/ Genoscope & CNRS UMR8030), the France G ́enomique and French Bioinformatics Institute national infrastructures (funded as part of Investissement d’Avenir program managed by Agence Nationale pour la Recherche, contracts ANR-10-INBS-09 and ANR-11-INBS-0013) are acknowledged for support within the MicroScope annotation platform. We thank Betty Bigai, Corinne Sannaire and platform Genomique Environnementale PGE, UMR CNRS 5557 for technical support

High-throughput detection of plant environmental stresses is required for minimizing the reduction in crop yield. Environmental stresses in plants have primarily been validated by the measurements of photosynthesis with gas exchange and chlorophyll fluorescence, which involve complicated procedures. Remote sensing technologies that monitor leaf reflectance in intact plants enable real-time visualization of plant responses to environmental fluctuations. The photochemical reflectance index (PRI), one of the vegetation indices of spectral leaf reflectance, is related to changes in xanthophyll pigment composition. Xanthophyll dynamics are strongly correlated with plant stress because they contribute to the thermal dissipation of excess energy. However, an accurate assessment of plant stress based on PRI requires correction by baseline PRI (PRIo) in the dark, which is difficult to obtain in the field. In this study, we propose a method to correct the PRI using NPQT, which can be measured under light. By this method, we evaluated responses of excess light energy stress under drought in wild watermelon (Citrullus lanatus L.), a xerophyte. Demonstration on the farm, the stress behaviors were observed in maize (Zea mays L.). Furthermore, the stress status of plants and their recovery following re-watering were captured as visual information. These results suggest that the PRI is an excellent indicator of environmental stress and recovery in plants and could be used as a high-throughput stress detection tool in agriculture.

Salvadora oleoides Decne. (Salvadoraceae) is a facultative and mesomorphic xerophyte, well adapted to arid and semi-arid regions. Twelve populations were selected from different ecological regions of Punjab to investigate structural modifications that are essential for water conservation, by either improving water-storing capacity or preventing water loss from the plant body, hence, enabling this species to cope with environmental extremities. We observed significant plasticity in structural features, which ensures ecological success in a variety of environmental conditions. Huge variation was seen in various tissue systems, i.e., epidermis and epidermal appendages, collenchyma, size of internal oil glands, storage parenchyma, shape, size and arrangement of vascular tissue, intensity of sclerification, and stomatal size, shape and orientation. The desert populations showed additional parenchymatous layer under multilayered epidermis, xylem completely surrounded by phloem, broad metaxylem vessels, intensive sclerification in and outside vascular tissue, and numerous and small sized stomata on abaxial leaf surface. Population from salt-affected areas showed greater stem cross-sectional area, enlarge palisade parenchymatous cells, multilayered epidermis, large storage parenchyma, and sclerified vascular bundles. Roadside populations possessed sclerified vascular bundles and dense hairiness on leaf surface.

Grazing is one of the predominant human activities taking place today inside protected areas, with both direct and indirect effects on the vegetation community. We analyzed the effects of grazing intensity on grass composition during four grazing seasons containing 78 plant species belonging to eight plant functional groups, which include perennial tall grass (6 species), perennial short grass (6 species), shrubs (3 species), legumes (9 species), Liliaceae herb (8 species), annual/biennial plants (11 species), perennial short forbs (16 species) and perennial tall forbs (18 species). We estimated grazing intensity at four levels, control, light, moderate and heavy grazing intensity corresponding to 0.00, 0.23, 0.46 and 0.92 animal units ha&minus, 1, respectively. We found that each plant functional group showed a different response to grazing intensity. Perennial tall grasses that were dominated by high palatable mesophyte and mesoxerophyte grass showed a significant decrease with grazing intensity, while the medium palatable xerophyte and widespread grasses that were the predominant short perennial increases with grazing intensity. The perennial tall forbs that were dominated by the mesophyte grass also decreased, but the decrease was statistically insignificant. The influence of grazing density on species is also related to soil factors (soil nutrient, soil moisture and soil temperature and soil bulk density). Some functional groups such as tall fescue and Liliaceae herbs, remained stable&mdash, which may be related to the changes in the soil environment caused by grazing activities. The findings of this study could provide a standpoint for assessing the current grazing management scenarios and conducting timely adaptive practices to maintain the long-term ability of grassland systems to perform their ecological functions.

