The profiles and tensile strength on straight roots of plants withstand transient tensile injured after self-repair

Plants roots are severely injured during the process of withstanding transient tensile, and the injured roots can self-repair. We investigated the change law of the growth characteristics and tensile strength on straight roots withstand transient tensile injured after self-repair. The survival rate of two kinds of injured plants roots was between 60 and 89%. The test roots after self-repaired, the tensile strength reduction rate of Hippophae rhamnoides L. roots was greater than that of Salix psammophila roots. The tensile force was positively related to the power function of root diameter, the tensile strength was negatively related to the root diameter in a power function. The tensile strength of straight roots under small injured force showed an increasing trend, but the straight roots under the large injured force showed the opposite result. The survival rate of rough roots was greater than that of fine roots. The large injured force was not conducive to the repair and force again of the straight roots of two kinds of plants. The reduction rate of tensile strength after repaired with small force was less than that of large force. The self-repair ability of fine roots was weaker than that of rough roots.

Diversity in sea buckthorn (Hippophae rhamnoides L.) accessions with different origins based on morphological characteristics, oil traits, and microsatellite markers

Sea buckthorn (Hippophae rhamnoides) is an ecologically and economically important species. Here, we assessed the diversity of 78 accessions cultivated in northern China using 8 agronomic characteristics, oil traits (including oil content and fatty acid composition) in seeds and fruit pulp, and SSR markers at 23 loci. The 78 accessions included 52 from ssp. mongolica, 6 from ssp. sinensis, and 20 hybrids. To assess the phenotypic diversity of these accessions, 8 agronomic fruit traits were recorded and analyzed using principal component analysis (PCA). The first two PCs accounted for approximately 78% of the variation among accessions. The oil contents were higher in pulp (3.46–38.56%) than in seeds (3.88–8.82%), especially in ssp. mongolica accessions. The polyunsaturated fatty acid (PUFA) ratio was slightly lower in the seed oil of hybrids (76.06%) than that of in ssp. mongolica (77.66%) and higher than that of in ssp. sinensis (72.22%). The monounsaturated fatty acid (MUFA) ratio in the pulp oil of ssp. sinensis (57.00%) was highest, and that in ssp. mongolica (51.00%) was equal to the ratio in the hybrids (51.20%). Using canonical correspondence analysis (CCA), we examined the correlation between agronomic traits and oil characteristics in pulp and seeds. Oil traits in pulp from different origins were correlated with morphological groupings (r = 0.8725, p = 0.0000). To assess the genotypic diversity, 23 SSR markers (including 17 loci previously reported) were used among the 78 accessions with 59 polymorphic amplified fragments obtained and an average PIC value of 0.2845. All accessions were classified into two groups based on the UPGMA method. The accessions of ssp. sinensis and ssp. mongolica were genetically distant. The hybrid accessions were close to ssp. mongolica accessions. The 8 agronomic traits, oil characteristics in seed and pulp oils, and 23 SSR markers successfully distinguished the 78 accessions. These results will be valuable for cultivar identification and genetic diversity analysis in cultivated sea buckthorn.

Unusual isovalerylated flavonoids from the fruit of sea buckthorn (Elaeagnus rhamnoides) grown in Sokółka, Poland

Eight undescribed isorhamnetin glycosides, acylated with isovaleric acid were isolated from the fruit of sea buckthorn (Elaeagnus rhamnoides (L.) A. Nelson). Structures of the purified compounds were determined using one and two-dimensional NMR spectroscopy, mass spectrometry and chemical methods. In addition, the cytotoxic activity of the phenolic-rich fraction of sea buckthorn fruit and its major flavonoids against colon cell lines, HT-29, HCT-116 and Caco-2, was determined. While the phenolic fraction was moderately active against HT-29 and HCT-116, all investigated purified flavonoids showed significantly weaker activity. This is most probably the first report about isorhamnetin glycosides acylated with isovaleric acid.

RNA-seq data reveals a coordinated regulation mechanism of multigenes involved in the high accumulation of palmitoleic acid and oil in sea buckthorn berry pulp

BACKGROUND

Sea buckthorn is a woody oil crop in which palmitoleic acid (C16:1n7, an omega-7 fatty acid (FA)) contributes approximately 40% of the total FA content in berry pulp (non-seed tissue). However, the molecular mechanisms contributing to the high accumulation of C16:1n7 in developing sea buckthorn berry pulp (SBP) remain poorly understood.

