Eggplant (Solanum melongena L.) is a widely cultivated vegetable in India with enormous variability. Recent molecular techniques revealed three closely related but distinct Solanum species (S. melongena, S. incanum and S. insanum), with the Indian subcontinent being a domesticated centre. Spontaneous hybridization between S. insanum and S. melongena has led to the formation of naturally introgressed lines and limited studies are available to differentiate these genotypes using morphological key traits. Current study aimed to delineate naturally introgressed genotypes of Indian eggplant collections using morphological key traits for plant genetic resources (PGR) management and assess available genetic diversity. The study characterized a collection of 157 eggplant germplasm at ICAR-NBPGR, Regional Station, Kerala, and identified 30 naturally introgressed, 10 wild progenitors and 117 cultivated eggplants. The key morphological traits are prickliness (stem, petiole, calyx and pedicle), leaf base shape, fruit shape and size. Other fruit traits such as length, breadth and mesocarp texture could also provide some clues for delineating introgressed genotypes from S. insanum and S. melongena. Basic statistical analysis of six quantitative traits of 157 eggplant genotypes revealed the presence of considerable amount of variation (CV%) in which fruit length/breadth ratio showed higher variation (73.87) followed by fruit length (54.73) and average fruit weight (53.5). The frequency distribution of 14 qualitative traits revealed the presence of all character states among them. Key traits identified under study could provide clues to identify individual plants at field level to plant taxonomist/explorers and also to aid gene bank curators for PGR management.

Thailand’s northeast (NE) region is an area of high-quality cultivated rice (Oryza sativa L.) production. However, an outbreak of weedy rice has recently spread throughout the region. Weedy rice is phenotypically and morphologically similar to cultivated rice, making identification difficult. The prospective management of weedy rice in the future will involve the study of its genetic diversity and population structure in this region. This study assesses the genetic diversity and population structure of 380 weedy rice samples in the northeast of Thailand through simple sequence repeat (SSR) markers. Thirty-one SSR markers generated 213 alleles with an average of 6.87 per locus and an overall genetic diversity of 0.723. Based on its geographic origin, weedy rice in the Southern NE are showed greater genetic diversity than that in the Central NE and Northern NE areas. The outcrossing rate in all regions was relatively high, with the highest being in the Southern NE at 9.769%. According to genetic distance analysis, the clustering of weedy rice samples in northeast Thailand was not associated with the geographic region. Neighbor-joining and principal coordinate analysis revealed that the 380 weedy rice samples fell into two major clusters. Cluster I contained three weedy rice samples and four wild. In Cluster II, 377 weedy rice samples were closely related to the four cultivated rice cultivars as well as brownbeard rice (Oryza rufipogon Griffiths) wild species. The results suggest that weedy rice in northeast Thailand may have originated as a cross between cultivated and wild rice, as seen in the closely related species, O. rufipogon. Overall, the findings of this study demonstrate the high genetic diversity of weedy rice in this region. Notably, some samples adapted, performing more like cultivated rice, which may be problematic for the future production of high-quality rice in this region. The prevention of weedy rice should, therefore, be given greater consideration in future studies.

Teosinte, the wild progenitor of maize, has immense potential for providing unique traits and is more divergent compared to inbred lines and landraces. One hundred and sixty-nine teosinte-introgressed maize backcross inbred lines were developed to widen the genetic base of maize with predomestication alleles. The population was evaluated phenotypically and genotypic data of 76 SSR markers were used to map quantitative trait loci (QTLs) governing the targeted traits. Sixty-six QTLs were detected for eight plant architect-related traits that are spread over 10 different chromosomes with phenotypic variation ranging from 2.29 to 13.97%. Maximum three stable QTLs were recorded for days to anthesis (DA) followed by two for days to silking (DS), plant height (PH) and node bearing first ear (NBE). For rest of three traits namely flag leaf length (FLL), flag leaf width (FLW) and ears per plant (E/P) only one stable QTL was detected. Among the 16 common QTLs, the marker phi328178-linked QTL governed four characters (DA, DS, FLL, FLW) simultaneously, followed by umc1622-linked (ASI, FLW, E/P), umc2341-linked (DA, DS, NBE) and phi075-linked QTLs (ASI, PH, NBE) controlling three traits each. Remaining 12 QTLs controlled two characters. Molecular association between co-localized QTLs for different traits was also validated at the phenotypic level by significant correlation estimates. For eight studied traits, 53 superior lines were identified which along with parents (teosinte and maize inbred DI-103) were grouped into 12 clusters. Therefore, lines clustered independently can be combined to accumulate desirable traits for the improvement of maize.

