Chromosomal location of a race-specific resistance gene to <Emphasis Type="Italic">Mycosphaerella graminicola</Emphasis> in the spring wheat ST6

Septoria tritici blotch, caused by Mycosphaerella graminicola, is a serious foliar disease of wheat worldwide. Qualitative, race-specific resistance sources have been identified and utilized for resistant cultivar development. However, septoria tritici blotch resistant varieties have succumbed to changes in virulence of M. graminicola on at least three continents. The use of resistance gene pyramids may slow or prevent the breakdown of resistance. A clear understanding of the genetics of resistance and the identification of linked PCR-based markers will facilitate the recovery of wheat lines carrying multiple septoria tritici blotch resistance genes. The resistance gene in ST6 to isolate MG2 of M. graminicola was mapped with microsatellite markers in two populations, ST6/Erik and ST6/Katepwa. Bulk segregant analysis identified a marker on chromosome 4AL putatively linked to the resistance gene. A large linkage group was identified in each population using additional microsatellite markers mapping to chromosome 4AL. The resistance gene in ST6 mapped to the distal end of chromosome 4AL in each mapping population and was designated Stb7. Three of the microsatellite loci, Xwmc313, Xwmc219 and Xgwm160, mapped within 3.5 cM of Stb7; however, none flanked Stb7. Xwmc313 was the closest and mapped 0.3 and 0.5 cM from Stb7 in the crosses ST6/Katepwa and ST6/Erik, respectively. WMC313 will be very useful for marker-assisted selection of Stb7 in Canadian breeding programs because the ST6 allele of Xwmc313 was not identified in any of the Canadian common wheat cultivars tested.Communicated by P. Langridge     

Evolution of <Emphasis Type="Italic">mal</Emphasis> ABC transporter operons in the <Emphasis Type="Italic">Thermococcales</Emphasis> and <Emphasis Type="Italic">Thermotogales</Emphasis>

Background  

The mal genes that encode maltose transporters have undergone extensive lateral transfer among ancestors of the archaea Thermococcus litoralis and Pyrococcus furiosus. Bacterial hyperthermophiles of the order Thermotogales live among these archaea and so may have shared in these transfers. The genome sequence of Thermotoga maritima bears evidence of extensive acquisition of archaeal genes, so its ancestors clearly had the capacity to do so. We examined deep phylogenetic relationships among the mal genes of these hyperthermophiles and their close relatives to look for evidence of shared ancestry.     

Inheritance and localisation of resistance to <Emphasis Type="Italic">Mycosphaerella graminicola</Emphasis> causing septoria tritici blotch and plant height in the wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) genome with DNA markers

Resistance to the disease septoria tritici blotch of wheat (Triticum aestivum L.), caused by the fungus Mycosphaerella graminicola (Fuckel.) J. Schrot in Cohn (anamorph Septoria tritici Roberge in Desmaz.) was investigated in a doubled-haploid (DH) population of a cross between the susceptible winter wheat cultivar Savannah and the resistant cultivar Senat. A molecular linkage map of the population was constructed including 76 SSR loci and 244 AFLP loci. Parents and DH progeny were tested for resistance to single isolates of M. graminicola in a growth chamber at the seedling stage, and to an isolate mixture at the adult plant stage, in field trials. A gene located at or near the Stb6 locus mapping to chromosome 3A provided seedling resistance to IPO323. Two complementary genes, mapping to chromosome 3A, one of which was the IPO323 resistance gene, were needed for resistance to the Danish isolate Ris?97-86. In addition, a number of minor loci influenced the expression of resistance in the growth chamber. In the field, four QTLs for resistance to septoria tritici blotch were detected. Two QTLs, located on chromosomes 3A and 6B explained 18.2 and 67.9% of the phenotypic variance in the mean over two trials. Both these QTLs were also detected at the seedling stage with isolate Ris?97-86, whereas isolate IPO323 only detected the QTL on 3A. Additionally, two QTLs identified in adult plants on chromosomes 2B and 7B were not detected at the seedling stage. Four QTLs were detected for plant height located on chromosomes 2B, 3A, 3B and on a linkage group not assigned to a chromosome. The major QTLs on 3A and on the unassigned linkage group were consistent over two trials, and the QTL on 3A seemed to be linked to a QTL for septoria tritici blotch resistance.     

