Ancient DNA analysis of <Emphasis Type="Italic">Panicum miliaceum</Emphasis> (broomcorn millet) from a Bronze Age cemetery in Xinjiang,China

Panicum miliaceum L. (broomcorn millet) was an important cereal for Eurasian populations in prehistory. It was first domesticated in China and spread westwards into Central Asia and Europe later on. However, the domestication history and dispersal routes of this cereal are still not clear. The well desiccated P. miliaceum grains recovered from Xiaohe cemetery, a Bronze Age cemetery in Xinjiang, China, provide us with an invaluable opportunity to further explore this issue, especially considering Xinjiang’s critical geographical position at the crossroads of contact between the West and East. Here we present an analysis of ribosomal DNA (rDNA) internal transcribed spacer (ITS) and external transcribed spacer (ETS) sequences of P. miliaceum remains excavated from Xiaohe cemetery in comparison to modern landraces. The results show that the Xiaohe P. miliaceum exhibits heterogeneous characteristics in its rDNA, which are also commonly found in modern landraces. However, no exact sequence matching the Xiaohe millet was found in modern landraces so far, possibly suggesting the loss of genetic diversity through time. The most similar sequences are mainly present in landraces from India and Europe. Based on the genetic data of modern landraces and archaeological findings, we discuss the domestication of P. miliaceum and the possible prehistoric connections between northern China, Xinjiang and Europe in agricultural practices, as well as the potential routes westwards of P. miliaceum.     

Physiological characterization and allelic diversity of selected drought tolerant traditional rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.) landraces of Koraput,India

Water-deficit stress tolerance in rice is important for maintaining stable yield, especially under rain-fed ecosystem. After a thorough drought-tolerance screening of more than 130 rice genotypes from various regions of Koraput in our previous study, six rice landraces were selected for drought tolerance capacity. These six rice landraces were further used for detailed physiological and molecular assessment under control and simulated drought stress conditions. After imposing various levels of drought stress, leaf photosynthetic rate (P_N), photochemical efficiency of photosystem II (Fv/Fm), SPAD chlorophyll index, membrane stability index and relative water content were found comparable with the drought-tolerant check variety (N22). Compared to the drought-susceptible variety IR64, significant positive attributes and varietal differences were observed for all the above physiological parameters in drought-tolerant landraces. Genetic diversity among the studied rice landraces was assessed using 19 previously reported drought tolerance trait linked SSR markers. A total of 50 alleles with an average of 2.6 per locus were detected at the loci of the 19 markers across studied rice genotypes. The Nei’s genetic diversity (He) and the polymorphism information content (PIC) ranged from 0.0 to 0.767 and 0.0 to 0.718, respectively. Seven SSR loci, such as RM324, RM19367, RM72, RM246, RM3549, RM566 and RM515, showed the highest PIC values and are thus, useful in assessing the genetic diversity of studied rice lines for drought tolerance. Based on the result, two rice landraces (Pandkagura and Mugudi) showed the highest similarity index with tolerant check variety. However, three rice landraces (Kalajeera, Machhakanta and Haldichudi) are more diverse and showed highest genetic distance with N22. These landraces can be considered as the potential genetic resources for drought breeding program.     

Screening of rice landraces (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.) for seedling stage salinity tolerance using morpho-physiological and molecular markers