RESULTS

We identified 1737 unigenes associated with lipid metabolism through RNA-sequencing analysis of the four developmental stages of berry pulp in two sea buckthorn lines, 'Za56' and 'TF2-36'; 139 differentially expressed genes were detected between the different berry pulp developmental stages in the two lines. Analyses of the FA composition showed that the C16:1n7 contents were significantly higher in line 'Za56' than in line 'TF2-36' in the mid-late developmental stages of SBP. Additionally, qRT-PCR analyses of 15 genes involved in FA and triacylglycerol (TAG) biosynthesis in both lines revealed that delta9-ACP-desaturase (ACP-Δ9D) competed with 3-ketoacyl-ACP-synthase II (KASII) for the substrate C16:0-ACP and that ACP-Δ9D and delta9-CoA-desaturase (CoA-Δ9D) gene expression positively correlated with C16:1n7 content; KASII and fatty acid elongation 1 (FAE1) gene expression positively correlated with C18:0 content in developing SBP. Specifically, the abundance of ACP-Δ9D and CoA-Δ9D transcripts in line 'Za56', which had a higher C16:1n7 content than line 'TF2-36', suggests that these two genes play an important role in C16:1n7 biosynthesis. Furthermore, the high expressions of the glycerol-3-phosphate dehydrogenase (GPD1) gene and the WRINKLED1 (WRI1) transcription factor contributed to increased biosynthesis of TAG precursor and FAs, respectively, in the early developmental stages of SBP, and the high expression of the diacylglycerol O-acyltransferase 1 (DGAT1) gene increased TAG assembly in the later developmental stages of SBP. Overall, we concluded that increased ACP-Δ9D and CoA-Δ9D levels coupled with decreased KASII and FAE1 activity is a critical event for high C16:1n7 accumulation and that the coordinated high expression of WRI1, GPD1, and DGAT1 genes resulted in high oil accumulation in SBP.

CONCLUSION

Our results provide a scientific basis for understanding the mechanism of high C16:1n7 accumulation in berry pulp (non-seed tissue) and are valuable to the genetic breeding programme for achieving a high quality and yield of SBP oil.

ISSR markers for gender identification and genetic diagnosis of Hippophae rhamnoides ssp. turkestanica growing at high altitudes in Ladakh region (Jammu and Kashmir)

Hippophae rhamnoides L. ssp. turkestanica (Elaeagnaceae) is a predominantly dioecious and wind-pollinated medicinal plant species. The mature fruits of the species possess antioxidative, anti-inflammatory, antimicrobial, anticancerous, and antistimulatory properties that are believed to improve the immune system. The identification of male and female plants in H. rhamnoides ssp. turkestanica is quite difficult until flowering which usually takes 3-4 years or more. A sex-linked marker can be helpful in establishing the orchards through identification of genders at an early stage of development. Therefore, we studied the genetic diversity of populations in Ladakh with the aim to identify a gender-specific marker using ISSR markers. Fifty-eight ISSR primers were used to characterize the genome of H. rhamnoides ssp. turkestanica, of which eight primers generated 12 sex-specific fragments specific to one or more populations. The ISSR primer (P-45) produced a fragment which faithfully segregates all the males from the female plants across all the three valleys surveyed. This male-specific locus was converted into a SCAR. Forward and reverse primers designed from this fragment amplified a 750-bp sequence in males only, thus specifying it as an informative male-specific sex-linked marker. This SCAR marker was further validated for its capability to differentiate gender on an additional collection of plants, representing three geographically isolated valleys (Nubra, Suru, and Indus) from Ladakh region of India. The results confirmed sex-linked specificity of the marker suggesting that this conserved sequence at the Y chromosome is well preserved through the populations in Ladakh region. At present, there are no reliable markers which can differentiate male from female plants across all the three valleys of Ladakh region at an early stage of plant development. It is therefore envisaged that the developed SCAR marker shall provide a reliable molecular tool for early identification of the sex in this commercial crop. The genetic diversity of populations as surveyed by ISSR primers revealed 85.71 % polymorphism at the population level. The dendrogram obtained divided the genotypes into three different clusters, and the distribution of male and female genotypes in all the clusters was random. The Nei's genetic similarity index was in the range of 0.63-0.96.

Sea Buckthorn (Hippophaë rhamnoides ssp. rhamnoides) Berries in Nordic Environment: Compositional Response to Latitude and Weather Conditions

Flavonol glycosides (FGs) in sea buckthorn (Hippophaë rhamnoides ssp. rhamnoides) berries of varieties 'Tytti' and 'Terhi', cultivated in northern Finland (68°02' N) for six years and southern Finland (60°23' N) for seven years, were investigated and compared by HPLC-DAD-ESI-MS/MS. The average total content of 23 identified glycosides of isorhamnetin and quercetin was 103 ± 23 and 110 ± 21 mg/100 g fresh berries in 'Terhi' and 'Tytti', respectively. The total contents of FGs, flavonol diglycosides, and triglycosides in both varieties were higher in the north than in the south, whereas total flavonol monoglycoside content behaved vice versa (p < 0.05). Among the 89 weather variables studied, the sum of the daily mean temperatures that are 5 °C or higher from the start of growth season until the day of harvest was the most important variable which associated negatively with the accumulation of FGs in berries. Such influence was much stronger in berries from the north than from the south.

