基于ITS及GPD序列分析对贵州紫花菌的分类鉴定

明确贵州省紫花菌分类地位,对其人工驯化、加工及活性物质开发利用提供理论支撑。在贵州4个具有代表性的紫花菌产地附近的农贸市场,收集紫花菌样本进行组织分离,利用形态学结合分子系统学的方法进行鉴定。通过分离纯化获得20株菌株,根据子实体形态特征,在贵州市场收集的紫花菌主要分为两类,一类形态特征与鲜艳乳菇(Lactarius vividus)一致,另一类形态特征与红汁乳菇(L. hatsudake)一致。基于ITS和GPD基因序列的遗传距离和系统发育分析,显示分离获得的15株菌株与鲜艳乳菇(L. vividus)的遗传距离为0,在系统发育树上以较高的自举支持率与鲜艳乳菇(L. vividus)聚为一支,将15株菌株鉴定为鲜艳乳菇(L. vividus);5株菌株与红汁乳菇(L. hatsudake)的遗传距离为0,在系统发育树上与红汁乳菇(L. hatsudake)聚为一支,自举支持率为100%,将5株菌株鉴定为红汁乳菇(L. hatsudake)。笔者在贵州市场上收集到的紫花菌中没有鉴定出松乳菇(L. deliciosus),可能与近年松乳菇采集过度或因环境改变导致其发生量减少有关,也有可能是松乳菇与鲜艳乳菇、红汁乳菇形态较为接近,不易区分导致错误鉴定有关。

Effect of Different Kinds of Growth-promoting Rhizobacteria on Physiological and Biochemical Characteristics of Medicago sative Linn. Seedlings under the Stress of Na_2CO_3

[Objective] The study aimed to explore the influences of Plant growth-promoting rhizobacteria（PGPR）on salt tolerance and physiological effect of seedlings of Medicago sative L.[Method] Three different kinds of growth-promoting rhizobacteria solutions were used to spray on M.sative seedlings and the influences of different kinds of growth-promoting rhizobacteria on physiological and biochemical characteristics of M.sative seedlings under 75 mmol/L of Na2CO3 were studied.[Results] Compared with the control group,the chlorophyll,free proline,soluble sugar and soluble protein content of M.sative seedlings treated with different kinds of growth-promoting rhizobacteria were increased,while the effect of CS3 treatment was the best.[Conclusion] The growth-promoting rhizobacteria could promote growth and development of M.sative as well as increased its resistance.

Phosphorus Solubilizing Capability,IAA Secretion and Characteristics of Phosphorus-solubilizing Bacteria in Rhizosphere of Alfalfa in Guizhou Province

[Objective] The study aimed to isolate and screen efficient phosphorus-sol- ubilizing strains from the root soil of alfalfa in Guizhou, and investigate its growth promoting mechanism. [Method] Phosphorus solubilizing bacteria were isolated from rhizosphere of alfalfa with inorganic and organic phosphorous medium and the strains with higher capacity of dissolving phosphorus were screened through dissolv- ing phosphate zone and further researched. Meanwhile the phosphorus solubilizing capability of strains cultured in liquid medium was investigated by molybdenum blue colorimetric method. [Result] The capacity of dissolving calcium phosphate of 11 se- lected strains differed significantly and tended to be volatile from 150.40 to 268.20 μg/ml; phosphate solubilization capacity, IAA secretion and the pH of culture media did not show any significant correlation; all strains could produce IAA, and the se- cretion was from 12.09 to 22.16 μg/ml; the selected strains all could produce alka- line matter, and most of colonies were pale or milky white, irregular, opaque, jagged, flat and non-pigmented; utilization of carbon sources by different strains varied signifi- cantly. [Conclusion] The study laid the foundation for relieving phosphorus in unpro- ductive land, saving phosphate resources, reducing environmental pollution and pro- viding fertilizer in alfalfa production.

Screening of Highly Effective Sinorhizobium meliloti Strains for 'Vector' Alfalfa and Testing of Its Competitive Nodulation Ability in the Field

Seventeen Sinorhizobium meliloti strains from seven provinces in China were used to screen highly effective strains for alfalfa cultivar in a greenhouse study and their symbiotic relationship and competitive ability were studied in the field. CCBAU30138 was the most effective strain, as evidenced by increase in dry weights. A field experiment showed that the inoculation of alfalfa with CCBAU30138 resulted in increases of 11.9% and 19.6% of dry matter production and crude protein production, respectively, in forage of monocultured plants. The total dry matter yields of alfalfa and tall fescue in binary culture were increased by 16.3% by inoculation of alfalfa with this strain. These results showed that S. rneliloti strain CCBAU30138 was an effective inoculant both in the greenhouse and in the field. The analysis of randomly amplified polymorphic DNA （RAPD） by polymerase chain reaction （PCR） from nodule extracts showed that the strain CCBAU30138 had high competitiveness in the field. It occupied 47.5% of nodules in alfalfa monoculture and 44.4% of nodules in alfalfa-tall fescue binary culture after 20 weeks of growth. In conclusion, a simple system to select highly effective and competitive symbiotic strains specific to alfalfa was established. Using this system, a s.train suitable for the alfalfa cultivar ‘Vector＇ grown in Wuqiao County of Hebei Province was obtained.

Sinorhizobium meliloti nifA mutant induces different gene expression profile from wild type in Alfalfa nodules

Several studies have demonstrated that the Rhizobium nifA gene is an activator of nitrogen fixation acting in nodule bacteria. To understand the effects of the Sinorhizobium meliloti nifA gene on Alfalfa, the cDNA-AFLP technique was employed to study the changes in gene expression in nifA mutant nodules. Among the approximately 3,000 transcriptderived fragments, 37 had differential expression levels. These expression levels were subsequently confirmed by reverse Northern blot and RT-polymerase chain reaction. Sequence analyses revealed that 21 cDNA fragments corresponded to genes involved in signal communication, protein degradation, nutrient metabolism, cell growth and development.

Isolation, characterization and antioxidant activities of the endophytic fungi from Hosta. Ventricosa

A total of 13 types of endophytic fungi,classified into six genera,were isolated from Hosta.ventricosa based on 18 S rDNA sequencing of ITS region and microscopic examination.The antioxidant activities of the crude extracts were investigated by T-AOC,DPPH and ABTS＋ methods.The results showed that the crude extracts from Fusarium oxysporum（HoV1） and Epicoccum（HoV4）,which presented higher phenol levels（1.90±0.03 mg/g,and 2.41±0.01 mg/g,respectively）,exhibited stronger comprehensive antioxidant activities,with higher T-AOC values（63.46±0.26 U/g,and 66.05±0.71 U/g,respectively）,lower EC_（50） values against ABTS~＋（30.25±0.05 μg/m L,and 24.66±0.65 μg/m L,respectively） and DPPH radicals（83.42±0.24 μg/m L,and 59.136 μg/m L,respectively）.Moreover,Fusarium oxysporum（Ho V8） showed excellent scavenging activity against DPPH radicals（EC_（50） = 16.02 μg/m L）,which was better than BHT.All of them could be useful in the developing of new natural antioxidant agents.