Hordeum Brevisubulatum Research Articles

Overexpression of HbMBF1a, encoding multiprotein bridging factor 1 from the halophyte Hordeum brevisubulatum, confers salinity tolerance and ABA insensitivity to transgenic Arabidopsis thaliana

Key messageHbMBF1a was isolated and characterized in H. brevisubulatum, and overexpressed HbMBF1a could enhance the salt tolerance and ABA insensitivity in Arabidopsis thaliana. The transcript levels of stress-responsive genes were significantly increased in the transgenic lines under salt and ABA conditions.Salinity is an abiotic stress that considerably affects plant growth, yield, and distribution. Hordeum brevisubulatum is a halophyte that evolved to become highly tolerant to salinity. Multiprotein bridging factor 1 (MBF1) is a transcriptional coactivator and an important regulator of stress tolerance. In this study, we isolated and characterized HbMBF1a based on the transcriptome data of H. brevisubulatum grown under saline conditions. We overexpressed HbMBF1a in Arabidopsis thaliana and compared the phenotypes of the transgenic lines and the wild-type in response to stresses. The results indicated that HbMBF1a expression was induced by salt and ABA treatments during the middle and late stages. The overexpression of HbMBF1a in A. thaliana resulted in enhanced salt tolerance and ABA insensitivity. More specifically, the enhanced salt tolerance manifested as the increased seed germination and seedling growth and development. Similarly, under ABA treatments, the cotyledon greening rate and seedling root length were higher in the HbMBF1a-overexpressing lines, suggesting the transgenic plants were better adapted to high exogenous ABA levels. Furthermore, the transcript levels of stress-responsive genes were significantly increased in the transgenic lines under salt and ABA conditions. Thus, HbMBF1a is a positive regulator of salt and ABA responses, and the corresponding gene may be useful for producing transgenic plants that are salt tolerant and/or ABA insensitive, with few adverse effects. This study involved a comprehensive analysis of HbMBF1a. The results may provide the basis and insight for the application of MBF1 family genes for developing stress-tolerant crops.

Effects of Epichloë endophyte infection on growth, physiological properties and seed germination of wild barley under saline conditions

AbstractWild barley (Hordeum brevisubulatum) is a grass that inhabits alkalized meadows in northern China. An asexual Epichloë bromicola endophyte was detected in seeds and leaf sheaths in all wild barley samples from Gansu Province, China. In this research, we determined the effects of the E. bromicola endophyte on growth, physiological properties and seed germination of wild barley under salt stress through a set of experiments. Our results demonstrate that endophyte‐infected (E+) plants produced more tillers, higher biomass and yield, higher chlorophyll content and superoxide dismutase activity than endophyte‐free (E−) plants under high salt stress. Seed germination parameters of E+ biotype were significantly higher than those of E− plants when NaCl concentration reached 200 and 300 mM. Our results demonstrate that E. bromicola endophytes increased tolerance to salt stress in wild barley by increasing seed germination and growth, and altering plant physiology.

Effects of Simulated Herbivory on the Vegetative Reproduction and Compensatory Growth of Hordeum brevisubulatum at Different Ontogenic Stages.

The response of plant vegetative reproduction and compensatory growth to herbivory has been widely discussed in biological and ecological research. Most previous research has supported the idea that both vegetative reproduction and compensatory growth are affected by their ontogenic stage. However, in many studies, the effects of foraging at different ontogenic stages was often confounded with the effects of foraging at different phenological periods for perennials. Our experiment was conducted in a natural meadow with a perennial grass, Hordeum brevisubulatum, and four ontogenic stages were chosen as our experimental objects. Three different clipping intensities during three phenological periods were implemented to explore the effects of simulating animal foraging on vegetative reproduction and compensatory plant growth. The results indicated that there were significant effects of ontogenic stage, phenological period, and clipping intensity on vegetative reproduction and compensatory growth. Moderate clipping intensities significantly increased the number of vegetative tillers, the total number of juvenile tillers and buds, and the aboveground biomass at early phenological periods for individuals at early ontogenic stages. Our results suggested that moderate clipping intensities could induce only an over-compensation response in perennial grasses at both the early ontogenic stage and phenological period, and the ability of compensatory growth gradually decreased with the progression of the ontogenic stage. This is of great significance to the primary production of grasslands subjected to herbivory.