Revision of the <Emphasis Type="Italic">Serrulati</Emphasis> species of <Emphasis Type="Italic">Penstemon</Emphasis> section <Emphasis Type="Italic">Saccanthera</Emphasis> subsection <Emphasis Type="Italic">Serrulati</Emphasis>

A revision of Penstemon sect. Saccanthera subsect. Serrulati includes a new species (P. salmonensis), a new variety (P. triphyllus var. infernalis), and the elevation of a subspecies to species (P. curtiflorus), bringing the total number of species to eight, which are keyed and described, complete with nomenclature and type citations.     

Biological characterization of two <Emphasis Type="Italic">Bacillus thuringiensis</Emphasis> strains toxic against <Emphasis Type="Italic">Spodoptera frugiperda</Emphasis>

Two Bacillus thuringiensis strains isolated from diseased Spodoptera frugiperda larvae collected in the northwest of Argentina were molecularly and phenotypically characterized. Insecticidal activity against Spodoptera frugiperda larvae was also determined. Both strains were highly toxic against first instar larvae. One strain (Bacillus thuringiensis LSM) was found to be even more toxic than the reference strain Bacillus thuringiensis var. kurstaki 4D1. This strong biological effect was represented by both a higher mortality which reached 90%, and a shorter LT₅₀. Molecular characterization showed that Bacillus thuringiensis LSM carried a cry gene profile identical to that of Bacillus thuringiensis var. kurstaki 4D1. Evaluation of length polymorphism of the intergenic transcribed spacers between the 16S and 23S rDNA genes revealed an identical pattern between native strains and Bacillus thuringiensis var. kurstaki 4D1. In contrast, phenotypic characterization allowed differentiation among the isolates by means of their extracellular esterase profiles. Lytic activity that would contribute to Bacillus thuringiensis effectiveness was also studied in both strains. Analyses like those presented in the current study are essential to identify the most toxic strains and to allow the exploitation of local biodiversity for its application in biological control programmes.     

<Emphasis Type="Italic">Ty</Emphasis>1<Emphasis Type="Italic">/copia</Emphasis>- and <Emphasis Type="Italic">Ty</Emphasis>3<Emphasis Type="Italic">/gypsy</Emphasis>-like DNA sequences in <Emphasis Type="Italic">Helianthus </Emphasis>species

Two repeated DNA sequences isolated from a partial genomic DNA library of Helianthus annuus, p HaS13 and p HaS211, were shown to represent portions of the int gene of a Ty3 /gypsy retroelement and of the RNase-Hgene of a Ty1 /copia retroelement, respectively. Southern blotting patterns obtained by hybridizing the two probes to BglII- or DraI-digested genomic DNA from different Helianthus species showed p HaS13 and p HaS211 were parts of dispersed repeats at least 8 and 7 kb in length, respectively, that were conserved in all species studied. Comparable hybridization patterns were obtained in all species with p HaS13. By contrast, the patterns obtained by hybridizing p HaS211 clearly differentiated annual species from perennials. The frequencies of p HaS13- and p HaS211-related sequences in different species were 4.3x10(4)-1.3x10(5) copies and 9.9x10(2)-8.1x10(3) copies per picogram of DNA, respectively. The frequency of p HaS13-related sequences varied widely within annual species, while no significant difference was observed among perennial species. Conversely, the frequency variation of p HaS211-related sequences was as large within annual species as within perennials. Sequences of both families were found to be dispersed along the length of all chromosomes in all species studied. However, Ty3 /gypsy-like sequences were localized preferentially at the centromeric regions, whereas Ty1/ copia-like sequences were less represented or absent around the centromeres and plentiful at the chromosome ends. These findings suggest that the two sequence families played a role in Helianthusgenome evolution and species divergence, evolved independently in the same genomic backgrounds and in annual or perennial species, and acquired different possible functions in the host genomes.     