[Difference of anti-fracture mechanical characteristics between lateral-root branches and adjacent upper straight roots of four plant species in vigorous growth period]

Taking four plant species, Caragana korshinskii, Salix psammophila, Hippophae rhamnides and Artemisia sphaerocephala, which were 3-4 years old and in vigorous growth period, as test materials, the anti-fracture forces of lateral-root branches and adjacent upper straight roots were measured with the self-made fixture and the instrument of TY 8000. The lateral-root branches were vital and the diameters were 1-4 mm. The results showed that the anti-fracture force and anti-fracture strength of lateral-root branches were lesser than those of the adjacent upper straight roots even though the average diameter of lateral-root branches was greater. The ratios of anti-fracture strength of lateral-root branches to the adjacent upper straight roots were 71.5% for C. korshinskii, 62.9% for S. psammophila, 45.4% for H. rhamnides and 35.4% for A. sphaerocephala. For the four plants, the anti-fracture force positively correlated with the diameter in a power function, while the anti-fracture strength negatively correlated with diameter in a power function. The anti-fracture strengths of lateral-root branches and adjacent upper straight roots for the four species followed the sequence of C. korshinskii (33.66 and 47.06 MPa) > S. psammophila (17.31 and 27.54 MPa) > H. rhamnides (3.97 and 8.75 MPa) > A. sphaerphala (2.18 and 6.15 MPa).

Metabolite profiling and expression analysis of flavonoid, vitamin C and tocopherol biosynthesis genes in the antioxidant-rich sea buckthorn (Hippophae rhamnoides L.)

In this study, phenolic compounds were analyzed in developing berries of four Canadian grown sea buckthorn (Hippophae rhamnoides L.) cultivars ('RC-4', 'E6590', 'Chuyskaya' and 'Golden Rain') and in leaves of two of these cultivars. Among phenolic acids, p-coumaric acid was the highest in berries, while gallic acid was predominant in leaves. In the flavonoid class of compounds, myricetin/rutin, kaempferol, quercetin and isorhamnetin were detected in berries and leaves. Berries of the 'RC-4' cultivar had approximately ⩾ 2-fold higher levels of myricetin and quercetin at 17.5mg and 17.2 mg/100 g FW, respectively, than the other cultivars. The flavonoid content in leaves was considerably more than in berries with rutin and quercetin levels up to 135 mg and 105 mg/100 g FW, respectively. Orthologs of 15 flavonoid biosynthesis pathway genes were identified within the transcriptome of sea buckthorn mature seeds. Semi-quantitative RT-PCR analysis of these genes in developing berries indicated relatively higher expression of genes such as CHS, F3'H, DFR and LDOX in the 'RC-4' cultivar than in the 'Chuyskaya' cultivar. Vitamin C levels in ripened berries of the Canadian cultivars were on the high end of the concentration range reported for most other sea buckthorn cultivars. Orthologs of genes involved in vitamins C and E biosynthesis were also identified, expanding the genomic resources for this nutritionally important plant.

Sex-Biased Temporal Gene Expression in Male and Female Floral Buds of Seabuckthorn (Hippophae rhamnoides)

Seabuckthorn is an economically important dioecious plant in which mechanism of sex determination is unknown. The study was conducted to identify seabuckthorn homologous genes involved in floral development which may have role in sex determination. Forty four putative Genes involved in sex determination (GISD) reported in model plants were shortlisted from literature survey, and twenty nine seabuckthorn homologous sequences were identified from available seabuckthorn genomic resources. Of these, 21 genes were found to differentially express in either male or female flower bud stages. HrCRY2 was significantly expressed in female flower buds only while HrCO had significant expression in male flowers only. Among the three male and female floral development stages (FDS), male stage II had significant expression of most of the GISD. Information on these sex-specific expressed genes will help in elucidating sex determination mechanism in seabuckthorn.

Effect of monospecific and mixed sea-buckthorn (Hippophae rhamnoides) plantations on the structure and activity of soil microbial communities

This study aims to evaluate the effect of different afforestation models on soil microbial composition in the Loess Plateau in China. In particular, we determined soil physicochemical properties, enzyme activities, and microbial community structures in the top 0 cm to 10 cm soil underneath a pure Hippophae rhamnoides (SS) stand and three mixed stands, namely, H. rhamnoides and Robinia pseucdoacacia (SC), H. rhamnoides and Pinus tabulaeformis (SY), and H. rhamnoides and Platycladus orientalis (SB). Results showed that total organic carbon (TOC), total nitrogen, and ammonium (NH₄⁺) contents were higher in SY and SB than in SS. The total microbial biomass, bacterial biomass, and Gram⁺ biomass of the three mixed stands were significantly higher than those of the pure stand. However, no significant difference was found in fungal biomass. Correlation analysis suggested that soil microbial communities are significantly and positively correlated with some chemical parameters of soil, such as TOC, total phosphorus, total potassium, available phosphorus, NH₄⁺ content, nitrate content (NH₃⁻), and the enzyme activities of urease, peroxidase, and phosphatase. Principal component analysis showed that the microbial community structures of SB and SS could clearly be discriminated from each other and from the others, whereas SY and SC were similar. In conclusion, tree species indirectly but significantly affect soil microbial communities and enzyme activities through soil physicochemical properties. In addition, mixing P. tabulaeformis or P. orientalis in H. rhamnoides plantations is a suitable afforestation model in the Loess Plateau, because of significant positive effects on soil nutrient conditions, microbial community, and enzyme activities over pure plantations.

