Representation of wild Lactuca spp. (Asteraceae, Lactuceae) in world genebank collections

The spread of the genus Lactuca worldwide includes 16 species in Europe, 51 in Asia, 43 in Africa and 12 in America (mostly North American subcontinent). Natural distributions of Lactuca spp. are compared with the representation of wild Lactuca spp. in world genebank collections as recently summarized in the International Lactuca database (ILDB). A total of 27 wild Lactuca species are reported in world genebank collections in the ILDB, however, due to incorrect taxonomic determination the real number of species is lower. The substantial part (92%) of the collections is represented only by three species (L. serriola, L. saligna, L. virosa) and from a geographic viewpoint they are mostly European in origin. The autochthonous species originating from other continents (Asia, Africa, America), which form c. 83% of known Lactuca spp. richness, are very poorly represented in collections (only c. 3%). The majority of accessions originate from Europe (59%) and Asia (37%), nevertheless the whole area of natural distribution is not well covered. An extremely low number of accessions is available from Africa and America (2% each). Thus, the global biodiversity of Lactuca spp. germplasm is represented very poorly and is biased in genebank collections. For future studies of taxonomy, phytogeography, ecology, phylogenetic relationships, genetic diversity, inter- and intra-population structure, resistance research and practical breeding exploitation of wild Lactuca spp. germplasm, plant material from a wider ecogeographic distribution must be collected and introduced into genebank collections more intensively.     

Mineral-fixed ammonium in clay- and silt-size fractions of soils incubated with 15N-ammonium sulphate for five years

Summary Four soils with 6, 12, 23, and 47% of clay were incubated for 5 years with ¹⁵N-labeled (NH_{4 2}SO₄ and hemicellulose. The incubations took place at 20°C and 55% water-holding capacity. Samples of whole soils, and clay- (<2 m) and silt-(2–20 m) size fractions (isolated by ultrasonic dispersion and gravity sedimentation) were analysed for labeled and native mineral-fixed ammonium. Mineral-fixed ammonium in non-incubated soil samples accounted for 3.4%–8.3% of the total N and showed a close positive correlation with the soil clay content (r ² = 0.997). After 5 years of incubation, the content of mineral-fixed ammonium in the clay fraction was 255–430 g N g^–1, corresponding to 71%–82% of the mineral-fixed ammonium in whole soils. Values for silt were 72–166 g N g^–1 (14%–33% of whole soil content). In the soils with 6% and 12% clay, less than 1 % of the labeled clay N was present as mineral-fixed ammonium. In the soil with 23% clay, 3% of the labeled N in the clay was mineral-fixed ammonium. Labeled mineral-fixed ammonium was not detected in the silt fractions. For whole soils, and clay and silt fractions, the proportion of native N present as mineral-fixed ammonium varied between 3% and 6%. In contrast, the proportion of labeled N found as mineral-fixed ammonium in the soil with 4701o clay was 23%, 38% and 31% for clay, silt, and whole-soil samples, respectively. Corresponding values for native mineral-fixed ammonium were 12%, 16%, and 10%. Consequently, studies based on soil particle-size fractions and addressing the N turnover in clay-rich soils should consider the pool of mineral-fixed ammonium, especially when comparing results from different size fractions with those from fractions isolated from soils of a widely different textural composition.     

Rasterelektronenmikroskopische Untersuchungen an Samen der GattungAllium L. III.