Soybean varieties genetically free from Kunitz trypsin inhibitor (KTI) and lipoxygenase-2 (Lox2) are desirable to increase human consumption, as the former is an antinutritional factor that affects protein digestibility while the latter is a principal contributor to off-flavour. In the present investigation, soybean genotypes free from both these undesirable components were developed by introgression of null allele of Lox2 from NRC109 (lox2lox2) into two KTI-free soybean genotypes derived from genotypes JS97-52 and NRC7. Foreground selection of plants in F1, F2, BC1F1, BC1F2, BC2F1 and BC2F2 generations developed from two cross combinations i.e. NRC7-derived KTI-free genotype (N7KTIF)×NRC109 (parental combination 1) and JS97-52 derived KTI free genotype (JKTIF)×NRC109 (parental combination 2) was performed using null allele specific markers and tightly linked simple sequence repeat (SSR) markers for both KTI and Lox2 genes for the identification of homozygous recessive (titilox2lox2) plants. Background selection was performed using 239 and 241 polymorphic SSR markers across the genome. This resulted in the development of 9 and 13 soybean lines stacked for null alleles of both KTI and Lox2 (titilox2lox2) exhibiting recurrent parent genome content more than 97 and 96%, respectively. Days-to-flowering, days-to-maturity, 100-seed weight and yield per plant of the stacked lines developed from both the parental combinations were at par with the respective recurrent parents.

Leaf pubescence is widespread among higher plants. In bread wheat, a relationship was found between this trait and the efficiency of photosynthetic processes and productivity. In this work, we established the chromosomal localization of the gene for leaf pubescence introgressed from Triticum timopheevii into a bread wheat line 821 and studied its expression in the genetic background of two wheat cultivars differing in genetic control and phenotypic expression of pubescence. To obtain quantitative characteristics of pubescence in cultivars and hybrid populations, the LHDetect2 program was used, which makes it possible to estimate the length and number of trichomes on a leaf fold. A genetic analysis showed the dominant inheritance of the gene. Monosomic analysis F2 was used to establish chromosome localization and investigate the expression of the gene in cultivars Saratovskaya S29 (S29) and Diamant 2 (Dm2). As a result, the gene Hltt, introgressed from T. timopheevii, was identified and localized in the distal region of the long arm of 5A chromosome for the first time. In both F2 populations, the gene reduced the density of trichomes and formed long trichomes, uncharacteristic for the two recipient cultivars S29 and Dm2. A larger number of long trichomes was formed in the genetic background of S29, which carry the bread wheat gene Hl1 and Hl3 for leaf pubescence, than in Dm2. Development of substitution and isogenic lines with the fragment of introgression carrying the gene Hltt will allow determining function and assessing the adaptive significance of the gene more precisely.

DNA sequence data have become a crucial tool in assessing the relationship between morphological variation and genetic and taxonomic groups, including in the Antarctic biota. Morphologically distinct populations of submersed aquatic vascular plants were observed on sub-Antarctic Marion Island, potentially representing the two species of such plants listed in the island's flora, Limosella australis R.Br. (Scrophulariaceae) and Ranunculus moseleyi Hook.f. (Ranunculaceae). To confirm their taxonomic identity, we sequenced a nuclear locus (internal transcribed spacer; ITS) and two plastid loci (trnL-trnF, rps16) from three specimens collected on Marion Island and compared the sequences with those in public sequence databases. For all three loci, sequences from the Marion Island specimens were nearly identical despite morphological dissimilarity, and phylogenetic analyses resolved them to a position in Limosella. In phylogenetic trees and comparisons of species-specific sequence polymorphisms, the Marion Island specimens were closest to a clade comprising Limosella aquatica L., L. curdieana F.Muell. and L. major Diels for ITS and closest to L. australis for the plastid loci. Cytonuclear discordance suggests a history of hybridization or introgression, which may have consequences for morphological variability and ecological adaptation.