Haloxylon ammodendron is a perennial xerophyte that can survive in extremely harsh desert conditions of Central Asia. This study evaluated the effect of salinity, and their ability to recover on seed germination of H. ammodendron, which were collected at three different desert areas, Bakanas takyr plain (H1), Gurbant&uuml, ng&uuml, t Desert (H2), and Gobi Desert (H3), respectively. Seeds were treated with different concentrations of NaCl and Na2SO4 (0.00 (control), 0.05, 0.10, 0.20, 0.40, 0.60, 0.80, 1.00, 1.20, and 1.40 mol/L) to detemine the germination and recover ability to salt stress. The results of the study were that H. ammodendron were more resistant to Na2SO4 than to NaCl. Regarding inhibition of seed germination H. ammodendron was in the following order: H3 &gt, H2 &gt, H1. Based on the tolerance and recovery, seeds can be demonstrated as follows: NaCl: H3 &gt, H1 &gt, H2, Na2SO4: H1 = H2 = H3. Non-germinated seeds in all salt treatments with low osmotic potential showed high recovery when transferred to distilled water, indicating that these treatments were not too toxic to affect seed viability. These results suggest that H. ammodendron can withstand high levels of salinity at three desert environments. Thus, H. ammodendron could be used to reconstruct vegetation and sustanbility development in the desert areas with high salinity.

Revegetation is the most common procedure in the restoration of disturbed areas; this practice usually aims at reconstructing plant communities that can last without further management. A low-cost strategy to assist these efforts is the application of ecological knowledge in the design of the restoration. Promoting ecological processes that enhance the functioning of the restored community could result in higher restoration success. Among these processes, plant–plant interactions, e.g., facilitation and competition, can play an important role, both facilitating and impeding the development of a self-sustaining plant community. Although these processes have been well-studied in nature, we rarely have sufficient knowledge about the whole plant community. To develop that knowledge, we leverage on a restoration experiment that took place after a mine toxic spill, where ~15,000 woody plants from 13 species were planted and geolocated. Species were planted in three mixtures mimicking natural communities found along soil moisture gradients (xerophyte, intermediate, and hydrophyte). Plantings also varied in density. Approximately 2,600 plants were monitored for damage status, survival, and growth, for 4 yr. We analyzed growth performance of six targeted species as a function of their damage status, planted mixture, and density. Growth was also assessed on the basis of neighboring plants, accounting for the species identity and distance to the focal plant. Results show that survival among planted species was relatively high and was mostly unaffected by mixture or density of the plantings. Only very damaged plants in one species experienced a decrease in survival with increasing density. Neighborhood effects on growth show positive, neutral, and negative interactions among the tested species; these also varied depending on the type of growth performance considered (height, crown area, diameter). The species-specific results ranged from positive to negative, varying between pair of species and growth performance metric. Results gathered from our neighborhood analyses on plant growth provide valuable information for the design of planting schemes that could enhance the performance of the target species. The methods developed can be applied to other systems and species. Given the potential impacts that facilitation and competition may have during revegetation, these interactions could be considered in restoration operations.

The object of the present research is set-aside lands of various ages. The study was aimed to identify the main biological groups of weed growing on set-aside lands of the Volga Delta, which were removed from production in different years. Within the study, species composition of set-aside lands’ vegetation was defined, which amounted to 28 species and 16 families. The plant community of set-aside lands includes such large families as Asteraceae (5 species), Poaceae (4 species), Brassicaceae (3 species). It was observed that quantitative species composition of set-aside lands’ flora has been changing depending on its age: the older a set-aside land is, the less species grow there. In spring and summer seasons, ephemeral, annual and biennial weeds prevailed, while in autumn perennial plants did: the latter were estimated of 75-80%, their wet weight amounted up to 70-92% of total weight due to the plentiful growth and development of a perennial rhizome plant named Phragmites australis (Cav.) Trin. ex Steudel. The research has lasted for 10 years and allowed observing a 14-32% increase in a number of plants belonging to a xerophyte group on longstanding set-aside lands with low level of soil moisture. Agro-ecosystems of various-aged set-aside lands hosted the development of flora having different vegetative weight that is capable of accumulating solar energy. Significant amount of accumulated energy reduced the entropy of the environment and improved its ecological state. On an old-aged set-aside land, corps of perennial plants vegetating for a long time have been maximally accumulating energy and gained 25712.42 MJ/ha.