Zusammenfassung Die Testa-Epidermisskulpturen von weiteren Arten der GattungAllium L. wurden rasterelektronenmikroskopisch untersucht. Dabei konnten die bisherigen Befunde über die sektionsspezifische Ausbildung der Testaskulpturen weitgehend bestätigt werden.Die wenig differenzierten Testaskulpturen der sect.Anguinum G. Don exKoch wurden an weiteren Arten der Gattung nachgewiesen. Die untersuchten Arten der sect.Rhizirideum G. Don exKoch entsprechen in der Mehrzahl den charakteristischen granulösen Skulpturtypen dieser Sektion. Besonderheiten ergeben sich bei einzelnen Arten durch spezielle verrucose Skulpturen bzw. deutlich undulierte Antiklinalwände.Die Testaskulpturen einiger Arten der sect.Cepa (Miller)Prokh. konnten den für diese Sektion typischen Skulpturformen zugeordnet werden.Der einheitliche, verrucose Skulpturtyp der sect.Codonoprasum Reichenb. wurde durch weitere Arten bestätigt. Ebenso zeigen die Arten der sect.Caloscordum (Herb.)Bak. übereinstimmende Testamerkmale.Die untersuchten Sippen der sect.Lophioprason Traub entsprechen in ihrer Testaskulptur dem bisher bekannten Merkmalsspektrum der jeweiligen Artengruppe. Hierbei konnte auch der spezielle verrucose Skulpturtyp derAllium acuminatum-Gruppe an weiteren Arten dieser Gruppe nachgewiesen werden. Granulöse Skulpturformen wurden bei einzelnen Arten der sect.Rhophetoprason Traub und sect.Amerallium Traub gefunden.Die der sect.Allium L. und dem subgen.Melanocrommyum (Webb etBerth.)Rouy gemeinsame Testaform, die durch verrucose Skulpturen sowie eine ausgeprägte Antiklinalwand-Undulation gekennzeichnet ist, wurde durch weitere Arten dieses Verwandtschaftskreises bestätigt. Dabei unterscheidet sich der Undulationstyp der SektionenAllium L. undMegaloprason Wendelbo von den untersuchten Arten anderer Sektionen des subgen.Melanocrommyum (Webb etBerth.)Rouy.

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SEM investigations on seeds of the genusAllium L. III

Summary The structure of the testa epidermis of additional species ofAllium L. have been studied by means of SEM. Results obtained earlier for different sections of the genus could be confirmed:The less differentiated testa structure of sect.Anguinum G. Don exKoch has been observed in further species of this group.Most of the newly examined taxa of sect.Rhizirideum G. Don exKoch correspond to the already known testa types of this section and are characterized by granulate seed coat surfaces. Deviations have been found in some species which possess either a special type of verrucate sculptures or have distinctly undulated anticlinal walls of the testa cells.The earlier described two testa types of sect.Cepa (Mill.)Prokh. could be observed in some additional species of this section, too.Likewise the uniformly verrucate sculptures of sect.Codonoprasum Rchb. have been found in further species and also the taxa of sect.Caloscordum (Herb.)Bak. agree in their testa characters.Earlier described seed coat types for different species groups of sect.Lophioprason Traub could be confirmed, among them the verrucate sculptures of theAllium acuminatum-group. Granulate testa surfaces have been analyzed in several species of sect.Rhophetoprason Traub and sect.Amerallium Traub. The testa type commonly found in sect.Allium as well as in subgen.Melanocrommyum (Webb etBerth.)Rouy and characterized by verrucate sculptures and strong undulation of the anticlinal cell walls could be observed in further species of these infrageneric groups. The undulation pattern of sect.Allium and sect.Megaloprason Wendelbo however differs from that of other sections of subgen.Melanocrommyum (Webb etBerth.)Rouy.

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Allium L. . III.

Allium L. . , - . Anguinum G. Don exKoch . Rhizirideum G. Don exKoch , . . Cepa (Miller)Prokh. . Codonoprasum Reichenb. . Caloscordum (Herb.)Bak. . Lophioprason Traub , . , Allium acuminatum- . Rhophctoprason Traub Amerallium Traub. Allium L. Melanocrommyum (Webb et.Berth.)Rouy, , , . Allium L. Megaloprason Wendelbo Melanocrommyum (Webb etBerth.)Rouy.

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Einige der untersuchten Arten konnten während der gemeinsamen Expeditionen in der Georgischen SSR gesammelt werden, die von Frau Dr.R. K. Beridze, Botanisches Institut der Georgischen Akademie der Wissenschaften, in bewährter Weise organisiert wurden. Dieses ist eine willkommene Gelegenheit, ihr diesen Beitrag anläßlich ihres 70. Geburtstages zu widmen.     

Changes in metabolic and structural diversity of a soil bacterial community in response to cadmium toxicity

Cadmium toxicity reduces the species diversity of soil microbial communities and their ability to metabolize different carbon substrates. However, it is not yet clear whether there is a relationship between loss of species diversity and the metabolic rates at which different substrates are used. In this research, the ability of a soil microbial community to metabolize 31 C substrates was examined using Biolog Ecoplates amended with Cd over a range of concentrations (0, 5, 10, 20, 50 g ml^–1). After 48 h growth, the bacterial communities that were produced on ten of the substrates were characterized in relation to their 16S rDNA profiles by PCR denaturing-gradient gel electrophoresis. Results showed that both the microbial growth rates and the numbers of substrates that were used were reduced with increasing Cd concentration. When examined across all substrates, approximately 30% of the 16S rDNA bands representing different bacterial species were eliminated by 5 g Cd ml^–1. However, there was considerable variation in the bacterial community responses with different C substrates. Both cluster analysis and discriminant analysis indicated that the bacterial community structures could be grouped into sensitive, moderately sensitive, and Cd-resistant communities.     

