Fungal microbiota from rain water and pathogenicity of Fusarium species isolated from atmospheric dust and rainfall dust

In order to determine the presence of Fusarium spp. in atmospheric dust and rainfall dust, samples were collected during September 2007, and July, August, and October 2008. The results reveal the prevalence of airborne Fusarium species coming from the atmosphere of the South East coast of Spain. Five different Fusarium species were isolated from the settling dust: Fusarium oxysporum, F. solani, F. equiseti, F. dimerum, and F. proliferatum. Moreover, rainwater samples were obtained during significant rainfall events in January and February 2009. Using the dilution-plate method, 12 fungal genera were identified from these rainwater samples. Specific analyses of the rainwater revealed the presence of three species of Fusarium: F. oxysporum, F. proliferatum and F. equiseti. A total of 57 isolates of Fusarium spp. obtained from both rainwater and atmospheric rainfall dust sampling were inoculated onto melon (Cucumis melo L.) cv. Piñonet and tomato (Lycopersicon esculentum Mill.) cv. San Pedro. These species were chosen because they are the main herbaceous crops in Almeria province. The results presented in this work indicate strongly that spores or propagules of Fusarium are able to cross the continental barrier carried by winds from the Sahara (Africa) to crop or coastal lands in Europe. Results show differences in the pathogenicity of the isolates tested. Both hosts showed root rot when inoculated with different species of Fusarium, although fresh weight measurements did not bring any information about the pathogenicity. The findings presented above are strong indications that long-distance transmission of Fusarium propagules may occur. Diseases caused by species of Fusarium are common in these areas. They were in the past, and are still today, a problem for greenhouses crops in Almería, and many species have been listed as pathogens on agricultural crops in this region. Saharan air masses dominate the Mediterranean regions. The evidence of long distance dispersal of Fusarium spp. by atmospheric dust and rainwater together with their proved pathogenicity must be taken into account in epidemiological studies

Differential requirements for Tousled-like kinases 1 and 2 in mammalian development

The regulation of chromatin structure is critical for a wide range of essential cellular processes. The Tousled-like kinases, TLK1 and TLK2, regulate ASF1, a histone H3/H4 chaperone, and likely other substrates, and their activity has been implicated in transcription, DNA replication, DNA repair, RNA interference, cell cycle progression, viral latency, chromosome segregation and mitosis. However, little is known about the functions of TLK activity in vivo or the relative functions of the highly similar TLK1 and TLK2 in any cell type. To begin to address this, we have generated Tlk1- and Tlk2-deficient mice. We found that while TLK1 was dispensable for murine viability, TLK2 loss led to late embryonic lethality because of placental failure. TLK2 was required for normal trophoblast differentiation and the phosphorylation of ASF1 was reduced in placentas lacking TLK2. Conditional bypass of the placental phenotype allowed the generation of apparently healthy Tlk2-deficient mice, while only the depletion of both TLK1 and TLK2 led to extensive genomic instability, indicating that both activities contribute to genome maintenance. Our data identifies a specific role for TLK2 in placental function during mammalian development and suggests that TLK1 and TLK2 have largely redundant roles in genome maintenance

L'intérêt de lignées collectées en Haïti pour l'amélioration variétale du haricot grain (Phaseolus vulgaris L)