<Emphasis Type="Italic">Agrobacterium</Emphasis><Emphasis Type="Italic">tumefaciens</Emphasis>-mediated transformation of callus cells of <Emphasis Type="Italic">Crataegus</Emphasis><Emphasis Type="Italic">aronia</Emphasis>

A genetic transformation system has been developed for callus cells of Crataegus aronia using Agrobacterium tumefaciens. Callus culture was established from internodal stem segments incubated on Murashige and Skoog (MS) medium supplemented with 5 mg l⁻¹ Indole-3-butyric acid (IBA) and 0.5 mg l⁻¹ 6-benzyladenine (BA). In order to optimize the callus culture system with respect to callus growth and coloration, different types and concentrations of plant growth regulators were tested. Results indicated that the best average fresh weight of red colored callus was obtained on MS medium supplemented with 2 mg l⁻¹ 2,4-dichlorophenoxyacetic acid (2,4-D) and 1.5 mg l⁻¹ kinetin (Kin) (callus maintenance medium). Callus cells were co-cultivated with Agrobacterium harboring the binary plasmid pCAMBIA1302 carrying the mgfp5 and hygromycin phosphotransferase (hptII) genes conferring green fluorescent protein (GFP) activity and hygromycin resistance, respectively. Putative transgenic calli were obtained 4 weeks after incubation of the co-cultivated explants onto maintenance medium supplemented with 50 mg l⁻¹ hygromycin. Molecular analysis confirmed the integration of the transgenes in transformed callus. To our knowledge, this is the first time to report an Agrobacterium-mediated transformation system in Crataegus aronia.     

<Emphasis Type="Italic">Galleria</Emphasis><Emphasis Type="Italic">mellonella</Emphasis> are Resistant to <Emphasis Type="Italic">Pneumocystis</Emphasis><Emphasis Type="Italic">murina</Emphasis> Infection

Studying Pneumocystis has proven to be a challenge from the perspective of propagating a significant amount of the pathogen in a facile manner. The study of several fungal pathogens has been aided by the use of invertebrate model hosts. Our efforts to infect the invertebrate larvae Galleria mellonella with Pneumocystis proved futile since P. murina neither caused disease nor was able to proliferate within G. mellonella. It did, however, show that the pathogen could be rapidly cleared from the host.     

<Emphasis Type="Italic">Xanthium italicum</Emphasis>, <Emphasis Type="Italic">Xanthium strumarium</Emphasis> and <Emphasis Type="Italic">Arctium lappa</Emphasis> as new hosts for <Emphasis Type="Italic">Diaporthe helianthi</Emphasis>

Sunflower (Helianthus annuus) stem canker caused by Diaporthe helianthi is one of the most important sunflower diseases in Croatia. Until recently, sunflower was the only known host for D. helianthi. In our research carried out in the area of Eastern Croatia, isolates of Diaporthe/Phomospis were collected from Xanthium italicum, X. strumarium and Arctium lappa. Using morphological, cultural and molecular ITS rDNA data, isolates from these weeds were identified as D. helianthi. The following isolates were used in the pathogenicity test: one isolate originated from sunflower (Su5/04), three from X. italicum (Xa2, Xa3 and Xa5), two from X. strumarium (Xa9 and Xa12), one from Xanthium sp. (Xa13) and one from A. lappa (Ar3). According to the results, it was determined that isolate Xa5 (originated from X. italicum) was the most pathogenic to sunflower stems. The average length of the lesion was 11.3 cm. The lowest level of pathogenicity was found in Xa9 (isolated from X. strumarium). The length of the lesion was 0.1 cm.     