[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.

[Response of sloping water erosion to rainfall and micro-earth pattern in the loess hilly area]

Severe water erosion in the key loess hilly area is affected by the coupling role of rainfall and earth surface features. In this study, rainfall simulation techniques at the micro-plot scale (1.2 m x 1.2 m; 2 m x 1.2 m) was used as the basic measures, the relations between rainfall depth, intensity and runoff-erosion under different plant morphology features as well as micro-landscape positions were quantified and analyzed. Several key findings were captured. Firstly, rainfall depth and intensity both affected water erosion significantly, while the role of the rainfall intensity was more important than that of the depth. Secondly, a strong negative correlation was found between the antecedent soil moisture content and the generation timing of surface runoff, while water erosion had a positive relation with the antecedent soil moisture. Thirdly, different plant morphology and micro-landscape positions of shrub plant (seabuckthorn) played different roles leading to different rates of surface runoff and soil erosion. Dominated by a rainfall intensity ranging from 50 to 60 mm x h(-1), runoff coefficient in those micro-plots covered by seabuckthorn was about 5%-8%, and changed into 25%, 45% and 63% in grassland-plots, bared plots covered by biological-crust and bared plots without any coverage, respectively. Fourthly, the specific landscape position of seabuckthorn in the plots was also found to play a key role in affecting water erosion processes, and seabuckthorn at the lower landscape position, rather than the upper and middle position, played a better buffering role in reducing runoff and soil loss.

Fatty acid composition of developing sea buckthorn (Hippophae rhamnoides L.) berry and the transcriptome of the mature seed

Background

Sea buckthorn (Hippophae rhamnoides L.) is a hardy, fruit-producing plant known historically for its medicinal and nutraceutical properties. The most recognized product of sea buckthorn is its fruit oil, composed of seed oil that is rich in essential fatty acids, linoleic (18∶2ω-6) and α-linolenic (18∶3ω-3) acids, and pulp oil that contains high levels of monounsaturated palmitoleic acid (16∶1ω-7). Sea buckthorn is fast gaining popularity as a source of functional food and nutraceuticals, but currently has few genomic resources; therefore, we explored the fatty acid composition of Canadian-grown cultivars (ssp. mongolica) and the sea buckthorn seed transcriptome using the 454 GS FLX sequencing technology.

Results

GC-MS profiling of fatty acids in seeds and pulp of berries indicated that the seed oil contained linoleic and α-linolenic acids at 33–36% and 30–36%, respectively, while the pulp oil contained palmitoleic acid at 32–42%. 454 sequencing of sea buckthorn cDNA collections from mature seeds yielded 500,392 sequence reads, which identified 89,141 putative unigenes represented by 37,482 contigs and 51,659 singletons. Functional annotation by Gene Ontology and computational prediction of metabolic pathways indicated that primary metabolism (protein>nucleic acid>carbohydrate>lipid) and fatty acid and lipid biosynthesis pathways were highly represented categories. Sea buckthorn sequences related to fatty acid biosynthesis genes in Arabidopsis were identified, and a subset of these was examined for transcript expression at four developing stages of the berry.

Conclusion

This study provides the first comprehensive genomic resources represented by expressed sequences for sea buckthorn, and demonstrates that the seed oil of Canadian-grown sea buckthorn cultivars contains high levels of linoleic acid and α-linolenic acid in a close to 1∶1 ratio, which is beneficial for human health. These data provide the foundation for further studies on sea buckthorn oil, the enzymes involved in its biosynthesis, and the genes involved in the general hardiness of sea buckthorn against environmental conditions.

Effects of genotype, latitude, and weather conditions on the composition of sugars, sugar alcohols, fruit acids, and ascorbic acid in sea buckthorn (Hippophaë rhamnoides ssp. mongolica) berry juice

Sea buckthorn berries (Hippophaë rhamnoides ssp. mongolica) of nine varieties were collected from three growth locations in five inconsecutive years (n = 152) to study the compositional differences of sugars, sugar alcohols, fruit acids, and ascorbic acid in berries of different genotypes. Fructose and glucose (major sugars) were highest in Chuiskaya and Vitaminaya among the varieties studied, respectively. Malic acid and quinic acid (major acids) were highest in Pertsik and Vitaminaya, respectively. Ascorbic acid was highest in Oranzhevaya and lowest in Vitaminaya. Berry samples of nine varieties collected from two growth locations in five years (n = 124) were combined to study the effects of latitude and weather conditions on the composition of H. rhamnoides ssp. mongolica. Sea buckthorn berries grown at lower latitude had higher levels of total sugar and sugar/acid ratio and a lower level of total acid and were supposed to have better sensory properties than those grown at higher latitude. Glucose, quinic acid, and ascorbic acid were hardly influenced by weather conditions. The other components showed various correlations with temperature, radiation, precipitation, and humidity variables. In addition, fructose, sucrose, and myo-inositol correlated positively with each other and showed negative correlation with malic acid on the basis of all the samples studied (n = 152).

