ResumoNo período, de janeiro a março de 2005, foi desenvolvido um experimento em abrigo telado para avaliar o efeito de fontes e níveis de salinidade sobre a emergência e desenvolvimento inicial de plântulas de mamão Havaí cv. Sunrise Solo. Os tratamentos foram distribuídos em delineamento inteiramente casualizado, em esquema fatorial 3×5, correspondente a três fontes (água salina de barragem (AS), água concentrada em cloreto de sódio (NaCl) e água rica em sulfato de sódio (Na 2 SO 4 ) e cinco níveis de salinidade (0,4; 2,0; 4,0; 6,0 e 8,0 dS m -1 ) em cinco repetições. Aos 60 dias após a emergência foram avaliadas as seguintes variáveis: Condutividade elétrica do extrato de saturação do solo (CEes), % de emergência de sementes, altura de plantas, diâmetro caulinar na altura do colo e biomassa seca de parte aérea e raízes. A CEes do substrato foi elevada, independentemente da fonte utilizada, com maior expressividade para a água de barragem, e as variáveis de crescimento vegetativo avaliadas foram inibidas, independentemente da fonte utilizada, com o incremento da salinidade da água de irrigação. Palavras-chave: Carica papaya L, propagação, água de barragem, cloreto de sódio, sulfato de sódio AbstractFrom January to March of 2005 one experiment was developed in a screen house to evaluate the effect of sources and levels of water salinity on emergence and initial development of papaya seedlings cv. Sunrise Solo. A completely randomized experimental design was used and treatments were distributed in a factorial arrangement 3×5, corresponding to three sources (dam water, water salinized with sodium and water salinized with sodium sulfate) and five water saline levels (0.4; 2.0; 4.0; 6.0 e 8.0 dS.m -1 ) and five replications. At 60 days after seedling emergence the following variables were evaluated: soil electrical conductivity, seedling emergence, plant height, stem diameter and dry mass of shoots and roots. The soil electrical conductivity increased independently of salt source, with more expressiveness for dam water, and all evaluated variables of plant growth were inhibited with water salinity increase.

We have isolated and characterized a complete retrotransposon sequence, named PpRT1, from the genome of Pinus pinaster. PpRT1 is 5,966 bp long and is closely related to IFG7 gypsy retrotransposon from Pinus radiata. The long terminal repeats (LTRs) have 333 bp each and show a 5.4% sequence divergence between them. In addition to the characteristic polypurine tract (PPT) and the primer binding site (PBS), PpRT1 carries internal regions with homology to retroviral genes gag and pol. The pol region contains sequence motifs related to the enzymes protease, reverse transcriptase, RNAseH and integrase in the same typical order known for Ty3/gypsy-like retrotransposons. PpRT1 was extended from an EST database sequence indicating that its transcription is occurring in pine tissues. Southern blot analyses indicate however, that PpRT1 is present in a unique or a low number of copies in the P. pinaster genome. The differences in nucleotide sequence found between PpRT1 and IFG7 may explain the strikingly different copy number in the two pine species genome. Based on the homologies observed when comparing LTR region among different gypsy elements we propose that the highly conserved LTR regions may be useful to amplify other retrotransposon sequences of the same or close retrotransposon family.

Abstract• Relatedness among parents, variation in clonal fertility and background pollination deviate the realized genetic gain and the gene diversity of open pollinated seed orchard from expectation, in particular in wind pollinated species such as Pinus pinaster Aiton.• This work investigates the genetic variation, the mating system and the pollen contamination in a P. pinaster clonal seed orchard (CSO), by screening the 60 clones from the CSO and the seeds collected from 21 mother-trees with three nuclear microsatellites.• The expected diversity was similar, but the observed heterozygosity decreased 20% in the progenies compared with the parental trees. The outcrossing rate was 90.1%, the biparental inbreeding 21.7% computed through a multilocus approach, and the observed selfing 3.9%. The observed gene flow from outside the CSO was 52.4%.• From the results we concluded that the observed gene flow and the biparental inbreeding were high, and care should be taken in the implementation and management of future CSO, in particular clones should be checked for relatedness and the ramet number could be directly proportional to their breeding value. • L'apparentement entre parents, la variation de fertilité entre clones et la pollution pollinique font dévier le gain génétique réalisé et la diversité génétique des valeurs attendues en verger à graines de clones à pollinisation libre, en particulier pour une espèce à pollinisation anémophile comme Pinus pinaster Aiton. Mots-clés• Ce travail étudie la variation génétique, le système de reproduction et la contamination du pollen d'un verger à graines de clones (VGC) de P. pinaster, en génotypant les 60 clones du VGC et les graines récoltées sur 21 arbres-mères pour trois marqueurs microsatellites nucléaires.• La diversité attendue s'est révélée similaire mais l'hétérozygotie observée a diminué de 20 % chez les descendants par rapport aux parents. Le taux d'allofécondation était de 90,1 %, la consanguinité biparentale calculée grâce à une approche multilocus était de 21,7 % et le taux d'autofécondation observé était de 52,4 %.• D'après ces résultats, nous avons conclu que les flux de gènes observés et la consanguinité biparentale étaient élevés et que des précautions devaient être prises dans la mise en place et la gestion de futurs VGC, l'apparentement entre clones devrait en particulier être vérifié et le nombre de copies d'un individu pourrait être directement proportionnel à sa valeur génétique.