Effect of regeneration procedures on genetic diversity in Brassica napus and B. rapa as estimated by isozyme analysis

This investigation was conducted to assess changes in the genetic structure of two varieties of two species of annual Brassica. Seeds of B. napus cv. Topas and B. rapa Broccoletto were sent to nine research institutes in different geographical areas of Europe for regeneration. The multiplied material was sent back after one year of regeneration and analysed electrophoretically. The original populations of each species and their multiplied samples were stained for 12 different enzymes, of which 4 were found to be polymorphic (DIA, SKD, GPI and PER). It was possible to detect considerable differences in isozyme patterns in B. napus and allelic frequencies in B. rapa, both within and between populations. When the original population was compared with the regenerated samples, the Chi-square homogeneity test for all pairwise comparisons revealed distinctness with a 99% probability for B. napus and 95% probability for B. rapa with one or more of the enzyme systems examined. Furthermore, the average of gene diversity analysis (Nei, 1973) revealed that some regenerated populations have less while others have increased genetic variation compared with the original population. These observations indicated that the frequencies were non-random and considerable shifts in genetic diversity have occurred during multiplication. In addition, different regeneration procedures have caused the fixation of certain alleles.     

Use of land-races in Czechoslovak wheat breeding

Summary Four groups of Czechoslovak land-races (Czech alternate, Czech red, Moravian white, awnless, South Moravian and Slovak awned wheats) are characterized on the base of wheat collection studies in the Research Institute for Crop Production, Praha-Ruzyn, and their use in the breeding in SSR. A review of Czechoslovak cultivars of winter and spring wheats registered in the years 1921–1980 (table 1 and 2) and the registration period of the most important older Czechoslovak cultivars (table 3) is presented.Of the total number of 284 registered Czechoslovak cultivars in the years 1921–1980 93 cultivars were developed by selection from land-races; 70% of 87 cultivars originated from crosses had a land-race or its derivative as one of its parents. From land-races derived cultivars Chlumecká 12, eská Pesívka, Slovenská 777, Dobrovická 10 displayed the longest duration in the registration.

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Die Verwendung von Landsorten in der tschechoslowakischen Weizenzüchtung

Zusammenfassung Vier Gruppen von tschechoslowakischen Weizenlandsorten werden auf der Grundlage von Untersuchungen an der Weizenkollektion im Institut für Pflanzenproduktion, Prag-Ruzyn, und ihrer Nutzung in der Züchtung in der SSR beschrieben. Es sind (1) tschechische Wechselweizen, (2) tschechische rote, (3) mährische weiße, grannenlose und (4) südmährische und slowakische begrannte Weizen. Ein Überblick über die in den Jahren 1921–1980 registrierten tschechoslowakischen Winter- und Sommerweizen (Tab. 1 und 2) sowie die Zeitdauer der Registrierung der bedeutendsten älteren tschechoslowakischen Sorten (Tab. 3) schließt sich an.Von insgesamt 284 in den Jahren 1921–1980 registrierten tschechoslowakischen Sorten entstanden 93 durch Auslese aus Landsorten. Bei den 87 Sorten, die aus Kreuzungen hervorgingen, hatten 70% entweder eine Landsorte oder den Abkommen einer Landsorte unter den Eltern. Die aus Landsorten hervorgegangenen Sorten Chlumecká 12, eská Pesívka, Slovenská 777 und Dobrovická 10 waren am längsten registriert.

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- : (1) , (2) , (3) , (4) . , 1921–1980 . (. 1 2), ( ) (. 3). 284 , 1921–1980 ., 93 ë . 87- , ë , 70% . ( ) : 12, , 777 10.

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Paper not delivered during the symposium     

Die Anwendung von Triphenyltetrazoliumchlorid zur Schnellprüfung der Keimfähigkeit bei Samen vonCoffea arabica L.

