卷荚相思根瘤菌的生物学特性

为探讨卷荚相思根瘤菌的生物学特性,从广西高峰林场卷荚相思林分采集分离到12株根瘤菌,对这些菌株进行了生理生化试验,并利用这些菌株对厚荚相思苗木进行接种结瘤试验。结果表明:(1)依据生长代时和单个菌落形成测定结果,分离获得的12个菌株可以分为9个快生菌株和3个慢生菌株。(2)大部分的供试根瘤菌菌株可以利用无机氮源作为其生长所需的氮源,但对供试用的糖源利用存在着较大的差别。(3)所有供试菌株在3一酮基乳糖反应、牛肉膏蛋白胨、淀粉水解试验中呈阴性,所有供试的12个菌株均能进行利用柠檬酸盐,在BTB试验中均产酸,在石蕊牛奶反应均产碱。(4)12个卷荚相思根瘤菌菌株接种到厚荚相思苗木后,均能使其根部结瘤,并进一步筛选出结瘤效果和固N效果比较好的供试菌株是快生型菌株(J003、J004、J005、J008)和慢生型菌株(J012)。这为从华南的酸性土壤中寻找和利用土著根瘤菌资源提供了科学依据。     

大豆基因工程根瘤菌田间结瘤和共生固氮效应

利用三亲本接合转移方法,将快生型大豆根病菌B_(52)的基因文库克隆转移到受体菌慢生型大豆根瘤菌2210中,获得4株大豆基因工程根瘤菌(32.43、B—2—6、B—3—8)。田间接种试验表明:在大豆分枝期(V2),43和32结瘤效分别比不接种对照增加117.9％和100.4％;在初花期(R_1),32和B—2—6结瘤数分别比对照增加122.5％和91.6％,根瘤固氮酶活性增加233.3％和195.6％;在结荚始期(R3),B—2—6和32结瘤数比对照增加78.5％和70.1％,根瘤固氟酶活性43和B—2—6分别比对照增加53.4％和49.3％。产量统计表明:32、B—2—6和43比对照分别增产16.8％、14.3％和12.2％,亩增收大豆分别为28.2、24.1和20.6公斤。以上三个菌株均比受体菌株2210增产率高。     

接种根瘤菌对刺槐生长的影响

以刺槐根瘤菌接种于刺槐小苗的研究表明,接种刺槐的株高、地径、根瘤、生物量分别比对照平均增加１３．８、１４．７、３２．８、２４．８％,植株含Ｎ量比对照增加２０－４０％。液体根瘤菌剂及其与ＶＡ菌根孢子土双种接效果明显,其生物量分别增加约２０和４０％。     

根瘤菌菌株的结瘤拮抗性:一种定量研究

当二个或二个以上根瘤菌菌株在形成根瘤发生拮抗时,每一个菌株形成的根瘤数量依赖于菌株的拮抗性和每一菌株活菌的相对数量。为了预告一个接种菌株的成功结瘤,必须知道接种剂与土壤中的根瘤菌的比例以及接种菌株形成的根瘤比例关     

山西锦鸡儿根瘤菌资源分布与生态学研究

研究了山西锦鸡儿根瘤菌资源分布、菌种形态特征、理化特性及其生态学适应性与生态效应。结果表明,山西锦鸡儿根瘤菌资源分布广、结瘤率高,根瘤大,固氮周期长,耐盐碱,用高效抗逆菌株接种,明显促进植株的生长发育,可增加干重28．9％—79．5％。     

接种S.fredii WGF03及突变体对大豆土壤微生物群落结构的影响

为了研究接种S.fredii WGF03及其exo D基因突变体对大豆结瘤及土壤的微生物群落影响,进一步了解exo D基因的功能,在大豆盛花期摘取每株大豆的根瘤并计数,利用PCR-DGGE电泳结合测序技术分析土壤的微生物群落。结果表明,大豆接种S.fredii WGF03后,根瘤数比不接种组增加191.67%。而大豆接种驻exo D突变体的根瘤数最少,比不接种组减少了16.67%。与空白相比,种植大豆后土壤细菌的种类和数量明显增加;接种不同根瘤菌后,细菌种类及细菌多样性也有变化;测序结果显示,土壤中细菌以Proteobacteria为主,占45.5%,土壤中土著根瘤菌为Bradyrhizobium。总之,S.fredii WGF03能够促进大豆结瘤,种植作物比接种根瘤菌对土壤细菌群落的影响更大。     

