Host range differentiation of spore-positive and spore-negative strain types of Frankia in stands of Alnus glutinosa and Alnus incana in Finland

Host compatibility of different spore-positive (Sp⁺)and spore-negative (Sp^?) strain types of Frankia from alder stands in Finland was studied in Modulation tests with hydrocultures of Alnus glutinosa (L.) Gaertner, A. incana (L.) Moench and A. nitida Endl. Root nodules and soil samples from stands of A. incana (Lammi forest and Hämeenlinna forest) were dominated by Sp ⁺ types of Frankia (coded AiSp⁺ and AiSp⁺ H. respectively), which caused effective root nodules in test plants of A. incana, but failed to induce nodules in A. nitida. In A. glutinosa Frankia strain types AiSp ⁺ and AiSp ⁺ H caused small, ineffective root nodules with sporangia (coded Ineff ^?), which were recognized by the absence or near absence of vesicles in the nodule tissue. Ineffective nodules without sporangia (coded Ineff ^?) were induced on A. glutinosa with soil samples collected at Lammi swamp. The spore-negative strain type of Frankia was common in root nodules of A. glutinosa in Finland (Lammi swamp) and caused effective Sp^? type root nodules (coded AgSp ^?) in hydrocultures of A. incana, A. glutinosa and A. nitida. A different Sp ⁺ strain type of Frankia. coded AgSp⁺ Finland, was occasionally found in stands of A. glutinosa. It was clearly distinguished from strain type AiSp ⁺ by the ability to produce effective nodules on both A. glutinosa and A. incana. The nodulation capacities of soil and nodule samples were calculated from the nodulation response in hydrocutlure and served as a measure for the population density of infective Frankia particles. Sp ⁺ nodules from both strain types had equal and high nodulation capacities with compatible host species. The nodulation capacities of Sp type root nodules from A. glutinosa were consistently low. High frequencies of Frankia AiSp⁺ and AiSp⁺ H were found in the soil environment of dominant AiSp ⁺ nodule populations on A. incana. The numbers of infective particles of this strain type were insignificant in the soil environment of nearby Sp ^? nodule populations on A. glutinosa and in the former field at Hämeen-linna near the Sp⁺ nodule area in Hämeenlinna forest. Strain type AgSp^? had low undulation capacity in the soil environment of both A. incana and A. glutinosa stands, Explanations for the strong associations between Frankia strain types AiSp⁺ and AiSp ^? H and A. incana and between strain type AgSp^? and A. glutinosa are discussed in the light of host specificity and of some characteristics of population dynamics of both strain types. The possible need to adapt the concept of Frankia strain types Sp ⁺ and Sp ^? to strains with some variation in spore development was stressed by the low potentials of strain type AiSp ⁺ H to develop spores in symbioses with hydrocultures of A. incnna.     

Non-reciprocal cross-incompatibility in Trichogramma deion

In non-reciprocal cross-incompatibility (NRCI), the crossing of a female of a strain A with a male of a strain B results in hybrid offspring, whereas the reciprocal cross produces few or no hybrids. Only females are of hybrid origin in Hymenoptera because they arise from fertilized eggs; males arise from unfertilized (haploid) eggs. Crosses between many strains of Trichogramma deion showed some degree of NRCI. Crosses between a T. deion culture collected in Seven Pines, California (SVP) with one from Marysville, California (MRY) showed an extreme form of NRCI in which practically no female offspring was produced when MRY females were crossed with SVP males. The reciprocal cross produced a close to normal proportion of female and male offspring. Detailed studied of this cross indicated that 1) the female offspring produced in the compatible interstrain cross were not the result of parthenogenesis but were true hybrids, 2) the incompatible interstrain cross did not produce female offspring because fertilized eggs died during development, 3) the death of these eggs could not be prevented by either antibiotic or temperature treatment, 4) cytoplasmically inherited factors causing NRCI could be discounted because backcrossed females with the genome of MRY and the cytoplasm of SVP, exhibit the NRCI relationship characteristic of their genome. Therefore the NRCI between these strains appears to be caused by a modification coded for by the nuclear genes of MRY that results in incompatibility when SVP sperm fertilizes MRY eggs. In addition the level of incompatibility in crosses between the SVP females and MRY males is temperature sensitive, the higher the rearing temperature the lower the level of compatibility.     

