Effects of stumping on fine root architecture, growth, and physiology of Hippophae rhamnoides.

Background: Fine roots are vital to a plant's ability to absorb water and nutrients. Stumping is a practice that may encourage fine root growth and the rapid recovery of decaying Hippophae rhamnoides plants. However, the effect of stumping on the fine roots and physiological indices is still unknown. The differential indices between stumped forests and non-stumped forests must also be defined. Methods: We recorded the changes in the fine roots of structure H. rhamnoides one year after stumping. Using single factor analysis of variance and general linear models we comprehensively analyzed the number of root tips and the plant's growth and physiological indices in response to stumping. Partial least squares discriminant analysis (PLS-DA) was used to compare fine root growth and physiological indices with and without stumping in order to identify the differential indices. Results: The proportion of root tips in the vertical layers at 30-40 cm and 40-50 cm and in the horizontal layers at 60-80 cm and 80-100 cm, increased after stumping by 1.85%, 2.60%, 1.96% and 4.32%, respectively. In the 0-50 cm soil layer, the fine root dry weight rose by 27.6% compared with the control, which was not significant. However, other indices were significantly different from the control. The proportions in the growth indices in the 30-40 cm and 40-50 cm layers increased after stumping. Stumping had a significant, negative effect on proline and malondialdehyde content, which dropped by 40.95% and 55.32%, respectively, indicating that the harms caused by these two chemicals was alleviated. Stumping had a significant positive effect on root activity and soluble sugar contents, which increased by 68.58% and 36.87%, respectively, and improved the growing ability of fine roots. PLS-DA revealed that malondialdehyde, soluble sugars, root density, and the number of root tips ranked from having the least to greatest effect on the classification of stumping and no-stumping. Conclusions: The process of stumping may promote fine roots growth in H. rhamnoides, and is favorable for their longitudinal development. The fine root growing indices of H. rhamnoides responded positively to this process. Stumping promotes root activity and the creation of soluble sugar to maintain the growth and development of fine roots. It also inhibits the negative effects of proline and malondialdehyde on fine roots. Our study showed that the differential physiological indices were more important for classification than the differential growing indices.

Compensatory growth and understory soil stoichiometric features of Hippophae rhamnoides at different stubble heights.

Background: This study was aimed to explore the compensatory growth ability and influence mechanism of Hippophae rhamnoides at the decaying phase in feldspathic sandstone areas of Ordos, and clarify the stubble height when the compensatory growth ability of H. rhamnoides was the strongest. Methods: The H. rhamnoides forests in the decaying phase from an exposed feldspathic sandstone zone of Ordos were chosen. The compensatory growth ability of H. rhamnoides at stubble height of 0 cm (S1), 10 cm (S2), 15 cm (S3), 20 cm (S4) and control (CK) was investigated with H. rhamnoides forests at the decaying stage in the exposed feldspathic sandstone areas of Ordos. Relationships of compensatory growth ability of H. rhamnoides and understory soil properties with understory soil stoichiometric features as well as the response mechanism to stubble height were explored. Results: (1) Overcompensatory growth of H. rhamnoides in feldspathic sandstone areas occurred at all stubble heights. Especially, the plant height compensation index (1.45) and biomass compensation index (1.25) at the stubble height of 15 cm were both larger compared with other stubbling treatments. These results indicate the stubble height of 15 cm can well promote the growth of the ground part of H. rhamnoides. (2) All stubble heights significantly affected the contents and eco-stoichiometric ratios of soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP) in understory soils, but the influence rules differed. SOC, TN, and TP contents at all stubble heights were larger than those of the control, and maximized at the stubble height of 15 cm. The carbon(C): phosphorus(P) ratio, and nitrogen (N):(P) ratio after stubbling treatments were all lower compared with the control, and minimized to 19.52 and 1.84 respectively at the stubble height of 15 cm. (3) The understory C:N:P stoichiometric ratio of H. rhamnoides in feldspathic sandstone areas is jointly affected by compensatory growth, stubble height, and soil physicochemical properties. The total explanation rate determined from RDA is 93.1%. The understory soil eco-stoichiometric ratio of H. rhamnoides is mainly affected by soil moisture content (contribution of 87.6%) and total porosity (7.9%), indicating soil moisture content is the most influential factor. The findings will offer some new clues for eco-construction and theoretically underlie soil-water loss administration.