Zusammenfassung Durch Anwendung des TTC-Schnelltestes wurde versucht, ein praktisch brauchbares Keimprüfungsverfahren für Kaffeesamen zu entwickeln. Es wird eine Routinemethode zur Keimprüfung mit TTC vorgeschlagen, die mit isolierten Embryonen von Kaffee arbeitet. Dieses Verfahren wurde an 4 verschiedenen Samenproben von Kaffee überprüft. Die Übereinstimmung der Ergebnisse aus den Keimprüfungen, die vergleichend unter natürlichen Bedingungen vorgenommen wurden, mit denen des TTC-Testes war gut, so daß eine praktische Anwendung des Verfahrens für den Kaffeeanbau gerechtfertigt erscheint.

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Application of triphenyltetrazolium chloride for rapid testing of the viability of seeds fromCoffea arabica L.

Summary Using TTC we tried to develop a useful method for testing the germination capability of coffee seeds. A routine test method for germination using TTC is suggested, which works with isolated embryos of the coffee seeds. This method was tested with 4 different samples of coffee seeds and compared with the germination of coffee seeds at natural conditions. The agreement of the results from both germination tests was very good. Therefore the application of the test with TTC is proposed for the practical coffee farming.

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-- Coffea arabica L.

. , . 4 . , , , .

     

Towards the conservation of crop wild relative diversity in North Africa: checklist,prioritisation and inventory

Crop wild relatives (CWR) are wild species that are more or less genetically related to crops that can be used to introgress useful genes for improvement of productivity, resistance to biotic and abiotic stresses and quality of cultivated crops. They are important in crop improvement to achieve food security for an increasing population and to overcome the challenges caused by climate change and the new virulence of major diseases and pests. These genetic resources are increasingly threatened in their natural habitats through over-exploitation and land reclamation and degradation. Therefore, their efficient and effective conservation would be taxonomically and genetically valuable and will contribute to maintaining and promoting the sustainability of crop diversity, facilitating agricultural production and supporting the increasing demand for food, feed and natural resources. A checklist of 5780 Crop Wild Relatives (CWR) taxa from North Africa was obtained using the CWR Catalogue for Europe and the Mediterranean (PGR Forum). Of which consists 76% of the flora of North Africa. The checklist contains 5588 (~97%) native taxa and 192 introduced. Families with higher taxa richness are Fabaceae, Asteraceae, and Poaceae. These three families constitute more than 33% of the total taxa included in the checklist. About 9% (502) CWR taxa identified as a priority for conservation in North Africa using four criteria, the economic value of the crop, the relatedness degree of wild relatives to their crop, threat status using IUCN red list assessment, and finally the centre of origin and/or diversity of the crop. Of these, 112 taxa were assigned high, 268 medium and 122 low priorities for effective conservation. Those assessed as threatened using IUCN Red list and national assessment represent approximately 2% (119 taxa) of the CWR in the region. However, 21 taxa are assessed as critically endangered (CR), 53 as endangered (EN), and 45 as vulnerable (VU). Wild relatives of some globally important crops are present, with those related to wheat (Triticum aestivum L. and T. durum L.) and barley (Hordeum vulgare L.) among the highest priority crops for the North Africa region. Amongst CWR assessed as threatened, only 8 (6.7%) CWR are related to food crops, Avena agadiriana B.R. Baum. et G. Fedak (VU), A. atlantica B.R. Baum et G. Fedak (VU), A. murphyi Ladiz. (EN), Beta macrocarpa Guss. (EN), Olea europaea subsp. maroccana Guss. (VU), Rorippa hayanica Maire (VU) and Aegilops bicornis (Forssk.) Jaub. et Spach (VU). The wild relative of Safflower Carthamus glaucus M. Bieb is restricted to Egypt and Libya and assessed as rare in Egypt. The information available about the conservation and threat status of CWR in North Africa still lags behind, and more investigations are required.     

