Molecular mapping of a new gene Rrs4 CI 11549 for resistance to barley scald (Rhynchosporium secalis)

Doubled haploid (DH) progeny from a cross between the scald susceptible barley (Hordeum vulgare L.) cultivar Ingrid and the resistant accession CI 11549 (Nigrinudum) was evaluated for resistance in the pathogen Rhynchosporium secalis (Oudem) J.J. Davis. Two linked and incompletely dominant loci confer resistance CI 11549 against isolate 4004. One is an allele at the complex Rrs1 locus on chromosome 3H close to the centromere; the other is located 22 cM distally on the long arm. The latter locus is designated Rrs4. In BC₃-lines into Ingrid from CI 2222 (another Nigrinudum) resistance seems governed by one locus close to the telomeric region of chromosome 7H, probably allelic to Rrs2. In neither case did we find any trace of the recessive gene rh8 reported to be present in Nigrinudum. Various resistance donors of Ethiopian origin designated as Nigrinudum, Jet or Abyssinian were identical to a great extent with respect to markers, but differed in resistance to different isolates of scald or in barley yellow dwarf virus (BYDV) resistance. The implications for their use as differentials in scald tests and screening of germplasm collections are discussed.     

On morphological variation in Keratella cochlearis populations from Holstein lakes (Northern Germany)

Keratella cochlearis occurs in many Holstein lakes (northern Germany) as three well defined and separated forms: cochlearis, hispida, and tecta, each showing very little variation between the lakes. The present data show that the tecta form did not originate from a Lauterborn cycle.     

The assignment of a Thinopyrum distichum (Thunb.) Löve-derived translocation to the long arm of wheat chromosome 7D using endopeptidase polymorphisms

Summary Endopeptidase zymograms of the translocation line Indis revealed the presence of several major and minor bands that had differential expression in coleoptile and seed tissues. While Indis lacks Ep-D1a, which is present in the parental cultivar Inia 66, it also may not express any of the Th. distichum bands. The Indis zymogram was found to be identical to that of an isogenic line of Inia 66 possessing Lr19. Since the absence of an Ep-D1a product appears to be linked to the 7DL translocation, it is possible to use the null condition as a marker for both the Lr19 or Indis translocations. The Indis translocation also did not show recombination with the cn-D1 chlorophyl mutant on 7DL, confirming that a part of 7D was involved. The results of a telocentric mapping experiment involving the 7D telosomes indicated that in Indis a chromosome segment from Th. distichum replaced a large section of 7DL of Inia 66.     

First copulation increases longevity and fecundity of <Emphasis Type="Italic">Histiostoma feroniarum</Emphasis> (Acari: Astigmata: Acaridida) females

I investigated the influence of insemination at different life stages on female fitness in the mite Histiostoma feroniarum. In this species, males guard immature females at the tritonymph stage to inseminate them immediately after the last moulting. Four groups of females were studied (1) females inseminated naturally, i.e. mating occurred immediately after guarding, and then the male was removed (IF/0M), (2) naturally inseminated females, where after insemination the male was replaced by two additional males (IF/2M), (3) virgin females reared without males (VF/0M) and (4) mature, virgin females to which two virgin males were added 3 days after last moulting (VF/2DM). The results show that females inseminated naturally (IF/0M) have higher longevity and fecundity than either virgin (VF/0M) or late-inseminated females (VF/2DM). Furthermore, longevity and fecundity of the former (IF/0M) was also greater than that of females naturally inseminated and subsequently exposed to males (IF/2M). One may suggest that seminal fluids have a positive effect on female fitness. When delayed insemination occurs, such positive effect may not be observed due to a change in features of the sperm access system. Harassment may explain decreased longevity and fecundity of females inseminated naturally compared to females that received additional males.This revised version was published online in May 2005 with a corrected cover date.     