Lissonota holcocerica Sheng sp.n (Hymenoptera: Ichneumonidae) parasitizing Holcocerus hippophaecolus (Lepidoptera: Cossidae) from China

This paper describes Lissonota holcocerica Sheng sp.n. (Hymenoptera: Ichneumonidae), parasitizing Holcocerus hippophaecolus Hua, Chou, Fang and Chen (Lepidoptera: Cossidae) in Inner Mongolia, Liaoning, and Ningxia, China. The adults of L. holcocerica emerge from a cocoon during the daytime, mostly from 09:00 to 14:00 hr, then start calling and mating, mostly from 08:00 to 12:00 hr. Mating lasts from 15 sec to 15 min. The longevity of males is 5.8 ± 2.4 days, whereas for females longevity is 7.6 ± 4.6 days in the field. Nutritional supplements can significantly extend the life span of L. holcocerica. Mated females search for hosts by walking on the base of Hippophae rhamnoides L. (Rosales: Elaeagnaceae) stem infested by Ho. hippophaecolus, vibrating their antennae and tapping while searching the stem for oviposition sites. Parasitized cocoons of Ho. hippophaecolus collected in field were half the size of normal ones or even smaller.

[Characteristics of stemflow for typical alpine shrubs in Qilian Mountain]

Taking the typical alpine shrubs Potentilla fruticosa, Salix cupularis, Hippophae rhamnoides, and Caragana jubata in Qilian Mountain as test objects, a field investigation from June 1 to October 31, 2010 was conducted on the variation characteristics of the shrub stemflow, and analyzed the affecting effects of rainfall intensity and canopy structure morphology. The stemflow generated when the rainfall in early period was 2.1 mm, with an average of 3.4%, 3.2%, 8.0%, and 4.2% of the gross rainfall for P. fruticosa, S. cupularis, H. rhamnoides, and C. jubata, respectively. There was a significant positive linear correlation between the stemflow and rainfall intensity. With increasing rainfall, the stemflow percentage showed a trend of increase-decrease-increase. Stemflow played an important role in supplying water to the shrub rhizosphere, and the average funneling ratio was 59, 30, 110, and 49 for P. fruticosa, S. cupularis, H. rhamnoides, and C. jubata, respectively. The stemflow percentage had a significant exponential relationship with the maximum rain intensity in 10 minutes (I10). When the I10 was more than 6.0 mm x h(-1), the stemflow of H. rhamnoides and C. jubata showed a persistently increasing trend, while that of P. fruticosa and S. cupularis tended to be stable. Canopy structure morphology had complicated effects on the stemflow. In the same rainfall intensities, the height and crown projection area of the shrubs were the important factors affecting the generation of stemflow.

Cold-adapted and rhizosphere-competent strain of Rahnella sp. with broad-spectrum plant growth-promotion potential

A phosphate-solubilizing bacterial strain isolated from Hippophae rhamnoides rhizosphere was identified as Rahnella sp. based on its phenotypic features and 16S rRNA gene sequence. The bacterial strain showed the growth characteristics of a cold-adapted psychrotroph, with the multiple plant growth-promoting traits of inorganic and organic phosphate solubilization, 1-aminocyclopropane-1- carboxylate-deaminase activity, ammonia generation, and siderophore production. The strain also produced indole- 3-acetic acid, indole-3-acetaldehyde, indole-3-acetamide, indole-3-acetonitrile, indole-3-lactic acid, and indole-3- pyruvic acid in tryptophan-supplemented nutrient broth. Gluconic, citric and isocitric acids were the major organic acids detected during tricalcium phosphate solubilization. A rifampicin-resistant mutant of the strain exhibited high rhizosphere competence without disturbance to the resident microbial populations in pea rhizosphere. Seed bacterization with a charcoal-based inoculum significantly increased growth in barley, chickpea, pea, and maize under the controlled environment. Microplot testing of the inoculum at two different locations in pea also showed significant increase in growth and yield. The attributes of coldtolerance, high rhizosphere competence, and broad-spectrum plant growth-promoting activity exhibited the potential of Rahnella sp. BIHB 783 for increasing agriculture productivity.