Parmi d'autres légumineuses, les grains secs de haricots (Phaseolus vulgaris) tiennent une grande place dans l'alimentation haïtienne. Les types de haricots cultivés en Haïti sont très variés, mais ont une tendance générale à la précocité et à l'indifférence photopériodique. Les paysans cultivent des mélanges de gros grains produits par des plantes naines et de grains moyens et petits produits par des plantes à croissance indéterminée : économie de l'investissement en semences et assurance de meilleure régularité de récolte. Les principaux types variétaux cultivés en Haïti sont décrits, ainsi que les meilleures lignées qui en ont été tirées. Des croisements simples ou complexes faisant intervenir soit exclusivement des lignées haïtiennes, soit aussi des variétés provenant d'autres pays, ont permis d'obtenir des lignées améliorées, intéressant non seulement Haïti, mais cultivables également en Afrique et dans le Midi de la France.The value of common bean (Phaseolus vulgaris L) lines isolated in Haiti for bean varietal improvement. Dry beans and peas belonging to Phaseolus, Vigna, Cajanus and Lablab spp are an important constituent of the diet in Haiti. Of these, the common bean (Phaseolus vulgaris L) is cultivated on a widespread scale and is the most popular legume. No doubt for historic, sociological and agricultural reasons common beans grown in Haiti are extremely heterogeneous as regards growth habit, seed size and color, but have in common earliness and indifference to photoperiodicity. Haitian farmers grow mixtures of large beans (produced by dwarf plants), and medium-sized or small beans (produced by plants with indeterminate growth) for seed input saving, and to ensure yield regularity. From beans bought in the markets, or from superior plants chosen in the fields several hundred lines were extracted, 50 of which were preserved after severe elimination had been carried out in Guadeloupe (FWI) for powdery mildew susceptibility at the seedling stage or in southern France for summer heat or common mosaic susceptibility. The principal common bean categories grown in Haiti and the best lines found in each category are described: - large kidney-shaped beans (most of them mottled red) produced by dwarf plants (4 lines are described); - large ovoid beans (most of them mottled red) produced by dwarf plants (1 line described); - medium-sized black beans, produced by plants with indeterminate growth (4 lines described); - small-sized beans of various colors, produced by plants with indeterminate growth (4 lines described); - small-sized uniform red beans produced by plants which become climbing under good fertilization (one line described). Crosses were made in order to obtain still better lines for use in Haiti (and other countries), with tolerance to leaf diseases (such as powdery mildew, rust, and Isariopsis, Chaetoseptoria, Cercospora and Entyloma leaf spots), which in Haiti could result in a yield of 1 t/ha instead of 0.5, with 0.30.30 fertilization, but without fungicide sprays. The general objective was to propose to the farmers a "superior mixture" of the best lines. The programs were as follows: large mottled red-kidney-shaped beans; black beans; small pink or red-mottled beans (the best lines obtained, such as "Salagnac 90" for the first program, have been described). A fourth program aimed at obtaining fresh shell-beans for the FWI: red beans, red or red-striated pods (dwarf or climbing lines following the use in various seasons). Most of these breeding programs involved breeding generations alternated between different climates: Haiti/southern France, Haiti/Guadeloupe, or Haiti/southern France/Guadeloupe. As a consequence of the earliness and day-neutral behaviour of the germplasm used, and also possibly the alternated generations system utilized, the lines resulting from these programs show a wide climatic adaptation. Good results were obtained in some parts of Africa (the highlands of Comoro and the Réunion islands; Burkina-Faso), and southern France where most of them are easily grown and have a satisfactory yield

Sensibilité aux Pythium et mauvaise germination en sol froid chez le haricot (Phaseolus vulgaris L)