Diversity for abiotic and biotic stress resistance in the wild annual Cicer species

Data on 228 accessions of eight annual wild Cicer species and 20 cultivated chickpea check lines were evaluated for diversity in response to six of the most serious biotic and abiotic stresses which reduce crop yield and production stability of chickpea, i.e., ascochyta blight, fusarium wilt, leaf miner, bruchid, cyst nematode, and cold. Relative frequencies of score reactions to the above six stresses were recorded from all the annual wild Cicer species and the cultivated taxon. Patterns of distribution and amount of variation of the resistance reactions differed between stresses and species. C. bijugum, C. pinnatifidum and C. echinospermum showed accessions with at least one source of resistance (1 to 4 score reactions) to each stress. Overall, C. bijugum showed the highest frequencies of the highest categories of resistance. Next in performance was C. pinnatifidum followed by C. judaicum, C. reticulatum and C. echinospermum. Furthermore, C. bijugum had the highest number of accessions with multiple resistance to the six stresses; two accessions were resistant to five stresses and 16 to four. According to the Shannon-Weaver diversity indices (H), five species showed discrete mean diversity indices which varied from 0.649 in C. pinnatifidum to 0.526 in C. judaicum, whereas C. chorassanicum, C. cuneatum and C. yamashitae showed the lowest Hs, which were respectively 0.119, 0.174 and 0.216. Pair-wise correlations among the six biotic and abiotic stresses showed the possibility of combining these resistances. Interestingly, multiple resistant accessions were predominantly of Turkish origin.     

Biochemical mutants in higher plants as tools for chemical and physiological investigations — A survey

Summary A report is given on biochemical mutants in higher plants with emphasis on metabolic mutants. Since the discovery of thiamine-defective mutants inArabidopsis thaliana andLycopersicon esculentum some other mutants in different species became available. The first higher plant with an absolute requirement for an amino acid is a proline-deficient mutant inZea mays. Inchloronerva ofLycopersicon esculentum synthesis of nicotianamine is blocked. This is the first instance where a hitherto unknown function is attributed to an already known compound by work with a mutant of higher plants. Nicotianamine is distributed throughout all vascular plants and appears to be linked with short-distance iron transport. The wilty mutantflacca inL. esculentum lacks abscisic acid with some consequences to different parts of metabolism. In the same species the mutant T 3238btl/btl, fer/fer carries two separate, independent mutations which affect the transport of boron and iron, respectively. Selection for chlorate resistance led to the discovery of mutants with impaired nitrate reductase activity and nitrate uptake inArabidopsis thaliana and in consequence added new information to our knowledge of the regulation of nitrate assimilation. Other mutants of similar kind were detected inNicotiana tabacum andHordeum vulgare. Mutants with defects in the photosynthetic system were discovered inZea mays andHordeum vulgare. Plastome mutants inOenothera revealed a lack of ribulose-1,5-biphosphate carboxylase activity and showed interference between the genetic system of the plastids and that of the nucleus.The search for new mutations should be continued by different techniques, whereby the chance to find auxotrophic mutants by grafts should not be overlooked.

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Biochemische Mutanten höherer Pflanzen als Objekte für chemische und physiologische Untersuchungen. Eine Übersicht

Zusammenfassung Es wird über biochemische Mutanten höherer Pflanzen unter besonderer Berücksichtigung von Stoffwechsel-Mutanten berichtet. Seit der Entdeckung von Thiamin-Mangelmutanten beiArabidopsis thaliana undLycopersicon esculentum sind einige andere Mutanten verschiedener Arten bekannt geworden. Die erste höhere Pflanze mit einem absoluten exogenen Aminosäure-Bedürfnis ist eine Prolin-Mangelmutante vonZea mays. Inchloronerva vonLycopersicon esculentum ist die Synthese von Nicotianamin blockiert. Dieses ist der erste Fall, bei dem durch Untersuchungen an der Mutante einer höheren Pflanze Aufschluß über die Funktion einer bereits bekannten, hinsichtlich ihrer biochemischen Rolle aber noch unerforschten Verbindung gewonnen werden konnte. Nicotianamin ist wahrscheinlich in allen Gefäßpflanzen vorhanden und steht dort mit dem Eisen-Nahtransport in Beziehung. Die Welke-Mutanteflacca vonL. esculentum produziert keine Abscisinsäure, was Auswirkungen auf verschiedene Richtungen des Stoffwechsels hat. In der gleichen Species trägt die Mutante T 3238btl/btl, fer/fer gleichzeitig zwei verschiedene, voneinander unabhängige Mutationen, die den Bor- bzw. den Eisentransport betreffen. Selektion auf Chlorat-Resistenz führte beiArabidopsis thaliana zur Entdeckung von Mutanten mit blockierter Nitratreduktase-Aktivität und verminderter Nitrataufnahme. Untersuchungen mit diesen Formen erbrachten neue Vorstellungen über die Regulation der Nitratassimilation. Ähnliche Mutanten wurden auch beiNicotiana tabacum undHordeum vulgare gefunden. Mutanten mit defektem Photosynthese-System sind beiZea mays undHordeum vulgare bekannt. Eine Plastom-Mutante vonOenothera zeigt einen Synthese-Block im Hinblick auf Ribulose-1,5-biphosphat-Carboxylase, der sich auf beide Untereinheiten auswirkt, so daß Wechselwirkungen zwischen dem genetischen System der Piastiden und dem des Kernes angenommen werden müssen.