Синтаксономия луговой растительности Кулундинской и Касмалинской боровых лент (Алтайский край)

Синтаксономия луговой растительности Кулундинской и Касмалинской боровых лент (Алтайский край)

Effect of the fungal endophyte Epichloë bromicola on polyamines in wild barley (Hordeum brevisubulatum) under salt stress

The endophytic fungus Epichloe bromicola forms mutualistic symbiotic associations with wild barley (Hordeum brevisubulatum) in the saline-alkali areas of northwestern China. E. bromicola enhances the tolerance of H. brevisubulatum to salt stress. Because plant polyamine metabolism is closely related to microbial infection and tolerance to diverse abiotic stresses, we hypothesized that in symbiotic plants polyamine modification may result from E. bromicola infection, and that improved tolerance to abiotic stress by the presence of this endophyte might be related to polyamine modification. Our focus in this study was to investigate whether E. bromicola affects polyamine metabolism in host plants under salt stress. E. bromicola infected (E+) and endophyte free (E-) wild barley plants were subjected to NaCl treatments (0, 100, 200 and 300 mM). Dry weight, diamine putrescine (Put), triamine spermidine (Spd) and tetramine spermine (Spm) content and the content of their free, soluble conjugated and insoluble bound forms were measured after 21 d exposure to stress. E. bromicola infection led to significant amelioration of salt stress in H. brevisubulatum. The presence of the endophyte significantly increased dry weight, spermidine and spermine content, but decreased putrescine content and the putrescine: (spermidine + spermine) ratio. E. bromicola infection also lowered the proportion of putrescine in total polyamines, but increased the proportion of spermidine and spermine in total polyamines. Furthermore, E. bromicola infection significantly increased the proportion of insoluble bound forms of polyamines, and decreased the proportion of free forms of polyamines and soluble conjugated forms of polyamines. H. brevisubulatum salinity stress tolerance induced by E. bromicola infection correlated with enhanced conversion of putrescine to spermidine and spermine, as well as improved shift ability from free forms and soluble conjugated forms of polyamines to insoluble bound forms of polyamines.

Reference genes identification for normalization of qPCR under multiple stresses in Hordeum brevisubulatum

BackgroundReal-time quantitative PCR has been widely used as the most reliable method to measure gene expression, due to its high accuracy and specificity. Wild barley (Hordeum brevisubulatum (Trin.) Link) is a wild relative species in Triticeae that has strong tolerance to abiotic stresses and extremely wide adaptation. However, suitable references gene have not been documented for standardization of gene expression in wild barley under abiotic stress.ResultsHere we report the first systematic and comprehensive analysis of reference genes for quantitative real-time PCR standardization in wild barley. We selected 11 genes, including ACT (Actin), ADP (ADP-ribosylation factor 1), CYP2 (Cyclophilin 2), EF-1α (Elongation factor 1-alpha), GAPDH (Glyceraldehyde 3-phosphate dehydrogenase), HSP90 (Heat shock protein 90), TUBα (Alpha-tubulin), TUBβ6 (Beta-tubulin 6), UBI (Ubiquitin), 18SrRNA-1 (guanine1575-N7-methyltransferase) and 18SrRNA-3 (adenine1779-N6-dimethyltransferase) from a wild barley transcriptome database and analyzed their expression stabilities in shoots and roots of wild barley seedling under various stress conditions using comparative ΔCt, BestKeeper, Normfinder and geNorm software. The results demonstrated that ADP was the most suitable reference gene in salt stress while UBI showed peak stability under mannitol and ABA stress; EF-1α was the most appropriate reference gene for PEG, GA3, ethylene and heat stress; 18SrRNA-3 was the best choice for cold stress; and TUBα was the first stable gene across different tissues.ConclusionsOur main contribution was to identify reference genes with suitable and stable expression in wild barley under various stress conditions and in different tissues to provide a useful resource for future studies. The results demonstrate the importance of transcriptome data as a useful resource for the screening of candidate reference genes and highlight the need for specific reference genes for specific conditions. Furthermore, these findings will provide valuable information for wild barley and relative species for future research.