Effects of drawing damage on root growth and soil reinforcement of Hippophae rhamnoides in a coal mining subsidence area.

Roots can effectively consolidate and support the soil and are affected by external forces. To identify the survival strategies and soil reinforcement capability of roots against damaging forces, we investigated Hippophae rhamnoides taproots with a diameter of 1-4 mm in a coal mining subsidence area. To simulate root damage from erosion, an HG100 digital push&pull tester and self-developed experimental installation were used in situ. Relative growth rate, activity, tensile force, and strength of taproots were inhibited by damage. Significant differences occurred in these indicators depending on drawing damage type and level. Inhibition effects from persistent drawing damage on growth and tensile properties were markedly greater than those from instantaneous drawing. Inhibition effects of severe damage were markedly greater than those of mild damage. The number of living roots declined more after persistent drawing or severe injury than after instantaneous or mild damage. The taproots showed self-healing ability, and the inhibitory effect of drawing damage gradually weakened with the time of self-repair, ensuring H. rhamnoides taproots could continue to play a role in soil reinforcement. The self-healing ability of roots should be considered in vegetation restoration of erosion-prone areas to ensure that the roots' ability to resist erosion is accurately estimated. Novelty statementResearch on the soil reinforcement ability of damaged plant roots is very limited at present. This study provides a new perspective for soil reinforcement: roots can be destroyed by erosional forces while providing support for soil, the self-healing ability of plants determines whether they can provide effective support for soil in the erosive environment.

Unique features of the m6A methylome and its response to drought stress in sea buckthorn (Hippophae rhamnoides Linn.).

In plants, recent studies have revealed that N6-methyladenosine (m6A) methylation of mRNA has potential regulatory functions of this mRNA modification in many biological processes. m6A methyltransferase, m6A demethylase and m6A-binding proteins can cause differential phenotypes, indicating that m6A may have critical roles in the plant. In this study, we depicted the m6A map of sea buckthorn (Hippophae rhamnoides Linn.) transcriptome. Similar to A. thaliana, m6A sites of sea buckthorn transcriptome is significantly enriched around the stop codon and within 3'-untranslated regions (3'UTR). Gene ontology analysis shows that the m6A modification genes are associated with metabolic biosynthesis. In addition, we identified 13,287 different m6A peaks (DMPs) between leaf under drought (TR) and control (CK) treatment. It reveals that m6A has a high level of conservation and has a positive correlation with mRNA abundance in plants. GO and KEGG enrichment results showed that DMP modification DEGs in TR were particularly associated with ABA biosynthesis. Interestingly, our results showed three m6A demethylase (HrALKBH10B, HrALKBH10C and HrALKBH10D) genes were significantly increased following drought stress, which indicated that it may contributed the decreased m6A levels. This exhaustive m6A map provides a basis and resource for the further functional study of mRNA m6A modification in abiotic stress.

Arbuscular Mycorrhizal Fungi Enhance Sea Buckthorn Growth in Coal Mining Subsidence Areas in Northwest China.

Land subsidence induced by underground coal mining leads to severe ecological and environmental problems. Arbuscular mycorrhizal fungi (AMF) have the potential to improve plant growth and soil properties. We aimed to assess the effects of AMF on the growth and soil properties of sea buckthorn under field conditions at different reclamation times. Inoculation with AMF significantly promoted the survival rate of sea buckthorn over a 50-month period, while also increasing plant height after 14, 26, and 50 months. Crown width after 14 months and ground diameter after 50 months of inoculation treatment were significantly higher than in the uninoculated treatment. AMF inoculation significantly improved plant mycorrhizal colonization rate and promoted an increase in mycelial density in the rhizosphere soil. The pH and electrical conductivity of rhizosphere soil also increased after inoculation. Moreover, after 26 and 50 months the soil organic matter in the inoculation treatment was significantly higher than in the control. The number of inoculated soil rhizosphere microorganisms, as well as acid phosphatase activity, also increased. AMF inoculation may play an active role in promoting plant growth and improving soil quality in the long term and is conducive to the rapid ecological restoration of damaged mining areas.