Antifungal performance of extracellular chitinases and culture supernatants of <Emphasis Type="Italic">Streptomyces galilaeus</Emphasis> CFFSUR-B12 against <Emphasis Type="Italic">Mycosphaerella fijiensis</Emphasis> Morelet

The tropical and mycoparasite strain Streptomyces galilaeus CFFSUR-B12 was evaluated as an antagonist of Mycosphaerella fijiensis Morelet, causal agent of the Black Sigatoka Disease (BSD) of banana. On zymograms of CFFSUR-B12 culture supernatants, we detected four chitinases of approximately 32 kDa (Chi32), 20 kDa (Chi20), and two with masses well over 170 kDa (ChiU) that showed little migration during denaturing electrophoresis at different concentrations of polyacrylamide. The thymol-sulphuric acid assay showed that the ChiU were glycosylated chitinases. Moreover, matrix assisted laser desorption ionization time-of-flight MS analysis revealed that the ChiU are the same protein and identical to a family 18 chitinase from Streptomyces sp. S4 (gi|498328075). Chi32 was similar to an extracellular protein from Streptomyces albus J1074 (gi|478687481) and Chi20 was non-significantly similar to chitinases from five different strains of Streptomyces (P > 0.05). Subsequently, Chi32 and Chi20 were partially purified by anion exchange and hydrophobic interaction chromatography and tested against M. fijiensis. Chitinases failed to inhibit ascospore germination, but inhibited up to 35 and 62 % of germ tube elongation and mycelial growth, respectively. We found that crude culture supernatant and living cells of S. galilaeus CFFSUR-B12 were the most effective in inhibiting M. fijiensis and are potential biocontrol agents of BSD.     

Cloning of two SOS1 transporters from the seagrass <Emphasis Type="Italic">Cymodocea nodosa</Emphasis>. SOS1 transporters from <Emphasis Type="Italic">Cymodocea</Emphasis> and <Emphasis Type="Italic">Arabidopsis</Emphasis> mediate potassium uptake in bacteria

Two cDNAs isolated from Cymodocea nodosa, CnSOS1A, and CnSOS1B encode proteins with high-sequence similarities to SOS1 plant transporters. CnSOS1A expressed in a yeast Na⁺-efflux mutant under the control of a constitutive expression promoter mimicked AtSOS1 from Arabidopsis; the wild type cDNA did not improve the growth of the recipient strain in the presence of Na⁺, but a cDNA mutant that expresses a truncated protein suppressed the defect of the yeast mutant. In similar experiments, CnSOS1B was not effective. Conditional expression, under the control of an arabinose responsive promoter, of the CnSOS1A and CnSOS1B cDNAs in an Escherichia coli mutant defective in Na⁺ efflux was toxic, and functional analyses were inconclusive. The same constructs transformed into an E. coli K⁺-uptake mutant revealed that CnSOS1A was also toxic, but that it slightly suppressed defective growth at low K⁺. Truncation in the C-terminal hydrophilic tail of CnSOS1A relieved the toxicity and proved that CnSOS1A was an excellent low-affinity K⁺ and Rb⁺ transporter. CnSOS1B mediated a transient, extremely rapid K⁺ or Rb⁺ influx. Similar tests with AtSOS1 revealed that it was not toxic and that the whole protein exhibited excellent K⁺ and Rb⁺ uptake characteristics in bacteria.     

Mapping of quantitative trait loci for resistance to <Emphasis Type="Italic">Mycosphaerella pinodes</Emphasis> in <Emphasis Type="Italic">Pisum sativum</Emphasis> subsp. <Emphasis Type="Italic">syriacum</Emphasis>