Structural and molecular parameters of photosynthetic apparatus in plants with different strategies for the accumulation of salts were investigated. CO2 gas exchange rate, content of pigments, mesostructure, chloroplast ultrastructure and the biochemical composition of the membrane structural components in leaves were measured. The objects of the study were euhalophytes (Salicornia perennans, Suaeda salsa, Halocnemum strobilaceum), crynohalophyte (Limonium gmelinii), glycohalophyte (Artemisia santonica). Euhalophytes S. perennans and S. salsa belong to the plants of the halosucculent type, three other species represent the xerophilic type. The highest photosynthetic activity estimated by the average parameters of CO2 gas exchange rate in the leaves was observed in S. perennans plants. Plants of the xerophyte type including both H. strobilaceum euhalophyte and cryno- and glycohalophytes are described by lower values of these characteristics. Larger cells with a great number of chloroplasts and a high content of membrane glycerolipids and unsaturated C18:3 fatty acid, but with smaller pigment and light-harvesting complexes size characterise the features of euhalophytes with a succulent leaf type. Thus, features of the mesostructure, ultrastructure, and supramolecular interactions of the halophyte PA were closely related to the functional parameters of gas exchange, and were characterised by the strategy of species in relation to the accumulation of salts, the life form of plants, and the attitude to the method of water regulation.

In the course of studying the content of free amino acids in dry and germinating grains of wild cereals, some biochemical features of their dynamics were revealed depending on the osmotic pressure. In most species, except Agropyron cristatum, a significant increase in the concentration of amino acids occurred in the control on the first day after the start of the experiment; in the subsequent period, their decrease was observed. For Agropyron cristatum, a decrease in the index and a smooth increase after the first day were observed. Under the influence of osmolyte, the tendency to mobilize amino acids has changed and in some species (Stipa krylovii, Melica virgata, Melica turczaninowiana) the maximum amounts were observed on the first day from the beginning of the experiment, in the others to the second day. The total amount of free amino acids in the control and in the test was not significantly different. There was also a rapid mobilization of proteinogenic amino acids with increasing osmotic stress for the widespread Stipa krylovii and Agropyron cristatum in the region. A similar trend was noted for the xerophyte Tripogon chinensis. For grasses with a narrow ecological niche, which are characterized by xeromesophilia, osmotic stress suppressed the rapid mobilization of free amino acids. The content of individual groups of amino acids under the influence of osmotic stress was characterized by significant differences for species of the Melica genus in the number of acidic amino acids, for Tripogon chinensis an increase in the content of basic amino acids, and for Agropyron cristatum by a decrease in their concentration., В ходе изучения содержания свободных аминокислот в сухих и прорастающих зерновках дикорастущих злаков выявлены некоторые биохимические особенности их динамики в зависимости от осмотического давления. У большинства видов, кроме Agropyron cristatum, в контроле в первые сутки от начала эксперимента происходило значительное увеличение концентрации аминокислот, в последующий период наблюдалось их убыль. Для Agropyron cristatum вначале наблюдалось уменьшение показателя и плавный рост после первых суток. При действии осмолита тенденции к мобилизации аминокислот изменились и у части видов (Stipa krylovii, Melica virgata, Melica turczaninowiana) максимальные количества отмечались в первые сутки от начала опыта, у остальных – ко вторым суткам. Суммарное количество свободных аминокислот в контроле и опыте значимо не отличалось. Также отмечалась быстрая мобилизация протеиногенных аминокислот при возрастании осмотического стресса для широко распространенных в регионе Stipa krylovii и Agropyron cristatum выявлена. Аналогичная тенденция отмечена и для ксерофита Tripogon chinensis. Для злаков с узкой экологической нишей, обладающих признаками ксеромезофильности, осмотический стресс подавлял быструю мобилизацию свободных аминокислот. Содержание отдельных групп аминокислот при воздействии осмотического стресса характеризовалось значимыми отличиями для видов рода Melica в количестве кислых аминокислот, для Tripogon chinensis увеличением содержания основных аминокислот, а для Agropyron cristatum уменьшением их концентрации.