Evaluation of an exotic maize population adapted to a locality

Summary An exotic Zea mays L. population (Tuxpeno) was adapted to North Carolina conditions by first introducing genes for adaptability from two North Carolina varieties ([(Jarvis X Indian Chief)Tuxpeno]Tuxpeno) including four generations of intermating, and then selecting for adaptability using maturity as the primary measure. The study evaluated selection for adaptability and the diversity available between adapted Tuxpeno and the local varieties, Jarvis and Indian Chief. Analytical procedures were developed to quantify the diversity between populations and the complementation of local varieties by introduced germ plasms. The analyses utilized the specific effects available from the diallel mating design.Three replicate selections responded similarly under simple recurrent mass selection (1/10) for the earliest disease-free plants initially and additionally for plant types (primarily height) in the final generation. The 1/4 local germ plasm permitted rapid adaptation of Tuxpeno gene pool to local conditions. The adapted Tuxpeno populations yielded similarly to the local populations with an average heterosis for grain yield of 28% when crossed to the local populations used as source of genes for adaptability. The diversity found between adapted Tuxpeno lines and these local varieties based on genes affecting grain yield was 1.5 to 2.5 times that measured between the local varieties (Jarvis and Indian Chief). Diversity lost through intergradation with local material was a reasonable investment. Yield genes introduced from Tuxpeno complemented local gene pools through nonadditive, primarily dominance-associated, gene effects. Reassortment of major gene blocks apparently occurred leading to significant divergence among replicate selections involving both additive-associated and dominance-associated gene effects.Paper No. 6355 of the North Carolina Agri. Res. Ser., Raleigh, NC. Research supported in collaboration with the Rockefeller Foundation and CIMMYT, D.F. (Mexico)     

Genetic diversity in relation to heterosis and combining ability in spring wheat

Summary Genetic diversity among ten varieties of spring wheat used as parents in a diallel cross was assessed through multivariate analysis (D²-statistics) and then related to heterosis and SCA effects of their hybrids. The parents fell into three groups. Group I contained the varieties, Nobre, Girua and Carazinho; group II contained Sonalika, Lyallpur and Pitic 62 and group III contained Indus 66, Balaka, Sonora 64rs and MSl. The varieties of group I were good general combiners, while the varieties of group III were poor combiners. Significant heterotic and SCA effects for yield and yield components were observed in the hybrids of the parents belonging to different groups but not in the same group. Genetic divergence between the parents had a positive relationship with heterosis and SCA effects of the hybrids.     

High-level Expression of Maize <Emphasis Type="Italic">γ</Emphasis>-zein Protein in Transgenic Soybean (<Emphasis Type="Italic">Glycine max</Emphasis>)

Primers were developed for 118 microsatellites isolated from grape (Vitis vinifera) genomic libraries enriched for (AC)n repeats. Only one microsatellite sequence matched other grape SSR-sequences in the GeneBank database. Genotyping was carried out in the parental lines and four offspring of two pseudo-test-cross populations, Cabernet Sauvignon x Seyval and Chardonnay x Bianca, and a further six other grape genotypes (V. vinifera Sultanina, Merlot, Syrah, Müller-Thurgau, Vitis Regent and V. riparia Gloire de Montpellier). A total of 108 microsatellites showed easily scorable alleles and 100 of them segregated according to a configuration suitable for mapping in either cross. A further 8 SSRs, although unsuitable for mapping in those crosses, showed polymorphism in the other genotypes tested. This set of markers was used, along with 75 microsatellites of other repeat-types, to fingerprint 46 offspring of the cross Chardonnay x Bianca. For each full-sib, individual heterozygosity and distance in repeat units between pairs of alleles at each locus (mean d²) were calculated as a tool for predicting highly outbred recombinant individuals. Six microsatellites with segregation ratios significantly distorted towards the lack of homozygous sibs were identified and mapped to linkage groups LG 3 and LG 5. Estimation of heterozygosity at genome-wide level and genotyping at loci for which homozygous sibs are discriminated against are discussed for marker-assisted background selection in outcrossing grapevines.     

Endogenous abscisic acid and 2-trans-abscisic acid in alternate bearing ‘Wilking’ mandarin trees

The relationship of abscisic acid (ABA) and 2-trans-abscisic acid (t-ABA) to alternate bearing has been examined in Wilking mandarin (Citrus reticulata Blanco) trees. Leaves, stems and buds of trees loaded with fruit (on trees) had 4.3, 6.0 and 2.2 fold higher ABA levels than the corresponding organs from off trees. Leaves had higher ABA levels than stems and buds in both on and off trees. t-ABA was non-detectable in Wilking leaf, stem and bud tissue. Amounts of t-ABA not exceeding 40% of the ABA content, were found in Shamouti and Valencia orange buds and in Wilking fruit peel.The elevated levels of ABA in on tree organs may reflect a stress imposed by the fruit overload.     