Host shifts of parasites are often causing devastating effects in the new hosts. The Varroa genus is known for a lineage of Varroa destructor that shifted to the Western honey bee, Apis mellifera, with disastrous effects on wild populations and the beekeeping industry. Despite this, the biology of Varroa spp. remains poorly understood in its native distribution range, where it naturally parasitizes the Eastern honey bee, Apis cerana. Here, we combined mitochondrial and nuclear DNA analyses with the assessment of mite reproduction to determine the population structure and host specificity of V. destructor and Varroa jacobsonii in Thailand, where both hosts and several Varroa species and haplotypes are sympatric. Our data confirm previously described mite haplogroups, and show three novel haplotypes. Multiple infestations of single host colonies by both mite species and introgression of alleles between V. destructor and V. jacobsonii suggest that hybridization occurs between the two species. Our results indicate that host specificity and population genetic structure in the genus Varroa is more labile than previously thought. The ability of the host shifted V. destructor haplotype to spillback to A. cerana and to hybridize with V. jacobsonii could threaten honey bee populations of Asia and beyond.

To investigate the extent of suspected hybridization between the brolga Antigone rubicunda and the Australian sarus crane Antigone antigone gillae, first noted in the 1970s, we analysed the genetic diversity of 389 feathers collected from breeding and flocking areas in north Queensland, Australia. We compared these with 15 samples from birds of known identity, or that were phenotypically typical. Bayesian clustering based on 10 microsatellite loci identified nine admixed birds, confirming that Australian cranes hybridize in the wild. Four of these were backcrosses, also confirming that wild Australian crane hybrids are fertile. Genetic analyses identified 10 times more hybrids than our accompanying visual field observations. Our analyses also provide the first definitive evidence that both brolgas and sarus cranes migrate between the Gulf Plains, the principal breeding area for sarus cranes, and major non-breeding locations on the Atherton Tablelands. We suggest that genetic analysis of shed feathers could potentially offer a cost-effective means to provide ongoing monitoring of this migration. The first observations of hybrids coincided with significantly increased opportunities for interaction between the two species when foraging on agricultural crops, which have developed significantly in the Atherton Tablelands flocking area since the 1960s. As the sarus crane is declining in much of its Asian range, challenges to the genetic integrity of the Australian sarus crane populations have international conservation significance.

Although sorghum [Sorghum bicolor (L.) Moench ssp. bicolor] is the fifth most important grain crop in terms of global production, no commercial hybrids carry genetically engineered (GE) traits for resistance to insect pests or herbicides due to regulatory concerns about gene flow to weedy relatives. However, non-GE herbicide resistance currently is being developed in grain sorghum and will likely transfer to related weeds. Monitoring the impact of this new nuclear technology on the evolution and invasiveness of related weeds requires a baseline understanding of the population biology of grain sorghum genes once they transfer to in situ weed populations. We previously characterized the rate of gene flow from grain sorghum to shattercane [Sorghum bicolor (L.) Moench nothosubsp. drummondii (Steud.) de Wet ex. Davidse], a conspecific weed relatively common in North America; as well as the ecological fitness of an F1 population when S. bicolor nothosubsp. drummondii was the maternal parent. Here we report the ecological fitness of a S. bicolor nothosubsp. drummondii × S. bicolor ssp. bicolor F2 population relative to its crop and weed parents. Parental and F2 populations were grown in two Nebraska environments in 2012 and 2013. Traits evaluated included overwinter survival, field emergence, biomass production and partitioning at anthesis, total seed production, and 100-seed weight. Results indicated that F2 traits were generally intermediate between the parents, but more similar to S. bicolor nothosubsp. drummondii than to grain sorghum. The one exception was overwinter survival, which was nearly 0% for both the F2 and the grain sorghum parent in these northern environments. Thus, the frequency of crop alleles stably introgressed into S. bicolor nothosubsp. drummondii populations appears to primarily depend on overwinter survival of the F2 and which selective pressures are imposed upon it by the cropping system. These data provide needed baseline information about the environmental fate of nuclear genetic technologies deployed in this important global crop.

The two Sotalia species (the marine S. guianensis and the freshwater S. fluviatilis) have only recently been recognized, and both face several conservation challenges. We investigated the existence of hybridization between the two species in their possible area of sympatry in the Amazon Estuary, in northern Brazil. A fast and cheap PCR-RFLP diagnostic method using nuclear DNA was developed to discriminate between the two species, while allowing the detection of hybrids. All samples that could be identified (N = 51) were identified as S. guianensis, and no hybrids were detected. Our results, coupled with previous mitochondrial data, suggest that S. fluviatilis is not present in the Amazon delta. Thus, sympatry with S. guianensis, if it does occur, may be restricted to upstream areas of the Amazon River.