Two new loci for hybrid sterility in cultivated rice (Oryza sativa L.)

Female gamete abortion in Indica-Japonica crosses of rice was earlier identified to be due to an allelic interaction at the S-5 locus on chromosome 6. Recently, in other crosses of rice, similar allelic interactions were found at loci designated as S-7 and S-8, located on chromosomes 7 and 6 respectively. All of them are independent of each other. At the S-5 locus, Indica and Japonica rice have S-5 ⁱ and S-5 ^j alleles respectively and Javanicas, such as Ketan Nangka, have a neutral allele S-5 ⁿ .The S-5 ⁱ /S-5 ^j genotype is semi-sterile due to partial abortion of female gametes carrying S-5 ^j , but both the S-5 ⁿ /S-5 ⁱ and S-5 ⁿ /S-5 ^j genotypes are fertile. The S-5 ⁿ allele is thus a wide-compatibility gene (WCG), and parents homozygous for this allele are called wide-compatible varieties (WCV). Such parents when crossed with Indica or Japonica varieties do not show F₁ hybrid sterility. Wide-compatible parents have been used to overcome sterility barriers in crosses between Indica and Japonica rice. However, a Javanica variety, Ketan Nangka (WCV), showed typical hybrid sterility when crossed to the Indian varieties N22 and Jaya. Further, Dular, another WCV from India, showed typical hybrid sterility when crossed to an IRRI line, IR2061-628-1-6-4-3(IR2061-628). By genetic analyses using isozyme markers, a new locus causing hybrid sterility in crosses between Ketan Nangka and the Indicas was located near isozyme loci Est-1 and Mal-1 on chromosome 4, and was designated as S-9. Another new locus for hybrid sterility in the crosses between Dular and the IR2061-628 was identified and was found linked to four isozyme loci, Sdh-1, Pox-2, Acp-1 and Acp-2, on chromosome 12. It was designated as S-15. On the basis of allelic interactions causing female-gamete abortion, two alleles were found at S-9, S-9 ^kn in Ketan Nangka and S-9 ⁱ in N22 and Jaya. In the heterozygote, S-9 ^kn /S-9 ⁱ , which was semisterile, female gametes carrying S-9 ^kn were aborted. The hybrid of Dular and IR2061-628, with a genetic constitution of S-15 ^Du /S-15 ⁱ , was semi-sterile and the female gametes carrying S-15 ^Du were aborted. A Japonica tester variety, Akihikari, and an Indica variety, IR36, were found to have neutral alleles, S-9 nand S-15 n, at these loci, in addition to S-7 nand at S-7. The accumulation of three neutral alleles into a breeding line should help solve the hybrid sterility problem in wide crosses of rice.     

Quantitative assessment of pair formation behavior in captive whooping cranes (Grus americana)

Instantaneous scan sampling for mean distance and synchronous action patterns and all-occurrence sampling for unison call, dance, strut, and hoover-up behaviors were conducted for five potential whooping crane pairs at Patuxent Environmental Science Center, Laurel, Maryland. Dance, strut, and hoover-up differed among pairs, as did total frequency of social behaviors. It was unclear whether or not total frequency of social behaviors during pair formation can be used as an index for potential breeding success. The relative importance of different action patterns should be used as indices of pair compatibility in captive whooping cranes. © 1995 Wiley-Liss, Inc.     

Number of alleles at the incompatibility loci in Secale cereale L.

Summary Two experiments were performed to estimate the number of alleles at the two incompatibility loci of rye in the variety Halo. In one experiment I₁ progenies from enforced selfing under controlled conditions were isolated. In the other experiment a genotype, homozygous at both incompatibility loci, was used as pollinator for a sample of the Halo population, which was regarded as an equilibrium population. Genotypes, which are homozygous at both incompatibility loci, can be found after selfing. The estimate for the number of alleles was 6 to 7 at one locus and 12 to 13 at the other locus.     