Clinical writing and the documentary construction of schizophrenia

Psychiatric practice involves writing as much as it involves talking. This study examines the interpretive processes of reading, writing and interviewing which are central to the clinical interaction. It is part of a broader ethnographic study of an Australian psychiatric hospital (which specializes in the treatment of patients with a diagnosis of schizophrenia). The paper examines two major types of written assessment of patients — the admission assessment and the complete work-up. Writing is analyzed as performance, thereby focusing on the transformations that are effected in patients, their perceptions of their schizophrenia, and their total identity. One crucial transformation is from person suffering from schizophrenia to schizophrenic. The paper aims to show that as much as psychiatry is a talking cure it is also a writing cure.     

Identification of a 4A/7R and a 7B/4R wheat-rye chromosome translocation

Summary By producing chromosome substitutions with Imperial rye chromosomes 4R (C) and 7R (D) in the wheat cultivar Chinese Spring two spontaneous translocation lines were obtained. One involves segments of wheat chromosome 4A and rye chromosome 7R, the other involves portions of wheat chromosome 7B and rye chromosome 4R     

Nucellar callus of ‘Femminello’ lemon,selected for tolerance toPhoma tracheiphila toxin,shows enhanced release of chitinase and glucanase into the culture medium

Phoma tracheiphila is the causative agent of the disease mal secco. Citrus cultivars differ substantially in respect to their sensitivity to the pathogenP. tracheiphila and its toxin. Some cultivars (e.g., Femminello lemon) are inherently sensitive while others (e.g., Tarocco orange) are tolerant. Cell lines derived from nucellar tissue of Femminello, Tarocco and a cell line selected for tolerance to the fungal toxin (Femminello-S) were used to study host-pathogen interaction. Our results showed that calli or conditioned media of Tarocco and Femminello-S inhibited the size of co-cultivated fungal colonies when compared to Femminello. In addition, conditioned medium of Tarocco as well as FemminelloS, but not Femminello, promoted bursting of hyphal tips. A ten-fold increase in chitinase and glucanase enzymatic activity, as evaluated by radiometric assay and laminarin hydrolysis respectively, was detected in Femminello-S extracellular extracts as compared to Femminello. An increase in chitinase was also shown by immunoblot analysis. Our findings suggest a positive correlation between the presence of chitinase and glucanase in the conditioned media of the cultured cells and the tolerance of those cells toP. tracheiphila toxin.     

The impact of domestication on the genetic variability in the orange carrot,cultivated Daucus carota ssp. sativus and the genetic homogeneity of various cultivars

Summary Isozyme analysis of wild and domesticated accessions indicated that domestication of the cultivated carrot Daucus carota ssp. sativus resulted in an insignificant reduction of all genetic variability and genetic distance estimates. Although they are less variable genetically, cultivated forms maintain a high proportion of observed heterozygosity. Relative to the overall genetic variability of the species, samples from four common cultivars Red Cored Chantenay, Scarlet Nantes, Danvers Half Long and A Plus demonstrated a high degree of genetic similarity. This is attributed to the recent development of orange cultivars and the limited gene pool utilized in their development.     

DNA markers tightly linked to a gall midge resistance gene (Gm2) are potentially useful for marker-aided selection in rice breeding

We have developed a polymerase chain reaction (PCR)-based assay that could effectively reduce the time period required to screen and select for Gall Midgeresistant rice lines under field conditions. The primers for the assay were designed on the basis of sequence information of two phenotype specific random amplified polymorphic DNA fragments which were found to be tightly linked to Gall Midge biotype-1 resistance gene (Gm2). The two RAPD fragments, F8₁₇₀₀ in the susceptible parent ARC6650 and F10₆₀₀ in the resistant parent Phalguna, were identified after screening 5450 loci using 520 random primers on genomic DNAs of ARC6650 and Phalguna. These primers, when used in a multiplexed PCR, amplified specifically a 1.7-kb and 0.6-kb fragment in the susceptible and resistant parents, respectively. When this assay was performed on genomic DNAs of 44 recombinant inbred lines derived from ARC6650 x Phalguna and 5 lines derived from other crosses where one of the parents was Phalguna, ARC6650 or their derivatives, the primers amplified a 1.7-kb fragment in all of the susceptible lines or a 0.6-kb fragment in all of the resistant ones. These markers can be of potential use in the marker-aided selection of Gall Midge biotype-1 resistant phenotypes. As screening for resistance can now be conducted independent of the availability of insects, the breeding of resistant varieties can be hastened.     