Aschochyta blight, caused by Mycosphaerella pinodes, is one of the most economically serious pea pathogens, particularly in winter sowings. The wild Pisum sativum subsp. syriacum accession P665 shows good levels of resistance to this pathogen. Knowledge of the genetic factors controlling resistance to M. pinodes in this wild accession would facilitate gene transfer to pea cultivars; however, previous studies mapping resistance to M. pinodes in pea have never included this wild species. The objective of this study was to identify quantitative trait loci (QTL) controlling resistance to M. pinodes in P. sativum subsp. syriacum and to compare these with QTLs previously described for the same trait in P. sativum. A population formed by 111 F_6:7 recombinant inbred lines derived from a cross between accession P665 and a susceptible pea cultivar (Messire) was analysed using morphological, isozyme, RAPD, STS and EST markers. The map developed covered 1214 cM and contained 246 markers distributed in nine linkage groups, of which seven could be assigned to pea chromosomes. Six QTLs associated with resistance to M. pinodes were detected in linkage groups II, III, IV and V, which collectively explained between 31 and 75% of the phenotypic variation depending of the trait. While QTLs MpIII.1 and MpIII.2 were detected both for seedlings and field resistance, MpV.1 and MpII.1 were specific for growth chamber conditions and MpIII.3 and MpIV.1 for field resistance. Quantitative trait loci MpIII.1, MpII.1, MpIII.2 and MpIII.3 may coincide with other QTLs associated with resistance to M. pinodes previously described in P. sativum. Four QTLs associated with earliness of flowering were also identified. While dfIII.2 and dfVI.1, may correspond with other genes and QTLs controlling earliness in P. sativum, dfIII.1 and dfII.1 may be specific to P. sativum subsp. syriacum. Flowering date and growth habit were strongly associated with resistance to M. pinodes in the field evaluations. The relation observed between earliness, growth habit and resistance to M. pinodes is discussed.     

<Emphasis Type="Italic">Drosophila</Emphasis><Emphasis Type="Italic">P</Emphasis> transposons of the urochordata <Emphasis Type="Italic">Ciona intestinalis</Emphasis>

P transposons belong to the eukaryotic DNA transposons, which are transposed by a cut and paste mechanism using a P-element-coded transposase. They have been detected in Drosophila, and reside as single copies and stable homologous sequences in many vertebrate species. We present the P elements Pcin1, Pcin2 and Pcin3 from Ciona intestinalis, a species of the most primitive chordates, and compare them with those from Ciona savignyi. They showed typical DNA transposon structures, namely terminal inverted repeats and target site duplications. The coding region of Pcin1 consisted of 13 small exons that could be translated into a P-transposon-homologous protein. C. intestinalis and C. savignyi displayed nearly the same phenotype. However, their P elements were highly divergent and the assumed P transposase from C. intestinalis was more closely related to the transposase from Drosophila melanogaster than to the transposase of C. savignyi. The present study showed that P elements with typical features of transposable DNA elements may be found already at the base of the chordate lineage. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Micro-colinearity between rice, <Emphasis Type="Italic">Brachypodium</Emphasis>, and <Emphasis Type="Italic">Triticum monococcum</Emphasis> at the wheat domestication locus <Emphasis Type="Italic">Q</Emphasis>

Brachypodium, a wild temperate grass with a small genome, was recently proposed as a new model organism for the large-genome grasses. In this study, we evaluated gene content and microcolinearity between diploid wheat (Triticum monococcum), Brachypodium sylvaticum, and rice at a local genomic region harboring the major wheat domestication gene Q. Gene density was much lower in T. monococcum (one per 41 kb) because of gene duplication and an abundance of transposable elements within intergenic regions as compared to B. sylvaticum (one per 14 kb) and rice (one per 10 kb). For the Q gene region, microcolinearity was more conserved between wheat and rice than between wheat and Brachypodium because B. sylvaticum contained two genes apparently not present within the orthologous regions of T. monococcum and rice. However, phylogenetic analysis of Q and leukotriene A-4 hydrolase-like gene orthologs, which were colinear among the three species, showed that Brachypodium is more closely related to wheat than rice, which agrees with previous studies. We conclude that Brachypodium will be a useful tool for gene discovery, comparative genomics, and the study of evolutionary relationships among the grasses but will not preclude the need to conduct large-scale genomics experiments in the Triticeae.     