[Characterization of soil microbial community function and structure in rhizosphere of typical tree species and the meaning for environmental indication in the Loess Plateau]

Determination of the soil microbial community structure in rhizosphere of typical tree species in the Loess Plateau can be of great theoretical significance for correctly assessing the characteristics of soil ecological rehabilitation of the Loess Plateau. In this study,spore density analysis, microbial cultivation and BIOLOG were employed to evaluate the AMF spore density and soil microbial community diversity under four tree species with vesicular-arbuscular mycorrhizae in ecological rehabilitation area of the Loess Plateau, north Shaanxi Province. The results show that the different tree species differed significantly in both soil microbial number and microbial functional diversity, AMF spore density of Hippophae rhamnoides soil is 2.24 times than that of the Robinia pseudoacacia soil,and the rank as following order: Hippophae rhamnoides > Sophora viciifolia > Caragana microphylla > Robinia pseudoacacia . The statistical significant are detected in the bacteria and actinomyces numbers, however, there is no statistical significance in fungi number among the treatments. The principle component analyses indicates that scatter of Caragana microphylla and Hippophae rhamnoides are smaller than that of Sophora viciifolia and Robinia pseudoacacia, these results suggest that the soil community structure strongly varied among the different tree species. Numbers of carbon sources related to the first two components are 14 and 8. Correlation analysis shows that the AMF spore density appeared extremely significantly and positively correlated with the number of bacteria,and the metabolic of amino acids,amines and aromatic compounds, respectively. Moreover,AMF spore density positively correlated with the average well color development (AWCD), nevertheless, no correlations are found among AMF spore density, carboxylic acids,carbohydrates and polymers. These results suggest that AMF spore density is shown to be an important environmental biology parameter used in correctly assessing the soil bacteria metabolic community and diversity under the tree species in ecological rehabilitation of the Loess Plateau, north Shaanxi Province.

[Effects of NaCl stress on Hippophae rhamnoides and Shepherdia argentea seedlings growth and photosynthetic characteristics]

With two-year old seedlings of Hippophea rhamnoides and Shepherdia argentea as test materials, this paper studied their growth and photosynthetic characteristics under the stress of different concentration (0, 200, 400 and 600 mmol x L(-1)) NaCl. The results showed that the biomass and total leaf area per plant of H. rhamnoides and S. argentea seedlings decreased significantly with increasing NaCl concentration. Comparing with the control, the root/shoot ratio of H. rhamnoides and S. argentea seedlings under NaCl stress increased obviously, while the leaf mass per area (LMA) decreased slightly. When the NaCl concentration increased and the stress time prolonged, the net photosynthetic rate (P(n)), transpiration rate (T(r)), and stomatal conductance (G(s)) of H. rhamnoides and S. argentea seedlings declined markedly, the intercellular CO2 concentration (C(i)) increased after an initial decrease, whereas the water use efficiency (WUE) and stomatal limiting value (L(s)) decreased after an initial increase. The dynamic changes of G(s), C(i) and L(s) indicated that the decline of P(n) was mainly caused by the stomatal limitation in a short-term stress, and by non-stomatal limitation in a long-term stress. The poorer the salt tolerance of tree species and the higher the NaCl concentration, the earlier the transition from stomatal limitation to non-stomatal limitation would occur. As for H. rhamnoides, its morphological symptoms of salt injury appeared on the 10th day, and all of its seedlings were died on the 22th day under 600 mmol NaCl x L(-1) stress. In contrast, S. argentea could tolerate 600 mmol NaCl x L(-1) stress for above 30 days, illustrating that S. argentea, as an introduced tree species, had higher salt tolerance than H. rhamnoides, and could be planted widely in saline regions of China.

Effect of different organic farming methods on the phenolic composition of sea buckthorn berries

The effects of different organic cultivation methods on the berry phenolics of two Finnish sea buckthorn (Hippophae rhamnoides L. ssp. rhamnoides ) cultivars, 'Terhi' and 'Tytti', were studied in an experimental field at a coastal area in Merikarvia, western Finland. Cultivation methods included different fertilizers (designed for organic cultivation), mulches (organic and plastic), and land contours (flat land versus ridged beds). Two experiments were conducted: The first, a fertilization experiment, allowed for the estimation of the effects of cultivar, fertilizer, land contour, and all of their interactions. The second experiment, a mulch experiment, allowed for the estimation of the effects of mulch, land contours, and their interactions for the cultivar 'Tytti'. Berry phenolics were analyzed by high-performance liquid chromatography (HPLC) with ultraviolet (UV) detection. The results suggest that there are significant differences between the cultivars and cultivation methods. The concentrations of quercetin derivatives 1-3, isorhamnetin 3,7-diglucoside, quercetin-3-glucoside-7-rhamnoside, quercetin 3-glucoside, isorhamnetin 3-glucoside, and flavonoid derivative 3 were higher in 'Tytti' than in 'Terhi', while concentrations of isorhamnetin-glucoside 2 and 3 were higher in 'Terhi' than in 'Tytti'. Flat land increased the concentrations of isorhamnetin 3,7-diglucoside, isorhamnetin-glucoside 1, quercetin derivatives 2 and 4, and condensed tannins. Mulch did not have any significant effect on the concentrations of phenolic compounds. These results indicate that the phenolic accumulation in berries of studied sea buckthorn cultivars seems to be mainly dependent upon cultivar selection and soil structure.