Impact of phenolic compounds and vitamins C and E on antioxidant activity of sea buckthorn (Hippophaë rhamnoides L.) berries and leaves of diverse ripening times.

Bioactive compounds demonstrating antioxidant activity were analyzed in berries and leaves of nine cultivars of sea buckthorn (Hippophaë rhamnoides L.) of various ripening times. Total polyphenols were ranging between 0.70-3.62 g GAE.kg-1 (berries) and 1.88-3.72 g GAE.kg-1 (leaves). Leaves were significantly richer source of total flavonoids (14.40-49.44 mg RE.kg-1) in comparison with berries (0.55-4.11 mg RE.kg-1). Phenolic compounds, carotenoids and vitamins were determined using high-performance liquid chromatography with a diode array detection. The content of vitamin C was 0.98-3.65 g.kg-1 in berries and 22.81-46.32 g.kg-1 in leaves, vitamin E content was 6.98-29.91 g.kg-1 in berries and 71.54-153.99 g.kg-1 in leaves. Distribution of individual phenolic compounds varied, their total content in berries was considerably lower (76.1-205.2 mg.kg-1) than in leaves (1477.7-8709.0 mg.kg-1). Regarding antioxidant activity, Raisa and Slovan (berries) and Bojan and Maslicnaja (leaves) were evaluated as the best cultivars.

What causes the differences in cavitation resistance of two shrubs? Wood anatomical explanations and reliability testing of vulnerability curves.

Relationships between xylem anatomical traits and cavitation resistance have always been a major content of plant hydraulics. To know how plants cope with drought, it is extremely important to acquire detailed knowledge about xylem anatomical traits and assess the cavitation resistance accurately. This study aims to increase our knowledge in the methods determining cavitation resistance and xylem anatomical traits. We selected a semi-ring-porous species, Hippophae rhamnoides L., and a diffuse-porous species, Corylus heterophylla F., to clarify the reasons for the difference in cavitation resistance based on detailed xylem anatomical traits and reliable vulnerability curves (VCs). Both Cavitron and bench dehydration (BD) were used to construct VCs. Xylem anatomical traits, including pit membrane ultrastructure of these two species, were determined. The VCs obtained by the two different techniques were of different types for H. rhamnoides, its Cavitron VCs might be unreliable because of open-vessel artifacts. On the basis of BD VCs, H. rhamnoides showed higher cavitation resistance than C. heterophylla, and this is attributed to its low vessel connectivity as well as non-porous and thicker pit membranes.

Ecophysiolomic analysis of stress tolerant Himalayan shrub Hipppophae rhamnoides shows multifactorial acclimation strategies induced by diverse environmental conditions.

Climatic fluctuations are a major global concern, affecting the agronomic productivity of plants. Hippophae rhamnoides a naturally growing stress tolerant Himalayan shrub was chosen to understand its stress hardiness mechanism. Comparative proteomic and biochemical analysis were done for pooled berry populations (HrB13 and HrB14) growing in two different environmental conditions. HrB13, growing under sub-optimal environmental conditions exhibited differential abundance of stress responsive proteins, which were the rate limiting enzymes associated with stress-responsive metabolic pathways, including Xanthine dehydrogenase (reactive oxygen species [ROS] signaling), Farnesyl diphosphate synthase (phenylpropanoid pathway), endosomal BRO-1 domain protein (ultraviolet [UV]-light stress), Phosphofructokinase (sugar metabolism) and Ubiquitin thioesterase (protein alterations). Biochemical investigations showed a positive correlation between proteomic plasticity (HrB13) and 1.6 to 15-fold accumulation of downstream adaptive metabolic signatures like enzymes and antioxidants involved in ROS scavenging pathways (Catalase, Ascorbate peroxidase, Glutathione reductase, ascorbate and glutathione content), secondary metabolites (phenolics, flavonoids, carotenoids) and polyunsaturated fatty acids (∝ - linolenic acid and linoleic acid). Interactome and KEGG pathway analysis also supported interactions of differentially accumulated proteins with stress-responsive signaling components involved in physiological pathways associated with stress tolerance. This is the first 'ecophysiolomics' study, showing the response of seabuckthorn to multiple stress conditions via activation of multifactorial acclimation strategies leading to morphological, metabolic and physiological modifications, resulting in dark orange berries in HrB13. Higher accumulation of omega-6 fatty acids, carotenoids and ascorbate during suboptimal growth conditions, provides exciting prospects for enhancing pharmaceutical properties of seabuckthorn berries, emphasizing need to analyze diversity of plant signaling mechanisms under changing climate conditions.

