The need to boost agricultural production in the coming decades in a climate change scenario requires new approaches for the development of new crop varieties that are more resilient and more efficient in the use of resources. Crop wild relatives (CWRs) are a source of variation for many traits of interest in breeding, in particular tolerance to abiotic and biotic stresses. However, their potential in plant breeding has largely remained unexploited. CWRs can make an effective contribution to broadening the genetic base of crops and to introgressing traits of interest, but their direct use by breeders in breeding programs is usually not feasible due to the presence of undesirable traits in CWRs (linkage drag) and frequent breeding barriers with the crop. Here we call for a new approach, which we tentatively call 'introgressiomics', which consists of mass scale development of plant materials and populations with introgressions from CWRs into the genetic background of crops. Introgressiomics is a form of

Tomato spotted wilt virus (TSWV) causes severe economic losses in many crops worldwide and often overcomes resistant cultivars used for disease control. Comparison of nucleotide and amino acid sequences suggested that tomato resistance conferred by the gene Sw-5 can be overcome by the amino acid substitution C to Y at position 118 (C118Y) or T120N in the TSWV movement protein, NSm. Phylogenetic analysis revealed that substitution C118Y has occurred independently three times in the studied isolates by convergent evolution, whereas the substitution T120N was a unique event. Analysis of rates of non-synonymous and synonymous changes at individual codons showed that substitution C118Y was positively selected.Tomato spotted wilt virus (TSWV) is one of the most economically important plant viruses and causes damage in many agronomic crops worldwide (Adkins, 2000). TSWV is the type member of the genus Tospovirus, which contains the only plant-infecting members of the family Bunyaviridae. The genome consists of three negative-sense or ambisense RNA segments: segment L encodes a putative RNAdependent RNA polymerase (de Haan et al., 1991); segment M encodes the cell-to-cell movement protein, NSm (Li et al., 2009), and the precursor of the surface glycoproteins, G N / G C , involved in TSWV transmission by thrips (Sin et al., 2005;Naidu et al., 2008); and segment S encodes a silencing suppressor, NSs (Takeda et al., 2002), and the nucleocapsid, N (de Haan et al., 1990).Controlling TSWV in crop plants has proven difficult because of the wide range of plant hosts (.1000 species) and effective spread of TSWV by thrip vectors (Hanssen et al., 2010). Intense efforts have been made around the world to obtain genetically resistant cultivars against TSWV. Only the dominant genes Sw-5 and Tsw introgressed in tomato (Lycopersicon esculentum, 5Solanum lycopersicum) and pepper (Capsicum annuum) cultivars, respectively, have been found to confer resistance to a wide spectrum of TSWV isolates; they have been deployed in commercial cultivars worldwide. Sw-5 is also effective against two other tospoviruses, Tomato chlorotic spot virus (TCSV) and Groundnut ringspot virus (GRSV) (Soler et al., 2003). However, Sw-5 resistance-breaking (SRB) isolates have been detected in Hawaii, Australia, South Africa, Spain and Italy (Cho et al., 1996;Thompson & van Zijl, 1996;Latham & Jones, 1998;Aramburu & Martí, 2003;Ciuffo et al., 2005) and Tsw resistance-breaking (TRB) isolates have been detected in Brazil, USA, Italy, Spain and Australia (Boiteux et al., 1993;Hobbs et al., 1994;Roggero et al., 2002; Margaria et al., 2004;Sharman & Persley, 2006).Understanding the molecular mechanisms linked to resistance breakdown and the evolutionary processes involved in the emergence of resistance-breaking isolates is a major challenge. This is relevant to the development of more durable and efficient resistance, which would certainly have a considerable economic impact on agriculture. Since a reverse-genetics system based on infectious cDNA clones is not availab...

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Cannabis sativa L. is cultivated for its fiber or seeds (var. sativa; hemp), or for its high content in cannabinoids (var. indica; marijuana). Knowledge of the genetic structure of C. sativa var. indica is important for selection and breeding of cultivars with medicinal interest. We used six genomic SSRs (gSSRs) for genotyping 154 individual plants of 20 cultivars of C. sativa var. indica, plus two cultivars of C. sativa var. sativa. A very high polymorphism was observed, with an average of 17 alleles and 23.8 genotypes per locus. Expected (He) and observed (Ho) heterozygosities were high, with average values of 0.753 and 0.429, respectively. In some cultivars He and Ho presented similar values, while in others He was considerably higher than Ho suggesting that consanguinity and fixation had taken place during its development. In addition, some cultivars had a reduced number of alleles per locus (in some cases only two) indicating that a genetic bottleneck had taken place during its development. Gene flow (Nm) between both botanical varieties was high, with Nm=1.736. The molecular analysis of variance (AMOVA) revealed that only 31.94% of the molecular variation observed was caused by differences among cultivars, while the variation among plants of the same cultivar was of 37.11%, and within individual variation, due to heterozygosity, was of 30.96%. This indicates that a large variation exists within cultivars, which can be exploited for selection, but also complicates germplasm management and regeneration. The population structure analysis identified 14 genetic clusters, with most individuals of a single cultivar clustering together. This analysis, together with UPGMA cluster analysis shows that the two C. sativa var. sativa cultivars studied are differentiated from C. sativa var. indica, and that some cultivars of C. sativa var. indica seem to represent different selections from a common original cultivar. Our results represent the first comprehensive study of intra-3 varietal diversity in C. sativa var. indica and provide information of relevance for selection, breeding, and germplasm conservation, as well as for forensic studies in this crop.