Abstract ‘IAC Sempre Verde’ is a medium-seeded runner-type peanut highly resistant to late leaf spot and rust, the main diseases in peanut cultivation in Brazil. The newly released cultivar showed remarkable yield advantage over controls when diseases were not controlled and represents the first possibility for peanut cultivation under “Organic” management.

Abstract Peanut is a crop of the Kayabi tribe, inhabiting the Xingu Indigenous Park, Brazil. Morphological analysis of Xingu accessions showed variation exceeding that described for cultivated peanuts. This raised questions as to the origin of the Xingu accessions: are they derived from different species, or is their diversity a result of different evolutionary and selection processes? To answer these questions, cytogenetic and genotyping analyses were conducted. The karyotypes of Xingu accessions analyzed are very similar to each other, to an A. hypogaea subsp. fastigiata accession and to the wild allotetraploid A. monticola. The accessions share the number and general morphology of the chromosomes; DAPI+ bands; 5S and 45S rDNA loci distribution and a high genomic affinity with A. duranensis and A. ipaënsis genomic probes. However, the number of CMA3+ bands differs from those determined for A. hypogaea and A. monticola, which are also different from each other. SNP genotyping grouped all Arachis allotetraploids into four taxonomic groups: Xingu accessions were closer to A. monticola and A. hypogaea subsp. hypogaea. Our data suggests that the morphological diversity within these accessions is not associated with a different origin and can be attributed to morphological plasticity and different selection by the Indian tribes.

Abstract BRS 425 is a high-oleic runner peanut cultivar related to wild ancestral parents, partially resistant to early and late leaf spot and spotted wilt. It is large-seeded and contains 46% oil. BRS 425 is adapted to the main peanut-producing regions of Brazil.

O maior grupo de genes de resistência de plantas já clonados codifica para proteínas com um sítio de ligação a nucleotídios (NBS) na região N-terminal, e um domínio rico em repetições de leucina (LRR) na região C-terminal. Genes desta classe conferem resistência a diversos patógenos incluindo vírus, bactérias, fungos e nematóides. Para diferentes espécies do gênero Arachis, primers de "polymerase chain reaction" (PCR) degenerados foram construídos para a região NBS, e o produto de tradução putativo indicou similaridade com proteínas de resistência conhecidas sendo denominados análogos a genes de resistência (RGAs). Doze destes RGAs foram utilizados para o desenvolvimento de marcadores moleculares baseados em seus padrões de hibridização com DNA de Arachis spp. digerido com enzimas de restrição. Inicialmente, avaliou-se o polimorfismo de cada RGA como sonda nos parentais de uma população de mapeamento, contrastantes quanto à resistência as manchas foliares e nematóides das galhas, e no híbrido F1. Os RGAs, mesmo isolados de espécies diferentes do gênero Arachis apresentaram homologia com o DNA das espécies testadas, além de apresentarem múltiplas cópias e alto polimorfismo na progênie F2. Todas estas características tornam estes RGAs marcadores moleculares altamente informativos, sendo que alguns apresentaram segregação em "clusters" na F2, indicando que seus locos estão ligados. Estes marcadores serão incluídos em um mapa genético de Arachis spp., o que será de grande utilidade para os programas de melhoramento do amendoim (Arachis hypogaea) cultivado.

The majority of cloned plant pathogen resistance genes (R genes) encode a putative nucleotide binding site (NBS) domain and a leucine-rich repeat (NBS-LRR genes). Genes of this NBS-LRR class confer resistance to diverse pathogens such as viruses, bacteria, fungi, nematodes and aphids. The conserved NBS domain was used to generate resistance gene analogues (RGAs) fragments by polymerase chain reaction (PCR) using degenerated primers in different Arachis species. Twelve of these RGAs were used to develop molecular markers based on their patterns of hybridisation to restricted Arachis spp. DNA. An initial step was the evaluation of the polymorphism generated by each RGA in genomic fragments of contrasting parents of a mapping population that segregates for resistance to leaf spot and nematodes, and of the F1 hybrid. The RGAs isolated from different Arachis species showed high homology to the DNA of the parents and hybrid, multiple copies in the genome and high polymorphism in the F2 generation. Therefore, they were considered highly informative markers, with some segregating in clusters in the F2. These RGAs will be included in the Arachis genetic map, which will be of paramount importance for the Arachis spp. breeding programs.

Quatro populações de Plutella xylostella (L.) (Lepidoptera: Yponomeutidae) oriundas do Brasil, Ilha da Reunião, Filipinas e Benin foram avaliadas quanto à suscetibilidade ao B. thuringiensis através de bioensaios e quanto à variabilidade genética, através de RAPD-PCR. Os dois parâmetros avaliados mostraram similaridade de resultados entre as populações, sugerindo que as mesmas devem ser bastante homogêneas, embora estejam geograficamente distantes.

Four populations of Plutella xylostella (L.) (Lepidoptera: Yponomeutidae) isolated in Brazil, Reunion Island, Philippines and Benin were evaluated for susceptibility to B. thuringiensis. Genetic variability was accessed by RAPD analysis. Although the populations were originated from diverse geographical origins, the two evaluated parameters showed a high degree of similarity. This suggests that although the populations were geographically distant, they have a high degree of similarity.

O gênero Diadegma compreende espécies que são parasitóides de larvas da traça-das-crucíferas Plutella xylostella, uma das mais importantes pragas das plantas da família Brassicacea. Este gênero possui distribuição mundial. Neste trabalho, três populações de Diadegma spp. oriundas de diferentes países (Brasil, Ilha da Reunião e Malásia) foram caracterizadas geneticamente por meio da técnica de RAPD-PCR. Não foi constatada variabilidade intra-populacional, no entanto o alto coeficiente de similaridade entre populações sugeriram que esses insetos poderiam pertencer a espécies diferentes.

The genus Diadegma has species that are parasitoids of larvae of diamondback moth, Plutella xylostella, one of the most important pests of Brassicacea. This genus has a worldwide distribution. Representative samples of three Diadegma populations from Brazil, Reunion Island and Malaysia were characterized by RAPD-PCR. No intra-population variability was found. However, the high coefficient of genetic similarity between the populations suggests that they could belong to different species.