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. —

, ë , . - . , ë - . chloronerva . , , , , . , . flacca , . , 3238 btl/btl, fer/fer, , , . ë . . . . -1,5- -, , . , ë .

     

Gewebekulturen aus Alkaloidpflanzen

Zusammenfassung Gewebekulturen verschiedenerDatura-Arten zeigten in ihrem Alkaloid-spektrum erhebliche qualitative und quantitative Abweichungen von dem intakter Pflanzen. Hyoscyamin und Scopolamin konnten nicht nachgewiesen werden. Bei exogener Zufuhr von Hyoscyamin zuDatura-Gewebekulturen wurde während 14-tägiger Versuchsdauer ein erheblicher Schwund des zugesetzten Alkaloids beobachtet; eine Umwandlung von Hyoscyamin in Scopolamin, wie sie aus intakten Pflanzen bekannt ist, war nicht festzustellen.

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Tissue cultures of alkaloid-bearing plants

Summary The alkaloid spectrum ofDatura tissue cultures differed considerably from that of intact plants. Neither hyoscyamine nor hyoscine were detected in the tissue cultures. Hyoscyamine administered toDatura tissue cultures diminished in considerable quantity during the experimental period of 14 days but no conversion into hyoscine was detected as it is occuring in intactDatura plants.

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I. Mitteilung vgl. H. Koblitz, K Grützmann und I. Hagen. — Z. Pflanzenphysiol.56 (1967) 27–32.     

Multivariate analysis approach to evaluate a germplasm collection of Hedysarum coronarium L.

Autochthonous germplasm collected in Spain (Ca´diz and Baleares provinces), Italian ecotypes and cultivated material supplied by a commercial firm were analysed by using a multivariate approach applied to a set of morphological traits. According to these analyses the cultivated material could clearly be separated from the autochthonous germplasm. Variation was observed among the traits studied; Principal Stem Diameter, Leaf Area at Flowering and Susceptibility to Oidium were the main traits in grouping and separating sulla (Hedysarum coronarium L.) entries. A new ecotype (Tarifa) could be used in plant breeding as being a source of resistance to Oidium. The multivariate approach appears to be a valid system for germplasm evaluation in sulla with a higher discriminant capacity than multiple single trait analysis.     

Einfluß einiger Klima- und Anbaufaktoren auf die Ertragsbildung der Reissorte ‘IR-8’ in Cuba III. Klimaverhältnisse

Ohne Zusammenfassung

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Effect of some climatic and agricultural factors on yield formation by the rice variety IR-8 in Cuba. III. Climatic conditions. With 27 Figures

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Genetic variation in common and runner bean of the Northern Meseta in Spain

The genetic variation within and between Spanish landraces or varieties of Phaseolus vulgaris L. (common bean) and P. coccineus L. (runner bean) has been estimated by means of isozymes and random amplified polymorphic DNA (RAPD) analyses. Likewise, storage protein and amino acid content in dry seeds have been estimated. Fifteen landraces (60 accessions) of P. vulgaris and six of P. coccineus (six accessions) have been studied. Of the seven isozymatic systems analyzed only three systems and three loci showed variability in each species. Isozyme analyses revealed that genetic variability within and between landraces exist in both species. Even variability within accession was detected in some P. vulgaris landraces. Comparison of isozyme data indicated that Spanish landraces have a lower level of genetic variability than wild American materials and probably also lower than American landraces. RAPD analysis allowed for the uniquely distinguishing of all landraces. Genetic similarity among landraces, estimated by both isozymes and RAPDs, were not related with the seed morphological characters (color, size and shape) which define each variety or landrace. Variation in protein and amino acid content among landraces was also detected. The average protein content in common bean (20.48%) was similar to values previously reported in this species and higher than the average in the runner bean landraces (16.33%). In relation to the amino acid content methionine and cysteine showed the lowest values in all samples, although the content of these two amino acids varied widely among landraces.     