Les manques à la levée observés sur haricot en semis précoce au printemps sont principalement dus aux attaques de Pythium. D'importantes différences de sensibilité peuvent être mises en évidence entre variétés par des méthodes de contamination les mettant en présence de souches de Pythium douées de divers niveaux d'agressivité. Les variétés à grain coloré sont, de façon générale, moins sensibles que celles à tégument incolore, et parmi celles-ci les flageolets verts sont les plus sensibles. L'étude de la descendance d'un croisement (noir résistant x flageolet vert) met en évidence l'effet sensibilisant de 2 gènes récessifs, l'un conditionnant l'absence de coloration, l'autre le caractère «flageolet». Cependant, il y a aussi des différences de sensibilité entre variétés à grains noirs. Les variétés plus sensibles exsudent plus de sucres et de composés azotés en cours de germination, leurs téguments sont moins riches en leuco-anthocyanes. L'aptitude physiologique à germer et à croître à basse température intervient également dans la réussite des semis précoces. Elle a fait, elle aussi, l'objet d'une étude variétale qui met en évidence les qualités de la variété Vernandon.Pythium susceptibility and germination failure in common beans (Phaseolus vulgaris) sown in cold soils. Bean growers and the canning industry would appreciate the improved success of early sowings of common beans, which are frequently damaged by Pythium spp. Twenty strains were collected and classified for agressivity and taxonomy: P ultimum (most of them very agressive), P sylvaticum (most of them fairly agressive), and palmatecoralloid strains, which are weakly agressive. Laboratory methods are described for inoculation of bean seeds with Pythium, analysis of bean seed exudates and estimation of leucoanthocyanin content of the seed coat. Significant differences in Pythium susceptibility could be demonstrated between bean cultivars. Black beans, and also some red, buff-colored and mottled beans were more resistant than white ones, amongst which differences in susceptibility could be demonstrated by the use of weakly aggressive Pythium strains. The highest susceptibility occured for the French flageolet vert cultivars. A study of the progeny of a cross between PI226895 (the most resistant black bean) and Elsa (a 'flageolet vert) demonstrate the increases in susceptibility caused by the 2 recessive genes inducing the absence of coloration and flageolet quality. High levels of resistance could be found in buff-colored as well as in black-seeded lines in the progeny of this cross. At the biochemical level susceptibility is associated wtih high level of soluble substances (sugars, nitrogen compounds) in seed exudates during imbibition, low content in leucoanthocyanins, and seed coat thinness. The pleiotropic influence of the gene (p) on all these characters could be demonstrated by the study of white mutants of the black-seeded cultivars PI226895 and Aiguillon. Some discrepancies could appear between ranking for Pythium susceptibilities in experiments with 10 d incubation at 11 °C and ranking for these biochemical characters. They could be linked to differences in physiological ability to germinate and grow at low temperatures. These differences were also studied: the best cultivar found for this character was Vernandon. Integration of control measures has been discussed. Even the low levels of resistance which can be bred for white-seeded lines can be improved by seed treatment with low amounts of fungicides. White-seeded cultivars are preferred by the snap bean canning industry. The water in the snap bean cans is blue-gray with black-seed cultivars. Light-buff colored resistant lines can be bred, resulting in a less unpleasant water coloration in the cans

A new source of resistance to bacterial wilt of eggplants obtained from a cross: Solanum aethiopicum L × Solanum melongena L

As the eggplant hybrid F1 Kalenda no longer showed enough resistance to Pseudomonas solanacearum EF Smith in Guadeloupe and Martinique (French West Indies), a new breeding program was undertaken using Solanum aethiopicum as source of resistance. Despite sterility problems encountered during the first generations, selection was conducted under an artificial inoculation test according to a recurrent selection scheme including backcrosses by Solanum melongena. From the second backcross it was possible to obtain families with a high level of resistance to bacterial wilt, as well as a wide variation in the shape and colour of the fruits.Une nouvelle source de résistance au flétrissement bactérien obtenue à partir d'un croisement entre Solanum aethiopicum L et Solanum melongena L. Un nouveau programme de sélection d'aubergines utilisant Solanum aethiopicum L comme source de résistance à Pseudomonas solanacearum EF Smith a été lancé en Guadeloupe et en Martinique; l'hybride F1 Kalenda ne manifestant plus une résistance suffisante. La sélection a pu être réalisée malgré d'importants problèmes de stérilité rencontrés pendant les premières générations. Elle fut conduite généralement sous inoculation artificielle selon un modèle de sélection récurrente avec des phases de backcross par Solanum melongena L. Après le second backcross, il fut possible de sélectionner des familles manifestant un haut degré de résistance à la bactérie et possédant une très large variabilité pour la forme et la coloration du fruit