Characterization of the Hippophae rhamnoides WRKY gene family and functional analysis of the role of the HrWRKY21 gene in resistance to abiotic stresses.

Sea buckthorn (Hippophae rhamnoides L.) is a plant with economic and ecological value. It is uniquely capable of growing well under salt and drought stress. WRKY transcription factors play important roles in the ability of plants to resist stress. In this study, 48 HrWRKY genes were identified based on RNA sequencing of H. rhamnoides. Evaluation of expression pattern of HrWRKY1, HrWRKY17, HrWRKY18, HrWRKY21, HrWRKY33-2, HrWRKY40-2, HrWRKY41, and HrWRKY71 suggested that they were involved in abiotic stress. Interestingly, HrWRKY21, one of eight HrWRKY genes, was a positive regulator of abiotic stress tolerance in H. rhamnoides. In addition, most morphological attributes of roots in transgenic Nicotiana tabacum lines (overexpressing HrWRKY21) were also markedly increased compared with the wild-type (WT), including total lengths, specific root lengths, and surface areas. Stress tolerance of transgenic lines was also correlated with higher antioxidant activity (SOD and POD), lower percentage of relative conductivity (REC), and lower activity of malondialdehyde (MDA) under stress conditions. These findings represent a foundation of knowledge about the molecular mechanisms driving resistance to adverse conditions in plants; they are a promising step towards development of tree cultivars with improved tolerance to abiotic stress.

Transcriptomic analysis of drought stress responses of sea buckthorn (Hippophae rhamnoidessubsp. sinensis) by RNA-Seq.

Sea buckthorn is one of the most important eco-economic tree species in China due to its ability to grow and produce acceptable yields under limited water and fertilizer availability. In this study, the differentially expressed genes under drought stress (DS) of sea buckthorn were identified and compared with control (CK) by RNA-Seq. A total of 122,803 unigenes were identified in sea buckthorn, and 70,025 unigenes significantly matched a sequence in at least one of the seven databases. A total of 24,060 (19.59%) unigenes can be assigned to 19 KEGG pathways, and 1,644 unigenes were differentially expressed between DS and CK, of which 519 unigenes were up-regulated and 1,125 unigenes down-regulated. Of the 47 significantly enriched GO terms, 14, 7 and 26 items were related to BP, CC and MF, respectively. KEGG enrichment analysis showed 398 DEGs involved in 97 different pathways, of which 119 DEGs were up-regulated and 279 DEGs were down-regulated under drought stress. In addition, we found 4438 transcriptor factors (TFs) in sea buckthorn, of which 100 were differentially expressed between DS and CK. These results lay a first foundation for further investigations of the very specific functions of these unigenes in sea buckthorn in response to drought stress.

Genome-wide analysis of long non-coding RNAs at the mature stage of sea buckthorn (Hippophae rhamnoides Linn) fruit.

Long non-coding RNAs (lncRNAs), which are >200nt longer transcripts, potentially play important roles in almost all biological processes in plants and mammals. However, the functions and profiles of lncRNAs in fruit is less understood. Therefore, it is urgent and necessary to identify and analyze the functions of lncRNAs in sea buckthorns. Using RNA-sequencing, we synthetically identified lncRNAs in mature fruit from the red and yellow sea buckthorn. We obtained 567,778,938 clean reads from six samples and identified 3428 lncRNAs in mature fruit, including 2498 intergenic lncRNAs, 593 anti-sense lncRNAs, and 337 intronic lncRNAs. We also identified 3819 and 2295 circular RNAs in red and yellow sea buckthorn Fruit. In the aspects of gene architecture and expression, our results showed significant differences among the three lncRNA subtypes. We also investigated the effect of lncRNAs on its cis and trans target genes. Based on target genes analysis, we obtained 61 different expression lncRNAs (DE-lncRNAs) between these two sea buckthorns, including 23 special expression lncRNAs in red fruit and 22 special expression lncRNAs in yellow fruit. Importantly, we found a few DE-lncRNAs play cis and trans roles for genes in the Carotenoid biosynthesis, ascorbate and aldarate metabolism and fatty acid metabolism pathways. Our study provides a resource for lncRNA studies in mature fruit. It probably encourages researchers to deeply study fruit-coloring. It expands our knowledge about lncRNA biology and the annotation of the sea buckthorn genome.