Traditional rice landraces of coastal area in Bangladesh are distinct regarding their phenotype, response to salt stress and yield attributes. With characterization of these landraces, suitable candidate genes for salinity tolerance could be identified to introgress into modern rice varieties. Therefore, the aim of this experiment was to uncover prospective rice landraces tolerant to salinity. Relying on morphological, biochemical and molecular parameters 25 rice genotypes were tested for salt tolerance at germination and seedling stage. At germination stage 0 and 12 dSm^?1 salinity were imposed on rice genotypes. Ward’s cluster analysis divided rice genotypes into three clusters (susceptible, moderately tolerant and tolerant) based on the physiological indices. The tolerant rice landraces to salinity were Sona Toly, Nakraji and Komol Bhog. At seedling stage screening was performed following IRRI standard protocol at 12 dSm^?1 salinity level. Based on all morphological and biochemical parameters Komol Bhog was identified as the highly salinity tolerant landrace while Bolonga, Sona Toly, Dud Sail, Tal Mugur and Nakraji were found as tolerant to salinity. Molecular characterization using two simple sequence repeats (SSR) markers, viz. RM121 and RM337 displayed Bolonga, Til Kapor, Panbra, Sona Toly, Bina Sail, Komol Bhog, Nakraji, Tilkapur, Gajor Goria and Gota were tolerant landraces through genetic similarity in dendrogram. These identified salt-resistant landraces can be used as promising germplasm resources for breeding salt-tolerant high-yielding rice varieties in future.     

Analysis of genetic diversity and population structure in <Emphasis Type="Italic">Capsicum</Emphasis> landraces from North Eastern India using TE-AFLP markers

North eastern (NE) India harbours a precious germplasm repository of Capsicum in the form of various landraces. The present study was undertaken to characterise the extent of genetic variation present in different Capsicum landraces from north eastern India. A set of 171 Capsicum accessions were characterised using three-endonuclease amplified fragment length polymorphism (AFLP) markers. Out of 416 bands obtained from six primer combinations, 254 (61 %) were polymorphic. The pairwise genetic dissimilarity among accessions ranged from 0.03 to 0.97. Cluster analysis based on neighbour joining showed two major clusters. Cluster I contained most of the bhut jolokia accessions whereas cluster II contained all of the Capsicum annuum genotypes. Similar grouping was observed with population STRUCTURE analysis as well as principle coordinate analysis. Analysis of molecular variance (AMOVA) revealed 45 and 54 % variation among and within populations, respectively. This information on population structure analysis and molecular characterisation will be helpful for effective utilisation of this germplasm in Capsicum improvement programs.     

Interactions between <Emphasis Type="Italic">Glu-1</Emphasis> and <Emphasis Type="Italic">Glu-3</Emphasis> loci and associations of selected molecular markers with quality traits in winter wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) DH lines

The quality of wheat depends on a large complex of genes and environmental factors. The objective of this study was to identify quantitative trait loci controlling technological quality traits and their stability across environments, and to assess the impact of interaction between alleles at loci Glu-1 and Glu-3 on grain quality. DH lines were evaluated in field experiments over a period of 4 years, and genotyped using simple sequence repeat markers. Lines were analysed for grain yield (GY), thousand grain weight (TGW), protein content (PC), starch content (SC), wet gluten content (WG), Zeleny sedimentation value (ZS), alveograph parameter W (APW), hectolitre weight (HW), and grain hardness (GH). A number of QTLs for these traits were identified in all chromosome groups. The Glu-D1 locus influenced TGW, PC, SC, WG, ZS, APW, GH, while locus Glu-B1 affected only PC, ZS, and WG. Most important marker-trait associations were found on chromosomes 1D and 5D. Significant effects of interaction between Glu-1 and Glu-3 loci on technological properties were recorded, and in all types of this interaction positive effects of Glu-D1 locus on grain quality were observed, whereas effects of Glu-B1 locus depended on alleles at Glu-3 loci. Effects of Glu-A3 and Glu-D3 loci per se were not significant, while their interaction with alleles present at other loci encoding HMW and LMW were important. These results indicate that selection of wheat genotypes with predicted good bread-making properties should be based on the allelic composition both in Glu-1 and Glu-3 loci, and confirm the predominant effect of Glu-D1d allele on technological properties of wheat grains.     