[Phytochemical analysis of Hippophae rhamnoides L. fruits from Russian varieties cultivated in Finland and food products containing them]

Results of phytochemical analysis of the berries from six Russian Hippophae rhamnnoides L. varieties (Augustinka, Botanitseskaja, Ljubitelskaja, Vorobjvskaja, Pertsik, Trofimovskaja), cultivated in Finland, are presented. The contents of ascorbic acid (vitamin C), tocopherols (vitamin E), total flavonoid (vitamin P), total carotenoid (vitamin A) and total organic acids were analyzed in unfreezed berries. The same parameters were defined in food products (jelly, sweet sauce and compote) containing fruits of three Hippophae rhamnoides L. varieties (Botanitseskaja, Ljubitelskaja and Trofimovskaja). According to the results, Russian Hippophae rhamnoides L. varieties can be cultivated in South-Finland and different kinds of food products with high quality and concentration of biologically active compounds may be prepared from these berries.

Influence of ambient and enhanced ultraviolet-B radiation on the plant growth and physiological properties in two contrasting populations of Hippophae rhamnoides

Two contrasting sea buckthorn (Hippophae rhamnoides L.) populations from low and high altitude regions were employed to investigate the effects of prevailing and enhanced ultraviolet-B (UV-B) radiation on plant growth and physiological properties under a UV-B-enhanced/exclusion system. The experimental design included three UV-B regimes, including excluded (-UVB), near-ambient (NA) and enhanced UV-B (+UVB) radiation. Compared with the control (-UVB), NA caused the formation of smaller but thicker plant leaves in both sea buckthorn populations, paralleled with significant increments of carotenoids and UV-absorbing compounds as well as improved water economy. NA also induced more biomass partition from shoot to root, but CO(2) assimilation rate (A), photosynthetic area and biomass accumulation were unaffected. The low-altitude population seemed sensitive to +UVB, as indicated by the decreases in total biomass, A and ascorbic acid content (Asa, an antioxidant) compared with NA. However, little +UVB effect occurred on the high-altitude population, and we suggest that the higher tolerance of this population could be associated with its specific morphological and physiological characteristics, such as small but thick leaves and high-level of Asa content, as well as its greater physiological modification in response to NA, e.g., increases in protective compounds (carotenoids and UV-absorbing compounds) and improvement in water economy, in comparison to the low-altitude population, which form an effective adaptation strategy to enhanced UV-B stress.

[Dynamic changes of soil microbial biomass in the restoration process of shrub plantations in loess hilly area]

By the method of spatiotemporal substitution and taking a slope farmland and a natural Platycladus orientailis L. forest as the controls, this paper studied the dynamic changes of soil microbial biomass, microbial respiration, metabolic quotient (qCO2) and physicochemical properties under the Caragana korshinkii and Hippophae rhamnoides plantations with different restoration age in loess hilly area. The results showed that with the increasing restoration age of the shrubs, soil physicochemical properties improved obviously, and soil microbial biomass had a significant increase. After 7 years restoration of C. korshinkii plantation, soil microbial biomass C increased apparently, compared with that in farmland, and the increments after each 5-7 years were all significant. Microbial biomass N and P had no significant increase in the first 13 years but kept relatively stable in the 20-30 years restoration of C. korshinkii plantation, and were significantly higher than those in farmland but lower than those under P. orientailis plantation after 30 years restoration of C. korshinkii plantation. Soil microbial respiration was enhanced with the increasing restoration age of the shrubs, with the peak in the 20-25 years restoration. After then, it decreased rapidly, and bottomed out in the 30 years restoration. qCO2 was significantly higher under P. orientailis plantation than in farmland in the early periods of shrubs restoration, and then decreased rapidly. After 30 years restoration of C. korshinkii plantation, qCO2 was lower than that in farmland but still much higher than that under P. orientailis plantation. Different shrub plantations had different effects on soil properties. H. rhamnoides with the same restoration age of C. korshinkii contributed more to the increase of soil microbial biomass and respiration. There were significant correlations between the restoration age of test shrub plantations and the microbial biomass, qCO2, and physicochemical properties of soil. It was considered that vegetation restoration could be a feasible way in improving the eco-environment and soil quality in loess hilly area, but a longer period should be required to reach to the climax before vegetation destruction. It is necessary to strengthen and improve forest management to interfere and accelerate plant succession for a sustainable and healthy ecosystem.