Diversity in wild relatives of wheat: an expedition collection from cold-arid Indian Himalayas

Impact of climate change is of much concern across the globe in recent years and more specifically to the fragile ecosystems like cold-arid Himalayan region especially from a perspective on biodiversity and its conservation. Hence, collection and conservation of the biodiversity ex situ is a much better option to safeguard species at risk; especially for crop wild relatives with reference to agriculture. We have explored in 2014 and 2015 the cold-arid tracts of Himachal Pradesh and Jammu & Kashmir states in India and collected 169 accessions of wheat wild relatives comprising 12 taxa, viz., Elymus L. (8/139 acc.), Hordeum L. (2/4) and Leymus Hochst. (2/26) belonging to the tribe Triticeae. New geographic occurrence of six species—Elymus himalayanus (Nevski) Tzvelev, E. repens (L.) Gould, E. schrenkianus (Fisch. et C.A.Mey) Tzvelev, Hordeum brevisubulatum (Trin.) Link subsp. turkestanicum (Nevski) Tzvelev, H. bogdanii Wilensky and Leymus duthiei (Stapf ex Hook.f.) C. Yen, J.L. Yang et B.R. Baum was reported. Broader variability at inter- and intra-specific level in Elymus nutans Griseb., E. dahuricus Turcz. and Leymus secalinus across the ecological amplitude was observed. E. dahuricus population was heterogeneous for waxiness and pigmentation characters. Collected germplasm would serve as a potential resource for introgression of biotic and abiotic stress tolerance genes towards developing resilient wheat cultivars.

Infection by the fungal endophyte Epichloë bromicola enhances the tolerance of wild barley (Hordeum brevisubulatum) to salt and alkali stresses

Salinization is considered as a major environmental threat to agricultural systems. Infection with Epichloe fungal endophytes has been shown to increase tolerance to NaCl stress for several host grass species, but limited information is available regarding the effects of these endophytes under mixed salt (NaCl and Na2SO4) and mixed alkali (NaHCO3 and Na2CO3) stresses. Since these four compounds are considered very harmful to many inland areas in China, we conducted a study to determine the impact of Epichloe fungal endophyte infection on wild barley (Hordeum brevisubulatum) under both salt stress (SS) and alkali stress (AS). Wild barley with (E+) and without (E-) Epichloe endophyte was subjected to mixed salt (molar ratio of NaCl:Na2SO4 = 1:1) and mixed alkali (molar ratio of NaHCO3:Na2CO3 = 1:1) treatments (0, 100, 200, 300 and 400 mM). Photosynthetic parameters and chlorophyll content were measured after 21 days exposure to stress, and growth parameters, physiological indexes, sodium (Na+), potassium (K+), calcium (Ca2+), nitrogen (N), phosphorus (P) and carbon (C) contents were determined after 22 days exposure to stress. The harmful effect of alkali stress on the growth of wild barley was stronger than those of salt stress, irrespective of endophyte infection. Alkali stress had a greater impact on photosynthesis and chlorophyll content compared to salt stress and also accumulated more of the osmoprotectant glycine betaine. However, salt stress appeared to increase total antioxidant capacity as well as increasing K+ content (resulting in a relative low Na+/K+ ratio). Under alkali stress, Ca2+ content sharply increased in roots as opposed to a decrease under salt stress. In roots, the C, N, P contents and the C:N ratio was higher under salt stress compared to alkali stress whereas the C:P and N:P ratios were lower. In shoots, the N and P contents were higher under salt stress compared to alkali stress whereas the C content and the C:P and C:N ratios were lower. Interestingly, the presence of Epichloe endophyte infection on wild barley under both salt stress and alkali stress led to significant amelioration of both stresses. Epichloe infection significantly increased photosynthesis, chlorophyll content, total antioxidant capacity and glycine betaine content, whilst lowering leaf malondialdehyde content. Furthermore, Epichloe infection reduced Na+ content, the Na+/K+ ratio and shoot Ca2+ content but increased K+ content and the root Ca2+ content. Epichloe infected plants also had higher C, N and P contents but lower ratios of C:N, C:P and N:P than uninfected plants. The presence of the Epichloe endophyte suppresses the negative effect of salt stress and alkali stress on wild barley seedling growth. The possible mechanisms by which the presence of Epichloe endophyte enhances growth of plants exposed to those two stresses include improved photosynthetic ability, increased antioxidant potential, increased nutrient absorption, and osmotic and ionic adjustment. The study also found that alkali stress is more harmful to wild barley than salt stress.