A decrease in the amount of precipitation is observed on average 18 - 20 mm compared with the periods before the Aral crisis and the average annual temperature rise over the long-term period is 2.0°C in the Central part of Ustyurt. An increase in the Si index meaning an increase in the degree of drought every ten-flight is clearly expressed in the months March-July. Data Analysis 1981-2017 shows that within 36 years the species diversity in the monitoring sites of Kabanbay decreased by 2 - 3 times. In 1981 the number of species fluctuated between the values of 9 - 50, and in 2017 this figure is 4 - 17. The results of the analysis show that the forecast indicators of the old-current state (1981) of the vegetation coverage and number of species were stable or had tendencies with a low regressive character (r2 = 0.01). However, the current-state (2017) of the vegetation coverage and the species composition of the monitoring plots showed a low progressive trend (r2 = 0.03), i.e. in the future, the formation of plant communities with low vegetation coverage and species composition has a dominant status. The results show that in 1981, 65% - 80% of the species composition of plant communities consisted of halophyte and xerophyte groups. In 2017, this figure reaches 80% - 100%, i.e. this claims to increase xerophytization and halophytization of territories. An interesting fact is established with mesophyte group. In general, theoretically, the decrease in the number of mesophyte group of plants for 1981-2017 would have a direct correlation with the vegetation coverage and their active share in it. However, for 36 years, their active share in the vegetation coverage remained unchanged—amounting to 0% - 20%. Of course, in these years, the decrease in the number of mesophyte plants led to an increase in the number of plant communities, in which the proportion of vegetation coverage of mesophyte group is insignificant—0% - 5%. Despite the drought, the active part of the vegetation cover of mesophytic invasive species, such as Poa bulbosa, is consistently maintained.

In most terrestrial plants, large quantities of water inevitably are diffused into the air via open stomata for CO2 absorption during photosynthesis. It is difficult to reduce such an intrinsic demand of water for transpiration but still maintain photosynthesis. Interestingly, the xerophyte Zygophyllum xanthoxylum evolves an outstanding ability to resolve this dilemma by accumulating Na+ to stimulate growth while reducing transpiration. However, the underlying mechanisms are still unclear. Two-week-old Z. xanthoxylum plants were treated with 50 mM NaCl (Na) for 7 days to investigate their growth, gas-exchange related parameters, chlorophyll fluorescence parameters, leaf anatomical characteristics, and related biochemical traits. NaCl treatment reduced the stomatal opening and transpiration but markedly enhanced the plant biomass. Analysis showed that a higher efficiency of intrinsic water use (WUEi) and photosynthetic chlorophyll (PChl) in leaves of Na-treated plants. A lower CO2 partial pressure in substomatal cavities, mainly accounting for higher WUEi, which efficiently facilitates CO2 extraction from air via partially opening stomata in leaves of Na-treated plants, may be largely due to increased internal cell surface and reduced CO2 diffusion path between chloroplasts and corresponding cell wall, in addition to increased expression of aquaporin and induced C4 or CAM-like metabolism. Increased leaves area, reduced chlorophyll content per unit weight, and enhanced operating efficiency of Photosystem II allowed more efficient light harvesting, deeper light penetration and more light using efficiency, and so would also benefit this water-saving photosynthesis. Our data demonstrate that Z. xanthoxylum efficiently rematches both CO2 intake and light use to fulfill vigorous growth under significantly reduced stomatal aperture and markedly decreased water consumption. The mechanisms that Z. xanthoxylum uses to achieve more biomass while using less water give a valuable clue for future improvement of agricultural production in water-limited areas.