Growth vigour of some Egyptian cotton variety seedlings in relation to selected rhizospheric microflora antagonistic toRhizoctonia solani Kuhn

Summary Growth responses of Ashmouni and Karnak cotton variety seedlings toRhizoctonia solani, the damping-off fungus, or toBacillus subtilis (two different strains),Aspergillus terreus andAspergillus flavus isolated from the rhizosphere of cotton, and all antagonistic to the pathogen, were expressed in terms of growth-vigour criteria.The presence ofR. solani in the soil inhibited the growth vigour of both cotton variety seedlings. However, Karnak seedlings were more sensitive to the pathogen than Ashmouni seedlings. One of the strains ofB. subtilis andA. terreus generally increased the vigour of both cotton variety seedlings.A. flavus lowered most of the growth criteria of Karnak or Ashmouni cotton seedlings.

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Zusammenfassung Rhizoctonia solani, der Parasiet von Baumwolle-Keimlingen, wurde isoliert.Sowohl Bacillus subtilis als auchAspergillus terreus und Aspergillus flavus wurden von der Rhizosphere der Baumwolle-Pflanzen isoliert. Diese Organismen wurden als antagonistisch gegenRhizoctonia solani erkannt. Die Wirkung dieser Organismen auf das Wachstum von Keimlingen der Baumwolle sorten Ashmouni und Karnak wurde untersucht. R. solani hemmt das Wachstum der Keimlinge beider Baumwolle-Sorten. Es wurde festgestellt, dass Karnak empfindlicher ist als Ashmouni. Einer der Stämme vonB. subtilis undA. terreus erwiesen sich als Wachstum förderend bei beiden Baumwolle-Sorten.A. flavus dagegen vermindert das Wachstum von Karnak und Ashmouni.

     

Indirect effect of salmon carcasses on growth of a freshwater amphipod, <Emphasis Type="Italic">Jesogammarus jesoensis</Emphasis> (Gammaridea): An experimental study

The effect of salmon carcasses on the growth of a freshwater amphipod, Jesogammarus jesoensis (Schellenberg) (Gammaridea, Anisogammaridae), was examined experimentally. Growth rate was determined by rearing juvenile amphipods in four food treatments (leaves, salmon, leaves and salmon and leaves with salmon leachate) for 20days. Mass loss and oxygen consumption of the leaves were also measured in the three treatments with leaves. The oxygen consumption rate of leaves was lower in the leaves treatment than in either the leaves and salmon or leaves with salmon leachate treatments, indicating that microbial activity on leaves was enhanced by the presence of salmon carcasses. Mass loss of leaves did not differ between the three treatments with leaves. The growth rate of the amphipods did not differ between the leaves and salmon treatments, or between the leaves and salmon and leaves with salmon leachate treatments. Growth rates in the two latter treatments were higher than rates in the leaves treatment, but not higher than the rates in the salmon treatment. Therefore, it appears likely that consuming leaves fertilized with nutrients from salmon carcasses facilitates growth in this amphipod.     

Inheritance and linkage of isozyme loci in almond

The segregation of seven isozyme marker genes was investigated using eight controlled crosses in almond. The cultivar Nonpareil was the maternal parent in all crosses. Pollination was achieved using eight different cultivars, and a total of 3200 individual kernels were assessed. For each isozyme the goodness-of-fit test was used to test for departure from the expected frequencies assuming Mendelian inheritance. Given a higher than expected number of significant results for individual isozymes, independent segregation between pairs of isozymes was tested using the chi-square statistic on the resulting two-way contingency tables. In all crosses a highly significant association (P value< 0.001) was observed between (1) the AAT- 1 and IDH isozymes loci and (2) the LAP-1 and PGM-2 isozymes loci, which leads to the conclusion that the respective isozyme pairs are linked.In addition, a significant association (P value < 0.001) was observed between LAP-1 and GPI-2 when the pollen sources were Fritz, Mission, or Price, but this could not be tested for the remaining five pollen sources, Carmel, Grant, Keane, Ne plus Ultra, Peerless, because they are homozygous at these loci. If LAP-1 is linked with GPI-2 and PGM-2, it might be expected that we should find evidence of linkage between GPI-2 and PGM-2. The lack of a significant association between these two isozymes suggests that LAP-1 is located centrally on the chromosome. These three pairs of linked loci are the first to be reported in almond.     

