Seleção recorrente para produtividade e qualidade de frutos em abobrinha braquítica

Considerando-se que abobrinha (Cucurbita moschata) geralmente não apresenta perda de vigor pela endogamia, a seleção recorrente pode ser um método adequado para o melhoramento desta espécie. O objetivo deste trabalho foi avaliar a eficiência da seleção recorrente em abobrinha, cultivar Piramoita, visando aumento de produtividade e melhoria da qualidade de frutos. Foram realizados três ciclos de seleção recorrente a partir da cultivar Piramoita (população P0), com avaliação e seleção de progênies S1. Em todos os ciclos de seleção, os experimentos foram conduzidos em blocos ao acaso, com parcelas de cinco plantas, tendo a cultivar Piramoita como testemunha. O espaçamento foi de 2,0 x 1,0 m. Após cada ciclo de seleção, as sementes remanescentes das progênies selecionadas foram empregadas no ciclo seguinte de recombinação, cada progênie contribuindo em média com dez plantas tomadas ao acaso. As quatro populações (P0, PI, PII e PIII) foram avaliadas em blocos ao acaso, com oito repetições de cinco plantas por parcela. Foram avaliados número e massa total e comercial (retos, com pescoço comprido e sem defeitos aparentes) de frutos imaturos por planta e a proporção de frutos comerciais. Foram realizadas as análises de variância e regressão. Foram observados aumentos de produção lineares significativos ao longo dos ciclos de seleção. Na população PIII, os números de frutos total (17) e comercial (11) por planta, assim como a massa total (3,7) e comercial (2,6 kg planta-1), superaram a população inicial em 32, 63, 24 e 57%, respectivamente. Essas diferenças correspondem a um aumento superior a 11 t ha-1 ou mais de 36.000 frutos ha-1 em apenas três ciclos de seleção recorrente.Since squash (Cucurbita moschata) usually does not have inbreeding depression, recurrent selection may be an adequate method for squash breeding. In this study the recurrent selection efficiency was evaluated in squash, cultivar Piramoita, aiming to improving fruit yield and quality. Three generations were produced out of cultivar Piramoita (population P0), with evaluation and selection of S1 progenies. In all selection cycles, experiments were set up in randomized blocks design, with five plants per plot, with cultivar Piramoita as control. Spacing was 2.0 x 1.0 m. After each cycle, the remaining seeds of selected progenies were used in the following cycle of recombination, and each progeny was represented, on average, by ten random plants. The four populations (P0, PI, PII and PIII) were evaluated in randomized blocks design, with eight replicates and five-plant plots. Number and weight of total and commercial (straight fruits, with long neck and without visible defects) fruits per plant and the rate of commercial fruits were evaluated. Variance and regression analysis was performed and indicated a linear increase in yield due to selection cycles. In population PIII, total (17) and commercial (11) fruit number plant-1, and total (3.7) and commercial (2.6 kg) weight of fruits plant-1, overcame initial population in 32; 63; 24, and 57%, respectively. These differences correspond to an increase larger than 11 t ha-1 or more than 36000 fruits ha-1 in only three recurrent selection cycles

Geographic origin and taxonomic status of the invasive Privet, <i>Ligustrum robustum</i> (Oleaceae) in the Mascarene Islands, determined by chloroplast DNA and RAPDs.