Estimation of loci involved in non-shattering of seeds in early rice domestication

Rice (Oryza sativa L.) is widely cultivated around the world and is known to be domesticated from its wild form, O. rufipogon. A loss of seed shattering is one of the most obvious phenotypic changes selected for during rice domestication. Previously, three seed-shattering loci, qSH1, sh4, and qSH3 were reported to be involved in non-shattering of seeds of Japonica-type cultivated rice, O. sativa cv. Nipponbare. In this study, we focused on non-shattering characteristics of O. sativa Indica cv. IR36 having functional allele at qSH1. We produced backcross recombinant inbred lines having chromosomal segments from IR36 in the genetic background of wild rice, O. rufipogon W630. Histological and quantitative trait loci analyses of abscission layer formation were conducted. In the analysis of quantitative trait loci, a strong peak was observed close to sh4. We, nevertheless, found that some lines showed complete abscission layer formation despite carrying the IR36 allele at sh4, implying that non-shattering of seeds of IR36 could be regulated by the combination of mutations at sh4 and other seed-shattering loci. We also genotyped qSH3, a recently identified seed-shattering locus. Lines that have the IR36 alleles at sh4 and qSH3 showed inhibition of abscission layer formation but the degree of seed shattering was different from that of IR36. On the basis of these results, we estimated that non-shattering of seeds in early rice domestication involved mutations in at least three loci, and these genetic materials produced in this study may help to identify novel seed-shattering loci.     

Genetic analysis of forest species <Emphasis Type="Italic">Eugenia uniflora</Emphasis> L. through of newly developed SSR markers

Nine microsatellite loci for genetic analysis of three populations of the tropical tree Eugenia uniflora L. (pitanga or Brazilian cherry) from fragments of semideciduous forest were developed. We used the technique of building a (GA) _n and (CA) _n microsatellite-enriched library by capture with streptavidin-coated magnetic beads. We assessed the polymorphism of seven microsatellites in 84 mature trees found in three areas (Ribeirão Preto, Tambaú and São José do Rio Pardo), highly impacted by the agricultural practices, in a large region among Pardo river and Mogi-Guaçu river basins, in state of São Paulo, Brazil. All loci were polymorphic, and the number of alleles was high, ranging from 6 to 24, with a mean of 14.4. All stands showed the same high level of genetic diversity (mean H _E  = 0.83) and a low genetic differentiation (mean F _ST = 0.031), indicating that genetic diversity was higher within rather than among populations. Seven of the nine loci were highly variable, and sufficiently informative for E. uniflora. It was concluded that these new SSR markers can be efficiently used for gene flow studies.     

Molecular genetic diversity and association mapping of morphine content and agronomic traits in Turkish opium poppy (<Emphasis Type="Italic">Papaver somniferum</Emphasis>) germplasm

As the sole plant source of many potent alkaloids, opium poppy (Papaver somniferum L.) is an important medicinal crop. Nevertheless, few studies have characterized opium poppy germplasm with crop-specific molecular markers. Because Turkey is a diversity center for opium poppy, Turkish germplasm is a valuable genetic resource for association mapping studies aimed at identifying QTLs controlling morphine content and agronomic traits. In this study, the morphological diversity and molecular diversity of 103 Turkish opium poppy landraces and 15 cultivars were analyzed. Potentially useful morphological variation was observed for morphine content, plant height, and capsule index. However, the landraces exhibited limited breeding potential for stigma number, and seed and straw yields. Both morphological and molecular analyses showed distinct clustering of cultivars and landraces. In addition, a total of 164 SSR and 367 AFLP polymorphic loci were applied to an opium poppy association mapping panel composed of 95 opium poppy landraces which were grown for two seasons. One SSR and three AFLP loci were found to be significantly associated with morphine content (P < 0.01 and LD value (r ²) = 0.10–0.32), and six SSR and 14 AFLP loci were significantly associated with five agronomic traits (plant height, stigma number, capsule index, and seed and straw yields) (P < 0.01 and LD value (r ²) = 0.08–0.35). This is the first report of association mapping in this crop. The identified markers provide initial information for marker-assisted selection of important traits in opium poppy breeding.     