炭疽菌不利用硝酸盐突变体的筛选及鉴定

将从杉木和大叶黄杨上分离获得的８个胶孢炭疽菌（Colletoctrichum gloeosporioides）分离物培养在含氯酸钾的平板上,得到快速生长抗氯酸钾的不利用硝酸盐的突变体(Nit)。所有的突变体经鉴定分属于３种表现型,即硝酸还原酶结构位点（nit１）,硝酸盐同化途径的专化调节位点（nit３）,和钼辅因位点（nitM）。分离物发生突变的频率随氯酸钾浓度的增加而提高,并且不同的氮源在一定程度上会影响突变表型种类。除ＣＣ３外,所有的分离物都是自身亲和的,即不同表型的突变体能遗传互补,其     

5份粳型亲籼种质的生物学特性及育种利用

本研究以5份自主选育的粳型亲籼种质明恢413、明恢1616、明恢1707、明恢512和明恢509为研究材料,通过对其生物学特性和育种利用进行研究和评价,以期为今后开展粳型亲籼种质资源的选育和籼粳亚种间杂种优势的利用提供理论参考。生物学特性研究结果表明:5份粳型亲籼种质的播始历期偏长,株高适中,直立穗型,穗子小,着粒密,单株有效穗数多,结实率均在75%以上,千粒重中等。程式指数判定表明,明恢413、明恢1616、明恢1707、明恢512的籼粳属性为偏粳;明恢509的籼粳属性为粳。5份粳型亲籼种质均具有良好的亲籼性,与籼型两系不育系测交F1的结实率均在75%以上,最高可达89.80%;同时能够恢复野败型、印水型、K型等籼型三系不育系,测交F1的结实率均在80%以上,其恢复谱广、恢复力强。光合特性分析表明,其剑叶在生育后期能够保持较高的光合速率,利于籽粒的充实饱满。5份粳型亲籼种质的杂种优势表现:除播始历期、株高和千粒重外,在穗长、单株有效穗数、每穗总粒数、结实率、一次枝梗数和二次枝梗数等性状上均表现出明显的竞争优势。其中,穗长、一次枝梗数、二次枝梗数和每穗总粒数所表现出的竞争优势均超过10...     

香港巨牡蛎与长牡蛎种间配子兼容性

为了评估香港巨牡蛎与长牡蛎的配子兼容性,于2010年7月,以性腺成熟的香港巨牡蛎和长牡蛎为材料,研究了环境因子温度(16、20、24、28、32℃)、盐度(10、15、20、25、30)及内在因子精子浓度(100、101、102、103、104个/μL)、个体差异(240次杂交实验)对其受精率的影响,并计算了以上条件下的F50临界值。结果表明:香港巨牡蛎卵子可以与长牡蛎精子受精,但相反方向不能受精,存在着单向受精现象。温度是影响长牡蛎配子兼容性主要因子,盐度是影响香港巨牡蛎的主要因子,而温度、盐度交互作用是影响种间配子兼容性的最主要因子。种间配子温度、盐度的F50临界值分别为20.90℃、14.7。精子浓度及单对杂交中的个体差异均显著影响配子兼容性,精子浓度的F50临界值为2.40个/μL;在240次杂交实验中,有91次受精率不足50%,说明个体差异比例的F50临界值37.92%。从其内在因子来看,长牡蛎平均受精率最高(96.83%),配子兼容性较好;对于香港巨牡蛎(70.98%)与种间配子(58.70%)而言,受精水平相对较低,且存在着较大的个体差异。     

Characterization of six microsatellite markers in Trillium camschatcense using a dual‐suppression‐polymerase chain reaction technique

Trillium camschatcense is a herbaceous perennial plant distributed in Hokkaido and northern Honshu, Japan. Geographical variations in the breeding system (partial selfing or obligate outcrossing) are reported in the populations of Hokkaido. We isolated six polymorphic microsatellite loci from this species. The number of allele per locus ranged from four to 12, whereas the expected heterozygosities ranged from 0.69 to 0.83. These markers may allow further investigations to reveal the evolutionary and ecological processes of mating system in T. camschatcense.