Herbicide resistance has been reported in several Amaranthus species throughout the U.S. Because evidence exists of interspecies hybridization in some species of this genus, this study was conducted to determine whether acetolactate synthase (ALS)-inhibiting herbicide resistance could be transferred from Amaranthus palmeri to Amaranthus rudis through interspecific crosses. Plants of each species were grown in a growth chamber, and controlled interspecies crosses were made between ALS-resistant and -susceptible plants. A total of 15 putative hybrid plants were produced from an estimated 10,000 cross-pollinated flowers. Analysis of restriction enzyme digests of the ALS gene in which a single base substitution confers resistance inferred that herbicide resistance had been transferred from a resistant male A. rudis to the hybrid plant. Offspring of hybrid plants, backcrossed to the susceptible parent, survived herbicide treatment, demonstrating that herbicide resistance was transferred between species. DNA analysis also was performed using the amplified fragment length polymorphism (AFLP) technique between parental and putative hybrid plants. Several unique bands were found only in the hybrid.

Three Italian Lolium weed populations, one susceptible and two resistant to diclofop, were characterized by the technique of inter simple sequence repeats (ISSR). The goal of this study was to taxonomically identify these Lolium populations as well as to evaluate evidence for introgression of ISSR fragments from Festuca and the potential role of this introgression in the diclofop response. ISSR analysis confirmed the genomic background of the weed populations to be consistent with that of Lolium. However, the great range of variation in ISSR banding patterns highlighted that the three ryegrass accessions are mixed populations made up of individuals resulting presumably from intrageneric and intergeneric hybridization in the Lolium–Festuca complex. Two Festuca genus-discriminating and 20 Festuca species-discriminating ISSR markers were screened among all the three ryegrass populations. The resistant Tuscania population carried the highest percentage of Festuca genome (16.8%) followed by the resistant Roma (13.6%) and susceptible Vetralla (7.6%) populations. On the basis of these data some influence of Festuca genome in diclofop resistance levels of studied ryegrass populations could be hypothesized.

Imazamox-resistant wheat varieties carry the Imi1 allele, which confers resistance to the imidazolinone (IMI) herbicide imazamox. This resistance trait allows the selective control of jointed goatgrass, a difficult-to-control winter annual grass weed. Allele movement between IMI-resistant wheat and jointed goatgrass may occur via hybridization and backcross events. Hybrids (F1) of IMI-resistant wheat and jointed goatgrass were identified in 2008 in a commercial wheat field in Eastern Oregon. In 2009 and 2010, surveys were conducted in Eastern Oregon to determine the prevalence of the Imi1 allele in wheat × jointed goatgrass hybrids. Using polymerase chain reaction assays we detected the presence of the Imi1 allele. A total of 128 sites were surveyed over the 2 yr. Of 1,548 plants sampled, 1,100 were positive for the Imi1 alelle and of those, 1,087 were heterozygous and 13 were homozygous for the allele. We assessed hybrid yield components and how these components varied across the sampled sites. The association between the proportion of IMI-resistant hybrids and the area or management practice in the commercial fields was determined. Nonagricultural sites or production of IMI-resistant wheat in consecutive years were two factors associated with a greater proportion of IMI-resistant hybrids. Our results demonstrate that the Imi1 allele is moving from IMI-resistant wheat to jointed goatgrass, producing resistant hybrids and backcross plants. This is the first report of natural occurrence of IMI-resistant backcross plants in commercial wheat fields. Therefore, it is important to implement field management practices that reduce IMI-resistant hybrid production and to effectively manage nonagricultural areas with jointed goatgrass infestations to prevent introgression of the IMI-resistance allele.