Characterization of a flint maize (Zea mays var. indurata) Italian landrace, II. Genetic diversity and relatedness assessed by SSR and Inter-SSR molecular markers

A comparative characterization of 10 field populations of the maize (Zea mays var. indurata) landrace Nostrano di Storo was carried out using different types of PCR-based markers. The inbred line B73 and three synthetics (VA143, VA154 and VA157) selected from as many landraces were also used. Genetic diversity and relatedness were evaluated over 84 SSR and 53 I-SSR marker alleles using a total of 253 individual DNAs. Up to 23 alleles per SSR locus were scored while the average effective number of alleles per population was 6.99. Nei's total genetic diversity as assessed with SSR markers was H_T = 0.851 while the average diversity within populations was H_S = 0.795. The overall Wright's fixation index F_ST was as low as 0.066. Thus, more than 93% of the total variation was within population. Unique alleles over all SSR loci were found for six populations. An average of 17.7 marker alleles per I-SSR primer were scored with an effective number of marker alleles per locus of 1.34. The Shannon's diversity information index over all populations and I-SSR loci was 0.332, varying from 0.286 to 0.391. The extent of differentiation between populations was as low as G_ST = 0.091. Dice's genetic similarity matrices were estimated for both SSR and I-SSR markers. The mean genetic similarity coefficients within and between populations were respectively 0.269 and 0.217, for SSR markers, and 0.591 and 0.564, for I-SSR markers. UPGMA dendrograms displayed all field populations but one clustered into a distinct group, in which the synthetic VA154, selected from the Marano Vicentino landrace, was also included. One field population and the other two synthetics were clustered separately as well B73. The matrix correlation assayed by the Mantel's correspondence test was as high as 0.908. Findings suggest that, although a high variability can be found among plants, most plant genotypes belong to the same landrace called Nostrano di Storo. Although gene flow from commercial hybrids might have occurred, the large number of polymorphisms and the presence of both unique alleles and alleles unshared with B73 and synthetics are the main factors underlying the value of this flint maize landrace as a source of genetic variation and peculiar germplasm traits. Because of its exclusive utilization for human consumption, such a molecular marker characterization will be a key step for obtaining the IGP mark and so promote the in situ conservation and protection of the landrace Nostrano di Storo.     

Natural nitrogen-15 abundance and carbohydrate content and composition of organic matter particle-size fractions from a sandy soil

Sandy soil samples collected from under a woody/grass savanna in the Lamto experimental area (6°13N, 5°20W; Côte dIvoire, West Africa), were fractionated according to particle size with the aim of measuring the natural abundance of ¹⁵N and determining the contents and composition of hydrolysable carbohydrates of soil organo-mineral particles for a better understanding of the contribution of each individual fraction to the soil function. The contributions of the fractions <20 m to the total pool of organic matter were 77% for C and 84% for N. Larger amounts of carbohydrates were found in the clay and silt fractions (3,784–6,043 g g^–1 soil). The carbohydrate composition indicated that microbe-derived carbohydrates [e.g. galactose (Gal) and mannose (Man)] accumulated preferentially in the fine fractions while plant-derived sugars [e.g. arabinose (Ara) and xylose (Xyl)] were dominant in coarse fractions. A negative relationship was observed between C:N ratio and ¹⁵N natural abundance on the one hand, and on the other hand between C:N and (Gal+Man):(Ara+Xyl), Man:(Ara+Xyl) and Man:Xyl ratios, clearly indicating that the chemistry of the organic materials of the particle-size fractions reflects a change from soil chemistry dominated by plant materials to that dominated by microbial biomass and metabolites. The contribution of a given fraction to soil microbial activity is controlled by the quality or quantity of associated soil organic matter, its microbial biomass and also by the accumulation of microbial-derived carbohydrates which can be resynthesized or recycled.     