Physiological, biochemical, and proteome profiling reveals key pathways underlying the drought stress responses of Hippophae rhamnoides.

The effects of drought on plant growth and development are occurring as a result of climate change and the growing scarcity of water resources. Hippophae rhamnoides has been exploited for soil and water conservation for many years. However, the outstanding drought-resistance mechanisms possessed by this species remain unclear. The protein, physiological, and biochemical responses to medium and severe drought stresses in H. rhamnoides seedlings are analyzed. Linear decreases in photosynthesis rate, transpiration rate, and the content of indole acetic acid in roots, as well as a linear increase in the contents of abscisic acid, superoxide dismutase, glutathione reductase, and zeatin riboside in leaves are observed as water potential decreased. At the same time, cell membrane permeability, malondialdehyde, stomatal conductance, water use efficiency, and contents of zeatin riboside in roots and indole acetic acid in leaves showed nonconsistent changes. DIGE and MS/MS analysis identified 51 differently expressed protein spots in leaves with functions related to epigenetic modification and PTM in addition to normal metabolism, photosynthesis, signal transduction, antioxidative systems, and responses to stimuli. This study provides new insights into the responses and adaptations in this drought-resistant species and may benefit future agricultural production.

Evaluation of Limiting Climatic Factors and Simulation of a Climatically Suitable Habitat for Chinese Sea Buckthorn.

Chinese sea buckthorn (Hippophae rhamnoides subsp. sinensis) has considerable economic potential and plays an important role in reclamation and soil and water conservation. For scientific cultivation of this species across China, we identified the key climatic factors and explored climatically suitable habitat in order to maximize survival of Chinese sea buckthorn using MaxEnt and GIS tools, based on 98 occurrence records from herbarium and publications and 13 climatic factors from Bioclim, Holdridge life zone and Kria' index variables. Our simulation showed that the MaxEnt model performance was significantly better than random, with an average test AUC value of 0.93 with 10-fold cross validation. A jackknife test and the regularized gain change, which were applied to the training algorithm, showed that precipitation of the driest month (PDM), annual precipitation (AP), coldness index (CI) and annual range of temperature (ART) were the most influential climatic factors in limiting the distribution of Chinese sea buckthorn, which explained 70.1% of the variation. The predicted map showed that the core of climatically suitable habitat was distributed from the southwest to northwest of Gansu, Ningxia, Shaanxi and Shanxi provinces, where the most influential climate variables were PDM of 1.0-7.0 mm, AP of 344.0-1089.0 mm, CI of -47.7-0.0°C, and ART of 26.1-45.0°C. We conclude that the distribution patterns of Chinese sea buckthorn are related to the northwest winter monsoon, the southwest summer monsoon and the southeast summer monsoon systems in China.

DeepSAGE based differential gene expression analysis under cold and freeze stress in seabuckthorn (Hippophae rhamnoides L.).

Seabuckthorn (Hippophae rhamnoides L.), an important plant species of Indian Himalayas, is well known for its immense medicinal and nutritional value. The plant has the ability to sustain growth in harsh environments of extreme temperatures, drought and salinity. We employed DeepSAGE, a tag based approach, to identify differentially expressed genes under cold and freeze stress in seabuckthorn. In total 36.2 million raw tags including 13.9 million distinct tags were generated using Illumina sequencing platform for three leaf tissue libraries including control (CON), cold stress (CS) and freeze stress (FS). After discarding low quality tags, 35.5 million clean tags including 7 million distinct clean tags were obtained. In all, 11922 differentially expressed genes (DEGs) including 6539 up regulated and 5383 down regulated genes were identified in three comparative setups i.e. CON vs CS, CON vs FS and CS vs FS. Gene ontology and KEGG pathway analysis were performed to assign gene ontology term to DEGs and ascertain their biological functions. DEGs were mapped back to our existing seabuckthorn transcriptome assembly comprising of 88,297 putative unigenes leading to the identification of 428 cold and freeze stress responsive genes. Expression of randomly selected 22 DEGs was validated using qRT-PCR that further supported our DeepSAGE results. The present study provided a comprehensive view of global gene expression profile of seabuckthorn under cold and freeze stresses. The DeepSAGE data could also serve as a valuable resource for further functional genomics studies aiming selection of candidate genes for development of abiotic stress tolerant transgenic plants.