An induced mutation of the common wheat (2n = 6x = 42, AABBDD genomes) cultivar ‘Fidel’ has been shown to provide resistance to the imidazolinone class of herbicides. This class of herbicide gives broad-spectrum weed control including the weedy relative of wheat, jointed goatgrass (2n = 4x = 28, CCDD genomes). Because wheat and jointed goatgrass share a common genome, genes present on the D genome may transfer between the two species as a result of natural hybridization and selective pressures. Our objectives were to determine which genome of common wheat contained the herbicide resistance gene in the mutated Fidel and to genetically map its position. We investigated the chromosomal location of this gene using both durum (2n = 4x = 28, AABB genomes) and common wheat (6x) backgrounds. From crosses of durum wheat genotypes as the recurrent parent with mutated Fidel (cv. 9804, resistant), only BC1 plants containing chromosome 6D (inherited from cv. 9804) were resistant to applications of labeled rates of imazamox, an imidazolinone herbicide. No other D-genome chromosome was absolutely associated with herbicide resistance. To confirm this chromosomal location and genetically map the position of this gene, two populations of F3 families from the cross of cv. 9804 to the common wheat cultivars ‘Cashup’ and ‘Madsen’ were screened for reaction to imazamox, followed by genetic mapping with microsatellite markers. Two linked microsatellite markers were associated with the resistance trait, and one of them, Xgdm127, was located to chromosome 6D using aneuploid stocks, confirming the location of this gene on 6D. These results indicate that this resistance gene is in the genome that common wheat shares with jointed goatgrass. Therefore, imidazolinone-resistant wheat will need to be carefully managed to minimize the occurrence and spread of resistant jointed goatgrass, whether such plants arise because of hybridization with resistant common wheat or by independent mutation, a frequent occurrence with this herbicide class.

The spontaneous flow of genes from wheat to jointed goatgrass is of great concern to breeders intending to release herbicide-resistant wheat. The objectives of this research were to study how genes could flow from wheat to jointed goatgrass through crossing and backcrossing between these two species and, based on this knowledge, to propose possible ways to minimize the chance of gene flow between them. Results showed that the wheat × jointed goatgrass hybrid can only serve as a female parent to produce the BC1 generation. The BC1 generation was found to have 1.8% male fertility and 4.4% female fertility, indicating that it could serve as either the male or female parent to produce a BC2 generation. The fertility of the resultant BC2 generation further increased. The average male, female, and self-fertility was 8.9, 18.0, and 6.9%, respectively. After the BC2 generation, the backcross progeny has three possible ways to reproduce: to pollinate jointed goatgrass, to be pollinated by jointed goatgrass, or to pollinate itself. Restoration of the chromosome number of jointed goatgrass continues as the BC2 generation is selfed, but some plants can contain an alien chromosome over generations. The possible ways to reduce the chance of gene flow between these two species are (1) prevent the production of hybrids, (2) prevent the production of the BC1 generation, and (3) put a herbicide-resistant gene on the A- or B-genome of wheat.

The transfer of herbicide resistance genes from crops to related species is one of the greatest risks of growing herbicide-resistant crops. The recent introductions of imidazolinone-resistant wheat in the Great Plains and Pacific Northwest regions of the United States and research on transgenic glyphosate-resistant wheat have raised concerns about the transfer of herbicide resistance from wheat to jointed goatgrass via introgressive hybridization. Field experiments were conducted from 2000 to 2003 at three locations in Washington and Idaho to determine the frequency and distance that imidazolinone-resistant wheat can pollinate jointed goatgrass and produce resistant F1 hybrids. Each experiment was designed as a Nelder wheel with 16 equally spaced rays extending away from a central pollen source of ‘Fidel-FS4’ imidazolinone-resistant wheat. Each ray was 46 m long and contained three rows of jointed goatgrass. Spikelets were collected at maturity at 1.8-m intervals along each ray and subjected to an imazamox screening test. The majority of all jointed goatgrass seeds tested were not resistant to imazamox; however, 5 and 15 resistant hybrids were found at the Pullman, WA, and Lewiston, ID, locations, respectively. The resistant plants were identified at a maximum distance of 40.2 m from the pollen source. The overall frequency of imazamox-resistant hybrids was similar to the predicted frequency of naturally occurring acetolactate synthase resistance in weeds; however, traits with a lower frequency of spontaneous mutations may have a relatively greater risk for gene escape via introgressive hybridization.