应用BOX分子标记技术筛选南苜蓿高效根瘤菌菌株

【目的】应用BOX-PCR技术对12株南苜蓿(Medicago polymorpha)接种根瘤菌菌株在土壤中的竞争结瘤能力进行研究,以占瘤率的高低配合植物生长性状最终确定与南苜蓿共生的高效根瘤菌菌株。【方法】对接种根瘤菌产生的南苜蓿根瘤进行分离培养,选择部分结瘤菌株和12株全部供试接种菌株进行BOX分子指纹图谱研究,经过对图谱的比较与分析获得了各接种菌株的占瘤率。【结果】在供试菌株中,来自于云南盈江的菌株SWF67523占瘤率最高,为93.33%,说明菌株SWF67523具有较强的竞争结瘤能力,该菌株对南苜蓿干重增幅也较高,为100%;菌株SWF67409来自于云南楚雄,其占瘤率略低于菌株SWF67523,但其对提高植物干重的贡献最大(增幅106.5%);来自于云南楚雄的菌株SWF67394占瘤率较低,但其结瘤率高,对植物生长的影响作用也较明显。【结论】将根瘤菌菌株的竞争结瘤能力纳入南苜蓿高效根瘤菌菌株的筛选中,研究获得了一株竞争结瘤能力强、显著提高植物生物量的菌株SWF67523,以及促生根瘤菌菌株SWF67409和SWF67394,为生产高效根瘤菌菌剂提供了物质基础。     

优良大豆根瘤菌田间增产效果初报

我所将中国农科院土肥所生物固氮组从佳木斯地区土壤中根瘤分离的快。慢型大豆根瘤菌,从中筛选出的优良菌株２１７８、２１８７及其丸衣、２２３５、混合菌等接种于当地主载大豆品种合丰２５号、３１号、３３号上,表现出较高的田间共生效应,能促进生育、增加根瘤数和固氮量,产量两年比对照增产幅度在９．２—２５．４％,比６１Ａ７６增产４．６—１９．５％。     

用AFLP技术检测慢生型花生根瘤茵竞争结瘤的研究

以5株慢生型花生根瘤菌和天府3号花生为材料,用AFLP技术研究了慢生型花生根瘤菌Spr2—9、Spr3—3、Spr3—5、Spr4—5和Spr7—1的遗传特性和竞争结瘤能力。结果显示,供试条件下,传代次数对菌株的遗传性状无明显影响,28C培养条件下,花生根瘤菌连续传96代,其AFLP指纹未发生明显变化;37C培养,仅Spr3—3和Spr3—5能够存活并正常生长,其AFLP指纹也未发生明显改变,然而其它菌株不能生长。将供试慢生型花生根瘤菌分别接种天府3号花生。光照培养30d后,随机各取4个根瘤,从根瘤中提取类菌体DNA进行AFLP分析,各根瘤类菌体DNA的AFLP指纹图谱与该菌株纯培养物AFLP指纹相同。将5个菌株混合接种天府3号花生,不同菌株的占瘤率存在差异,Spr3—3和Spr3—5的竞争结瘤能力最强,两菌株的占瘤率之和为85．4％;Spr4—5的占瘤率为12．2％;Spr7—1为2．4％;而Spr2—9的竞争结瘤能力最差。本试验结果说明,AFLP技术用于根瘤菌生态和竞争结瘤能力研究,具有下列优点：简易、快速、准确;直接取豆科植物的根瘤提取DNA,进行原位研究;在不改变菌株遗传特性,即不使用突变株的前提下,可以直接测定已知菌株的竞争结瘤能力。     

豆科树种回接根瘤菌的研究

 作者对八种豆科树种的根瘤菌回接进行了研究,不回接根瘤菌的对照植株不结瘤或有少且小的根瘤,而接菌植株的根瘤数量多且个体大;接菌植株的株高、干重及总氮量分别比不接菌的对照植株高出0.7～3.2、1.3～15.8和11.3～14.8倍。根瘤固定的氮量占幼苗生长所需氮的一半以上,固定的氮绝大部分运输到植株其它部位,分配到地上部分的氮素多于根部。固氮量与幼苗生物量显著相关。固氮作用增加了植物对磷、钾元素的吸收和积累。速生树种南洋楹(Albizia falcata)和非速生树种格木(Erythrophloeum fordii)幼苗的结瘤、固氮及生长状况较好,表现出较高的结瘤固氮潜能。     