High-pressure/high-temperature wells are traditionally very challenging for biostratigraphical analyses. The temperatures achieved cause the organic matter to become highly mature and palynomorphs are altered, to an extent that can make identification extremely challenging. This study compares two wells and shows that the type of drilling bit and the control of drilling parameters can have a positive impact in the palynology recovery. Both wells are studied for palynology and the well with the best drilling parameters yielded generally good recovery, and although the palynomorphs also exhibit a high thermal maturity, it was possible to confidently identify enough palynomorphs to define the age of the penetrated sediments. The biostratigraphy study reveals a Rhaetian – Early Toarcian dataset from a complete stratigraphic succession that wasn't previously recorded in the Central North Sea. A lithostratigraphic unit is yet to be defined to characterise the sediments interpreted in this paper. The ecological analyses, using statistical methods, assessed the temporal and spatial variations in vegetation and palaeoenvironments. They focused on the Early Jurassic and indicate that during this time the landscape was diverse with a variety of habitats occupied by terrestrial plants dominated primarily by swamp and xerophyte types living near the coastal area.

Cuticular waxes, a waterproofing hydrophobic barrier that coats the aerial surfaces of all terrestrial plants, protects plants from various environmental stresses, particularly drought stress. The molecular basis of cuticular wax deposition in xerophytes (e.g. desert plants), including transport mechanisms of waxes to the cell wall, is poorly understood. Here, ZxABCG11 encoding an ATP binding cassette (ABC) transporter was isolated from the xerophyte Zygophyllum xanthoxylum, since we found it was predominantly expressed in young leaves and induced by salt, drought, heat, and combined drought and heat stresses. To ascertain the function of ZxABCG11, we introduced ZxABCG11 into Arabidopsis thaliana and found an increased abundance of cuticular wax on stems and leaves of the transgenic plants, which also exhibited a thickened cuticle and reduced cuticle permeability. Transcript expression analysis revealed that many genes related to wax biosynthesis and transport were up-regulated in these ZxABCG11 transgenic plants. Furthermore, compared with wild type Arabidopsis, ZxABCG11 transgenic plants displayed a higher biomass and survival rate under drought conditions. Taken together, we propose that the expression of ZxABCG11 in Arabidopsis promotes cuticular wax accumulation and thicker cuticle formation, thereby enhancing drought tolerance.

The forage spineless cacti are the main xerophilic crop grown in Brazil, however its growth and production may be influenced by the photochemical performance of Photosystem II, regardless of the cultivation system. In this context the objective was to evaluate the photochemical efficiency of Nopalea cochenillifera Salm-Dyck depending on ground cover at different schedules of evaluation. The research was carried out at the Pendencia Experimental Station, belonging to the Paraibana Company for Research, Rural Extension and Regularization Landholding (EMPAER-PB), municipality of Soledade, state of Paraiba, Brazil. The treatments were distributed in randomized blocks, with three repetitions in the 2 × 4 factorial scheme, corresponding to the soil with and without mulch and four chlorophyll fluorescence evaluation times at, 08:00, 11:00, 14:00 and 17:00 hours. The variables analyzed were: initial fluorescence, variable fluorescence, maximum fluorescence, variable/initial fluorescence ratio and potential quantum yield. The use of mulch increased the maximum and variable fluorescence, especially in the first schedules of evaluation, photosystem II photochemical activity was highest at 17:00 hours.