Red rice has long been a troublesome, conspecific weed of cultivated rice. Rice varieties carrying certain herbicide-resistant traits acquired through genetic modification (herbicide-resistant varieties) now offer new options for red rice control. In concert with this innovation is the risk of gene flow, which can result in the transfer of that specific herbicide resistance to red rice and thus render this weed control measure ineffective. Gene flow in concept is simple, however, the parameters that determine the establishment of a new trait in a weed population are complex. Cross-pollination to make hybrid seed and the subsequent fate of those hybrid families in the general weed population are some of the biological factors that influence gene flow between red rice and cultivated rice. Natural outcrossing among rice plants is generally low. Most of the pollen dispersal studies published to date indicated that rice × rice outcrossing rates were less than 1.0%. Numerous reports summarized in this study suggest that outcrossing rates between rice and red rice can be highly variable but usually are similar to or lower than this level. However, once hybrids form, they may introgress into a red rice population within only a few generations. If hybrid seed families are to persist and establish herbicide-resistant red rice populations, they must successfully compete in the crop–weed complex. The ability to survive a herbicide applied to a herbicide-resistant rice variety would be a strong selective advantage for these hybrid families. Thus, the well-established principles of weed resistance management appear to be relevant for herbicide-resistant crop systems and should be used in combination with practices to minimize coincident flowering to mitigate the potential impact of gene flow from herbicide-resistant rice into red rice. For the rice–red rice crop–weed complex, there are both biological factors and agricultural practices that can work together to preserve these new weed control options.

Several populations of different Amaranthus species have been reported resistant to single or multiple herbicides. Interspecific hybridization among amaranths is hypothesized to contribute to the evolution of herbicide resistance. Although other studies have shown the occurrence of interspecific Amaranthus hybrids, little has been done to establish the likelihood of hybridization under field conditions. The main objective of this study was to determine potential field frequencies of hybridization between tall waterhemp females and smooth pigweed. Field hybridization plots were established during each of two growing seasons. Individuals of the two species were transplanted to field plots and arranged at varying distances from each other. Hybrid progeny were detected using the acetolactate synthase (ALS) gene as a marker. Smooth pigweed parents were homozygous for a herbicide-resistance ALS allele, whereas maternal tall waterhemps were homozygous for a herbicide-sensitive ALS form. Heterozygous interspecific progeny were thus detected by means of herbicide selection. Molecular and cytogenetic tools were used to verify the validity of the data obtained. Averaged among female waterhemp plants and across the two field seasons, hybridization occurred at a frequency of 33%. A single tall waterhemp plant was capable of producing more than 200,000 hybrids, suggesting little if any gametic incompatibility. All flowering hybrids obtained from tall waterhemp females were of dioecious condition and female sex. Observed sexual segregation was consistent with previously postulated chromosomal XY-type system in tall waterhemp sex determination, where males are the heterogametic sex.

Hybridization of parasites is an emerging public health concern in our changing world. Hybridization and introgression in parasites and pathogens can have major impacts on the host and the epidemiology and evolution of disease. Schistosomiasis is a Neglected Tropical Disease of profound medical and veterinary importance across many parts of the world, with the greatest human burden within sub-Saharan Africa. Here we review how early phenotypic identification and recent confirmation through molecular studies on naturally occurring infections, combined with experimental manipulations, have revealed evidence of viable hybridization and introgressions within and between human and animal schistosome species. Environmental and anthropogenic changes in selective pressures following, for instance, new dam constructions, altered agricultural practices, together with mass drug administration programmes, may all be predicted to further impact the availability of suitable definitive and intermediate hosts for schistosomes. It is therefore imperative to understand the distribution and role of such novel zoonotic hybrid schistosomes on host range, drug efficacy, and hence ultimately transmission potential, if we are to achieve and maintain sustainable control.

Andean arracacha (Arracacia xanthorrhiza Bancr.) is a valuable but poorly known vegetatively reproduced root crop whose origin is still unresolved. Wild tuberous forms are present in the presumed areas of domestication and have a perennial or monocarpic life history. To elucidate the origin of the cultivated form, we surveyed a molecular analysis with amplified fragment length polymorphisms (AFLPs) in a representative sample of this crop and its wild relatives from Ecuador and Peru, the presumed areas of domestication. Wild species with tuberous and non-tuberous roots were included, as well as the perennial and monocarpic forms of the presumed wild ancestor. While the two wild varieties of A. xanthorrhiza were closest to the cultivars, they were distinguished by AFLPs. Unexpectedly, two clearly distinct groups were formed among the cultivars, one of which was significantly closer to the monocarpic wild form. However, the chloroplast DNA survey revealed greater similarity between all of the cultivars and the wild perennial A. xanthorrhiza. These results combined with the morphological and life history features, confirms the hypothesis that arracacha domestication started from the wild perennial form. We suggest this scenario of domestication followed by an unsuspected introgression in the cultivation, resulting in two cryptic genetic groups, well distinguished at the molecular level. This is an important revelation with implications in genetic resource conservation and breeding standpoints in this promissory crop.