[Root anatomical structure and hydraulic traits of three typical shrubs on the sandy lands of northern Shaanxi Province, China].

Root xylem anatomical structure and hydraulic traits of three typical shrubs, i.e., Salix psammophila, Caragana korshinskii and Hippophae rhamnoides, within two soil layers (0-20 cm and 30-50 cm) were compared. The results showed that S. psammophila had a higher leaf water potential than C. korshinskii and H. rhamnoides, the average maximum and minimum lumen diameter (d(max) and d(min), respectively), the average lumen area of vessels (Alum) and the ratio of lumen area of all vessels to xylem area (Aves/Axyl) in S. psammophila roots were also significantly higher than those in C. korshinskii and H. rhamnoides, and the root vessel density (VD) in S. psammophila was the same as that in H. rhamnoides but significantly higher than that in C. korshinskii. Root hydraulic conductivity in S. psammophila was 5 times of C. korshinskii and 2.8 times of H. hamnoides. The vulnerability index in S. psammophila roots was similar to that in C. korshinskii but higher than that in H. hamnoides. S. psammophila belonged to a water-spending species, whereas both C. korshinskii and H. rhamnoides were water-saving species, and C. korshinskii was more drought-resistant than H. rhamnoides. There was no difference of d(max), d(min) and Alum between roots in two soil layers, but roots within in the 30-50 cm soil layer had larger VD and Aves/Axyl. The root specific hydraulic conductivity within the 30-50 cm soil layer was significantly higher than within the surface soil layer, whereas the vulnerability index within the 30-50 cm soil layer was smaller, indicating roots in deep soil layers had higher hydraulic transport efficiency and lower hydraulic vulnerability.

Recalcitrant vulnerability curves: methods of analysis and the concept of fibre bridges for enhanced cavitation resistance.

Vulnerability curves (VCs) generally can be fitted to the Weibull equation; however, a growing number of VCs appear to be recalcitrant, that is, deviate from a Weibull but seem to fit dual Weibull curves. We hypothesize that dual Weibull curves in Hippophae rhamnoides L. are due to different vessel diameter classes, inter-vessel hydraulic connections or vessels versus fibre tracheids. We used dye staining techniques, hydraulic measurements and quantitative anatomy measurements to test these hypotheses. The fibres contribute 1.3% of the total stem conductivity, which eliminates the hypothesis that fibre tracheids account for the second Weibull curve. Nevertheless, the staining pattern of vessels and fibre tracheids suggested that fibres might function as a hydraulic bridge between adjacent vessels. We also argue that fibre bridges are safer than vessel-to-vessel pits and put forward the concept as a new paradigm. Hence, we tentatively propose that the first Weibull curve may be accounted by vessels connected to each other directly by pit fields, while the second Weibull curve is associated with vessels that are connected almost exclusively by fibre bridges. Further research is needed to test the concept of fibre bridge safety in species that have recalcitrant or normal Weibull curves.

Micromonospora is a normal occupant of actinorhizal nodules.

Actinorhizal plants have been found in eight genera belonging to three orders (Fagales, Rosales and Cucurbitales). These all bear root nodules inhabited by bacteria identified as the nitrogen-fixing actinobacterium Frankia. These nodules all have a peripheral cortex with enlarged cells filled with Frankia hyphae and vesicles. Isolation in pure culture has been notoriously difficult, due in a large part to the growth of fast-growing contaminants where, it was later found, Frankia was slow-growing. Many of these contaminants, which were later found to be Micromonospora, were obtained from Casuarina and Coriaria. Our study was aimed at determining if Micromonospora were also present in other actinorhizal plants. Nodules from Alnus glutinosa, Alnus viridis, Coriaria myrtifolia, Elaeagnus x ebbingei, Hippophae rhamnoides, Myrica gale and Morella pensylvanica were tested and were all found to contain Micromonospora isolates. These were found to belong to mainly three species: Micromonospora lupini, Micromonospora coriariae and Micromonospora saelicesensis. Micromonospora isolates were found to inhibit some Frankia strains and to be innocuous to other strains.