Identification of Epichloë endophytes associated with wild barley (Hordeum brevisubulatum) and characterisation of their alkaloid biosynthesis

ABSTRACTEpichloë species are biotrophic symbionts of many cool-season grasses that can cause grazing animal toxicosis. We identified fungi from Hordeum brevisubulatum as Epichloë bromicola based on morphological characteristics and tefA and actG gene sequences. Three isolates were examined, they contained perA gene and 10 out of the 14 EAS cluster genes, previously identified in Epichloë inebrians E818. Five out of 11 LTM/IDT cluster genes previously identified in Epichloë festucae Fl1 were present, but no idtG, indicating an inability to produce even early intermediates in the lolitrem B pathway. Only one lolC gene out of 11 LOL cluster genes previously identified in E. festucae E2368 was present in the three isolates. Chemotype analyses revealed infected samples contained only peramine, and not ergine, ergonovine, ergovaline or lolitrem B. This study provides new information about the host range and phylogenetic definition of E. bromicola and reveal a novel endophyte–grass combination in China.

Taxonomic analysis of saline habitats flora of the Southern Urals

The paper presents a taxonomic analysis of saline habitats flora of the southern Urals. The authors have established vegetation of 317 types of glycophytic and halophytic higher plants belonging to 172 genera and 44 families on the saline soils of the southern Urals (including adjacent territories). The number of halophytic species in the studied area is low and estimated at 59 or 18,6% of the total number of species. Among them are representatives of the genus Limonium, of the family Chenopodiaceae - Halimione verrucifera , Salicorna perennans , Suaeda acuminata , S. corniculata , S. prostrata ; family Asteraceae - Artemisia lerchiana , A. nitrosa , Cirsium esculentum , family Poaceae - Hordeum brevisubulatum , Puccinellia distans , etc. The vast majority of flora - 316 species (99,9%) - belong to the division Magnoliophyta, 251 species (79,4%) are Magnoliopsida members and 65 (20,6%) are registered in the class Liliopsida. The ratio of monocots and dicots is expressed in a proportion of 1: 3,8. The largest families in saline soils flora of the southern Urals are: Asteraceae, Poaceae, Chenopodiaceae, Fabaceae, Cyperaceae, Apiaceae, Rosaceae. Caryophyllaceae, Lamiaceae, Scrophulariaceae, Polygonaceae, Ranunculaceae number of species from 57 to 9, in total 247 species. There is a clear predominance of the hemicryptophytes - 232, 19 geoview, 11 - geloview, biennials - 9; one - biennials - 4, tirefits - 56, hamiphites - 19, nano phanerophytes - 5, - 1 phanerophytes. In halophytic communities on salted soils that form complexes with glycophyte ones 4 of relict and endemic species Koeleria sclerophylla , Glycyrrhiza korshinskyi , Nanophyton erinaceum , Ephedra distachya meet, 27 are in need of protection, including 4 halophyt ( Frankenia hirsuta , Limonium bellidifolium , L. macrorhizon , L. suffruticosum ).