Information concerning the area of origin, genetic diversity and possible acquisition of germplasm through hybridisation is fundamental to understanding the evolution, ecology and possible control measures for an introduced invasive plant species. Among the most damaging of alien plants that are invading and degrading native vegetation in the Mascarene Islands of the Indian Ocean is the Tree Privet, Ligustrum robustum. Exact information about the geographic source of introduced material of this species is lacking, in part because Ligustrum is a taxonomically difficult genus. Native material of L. robustum ssp. walkeri from Sri Lanka, L. robustum ssp. robustum from northeastern India, and the closely related L. perrottetii from southern India was compared with introduced material from La Reunion and Mauritius using chloroplast DNA RFLP markers and random amplified polymorphic DNA (RAPDs). Sri Lankan and introduced material was monomorphic for the same cpDNA haplotype that was absent from south and northeast Indian Ligustrum. Sri Lankan and introduced material was also clearly distinguished from Indian Ligustrum by RAPDs. It was concluded that material introduced and established in the Mascarene Islands is derived from the Sri Lankan subspecies L. robustum ssp. walkeri. No geographic structuring of genetic variation within Sri Lanka was detected for this taxon, so the location(s) within Sri Lanka from which introduced material is derived could not be pinpointed. RAPDs indicate that L. robustum ssp. walkeri in Sri Lanka is more similar to south Indian L. perrottetii than to northeast Indian L. robustum ssp. robustum. Moreover, RAPDs showed that introduced material in La Reunion has undergone little or no loss of genetic diversity since introduction. However, there was no evidence that it is introgressed with germplasm from two other alien Ligustrum species present on La Reunion.</p

Large-scale parentage analysis in an extended set of grapevine cultivars (Vitis vinifera L.).

Inheritance of nuclear microsatellite markers (nSSR) has been proved to be a powerful tool to verify or uncover the parentage of grapevine cultivars. The aim of the present study was to undertake an extended parentage analysis using a large sample of Vitis vinifera cultivars held in the INRA "Domaine de Vassal" Grape Germplasm Repository (France). A dataset of 2,344 unique genotypes (i.e. cultivars without synonyms, clones or mutants) identified using 20 nSSR was analysed with FAMOZ software. Parentages showing a logarithm of odds score higher than 18 were validated in relation to the historical data available. The analysis first revealed the full parentage of 828 cultivars resulting in: (1) 315 original full parentages uncovered for traditional cultivars, (2) 100 full parentages confirming results established with molecular markers in prior papers and 32 full parentages that invalidated prior results, (3) 255 full parentages confirming pedigrees as disclosed by the breeders and (4) 126 full parentages that invalidated breeders' data. Second, incomplete parentages were determined in 1,087 cultivars due to the absence of complementary parents in our cultivar sample. Last, a group of 276 genotypes showed no direct relationship with any other cultivar in the collection. Compiling these results from the largest set of parentage data published so far both enlarges and clarifies our knowledge of the genetic constitution of cultivated V. vinifera germplasm. It also allows the identification of the main genitors involved in varietal assortment evolution and grapevine breeding

Genetic diversity and parentage of Tunisian wild and cultivated grapevines (Vitis vinifera L.) as revealed by single nucleotide polymorphism (SNP) markers

Based on 261 single nucleotide polymorphism (SNP) markers, we analyzed 57 grapevine genotypes, consisting of 29 wild grapevines (Vitis vinifera subsp. sylvestris) prospected from the northwest part of Tunisia and 28 cultivated accessions (V. vinifera subsp. vinifera) maintained in the repository of the Arid Land Institute of Medenine (Tunisia). Pair-wise multilocus comparison with the ICVV SNP database allowed the identification of 13 cultivated genotypes, including ten synonymous groups with known Mediterranean or international varieties, three cases of color sports, and two misnomers. Genotypic analysis showed a high level of genetic diversity for both wild and cultivated groups. Multivariate and structure analyses clearly differentiated wild from cultivated grapevines and showed high average posterior probabilities of assignment to their group of origin. The clustering results largely supported the perceived classification and reflect that most of the present Tunisian cultivated varieties do not derive directly from the local wild populations but could correspond to materials introduced from different locations during historical times. Parentage analysis allowed the determination of the genetic origin of four Tunisian cultivars, "Garai", "Jerbi" (from Kerkennah), "Mahdoui", and "Reine de Vignes faux", and showed that "Heptakilo" and "Planta Fina", two old and widely distributed varieties in the Mediterranean basin, had an important role in the origin of Tunisian grapevines. The present study demonstrates the efficacy of SNP makers for germplasm characterization and genetic studies in grapevine. © 2014 Springer-Verlag Berlin Heidelberg