The fungal endophyte Epichloë gansuensis increases NaCl-tolerance in Achnatherum inebrians through enhancing the activity of plasma membrane H+-ATPase and glucose-6-phosphate dehydrogenase.

Salt stress negatively affects plant growth, and the fungal endophyte Epichloëgansuensis increases the tolerance of its host grass species, Achnatherum inebrians, to abiotic stresses. In this work, we first evaluated the effects of E. gansuensis on glucose-6-phosphate dehydrogenase (G6PDH) and plasma membrane (PM) H+-ATPase activity of Achnatherum inebrians plants under varying NaCl concentrations. Our results showed that the presence of E. gansuensis increased G6PDH, PM H+-ATPase, superoxide dismutase and catalase activity to decrease O2•-, H2O2 and Na+ contents in A. inebrians under NaCl stress, resulting in enhanced salt tolerance. In addition, the PM NADPH oxidase activity and NADPH/NADP+ ratios were all lower in A. inebrians with E. ganusensis plants than A. inebrians plants without this endophyte under NaCl stress. In conclusion, E. gansuensis has a positive role in improving host grass yield under NaCl stress by enhancing the activity of G6PDH and PM H+-ATPase to decrease ROS content. This provides a new way for the selection of stress-resistant and high-quality forage varieties by the use of systemic fungal endophytes.

Comprehensive analysis of correlations among codon usage bias, gene expression, and substitution rate in Arachis duranensis and Arachis ipaënsis orthologs.

The relationship between evolutionary rates and gene expression in model plant orthologs is well documented. However, little is known about the relationships between gene expression and evolutionary trends in Arachis orthologs. We identified 7,435 one-to-one orthologs, including 925 single-copy and 6,510 multiple-copy sequences in Arachis duranensis and Arachis ipaënsis. Codon usage was stronger for shorter polypeptides, which were encoded by codons with higher GC contents. Highly expressed coding sequences had higher codon usage bias, GC content, and expression breadth. Additionally, expression breadth was positively correlated with polypeptide length, but there was no correlation between gene expression and polypeptide length. Inferred selective pressure was also negatively correlated with both gene expression and expression breadth in all one-to-one orthologs, while positively but non-significantly correlated with gene expression in sequences with signatures of positive selection. Gene expression levels and expression breadth were significantly higher for single-copy genes than for multiple-copy genes. Similarly, the gene expression and expression breadth in sequences with signatures of purifying selection were higher than those of sequences with positive selective signatures. These results indicated that gene expression differed between single-copy and multiple-copy genes as well as sequences with signatures of positive and purifying selection.

Dahurelmusin A, a Hybrid Peptide-Polyketide from Elymus dahuricus Infected by the Epichloë bromicola Endophyte.

One novel hybrid peptide-polyketide, dahurelmusin A (1), was isolated from Elymus dahuricus infected by the Epichloë bromicola endophyte. Comprehensive spectroscopic analysis revealed that 1 is the first example of hybrid peptide-polyketide possessing an unprecedented 5-hydroxy-2,2,4,6-tetramethyl-3-oxooctanoic acid moiety. The single-crystal X-ray diffraction analyses allowed the absolute configuration assignment of this compound. Compound 1 also exhibited significant insecticidal activities against Rhopalosiphum padi and Brevicoryne brassicae with LC50 values of 0.092 and 0.251 mM, respectively.

Highly oxygenated triterpenoids from the roots of Schisandra chinensis and their anti-inflammatory activities.

A new highly oxygenated triterpenoid, schinchinenlactone D (1), and three known compounds (2-4) were isolated from the roots of Schisandra chinensis. Their structures were determined by combining the spectroscopic analysis with the theoretical computations. The anti-inflammatory activities of compounds 1-4 were evaluated, and compound 3 exhibits the most significant activity in the inhibition of NO production with an IC50 value of 10.6 µM.

Global transcriptome sequencing using the Illumina platform and the development of EST-SSR markers in autotetraploid alfalfa.