Mapping Plant Functional Groups in Subalpine Grassland of the Greater Caucasus

Plant functional groups—in our case grass, herbs, and legumes—and their spatial distribution can provide information on key ecosystem functions such as species richness, nitrogen fixation, and erosion control. Knowledge about the spatial distribution of plant functional groups provides valuable information for grassland management. This study described and mapped the distribution of grass, herb, and legume coverage of the subalpine grassland in the high-mountain Kazbegi region, Greater Caucasus, Georgia. To test the applicability of new sensors, we compared the predictive power of simulated hyperspectral canopy reflectance, simulated multispectral reflectance, simulated vegetation indices, and topographic variables for modeling plant functional groups. The tested grassland showed characteristic differences in species richness; in grass, herb, and legume coverage; and in connected structural properties such as yield. Grass (Hordeum brevisubulatum) was dominant in biomass-rich hay meadows. Herb-rich grassland featured the highest species richness and evenness, whereas legume-rich grassland was accompanied by a high coverage of open soil and showed dominance of a single species, Astragalus captiosus. The best model fits were achieved with a combination of reflectance, vegetation indices, and topographic variables as predictors. Random forest models for grass, herb, and legume coverage explained 36%, 25%, and 37% of the respective variance, and their root mean square errors varied between 12–15%. Hyperspectral and multispectral reflectance as predictors resulted in similar models. Because multispectral data are more easily available and often have a higher spatial resolution, we suggest using multispectral parameters enhanced by vegetation indices and topographic parameters for modeling grass, herb, and legume coverage. However, overall model fits were merely moderate, and further testing, including stronger gradients and the addition of shortwave infrared wavelengths, is needed.

Regrowth, yield and nutrition of Leymus chinensis and Hordeum brevisubulatum in response to defoliation intensity and frequency

Regrowth, yield and nutrition of Leymus chinensis and Hordeum brevisubulatum in response to defoliation intensity and frequency

The Effect of Seed-Borne Fungi and Epichloë Endophyte on Seed Germination and Biomass of Elymus sibiricus.

The interactive effects of asexual Epichloë (formerly known as Neotyphodium) endophytes isolated from Hordeum brevisubulatum, Elymus tangutorum and Achnatherum inebrians, and seed-borne fungi on Elymus sibiricus seeds, were determined by an in vitro study using supernatants from liquid cultures of the endophyte strains. In an 8 week greenhouse study, the effects on the seedlings growth was measured. The in vitro study was carried out with the seed-borne fungi Alternaria alternata, Bipolaris sorokiniana, Fusarium avenaceum, and a Fusarium sp. isolated from E. sibiricus. Different concentrations and combinations of the liquid cultures of endophytic fungi enhanced the interim germination, germination rate, length of coleoptile and radicle, and seedling dry weight of E. sibiricus under stress from seed-borne fungi. In the greenhouse study, different concentrations of the supernatant of the endophytes from H. brevisubulatum and E. tangutorum but not A. inebrians, signficantly (P < 0.05) enhanced E. sibiricus seed germination. There was no significant (P > 0.05) increase of the tiller numbers after 2 weeks. However, later on, there were significant (P < 0.05) increases in tiller number (4–8 weeks), seedling height (2–8 weeks) and dry weight (2–8 weeks). The application of Epichloë endophyte culture supernatants was an effective strategy to improve seed germination and growth under greenhouse conditions.

Nature's patchwork: How water sources and soil salinity determine the distribution and structure of halophytic plant communities in arid environments of the Eastern Pamir.

The eastern part of the Pamir Mountains, located in Central Asia, is characterized by great climatic continentality and aridity. Wetlands developed in this hostile region are restricted to spring areas, terraces of shallow lakes or floodplains along rivers, and provide diversified ecosystem services e.g. as water reservoirs, refugia for rare species and pastures for domestic cattle. These ecosystems are particularly susceptible to climate changes, that in the Pamir Mountains result in increased temperatures, intense permafrost/glacial melt and alterations of precipitation patterns. Climatic changes affect pasture management in the mountains, causing overutilization of sites located at lower elevations. Thus, both climate and man-induced disturbances may violate the existing ecological equilibrium in high-mountain wetlands of the Eastern Pamir, posing a serious risk to their biodiversity and to food security of the local population. In this context, we sought to assess how environmental drivers (with special focus on soil features and potential water sources) shape the distribution and diversity of halophytic plant communities developed in valleys in the Eastern Pamir. This task was completed by means of a vegetation survey and comprehensive analyses of habitat conditions. The lake terraces and floodplains studied were covered by a repetitive mosaic of plant communities determined by differences in soil moisture and salinity. On lower, wetter sites, this patchwork was formed by Blysmus rufus dominated salt marshes, saline small sedge meadows and saline meadows with Kobresia royleana and Primula pamirica; and on drier, elevated sites, by endemic grasslands with Hordeum brevisubulatum and Puccinellia species and patches of xerohalophytic vegetation. Continuous instability of water sources and summer droughts occurring in the Pamir Mountains may lead to significant structural and functional transformations of described wetland ecosystems. Species more tolerant to decreased soil moisture and/or increased soil salinity will expand, leading to alterations of ecosystem services provided by the Pamirs’ wetlands. The described research will help to assess the current state of the wetlands and to predict directions of their future changes.