Influence of ethnic traditional cultures on genetic diversity of rice landraces under on-farm conservation in southwest China

Background

Crop genetic resources are important components of biodiversity. However, with the large-scale promotion of mono-cropping, genetic diversity has largely been lost. Ex-situ conservation approaches were widely used to protect traditional crop varieties worldwide. However, this method fails to maintain the dynamic evolutionary processes of crop genetic resources in their original habitats, leading to genetic diversity reduction and even loss of the capacity of resistance to new diseases and pests. Therefore, on-farm conservation has been considered a crucial complement to ex-situ conservation. This study aimed at clarifying the genetic diversity differences between ex-situ conservation and on-farm conservation and to exploring the influence of traditional cultures on genetic diversity of rice landraces under on-farm conservation.

Methods

The conservation status of rice landrace varieties, including Indica and Japonica, non-glutinous rice (Oryza sativa) and glutinous rice (Oryza sativa var. glutinosa Matsum), was obtained through ethno-biology investigation method in 12 villages of ethnic groups from Guizhou, Yunnan and Guangxi provinces of China. The genetic diversity between 24 pairs of the same rice landraces from different times were compared using simple sequence repeat (SSR) molecular markers technology. The landrace paris studied were collected in 1980 and maintained ex-situ, while 2014 samples were collected on-farm in southwest of China.

Results

The results showed that many varieties of rice landraces have been preserved on-farm by local farmers for hundreds or thousands of years. The number of alleles (Na), effective number of alleles (Ne), Nei genetic diversity index (He) and Shannon information index (I) of rice landraces were significantly higher by 12.3–30.4 % under on-farm conservation than under ex-situ conservation. Compared with the ex-situ conservation approach, rice landraces under on-farm conservation programs had more alleles and higher genetic diversity. In every site we investigated, ethnic traditional cultures play a positive influence on rice landrace variety diversity and genetic diversity.

Conclusion

Most China’s rice landraces were conserved in the ethnic areas of southwest China. On-farm conservation can effectively promote the allelic variation and increase the genetic diversity of rice landraces over the past 35 years. Moreover, ethnic traditional culture practices are a crucial foundation to increase genetic diversity of rice landraces and implement on-farm conservation.

     

Genetic structure of populations and natural hybridization between <Emphasis Type="Italic">Dactylorhiza salina</Emphasis> and <Emphasis Type="Italic">D. incarnata</Emphasis> (Orchidaceae)

The results of studying the polymorphism and genetic structure of populations of D. salina and D. incarnata growing in Zabaykalsky krai and Buryatia are represented according to the data of allozyme analysis of eight genetic loci (PGI, NADHD, SKDH, GDH, PGM, DIA, ADH, and IDH). The specificity of the allelic structure of loci SKDH, PGM, and IDH is established, for which D. salina and D. incarnata reliably differ from each other. It is shown that interspecies introgressive hybrid complexes with different genetic structures were formed in Transbaikalia. Places of mass growth of D. incarnata were observed to have single plants of D. salina, the interspecies hybrids of the first and subsequent generations. Places of mass growth of D. salina were observed to contain only the hybrids that are not hybrids of the first generation. They were heterozygous not for three loci with differentiating alleles of both parents, SKDH, PGM, and IDH, but for only one of them. The degree of genetic differentiation among five populations of D. salina was on average 7.5% and that of D. incarnata was 7.1%, which in accordance with Wright’s estimation relates to mean values. The average value of FST for all studied populations of the two related species of the genus Dactylorhiza was 0.478, indicating a very high degree of genetic differentiation between D. salina and D. incarnata growing in Transbaikalia. The greatest differences between the species are for the allelic structure of loci SKDH, PGM, and IDH (FST was equal to 0.705, 0.976, and 0.762, respectively). Analysis of molecular variance (AMOVA) showed that populations of D. salina and D. incarnata in the zone where their ranges in Zabaykalsky krai and Buryatya overlap have essential differences both for the variation of alleles frequencies of eight loci (71%, d.f. = 9) and for the variability of genotypes (61%, d.f. = 9). Despite the fact that D. salina and D. incarnata explicitly share a gene flow as a result of interspecies hybridization, the genetic differentiation of populations of these related species remains at a high level.     