Phenotypic Switching of <Emphasis Type="Italic">Cryptococcus neoformans</Emphasis> and <Emphasis Type="Italic">Cryptococcus</Emphasis><Emphasis Type="Italic">gattii</Emphasis>

Microorganisms that live in fluctuating environments must constantly adapt their behavior to survive. The host constitutes an important microenvironment in opportunistic and primary fungal pathogens like Cryptococcus neoformans (C. neoformans) and Cryptococcus gattii (C. gattii). In clonal populations, adaptation may be achieved through the generation of diversity. For fungi phenotype switching constitutes a mechanism that allows them to change rapidly. Both C. neoformans and C. gattii undergo phenotypic switching, which allows them to be successful pathogens and cause persistent disease. Similar to other encapsulated microbes that exhibit phenotypic variation, phenotypic switching in Cryptococcus changes the polysaccharide capsule. Most importantly, in animal models phenotypic switching affects virulence and can change the outcome of infection. Virulence changes because C. neoformans and C. gattii switch variants elicit different inflammatory responses in the host. This altered host response can also affect the response to antifungal therapy and in some cases may even promote the selection of switch variants. This review highlights the similarity and differences between phenotypic switching in C. neoformans and C. gattii, the two dominant species that cause cryptococcosis in humans.     

<Emphasis Type="Italic">Catenaria anguillulae</Emphasis> Sorokin: a Natural Biocontrol Agent of <Emphasis Type="Italic">Meloidogyne graminicola</Emphasis> Causing Root Knot Disease of Rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.)

Summary Catenaria anguillulae parasitized and killed the eggs and second stage juveniles (J₂) of Meloidogyne graminicola under natural conditions. The percentage of infection in eggs was higher than J₂ of M.␣graminicola, which ranged between 0–50.3% and 0–18.9% in 2004 and 0–46.6% and 0–21.7% in 2005, respectively. The higher parasitism of eggs and J₂ was recorded from those fields in which plants were severely infected with M. graminicola. The degree of parasitism of eggs and J₂ by C. anguillulae varied with severity of root knot disease. The fields with a higher root gall index recorded a higher percentage of infection in eggs and J₂ of M. graminicola. In general, old galls when teased and incubated, recorded higher parasitism of eggs and juveniles than young galls.     

Ectomycorrhizae of <Emphasis Type="Italic">Tuber huidongense</Emphasis> and <Emphasis Type="Italic">T. liyuanum</Emphasis> with <Emphasis Type="Italic">Castanea mollissima</Emphasis> and <Emphasis Type="Italic">Pinus armandii</Emphasis>

Tuber huidongense and T. liyuanum are common commercial white truffles in China that belong to the Rufum and Puberulum groups of the genus Tuber, respectively. Their mycorrhizae were successfully synthesized with two native trees—Castanea mollissima and Pinus armandii—under greenhouse conditions. The identities of the mycorrhizae were confirmed through internal transcribed spacer (ITS) sequence analyses, and their morphological characteristics were described. All of the obtained mycorrhizae have an interlocking pseudoparenchymatous mantle, which is a typical feature of truffle mycorrhizae. The mycorrhizae of T. huidongense on the two trees have hyaline branched emanating hyphae, similar to the documented mycorrhizae of the Rufum group. The unramified, spiky, and hyaline cystidia on the mycorrhizae of T. liyuanum with both C. mollissima and P. armandii further confirmed that this characteristic is constant for the mycorrhizae of the Puberulum group. The successful mycorrhizal syntheses on the two nut-producing trees will be of economic importance in the cultivation of the two truffles.     

Expression of<Emphasis Type="Italic"> FoxE</Emphasis> and<Emphasis Type="Italic"> FoxQ</Emphasis> genes in the endostyle of<Emphasis Type="Italic"> Ciona intestinalis</Emphasis>

We have analyzed the expression patterns of two Fox genes, FoxE and FoxQ, in the ascidian Ciona intestinalis. Expression of Ci-FoxE was specific to the endostyle of adults, being prominent in the thyroid-equivalent region of zone 7. Ci-FoxQ was expressed in several endodermal organs of adult ascidians, such as the endostyle, branchial sac and esophagus. In the endostyle, the pattern of Ci-FoxQ expression was similar to that of CiTTF-1, being prominent in the thyroid-equivalent regions of zones 7 and 8. Therefore, these Fox genes may perform thyroid-equivalent functions in the ascidian endostyle.Edited by N. Satoh