Our results showed that in addition to sodium (Na+), succulent xerophyte Haloxylon ammodendron was more inclined to absorb and accumulate large amount of calcium (Ca2+) than potassium (K+) as an important osmotica for osmotic adjustment (OA) under arid environments. To further reveal the possible physiological mechanisms of Ca2+ accumulation involved in drought resistance of H. ammodendron, 8-week-old plants were treated with a series concentration of external Ca2+ (calcium chloride, 1 × 10−4 to 8 × 10−4 g CaCl2 g−1 dry soil) by potted sandy soil culture experiments in field. Plants were also subjected to water deficit (30% of field water capacity) in the presence or absence of Ca2+ (4 × 10−4 g CaCl2 g−1dry soil) by potted sand culture experiments in greenhouse. The results showed that 4 × 10−4 g CaCl2 g−1 soil resulted in optimal plant growth and effectively mitigated harmful impacts of water deficit on the growth of H. ammodendron, by inducing a significant drop in PB water potential and, concomitantly, increasing PB turgor pressure and chlorophyll concentration resulting in an enhancement of overall plant photosynthetic activity. Furthermore, 4 × 10−4 g CaCl2 g−1 soil had no effects on the photosystem II photochemistry, but mitigated the inhibitory effect of water deficit on the activity of photosystem II in H. ammodendron. The contribution of Ca2+ to the total osmotic potential varied from 6.2% in the control to 11.4% in plants subjected to water deficit and, surprisingly, to 21.6% in plants grown in the presence of 4 × 10−4 g CaCl2 g−1 soil under water deficit; however, the contribution of K+ significantly decreased from 12.1 to 7.0%. These findings suggest that, under arid environments, H. ammodendron is able to accumulate high concentration of Ca2+ in its PB and use it directly for OA, which was coupled with an improvement in PB hydration and photosynthetic activity.

To provide a better understanding of spatial pattern and habitat preferences for a cryptic xerophyte, a number of variables were investigated in a 10,000 m 2 (1 ha) study area in a population of L. pseudotruncatella ; plant density, spatial arrangement of plants, and habitat specificity. Two censuses, carried out in dry season and in rainy season, revealed a total of 448 and 860 plants, respectively, with a severely clumped distribution. Five out of seven plant density estimation methods, applied in dry season, produced data that vastly over-or under-estimated plant number while Adaptive Cluster Sampling and the Belt Transect method were more accurate, with 557 and 540 plants, respectively. Plant number in 10 × 10 m test plots within the study area was positively associated with a high percentage cover of gravel and pebbles as opposed to sand or stones, and with a gentle rise as opposed to a slope in the topography of the plots. A significant association was found between the occurrence of Lithops and Avonia albissima in the test plots suggesting that the latter, which is more visible, can be used as an indicator of Lithops in the field.

Summary The inward-rectifying K+ channel AKT1 constitutes an important pathway for K+ acquisition in plant roots. In glycophytes, excessive accumulation of Na+ is accompanied by K+ deficiency under salt stress. However, in the succulent xerophyte Zygophyllum xanthoxylum, which exhibits excellent adaptability to adverse environments, K+ concentration remains at a relatively constant level despite increased levels of Na+ under salinity and drought conditions. In this study, the contribution of ZxAKT1 to maintaining K+ and Na+ homeostasis in Z. xanthoxylum was investigated. Expression of ZxAKT1 rescued the K+-uptake-defective phenotype of yeast strain CY162, suppressed the salt-sensitive phenotype of yeast strain G19, and complemented the low-K+-sensitive phenotype of Arabidopsis akt1 mutant, indicating that ZxAKT1 functions as an inward-rectifying K+ channel. ZxAKT1 was predominantly expressed in roots, and was induced under high concentrations of either KCl or NaCl. By using RNA interference technique, we found that ZxAKT1-silenced plants exhibited stunted growth compared to wild-type Z. xanthoxylum. Further experiments showed that ZxAKT1-silenced plants exhibited a significant decline in net uptake of K+ and Na+, resulting in decreased concentrations of K+ and Na+, as compared to wild-type Z. xanthoxylum grown under 50 mm NaCl. Compared with wild-type, the expression levels of genes encoding several transporters/channels related to K+/Na+ homeostasis, including ZxSKOR, ZxNHX, ZxSOS1 and ZxHKT1;1, were reduced in various tissues of a ZxAKT1-silenced line. These findings suggest that ZxAKT1 not only plays a crucial role in K+ uptake but also functions in modulating Na+ uptake and transport systems in Z. xanthoxylum, thereby affecting its normal growth.