Genetic diversity of three Chinese native sheep breeds

The sheep (Ovis aries L.) has been an important farm animal species since its domestication. A wide array of indigenous sheep breeds with abundant phenotypic diversity exists for domestication and selection. Therefore, assessing the genetic diversity of a local sheep resource using a multi-molecular system is helpful for maintaining and conserving those breeds. This study aimed to investigate the genetic diversity of three native Chinese sheep breeds (Tibetan sheep, Sishui Fur sheep, and Small-tailed Han sheep) using 15 microsatellite markers and the second exon of the DRA gene. In regards to the microsatellites, on average, 19 alleles per loci were observed among all individuals. Across loci, the HO within the population was 0.652 ± 0.022 in Tibetan sheep, 0.603 ± 0.023 in Small-tailed Han sheep and 0.635 ± 0.022 in SFS, and for most populations, the H _E and H _O were inconsistent. In addition, affluent private alleles within the breed indicated that the breeds have different domestication histories or sites. In regards to the 2 exon of the DRA gene, three haplotypes were constructed by seven single-nucleotide polymorphisms (SNPs), which were identified in the second DRA exon and inferred the potential for phenotypic variety in these Chinese native sheep. In summary, the current study reveals the importance of implementing effective conservation strategies for these three native Chinese sheep.     

Genetic structure of the populations of <Emphasis Type="Italic">Dactylorhiza ochroleuca</Emphasis> and <Emphasis Type="Italic">D. incarnata</Emphasis> (Orchidaceae) in the area of their joint growth in Russia and Belarus

We carried out an allozyme analysis to investigate polymorphism and genetic structure of the populations of D. incarnata and D. ochroleuca in regions of their joint growth in Russia and Belarus. We found that D. ochroleuca individuals in the populations of the Urals and Siberia, which are distant fragments from the main range of the species, do not differ significantly from individuals within the main part of the area (Belarus) on the basis of the allelic composition of eight gene loci. We revealed that D. ochroleuca and D. incarnata are differentiated by different alleles of the GDH locus. Thus, we established a genetic marker suitable to distinguish these closely related taxa. In addition to the GDH locus, D. ochroleuca and D. incarnata in the places of their joint growth, differ in the allelic structure of the PGI and NADHD loci. D. incarnata from the Urals and Siberia were polymorphic for both loci, and individuals from Belarus were polymorphic for one locus (PGI). In contrast, all D. ochroleuca individuals growing in sympatric populations with polymorphic D. incarnata were homozygous for the same alleles. Thus, comparison of the genetic structure of D. ochroleuca and D. incarnata points to the existence of a genetic isolation and a functioning isolation mechanism even under conditions of their joint growth. We found that the GDH locus in D. incarnata is polymorphic only in populations which grow together with D. ochroleuca, with exception a few examples. Thus, we conclude that variability of the GDH locus in D. incarnata is associated with hybridization with D. ochroleuca.     

QTL mapping of domestication and diversifying selection related traits in round-fruited semi-wild Xishuangbanna cucumber (<Emphasis Type="Italic">Cucumis sativus</Emphasis> L. var. <Emphasis Type="Italic">xishuangbannanesis</Emphasis>)

Key message

QTL analysis revealed 11 QTL underlying flowering time and fruit size variation in the semi-wild Xishuangbanna cucumber, of which, FT6.2 and FS5.2 played the most important roles in determining photoperiod-dependent flowering time and round-fruit shape, respectively.