Advances in improvement of quality and resistance in a multipurpose crop: sea buckthorn.

Sea buckthorn is a berry crop with multiple uses. The berries are highly appreciated for their unique taste but are also very rich in bioactive compounds with powerful nutritional and medicinal values. In addition, the plants grow well under adverse conditions, and are often used to fight soil erosion. Utilization of sea buckthorn has therefore increased around the world but serious problems have, nevertheless, been encountered due to drought, salinity, diseases and insect pests. This review covers important aspects of sea buckthorn research, such as heritable and environmentally induced variation in biochemical compounds, causes and effects of the devastating dried-shrink disease, susceptibility to insect pests, methods for conventional breeding, and the utilization of DNA markers for taxonomical and population genetic analyses, and for investigating the inheritance of quality and resistance traits. We also present possibilities to implement innovative biotechnological breeding methods, especially metabolite profiling and MAS/GRC-based markers, for fast and efficient development of elite genotypes with specific nutritional- and health-related bioactive compounds and strong resistance to biotic and abiotic stress.

Response pattern of amino compounds in phloem and xylem of trees to soil drought depends on drought intensity and root symbiosis.

This study aimed to identify drought-mediated differences in amino nitrogen (N) composition and content of xylem and phloem in trees having different symbiotic N(2)-fixing bacteria. Under controlled water availability, 1-year-old seedlings of Robinia pseudoacacia (nodules with Rhizobium), Hippophae rhamnoides (symbiosis with Frankia) and Buddleja alternifolia (no such root symbiosis) were exposed to control, medium drought and severe drought, corresponding soil water content of 70-75%, 45-50% and 30-35% of field capacity, respectively. Composition and content of amino compounds in xylem sap and phloem exudates were analysed as a measure of N nutrition. Drought strongly reduced biomass accumulation in all species, but amino N content in xylem and phloem remained unaffected only in R. pseudoacacia. In H. rhamnoides and B. alternifolia, amino N in phloem remained constant, but increased in xylem of both species in response to drought. There were differences in composition of amino compounds in xylem and phloem of the three species in response to drought. Proline concentrations in long-distance transport pathways of all three species were very low, below the limit of detection in phloem of H. rhamnoides and in phloem and xylem of B. alternifolia. Apparently, drought-mediated changes in N composition were much more connected with species-specific changes in C:N ratios. Irrespective of soil water content, the two species with root symbioses did not show similar features for the different types of symbiosis, neither in N composition nor in N content. There was no immediate correlation between symbiotic N fixation and drought-mediated changes in amino N in the transport pathways.

[Characteristics of rainfall interception by Caragana korshinskii and Hippophae rhamnoides in Loess Plateau of Northwest China].

From May to October 2011, an investigation was conducted on the effects of rainfall and its intensity on the canopy interception, throughfall, and stemflow of Caragana korshinskii and Hippophae rhamnoides, the main shrub species commonly planted to stabilize soil and water in the Anjiagou catchment of Loess Plateau. A total of 47 rainfall events were observed, most of which were featured with low intensity, and the total amount and average intensity of the rainfalls were 208.9 mm and 2.82 mm x h(-1), respectively. As a whole, the rainfall events of 2-10 mm and 0.1-2 mm x h(-1) had the highest frequency. The canopy interception, throughfall, and stemflow of C. korshinski were 58.5 mm (28%), 124.7 mm (59.7%), and 25.7 mm (12.3%), while those of H. rhamnoides were 17.6 mm (8.4%), 153. 1 mm (73.3%), and 38.2 mm (18.3%), respectively. Regression analysis showed that the canopy interception, throughfall, and stemflow of the two shrub species all had significant positive correlations with the rainfall amount, and had exponent or power correlations with the rainfall amount and the maximum rainfall intensity in 10 minutes.