BACKGROUND: Alfalfa is the most widely cultivated forage legume and one of the most economically valuable crops in the world. The large size and complexity of the alfalfa genome has delayed the development of genomic resources for alfalfa research. Second-generation Illumina transcriptome sequencing is an efficient method for generating a global transcriptome sequence dataset for gene discovery and molecular marker development in alfalfa. METHODOLOGY/PRINCIPAL FINDINGS: More than 28 million sequencing reads (5.64 Gb of clean nucleotides) were generated by Illumina paired-end sequencing from 15 different alfalfa tissue samples. In total, 40,433 unigenes with an average length of 803 bp were obtained by de novo assembly. Based on a sequence similarity search of known proteins, a total of 36,684 (90.73%) unigenes were annotated. In addition, 1,649 potential EST-SSRs were identified as potential molecular markers from unigenes with lengths exceeding 1 kb. A total of 100 pairs of PCR primers were randomly selected to validate the assembly quality and develop EST-SSR markers from genomic DNA. Of these primer pairs, 82 were able to amplify sequences in initial screening tests, and 27 primer pairs successfully amplified DNA fragments and detected significant amounts of polymorphism among 10 alfalfa accessions. CONCLUSIONS/SIGNIFICANCE: The present study provided global sequence data for autotetraploid alfalfa and demonstrates the Illumina platform is a fast and effective approach to EST-SSR markers development in alfalfa. The use of these transcriptome datasets will serve as a valuable public information platform to accelerate studies of the alfalfa genome.

Effects of cadmium stress on seed germination and seedling growth of Elymus dahuricus infected with the Neotyphodium endophyte.

Various cadmium (Cd) concentrations (0, 50, 100, 200 and 300 µmol L(-1)) affected Elymus dahuricus seed germination, seedling growth, antioxidative enzymes activities (AEA), and amounts of malondialdehyde (MDA) and proline present. These influences were determined for separate E. dahuricus cohorts known to be either infected (E+) or non-infected (E-) by a Neotyphodium endophyte. Under high Cd concentrations (100, 200 and 300 µmol L(-1)), E+ specimens showed a significantly (P<0.05) higher germination rate and index, as well as higher values for shoot length, root length and dry biomass. However, the germination rate and index, root length and dry weight did not show a significant (P<0.05) difference under the low Cd concentrations (0 and 50 µmol L(-1)). AEA and proline content increased, as did MDA content, in the E+ (vs. E-) specimens under high Cd concentrations. There was no significant (P>0.05) difference under low Cd concentrations. Endophyte infection was concluded to be of benefit to E. dahuricus exposed to high Cd concentrations.

Effects of cadmium stress on growth and anti-oxidative systems in Achnatherum inebrians symbiotic with Neotyphodium gansuense.

The effects of cadmium on biomass production and growth parameters of drunken horse grass (Achnatherum inebrians) over an 8-week period were determined in a controlled-environment experiment. Changes were determined for relative water content, anti-oxidative enzymes (i.e., catalase (CAT), superoxide dismutase (SOD), peroxidase (POD), and ascorbate peroxidase (APX)) and for H(2)O(2) content, as well as levels of proline, malondialdehyde (MDA), and chlorophylls "a" and "b" present within leaves infected with Neotyphodium gansuense vs. non-infected controls. Observations began 4 weeks after addition of CdCl(2) (0, 50, 100 and 200 microM) to the nutrient solution. Under high concentrations (100 and 200 microM) of CdCl(2), endophyte-infected plants produced more biomass and had higher values for plant height and tiller number compared to non-infected controls, but there was no significant difference (P>0.05) under 0 and 50 microM CdCl(2). Anti-oxidative enzyme activities, H(2)O(2) concentration, and chlorophylls "a" and "b" levels increased, but proline and malondialdehyde content declined in the infected plants vs. non-infected plants under high (100 and 200 microM) concentrations of CdCl(2). There was no significant difference (P>0.05) under 0 and 50 microM CdCl(2). Endophyte infection was concluded to be of benefit to the growth and anti-oxidative mechanisms within A. inebrians under high concentrations exposures to CdCl(2).

[Effect of pesticides on field-controlling root rot of Vicia faba].

The effect of pesticides on field-controlling root rot of Vicia faba was studied in two consecutive years by seed treatment of fungicides and their combination. The results of the first year field experiments showed that among the 11 treatments tested, triadimefon of 0.01 g a.i.kg-1 seeds was more effective than other fungicides applied singly or in combinations. The other test fungicides included thiophanate-methyl, thiram, oxadixyl and metalaxyl. Compared to the control, triadimefon treatment reduced the root rot index of 6-week-old seedlings by 51.5%, and plant accumulated percent mortality by 36%. Consequently, the treatment increased seed yield/plant by 21% and seed yield/ha by 97.6%. In the trials carried out in the following year, the plant percent mortality was reduced by 31.9% and seed yield increased by 19.6% under triadimefon seed treatment. It is demonstrated that seed treatment by triadimefon effectively controlled root rot, promoted plant growth, and increased seed yield of faba bean in the fields.