Abstract

Flowering time and fruit size are two important traits in domestication and diversifying selection in cucumber, but their genetic basis is not well understood. Here we reported QTL mapping results on flowering time and fruit size with F₂ and F_2:3 segregating populations derived from the cross between WI7200, a small fruited, early flowering primitive cultivated cucumber and WI7167, a round-fruited, later flowering semi-wild Xishuangbanna (XIS) cucumber. A linkage map with 267 microsatellite marker loci was developed with 138 F₂ plants. Phenotypic data of male and female flowering time, fruit length and diameter and three other traits (mature fruit weight and number, and seedling hypocotyl length) were collected in multiple environments. Three flowering time QTL, FT1.1, FT5.1 and FT6.2 were identified, in which FT6.2 played the most important role in conferring less photoperiod sensitive early flowering during domestication whereas FT1.1 seemed more influential in regulating flowering time within the cultivated cucumber. Eight consensus fruit size QTL distributed in 7 chromosomes were detected, each of which contributed to both longitudinal and radial growth in cucumber fruit development. Among them, FS5.2 on chromosome 5 exhibited the largest effect on the determination of round fruit shape that was characteristic of the WI7167 XIS cucumber. Possible roles of these flowering time and fruit size QTL in domestication of cucumber and crop evolution of the semi-wild XIS cucumber, as well as the genetic basis of round fruit shape in cucumber are discussed.

     

Identification of candidate genes of QTLs for seed weight in <Emphasis Type="Italic">Brassica napus</Emphasis> through comparative mapping among <Emphasis Type="Italic">Arabidopsis</Emphasis> and <Emphasis Type="Italic">Brassica</Emphasis>species

Background

Map-based cloning of quantitative trait loci (QTLs) in polyploidy crop species remains a challenge due to the complexity of their genome structures. QTLs for seed weight in B. napus have been identified, but information on candidate genes for identified QTLs of this important trait is still rare.

Results

In this study, a whole genome genetic linkage map for B. napus was constructed using simple sequence repeat (SSR) markers that covered a genetic distance of 2,126.4 cM with an average distance of 5.36 cM between markers. A procedure was developed to establish colinearity of SSR loci on B. napus with its two progenitor diploid species B. rapa and B. oleracea through extensive bioinformatics analysis. With the aid of B. rapa and B. oleracea genome sequences, the 421 homologous colinear loci deduced from the SSR loci of B. napus were shown to correspond to 398 homologous loci in Arabidopsis thaliana. Through comparative mapping of Arabidopsis and the three Brassica species, 227 homologous genes for seed size/weight were mapped on the B. napus genetic map, establishing the genetic bases for the important agronomic trait in this amphidiploid species. Furthermore, 12 candidate genes underlying 8 QTLs for seed weight were identified, and a gene-specific marker for BnAP2 was developed through molecular cloning using the seed weight/size gene distribution map in B. napus.

Conclusions

Our study showed that it is feasible to identify candidate genes of QTLs using a SSR-based B. napus genetic map through comparative mapping among Arabidopsis and B. napus and its two progenitor species B. rapa and B. oleracea. Identification of candidate genes for seed weight in amphidiploid B. napus will accelerate the process of isolating the mapped QTLs for this important trait, and this approach may be useful for QTL identification of other traits of agronomic significance.

     

<Emphasis Type="Italic">Miscanthus</Emphasis> sp.: Genetic Diversity and Phylogeny in China

Miscanthus genetic resources are widely distributed throughout China. However, genetic studies on Miscanthus lagged far behind other crops (e.g., sorghum, maize). To establish the comprehensive genetics knowledge of Miscnathus in China, here we report the genetic and phylogenetic diversity of 174 domestic Miscanthus accessions, along with an external Miscanthus × giganteus control. Cytological observations and flow cytometry analyses indicated that there were two major Miscanthus cytotypes in China: diploid (86.86%) and tetraploid (12.57%) without triploid. A total of 108 polymorphic loci generated from 25 SSR primers were used to evaluate the genetic variation. Large variations in genetic similarity coefficients (GSCs), ranging from 0.08 to 0.97 with a mean value of 0.39, were observed between these Miscanthus accessions. Our phylogenetic data revealed that these accessions were clustered into four main clades: M. section Miscanthus, M. section Diandranthus, M. section Triarrhena, and hybrids. The average percentage of polymorphic loci (P), gene diversity (H), and Shannon’s diversity index (I) among Miscanthus species are 70.93%, 0.22, and 0.34, respectively. These were consistent with the analysis of molecular variance (AMOVA) results, showing that 85% of genetic variation was found within clades. This study investigated the clear phylogenetic relationship of Miscanthus species in China, which will be valuable for further utilization of the germplasm in genetic improvement and hybrid breeding of Miscanthus.     