Effect of Mixed-Salt Salinity on Growth and Ion Relations of a Barnyardgrass Species

ABSTRACT

Recent investigations of the plant genome have revealed a large degree of similarity among cereal crops (specifically within the family Triticeae) and other related grass species. Recognition of the close genetic relationship among the grasses indicates that more exotic species, such as weedy grasses, may be exploited by plant breeders to enhance biotic/abiotic stress tolerance in cereal crops. Echinochloa crus-galli (L.) ^{1 1} Mention of company names or products is for the benefit of the reader and does not imply endorsement, guarantee, or preferential treatment by the USDA or its agents. Beauv. (barnyardgrass), a wide-spread, persistent C₄ weed species of agricultural importance, is reported to tolerate high levels of salinity. Growth and ion relations were studied in barnyardgrass using mixed-salt salinity (with final electrical conductivities (ECi) of 3 (control), 7, 11, and 19 dS m^?1 in the irrigation water) to determine whether the mechanism(s) for its salt tolerance are similar to those previously reported for other cereal crops. Such a finding would indicate that barnyardgrass may possess valuable genetic traits. Ion accumulation and ion selectivity ratios in the various treatments were determined from oven-dried shoot tissue. Significant (P < 0.01) linear regressions were obtained between either fresh weight or plant height and ECi. The point of 50% reduction (C₅₀) in fresh weight was predicted to occur at about 13.9 dS m^?1; the C₅₀ value for plant height was at about 22.9 dS m^?1. Statistical analysis of calculated Gapon constants for potassium (K)/sodium (Na) indicated that ion selectivity was not affected until after 11 dS m^?1. Calcium (Ca)/Na selectivity was not significantly affected by salinity. We concluded that, similar to some cereal crops, barnyardgrass maintains growth under saline conditions by maintaining high K/Na ratios, possibly because of better membrane integrity due to high Ca selectivity.     

The Prospects of Tissue Culture and Genetic Engineering for Strawberry Improvement

Abstract

Strawberry shoot meristem cultures have been used for producing virus-free strawberry plants. Plantlet regneration from leaf mesophyll protoplasts, and Agrobacterium tumefaciens mediated genetic transformation, mark the beginning of strawberry improvement with biotechnologies. The use of biotechnological tools has a greater potential in producing strawberry plants with traits such as early maturation, frost and disease resistance, mite and nematode resistance, high yield, better quality, suitability for mechanical harvesting, shipping ability, ellgaic acid content, aroma compounds and cost-effective micropropagation. Gene identification and mapping with RFLPs or RAPDs would be desirable. Transgenic strawberries should be tested for their quality before releasing to the consumers.     

Variability for seed glucosinolates in a germplasm collection of the genus Brassica

A renewed interest in glucosinolates (GSLs) as compounds with biocidal and anticarcinogenic activity demands evaluation of the available variability in germplasm collections. The objective of the present study was to evaluate a germplasm collection of the genus Brassica for total content and profile of seed GSLs. A total of 1708 entries from 20 Brassica species were nondestructively analysed by near-infrared reflectance spectroscopy. The total GSL content and the concentrations of sinigrin, progoitrin, gluconapin, glucoerucin, glucoiberin, and 4-hydroxyglucobrassicin were estimated by means of previously developed calibration equations. One hundred and fifty entries, having either high GSL content or potentially interesting GSL profiles, were selected and further analysed by high-performance liquid chromatography. The collection contained great variability for GSL content and profile. Very high GSL contents (>200 mol g^-1) were measured in accessions of B. montana, B. nigra, and B. oleracea. The greatest intraspecific variability occurred in B. oleracea, where six contrasting GSL profiles were identified. The detected variability might be useful for the development of Brassica crops containing high GSL content and specific GSL profiles.     

Determination of genetic variability by RAPD markers in cauliflower,cabbage and kale local cultivars from France

RAPD markers were used to analyse the genetic variability among a cole crop cultivar collection from France and to identify possible duplicate accessions for facilitating the germplasm multiplication. We surveyed 24 cauliflower, 24 cabbage and 48 kale populations using 62, 100 and 89 RAPD markers respectively on 40 seed bulk samples per accession. Genetic distances were calculated on the basis of these markers. Using the phylogenetic package PAUP we compared the genetic clusters obtained for the RAPD markers with the groups based on morphologic and agronomic data. For cauliflowers and cabbages a drastic selection by growers led to an extensive differentiation of morphologic and precocity traits related to geographic origin, which matches the grouping based on RAPD markers. Furthermore, RAPDs detected in some cases misclassification of accessions in the collection. Kales formed an homogeneous group probably due to extensive genetic exchanges leading to a continuous diversity. For the other crops, different horticultural types were separated in several subgroups by the RAPD markers suggesting different genetic origins. RAPD markers provide a rapid and informative approach to analyze the genetic variability in a collection. It can be applied to autogamous (spring cauliflower) or allogamous (winter cauliflower) crops, even in cases where the intra-population diversity is extensive (cabbages).