Peanut, Arachis hypogaea L., is a protein-rich species consumed worldwide. A key improvement to peanut culture involves the development of cultivars that resist fungal diseases such as rust, leaf spot and scab. Over three years, we evaluated fungal resistance under field conditions of 43 wild accessions and three interspecific hybrids of the genus Arachis, as well as six A. hypogaea genotypes. In the first year, we evaluated resistance to early and late leaf spot, rust and scab. In the second and third years, we evaluated the 18 wild species with the best resistance scores and control cultivar IAC Caiapó for resistance to leaf spot and rust. All wild accessions displayed greater resistance than A. hypogaea but differed in their degree of resistance, even within the same species. We found accessions with as good as or better resistance than A. cardenasii, including: A. stenosperma (V15076 and Sv 3712), A. kuhlmannii (V 6413), A. kempff-mercadoi (V 13250), A. hoehnei (KG 30006), and A. helodes (V 6325). Amphidiploids and hybrids of A. hypogaea behaved similarly to wild species. An additional four accessions deserve further evaluation: A. magna (V 13751 and KG 30097) and A. gregoryi (V 14767 and V 14957). Although they did not display as strong resistance as the accessions cited above, they belong to the B genome type that is crucial to resistance gene introgression and pyramidization in A. hypogaea.

The narrow genetics of most crops is a fundamental vulnerability to food security. This makes wild crop relatives a strategic resource of genetic diversity that can be used for crop improvement and adaptation to new agricultural challenges. Here, we uncover the contribution of one wild species accession, Arachis cardenasii GKP 10017, to the peanut crop (Arachis hypogaea) that was initiated by complex hybridizations in the 1960s and propagated by international seed exchange. However, until this study, the global scale of the dispersal of genetic contributions from this wild accession had been obscured by the multiple germplasm transfers, breeding cycles, and unrecorded genetic mixing between lineages that had occurred over the years. By genetic analysis and pedigree research, we identified A. cardenasii–enhanced, disease-resistant cultivars in Africa, Asia, Oceania, and the Americas. These cultivars provide widespread improved food security and environmental and economic benefits. This study emphasizes the importance of wild species and collaborative networks of international expertise for crop improvement. However, it also highlights the consequences of the implementation of a patchwork of restrictive national laws and sea changes in attitudes regarding germplasm that followed in the wake of the Convention on Biological Diversity. Today, the botanical collections and multiple seed exchanges which enable benefits such as those revealed by this study are drastically reduced. The research reported here underscores the vital importance of ready access to germplasm in ensuring long-term world food security.

RESUMONa cultura do algodoeiro, Gossypium hirsutum L., o pulgão Aphis gossypii Glover, 1877 (Hemiptera: Aphididae) destaca-se pela transmissão do vírus do mosaico-das-nervuras do algodoeiro. O objetivo deste trabalho foi avaliar a persistência da transmissão desse vírus por A. gossypii e determinar o período necessário para sua inoculação. No ensaio de persistência, 20 pulgões ápteros virulíferos foram individualizados e transferidos diariamente para plantas de algodoeiro sadias. O período necessário para inoculação foi determinado em adultos ápteros e alados virulíferos, que permaneceram confinados isoladamente em plantas sadias por períodos de 40 segundos, 45 minutos, 1,5 hora, 3, 6, 12, 24 e 48 horas. Observou-se que 35% dos pulgões transmitiram o vírus por mais de cinco plantas sucessivamente, no ensaio de persistência. Verificouse transmissão por um período máximo de 12 dias após a aquisição, o que caracteriza a relação vírus-vetor como persistente. Os adultos ápteros transmitiram o vírus para maior percentual de plantas (75,0%) quando o período de acesso à inoculação foi de 24 horas. Os alados transmitiram o vírus em todos os períodos de acesso à inoculação, com porcentagens variando de 5,0% (40 segundos) a 60,0% (48 horas). A persistência da transmissão do vírus pelo pulgão e o aumento na eficiência de transmissão em função do aumento do período de acesso à inoculação revelam que a transmissão é do tipo circulativa.Palavras-chaves: Gossypium hirsutum, Cotton leafroll dwarf virus, afídeo, interação vírus-vetor, doença azul. ABSTRACT CHARACTERIZATION OF THE COTTON VEIN MOSAIC VIRUS BY APHIS GOSSYPII TRANSMISSION WITH RELATION TO PERSISTENCE AND TIME NECESSARY FOR INOCULATIONIn cotton crops (Gossypium hirsutum L.), the aphid Aphis gossypii Glover, 1877 (Hemiptera: Aphididae) is a major sanitary factor due forts efficiency on transmission of cotton vein mosaic virus (CVMV). The objective of this work was to evaluate the persistence of CVMV on transmission by A. gossypii and to determine the necessary feeding period for inoculation. In the persistence assay, individual aphids wingless viruliferous were separately transferred daily to successive series of healthy plants. The necessary period for inoculation was determined in individual winged and wingless adults viruliferous that were confined in healthy plants for different periods (40 s, 45 min, 1.5 h, 3.0 h, 6.0 h, 12.0 h, 24.0 h and 48.0 h). In the persistence assay, 35% of total aphids transmitted the virus for more that five plants. Transmission for a maximum period of 12 days was verified after the acquisition, thus characterizing the relation virus-vector as persistent. The viruliferous wingless adults transmitted the virus from 1.50 h (5.0% of plants) and attain the maximum percentage in inoculation access period of the 24 h (75.0%). The viruliferous winged adults transmitted in all inoculation access periods, with maximum transmission in period of the 48 h (60.0%). The persistence mode of transmission of CVMV by aphid and the increased efficiency of t...

This study aimed to determine the levels of fumonisins produced by Fusarium verticillioides and FUM gene expression on Bt (Bacillus thuringiensis) and non-Bt maize, post harvest, during different periods of incubation. Transgenic hybrids 30F35 YG, 2B710 Hx and their isogenic (30F35 and 2B710) were collected from the field and a subset of 30 samples selected for the experiments. Maize samples were sterilized by gamma radiation at a dose of 20 kGy. Samples were then inoculated with F. verticillioides and analyzed under controlled conditions of temperature and relative humidity for fumonisin B1 and B2 (FB1 and FB2) production and FUM1, FUM3, FUM6, FUM7, FUM8, FUM13, FUM14, FUM15, and FUM19 expression. 2B710 Hx and 30F35 YG kernel samples were virtually intact when compared to the non-Bt hybrids that came from the field. Statistical analysis showed that FB1 production was significantly lower in 30F35 YG and 2B710 Hx than in the 30F35 and 2B710 hybrids (P < 0.05). However, there was no statistical difference for FB2 production (P > 0.05). The kernel injuries observed in the non-Bt samples have possibly facilitated F. verticillioides penetration and promoted FB1 production under controlled conditions. FUM genes were expressed by F. verticillioides in all of the samples. However, there was indication of lower expression of a few FUM genes in the Bt hybrids; and a weak association between FB1 production and the relative expression of some of the FUM genes were observed in the 30F35 YG hybrid.