Modelling biomass of mountainous grasslands by including a species composition map

High mountain grasslands offer multiple goods and services to society but are severely threatened by improper land use practices such as abandonment or rapid intensification. In order to reduce abandonment and strengthen the common extensive agricultural practice a sustainable land use management of high mountain grasslands is needed. A spatially detailed yield assessment helps to identify possible meadows or, on the contrary, areas with a low carrying capacity in a region, making it easier to manage these sites. Such assessments are rarely available for remote and inaccessible areas. Remotely sensed vegetation indices are able to provide valuable information on grassland properties. These indices tend, however, to saturate for high biomass. This affects their applicability to assessments of high-yield grasslands.The main aim of this study was to model a spatially explicit grassland yield map and to test whether saturation issues can be tackled by consideration of plant species composition in the modelling process. The high mountain grassland of the subalpine belt (1800 – 2500m a.s.l.) in the Kazbegi region, Greater Caucasus, Georgia, was chosen as test site for its strong species composition and yield gradients.We first modelled the species composition of the grassland described as metrically scaled gradients in the form of ordination axes by random forest regression. We then derived vegetation indices from Rapid Eye imagery, and topographic variables from a digital elevation model, which we used together with the multispectral bands as predictive variables. For comparison, we performed two yield models, one excluding the species composition maps and one including the species composition map as predictors. Moreover, we performed a third individual model, with species composition as predictors and a split dataset, to produce the final yield map.Three main grassland types were found in the vegetation analysis: Hordeum violaceum-meadows, Gentianella caucasea-grassland and Astragalus captiosus-grassland. The three random forest regression models for the ordination axes explained 64%, 33% and 46% of the variance in species composition. Independent validation of modelled ordination scores against a validation data set resulted in an R2 of 0.64, 0.32 and 0.46 for the first, second and third axes, respectively. The model based on species composition resulted in a R2=0.55, whereas the benchmark model showed weaker relationships between yield and the multispectral reflectance, vegetation indices, and topographical parameters (R2=0.42). The final random forest yield model used to derive the yield map resulted in 62% variance explained and an R2=0.64 between predicted and observed biomass. The results further indicate that high yields are generally difficult to predict with both models.The benefit of including a species composition map as a predictor variable for grassland yield lies in the preservation of ecologically meaningful features, especially the occurrence of high yielding vegetation type of Hordeum violaceum meadows is depicted accurately in the map. Even though we used a gradient based design, sharp boundaries or immediate changes in productivity were visible, especially in small structures such as arable fields or roads (Fig. 6b), making it a valuable tool for sustainable land use management. The saturation effect however, was mitigated by using species composition as predictor variables but is still present at high yields.

ТАТМЫН НУГЫН ҮЕТЭН-АЛАГ ӨВСТ БҮЛГЭМДЭЛД ЗОНХИЛОХ ЗАРИМ ЗҮЙЛ УРГАМЛЫН ЦЕНОПОПУЛЯЦИЙН СУДАЛГАА

The Hordeum brevisubulatum is indicator of meadow was growing and cover was increased in heavily degraded meadow community due to grazing had been fenced for 4 years is indicating that meadow vegetation has resilience after heavy grazing.As a result of cenopopulation, palatable and high nutrient plants such as Коeleria macrantha, Leymus chinensis, Agrostis Trinii role were decreased in community whereas adults individual with shoots were dominated that is related to the at this phase this kind of plants contains more cellulose thus stem become hard depending on it palatibility is decreased. Therefore fencing of heavily degraded rangeland is main scientific background for proper grazing depending on plant phenology and biology of plants.