Preliminary studies on the genetic variability of six Hungarian common carp strains using microsatellite DNA markers

Genetic variation in six Hungarian common carp (Cyprinus carpio L.) strains was evaluated using 12 microsatellite loci. The domesticated (Tatai, Biharugrai and Szarvasi) strains were derived from fish farms. Two of wild strains (Tiszai and Dunai) were sampled from brood stocks maintained at fish farms for breeding, and Kis-Balatoni wild carp were sampled from the Small Balaton Lake. Pairwise Fst-values (0.013–0.161) were highly significant (p<0.0001), demonstrating differentiation among strains. The mean number of alleles ranged between 3.9 and 8.2. Overall mean observed heterozygosity was lower (0.557) than the mean expected heterozygosity (0.700). By strain, the only exception to this trend was the Dunai (Danubian), which showed higher mean observed heterozygosity (0.764) than expected (0.602). For five loci the Dunai strain showed extremely high levels of heterozygosity (1.00). Two wild strains exhibited a number of loci (Tiszai, 4; Dunai, 6) that were not in Hardy–Weinberg equilibrium. A relatively high number of private alleles overall (n=26), as well as differences in allele frequencies supported our ability to assign most individual fish (over 90%) to each strain.     

Genetic linkage maps of two apple cultivars (<Emphasis Type="Italic">Malus</Emphasis> × <Emphasis Type="Italic">domestica</Emphasis> Borkh.) based on AFLP and microsatellite markers

Genetic linkage maps for two apple cultivars were constructed using AFLP and SSR markers and the pseudo-testcross mapping strategy. The F₁-mapping population was produced by crossing the cultivar Braeburn to the cultivar Telamon and consisted of 257 individuals. Out of the 182 AFLP primer combinations screened, a total of 48 were selected. Using these, 463 AFLP markers segregating 1:1 in the progeny were identified, of which 231 were heterozygous in Telamon and 232 in Braeburn. Eighty-five AFLP markers present in both cultivars (3:1 segregation) were scored in the whole mapping population. Twenty-one SSR primer pairs were tested, which clearly screened 23 loci (some multi-locus markers). This resulted in the identification of 3 loci heterozygous only in Telamon (1:2:1), 5 loci heterozygous only in Braeburn (1:2:1) and 15 loci which were heterozygous in both cultivars (1:1:1:1). Two linkage maps were produced. The Telamon map comprised 259 markers (242 AFLPs and 17 SSRs) divided into 17 linkage groups. The total map length was 1039 cM with a marker density of 4.0 cM. At = 0.05, 8.9% of the mapped loci showed distorted segregation. The Braeburn map consisted of 264 markers (245 AFLPs and 19 SSRs) mapped on 17 linkage groups and spanning 1245 cM. The average distance between two markers was 4.7 cM and segregation distortion was observed for 18.6% of the mapped markers ( = 0.05). Fourty-six markers common to both maps (32 AFLPs and 14 SSRs) allowed the identification of 16 homologous linkage groups. The seventeenth pair of homologous linkage groups from Telamon and Braeburn was identified by 2 SSR markers which were in common to the genetic linkage maps of Fiesta and Discovery, two other apple cultivars.     

Partitioning the parameters of stony soils,important in moisture determinations into their constituents

Partitioning the parameters of stony soils in order to express their water content on a volumetric basis, into their pure stone and pure soil constituents, is an important step towards understanding the behavior of such nonhomogeneous systems.The equations derived are exact mathematical identities. Their applications are discussed.Contribution from Agricultural Research Organization, Volcani Center, Bet Dagan, Israel. Serial No. 226-E.     

Comparative study on the chloroplast,mitochondrial and nuclear genome differentiation in two cultivated rice species,Oryza sativa and O. glaberrima,by RFLP analyses

Summary Restriction fragment length polymorphisms of chloroplast (ct), mitochondrial (mt) and nuclear DNA were investigated using eight cultivars of Oryza sativa and two cultivars of O. glaberrima. Relative variability in the nuclear and cytoplasmic genomes was estimated by a common measure, genetic distance. Based on the average genetic distances among ten cultivars for each genome, the evolutionary variabilities of the mitochondrial and nuclear genomes were found to be almost the same, whereas the variability of the chloroplast genome was less than half that of the other two genomes. Cluster analyses on ct and mt DNA variations revealed that chloroplast and mitochondrial genomes were conservative within a taxon and that their differentiations were well-paralleled with respect to each other. For nuclear DNA variation, an array of different degrees of differentiation was observed in O. sativa, in contrast with little variation in O. glaberrima. As a whole, differentiation between O. sativa and O. glaberrima was clearly observed in all three genomes. In O. sativa, no notable difference was found between the cultivars Japonica and Javanica, whereas a large differentiation was noticed between Japonica (including Javanica) and Indica. In all three genomes, the average genetic distances within Indica were much larger than those within Japonica (including Javanica), and almost similar between Japonica (including Javanica) and Indica. These facts indicate that differentiation in O. sativa was due mainly to Indica.