In this comparative research of the leaf anatomy of Phlox sibirica and Phlox sibirica var. borealis, we discovered that morphometric features of the leaf blades structure in 95 % of cases significantly differ at a significance level of P < 0.05. Statistically significant differences were not found only in determining the stomatal index, the value of which also corresponds to other types of groundcover phlox. The studied taxa are characterized by collateral vascular bundles, an anomocytic type of the stomatal apparatus and elongated, winding epidermal cells. Phlox sibirica is distinguished by a better development of collenchyma strands, which provides sheet rigidity even with the loss of turgor, xylem, and the most photosynthetically active layer of mesophyll (cells of the upper layer). Thus, in the anatomical structure of the studied phloxes, the features characteristic of xerophytic-heliophytic species, more pronounced in Phlox sibirica, were revealed. The leaf anatomy of the studied taxa reflects their adaptation to conditions with an unfavorable water regime (ensures the maintenance of a normal water balance) and excessive lighting., Проведенное сравнительное изучение анатомии листьев Phlox sibirica и Phlox sibirica var. borealis позволило выявить, что морфометрические признаки строения листьев в 95 % случаев достоверно отличаются при уровне значимости P < 0,05. Статистически значимых отличий не было обнаружено только при определении устьичного индекса, значение которого также соответствует другим видам почвопокровных флоксов. Для изученных таксонов характерны закрытые коллатеральные пучки, аномоцитный тип устьичного аппарата и удлиненные, извилистые эпидермальные клетки. Phlox sibirica отличается большим развитием тяжей колленхимы, обеспечивающей жесткость листа даже при потере тургора, ксилемы, наиболее фотосинтетически активного слоя мезофилла (клеток верхнего слоя). Таким образом, в анатомическом строении листьев изученных флоксов выявлены признаки, свойственные для ксерофитно-гелиофитных видов, более выраженные у Phlox sibirica. Анатомия листьев изученных таксонов отражает их адаптацию к условиям с неблагоприятным водным режимом (обеспечивает поддержание нормального водного баланса) и избыточным освещением.

Aloe vera (L.) Burm.f. (Aloe barbadensis Miller) is a perennial xerophyte plant that has many medicinal applications. A. vera leaves contain water storage tissue, which is fundamentally made up of a viscous mucilage contained in the parenchyma cells. A. vera whole leaf extract refers to the product obtained from grinding the entire leaf (i.e. the rind, vascular bundles, and pulp) and removing the anthraquinones such as aloin by means of charcoal filtration. On the other hand, A. vera gel refers to the clear viscous mucilage contained within the parenchyma cells but is sometimes also interchangeably used to describe the complete intact fleshy inner part of the leaf or pulp. The mucilage gel primarily consists of polysaccharides dissolved in water (water content >98%) but also contains other compounds such as enzymes, minerals, and organic acids [1–3]. Materials that can be used as pharmaceutical excipients from renewable, natural sources are sought after due to their sustainable mass production potential. The polysaccharide-rich gel and whole leaf extract materials obtained from A. vera have shown the potential to be used as filler-type excipients in sustained-release matrix tablets. The A. vera leaf materials exhibited sufficient powder flow and compression properties to be used in the manufacture of direct compressible sustained-release matrix-type tablets [4,5]. The absorption enhancement effects of A. vera gel and A. vera whole leaf extract liquid products were first discovered during an in vivo study in human subjects. The randomized, double-blind, cross-over trial consisted of 11 healthy subjects who consumed a 500 mg vitamin C (ascorbic acid) tablet or a 420 mg vitamin E (tocopherol) capsule either with 60 ml of water alone (control) or with an A. vera gel or an A. vera whole leaf liquid product. When comparing the areas under the plasma concentration–time curves (AUC values), it was found that the AUC of vitamin C alone (339 ± 124 μM/h) was increased 3.04-fold (1 031 ± 513 μM/h) when co-administered with the A. vera gel liquid product. The AUC of vitamin E was increased 1.98-fold when co-administered with the A. vera whole leaf extract liquid product, while the A. vera gel product was capable of achieving a 3.69-fold increase in the AUC of vitamin E [2]. These results revealed the potential of A. vera gel and whole leaf products to increase the bioavailability of co-administered compounds. This article focuses on the current state of research with regard to A. vera gel and whole leaf materials being used as a functional excipient for oral (intestinal), buccal, and transdermal drug delivery