The coordinated regulation of Na+ and K+ in Hordeum brevisubulatum responding to time of salt stress

Hordeum brevisubulatum, called as wild barley, is a useful monocotyledonous halophyte for soil improvement in northern China. Although previously studied, its main salt tolerance mechanism remained controversial. The current work showed that shoot Na+ concentration was increased rapidly with stress time and significantly higher than in wheat during 0–168h of 100mM NaCl treatment. Similar results were also found under 25 and 50mM NaCl treatments. Even K+ was increased from 0.01 to 50mM in the cultural solution, no significant effect was found on tissue Na+ concentrations. Interestingly, shoot growth was improved, and stronger root activity was maintained in H. brevisubulatum compared with wheat after 7days treatment of 100mM NaCl. To investigate the long-term stress impact on tissue Na+, 100mM NaCl was prolonged to 60 days. The maximum values of Na+ concentrations were observed at 7th in shoot and 14th day in roots, respectively, and then decreased gradually. Micro-electrode ion flux estimation was used and it was found that increasing Na+ efflux while maintaining K+ influx were the major strategies to reduce the Na+ concentration during long-term salt stress. Moreover, leaf Na+ secretions showed little contribution to the tissue Na+ decrease. Thereby, the physiological mechanism for H. brevisubulatum to survive from long-term salt stress was proposed that rapid Na+ accumulation occurred in the shoot to respond the initial salt shock, then Na+ efflux was triggered and K+ influx was activated to maintain a stable K+/Na+ ratio in tissues.

Identification and Expression Analysis of a Novel HbCIPK2-Interacting Ferredoxin from Halophyte H. brevisubulatum.

Ferredoxin is a small iron-sulfer protein involved in various one-eletron transfer pathways. Little is known about how ferredoxin is regulated to distribute electron under abiotic stress. Our previous study has showed that HbCIPK2 conferred salinity and drought tolerance. Thus, we hypothesized that HbCIPK2 could mediate the activities of interacting partners as a signal transducer. In this report, we identified a novel HbCIPK2-interacting ferredoxin (HbFd1) from halophyte Hordeum brevisubulatum by yeast two-hybrid screens, confirmed this interaction by BiFC in vivo and CoIP in vitro, and presented the expression pattern of HbFd1. HbFd1 was down-regulated under salinity and cold stress but up-regulated under PEG stress, its expression showed tissue-specific, mainly in shoot chloroplast, belonging to leaf-type subgroup. Moreover, HbCIPK2 could recruit HbFd1 to the nucleus for their interaction. The C-terminal segment in HbFd1 protein was involved in the interaction with HbCIPK2. These results provided insight into the connection between CBL-CIPK signaling network and Fd-dependent metabolic pathways.

An asexual Epichloë endophyte modifies the nutrient stoichiometry of wild barley (Hordeum brevisubulatum) under salt stress

Background and aims Salinization of soils causes severe problems to plant growth. With the important role of stoichiometry in many ecological processes, this study investigated the effect of an asexual Epichloe endophyte on the nutrient stoichiometry of wild barley (Hordeum brevisubulatum) under salt stress.

An asexual Epichloë endophyte enhances waterlogging tolerance of Hordeum brevisubulatum

Using field collected asexual Epichloë endophyte infected (E+) and endophyte free (E−) Hordeum brevisubulatum plants in a greenhouse experiment, we demonstrate that endophyte infection increases host plant resistance to waterlogging. All plants assigned to waterlogging treatment started to wither and lose their root vitality, and consequently lost considerable photosynthesizing and root tissues. However, E+ plants showed significantly less symptoms of damage, and they produced significantly greater content of chlorophyll, more tillers, higher shoots and higher under-ground biomass compared to E− plants. Waterlogging induced osmoprotective proline production particularly in E+ plants and had lower malondialdehyde content and electrolyte leakage, suggesting that endophyte infection positively affects osmotic potential and oxidative balance of the host plant. We propose that higher resistance of E+ plants of H. brevisubulatum to waterlogging should be acknowledged in breeding programmes and the scenarios of changes in grassland ecosystems as a result of climate change.