Isolation of 15 polymorphic microsatellite loci in Acacia hybrid (Acacia mangium×Acacia auriculiformis)

This study reports the isolation of 15 microsatellites in Acacia hybrid (Acacia mangium×Acacia auriculiformis) based on the 5′ anchored polymerase chain reaction technique. Polymorphism of these loci was evaluated in a sample of 24 hybrid individuals. The level of polymorphism ranged from two to eight alleles with an observed heterozygosity ranging from 0.083 to 0.875. These loci were also characterized in both the parental species. The number of alleles ranged from two to six for both A. mangium and A. auriculiformis with the observed heterozygosity values ranging from 0.167 to 0.625 and 0.042 to 0.458 respectively. Five of these loci demonstrated Mendelian inheritance in a segregating F₁ population; four presented a distorted ratio and the remaining six did not segregate in progenies as they were homozygous in both parents.     

Cyanogenesis in Acacia sutherlandii

Two cyano-glucosides have been isolated from leaves of Acacia sutherlandii. One is the previously described cyanogenic glucoside proacacipetalin and the other is the novel, non-cyanogenic, glycoside 1-cyano-2-β-D-glucopyranosyloxymethyl-(Z)-prop-1-en-3-ol which has been given the trivial name sutherlandin.     

Cyanogenesis in Acacia farnesiana

Linamarin and lotaustralin are the major cyanogens of Acacia farnesiana; a third unidentified cyanogen is also present. The amount of cyanide produced by plants within one population of the taxon varies from below the level of detection with picrate paper to approximately 5 μmol per g (1.4%) dried plant material.     

Acacia Farnesiana W.

Ohne Zusammenfassung     

Natural and induced polyploidy in Acacia dealbata Link. and Acacia mangium Willd

Seeds were obtained from seven natural populations of Acacia dealbata, three natural populations of A. mangium and a seed orchard of A. mangium, representing the natural range of the two species. Polyploids were discovered in two of the seven populations of A. dealbata. The 2C DNA amount for diploid A. dealbata (2n = 2x = 26) was 1.74 pg, and for diploid A. mangium (2n = 2x = 26) was 1.30 pg. A naturally occurring tetraploid of A. dealbata (2n = 4x = 52) had a 2C DNA amount of 3.41 pg and a naturally occurring triploid genotype had a 2C DNA amount of 2.53 pg. The use of colchicine and oryzalin was investigated as a means of producing higher frequencies of tetraploids of both A. mangium and A. dealbata for incorporation into breeding programmes. Colchicine treatment gave tetraploid frequencies up to 29% for A. dealbata seedlings, and up to 18% for A. mangium seedlings. In contrast, no tetraploid A. mangium was detected following oryzalin treatment, and the low frequencies of tetraploids observed in A. dealbata could be attributed to their natural occurrence.     

Nitrogen fixation in Faidherbia albida,Acacia raddiana,Acacia senegal and Acacia seyal estimated using the 15N isotope dilution technique

A pot experiment was conducted in a greenhouse using the ¹⁵N isotope dilution method and two reference plants, Parkia biglobosa and Tamarindus indica to estimate nitrogen fixed in four Acacia species: A raddiana, A. senegal, A. seyal and Faidherbia albida (synonym Acacia albida). For the reference plants, the ¹⁵N enrichments in leaves, stems and roots were similar. With the fixing plants, leaves and stems had similar ¹⁵N enrichments; they were higher than the ¹⁵N enrichment of roots. The amounts of nitrogen fixed at 5 months after planting were similar using either reference plant. Estimates of the percentage of N derived from fixation (%Ndfa) for the above ground parts, in contrast to %Ndfa in roots, were similar to those for the whole plant. However, none of the individual plant parts estimated accurately total N fixed in the whole plant, and excluding the roots resulted in at least 30% underestimation of the amounts of N fixed. Between species, differences in N₂ fixation were observed, both for %Ndfa and total N fixed. For %Ndfa, the best were A. seyal (average, 63%) and A. raddiana (average, 62%), being at least twice the %Ndfa in A. senegal and F. albida. Because of its very high N content, A. seyal was clearly the best in total N fixed, fixing 1.62 g N plant^–1 compared to an average of 0.48 g N plant^–1 for the other Acacia species. Our results show the wide variability existing between Acacia species in terms of both %Ndfa and total N fixed: A. seyal was classified as having a high N₂ fixing potential (NFP) while the other Acacia species had a low NFP.