[Species diversity and interspecific association in development sequence of Hippophae rhamnoides plantations in Loess hilly region]

Based on field investigation, this paper analyzed the characteristics of species diversity and interspecific association at different development stages of Hippophcze rhamnoides plantations. The results showed that the species diversities of shrub layer, grass layer, and whole community of H. rharnnoides plantations were all fluctuated in "S" shape. At different development stages, the species richness and diversity were higher in grass layer than in shruh layer. The shrub species diversity was lower on hare land, but increased gradually with development stage. Shrub evenness index was higher in 13-year forest stand, while grass diversity index was higher in 3-year plantation, lower in 8-year plantation, and higher in 25-year plantation. The positive and negative absolute values of interspecific association between H. rharnnoides and other principal species changed in parabola shape, and the notable degree and the interspecific association intensity were weaker in 13-year plantation, showing that the species substitution rate was slower, competition was less, and community composition and its structure were relatively stable. To improve ecological environment, the H. rhamnoides plantations younger than 13 years old should he given priority to protection, while for those of 25 years old, moderate thinning should be made to promote the regeneration.

Effects of different organic farming methods on the concentration of phenolic compounds in sea buckthorn leaves

The effects of different cultivation methods on the amount of phenolic compounds in leaves of 1-year-old seedlings of two Finnish sea buckthorn (Hippophae rhamnoides L. ssp. rhamnoides) cultivars 'Terhi' and 'Tytti' were studied in a field experiment established at coastal area in Merikarvia, western Finland. The cultivation methods included different fertilizers (suitable for organic cultivation), mulches (organic and plastic), and land contours (flat vs low hill surface). Two experiments were conducted. The first allowed the estimation of the effects of cultivar, fertilizer, surface contour, and all their interactions, while the other allowed the estimation of the effects of mulches, land contours, and their interactions for the cultivar 'Tytti'. Eleven different hydrolyzable tannins, pentagalloylglucose, and 14 other phenolic compounds were detected by chemical analysis with high-performance liquid chromatography (HPLC). The amount of phenolic compounds varied between different land contours and mulches. The concentrations of gallic acid, pentagalloylglucose, quercetin-3-rhamnoside, monocoumaroyl astragalin A, total hydrolyzable tannins, and condensed tannins were significantly higher on the flat surface than on the low hill surface. The plastic mulch decreased the concentration of gallic acid, hydrolyzable tannins, and condensed tannins compared to the other mulches used. These results suggest ways to cultivate sea buckthorn to produce large amounts of valuable chemicals, especially tannins in the leaves.

[Accuracy analysis of vegetation mapping for Meili Snow Mountain area, northwest Yunnan, China]

The Meili Snow Mountain (28 degrees 20'-28 degrees 33'N, 98 degrees 30'-8 degrees 52'E) is a very famous mountain in Northwest Yunnan of China by its rich and well protected biodiversity and Tibetan cultural diversity. By applying 3S (RS-Remote Sensing, GIS-Geography Information System, GPS-Global Position System) technology, the 1:50000 vegetation map of Meili Snow Mountain area (total about 332 km2) was drawn out. The vegetation in this area was classified into 18 vegetation types except for stone, glacier and river system. The vegetation map was rectified by applying the GPS points got from the fields. The numbers of GPS points were calculated by the formula of numbers of samples in statistics. 313 GPS points were used to rectify the vegetation map. The numbers were fit for the formula of numbers of samples in Statistics. The accuracy and verify of vegetation types distribution in the map was analyzed by building a Probability Error Matrix (PEM) and through the variance analysis. The results indicated that the overall accuracy (OA) of the vegetation map was 84.7%. The accuracy of vegetation map finished by 3S technology was lied on the area of the region and the grade of vegetation class first, but the grade of vegetation class classified by remote sensing technology disaccord with the traditional vegetation class system. The other factos deciding the accuracy of vegetation were the distinguish ability of Remote Sensing image, the accuracy of distinguish, and the numbers of the samples, including vegetation class experts knowledge.

[Relationships between water and productivity of seabuckthorn (Hippophae) in different habitats of the Loess Plateau, China]

This paper deals with the relationships between water and productivity of seabuckthorn in different habitats of the Loess Plateau in north Shaanxi. The typical habitats were classified with hilltop, sunny, shady, semi-shady and semi-sunny hillside. The results showed that values of transpiration of five kinds of habitats were different, and transpiration of semi-shady was relatively stronger in the morning while others were weaker. With the variation of directions of sunshine, transpiration of shady and sunny was declining and meanwhile transpiration of hill-top was steady. transpiration of semi-shady reached the peak in 12:00. In the afternoon, these values of transpiration all reduced in different extents except seabuckthorn of shady, especially semi-shady. The mean transpiration of 5 habitats was ordered in semi-shade > shade > semi-sunny > hilltop > sunny. There were remarkable difference between diffuse resistance and transpiration, and same relationship was found between relative humidity and transpiration. But this relationship was not found between light intensity and transpiration. Different habitats had different productivities, and productivity of seabuckthorn in shade habitat was higher than those in other habitats.