Genetic diversity of the African poplar (<Emphasis Type="Italic">Populus ilicifolia</Emphasis>) populations in Kenya

We evaluated the genetic diversity of the African poplar (Populus ilicifolia) populations found in Kenya compared with reference samples of five poplar species from North America and one species introduced in Kenya from India (KEFRI-Kenya). Amplified fragment length polymorphism (AFLP) was used with the objective of providing important information for breeding and in situ/ex situ conservation of this species. Samples collected from three locations along the species’ natural range (Athi, Ewaso Nyiro, and Tana rivers) were compared with four samples of locally planted Populus deltoides stand introduced from India and ten reference samples from North America. Six AFLP primer combinations produced 521 clear bands for analysis. The percentage polymorphic loci were lowest in Tana (20.4 %) and highest in Athi (40.6 %). The average heterozygosity across the studied populations was between 0.07 and 0.3. AMOVA revealed more genetic variation partitioning within population (87 %; P?<?0.01) than among populations (13 %; P?<?0.01) suggesting significant genetic variation between populations. Further, UPGMA delineation showed two clusters of the Tana, Athi, and Ewaso Nyiro populations clustered together compared to the North America and India/KEFRI reference samples. Moreover, the study showed that the Athi population is more diverse than those of Tana and Ewaso Nyiro and may be important for conservation, domestication, and improvement studies. The genetic differentiation (F _ST ?=?0.134) among Kenyan P. ilicifolia populations suggests limited possibility of gene flow between these populations.     

<Emphasis Type="Italic">Fusarium verticillioides</Emphasis> and fumonisin contamination in <Emphasis Type="Italic">Bt</Emphasis> and non-<Emphasis Type="Italic">Bt</Emphasis> maize cultivated in Brazil

Fusarium verticillioides is one of the main pathogens of maize, causing ear and stalk rots. This fungus is also able to produce high levels of fumonisins, which have been linked to various illnesses in humans and animals. Previous studies have shown that maize hybrids genetically modified with the cry genes from the bacterium Bacillus thuringiensis (Bt) presented lower incidence of F. verticillioides and fumonisin levels, presumably through the reduction of insects, which could act as vectors of fungi. The aim of this study was to assess the incidence of F. verticillioides and the concentration of fumonisins in Bt and isogenic non-Bt hybrids (2B710Hx, 30F35YG, 2B710, and 30F35, respectively). The samples of 2B710Hx and 30F35YG presented lower F. verticillioides frequency than 2B710 and 30F35 samples. However, there was no statistical difference between fumonisin contamination when Bt and non-Bt samples were compared (P > 0.05). The results suggest that other environmental parameters could possibly trigger fumonisin production during plant development in the field; consequently, other management strategies should be applied to aid controlling fumonisin contamination in maize.     

An overlooked hybrid between the two diploid <Emphasis Type="Italic">Chenopodium</Emphasis> species in Central Europe determined by microsatellite and morphological analysis

The presence and extent of hybridization within the Chenopodium album aggregate (Amaranthaceae) is still unclear. Although many hybrid combinations have been described, their existence in the field has never been systematically studied and verified. The main aim of this study was to ascertain the extent of interspecific hybridization between the diploid species C. ficifolium and C. suecicum using highly variable nuclear microsatellite markers. Due to the absence of such kind of molecular markers for the whole C. album group, we divided the analysis into two steps: (1) Eleven microsatellite loci designed for the closely related species C. quinoa were cross-amplified in five Eurasian species of the C. album diploid–polyploid complex, i.e. C. album s.s. (6x), C. striatiforme (4x), C. strictum (4x), C. ficifolium (2x) and C. suecicum (2x); (2) For the detection of interspecific hybridization between C. ficifolium and C. suecicum, we sampled 480 individuals from five localities in Central Europe. We also investigated morphological differences between the parental taxa and their hybrid and devised a key for their determination. Analysis of variation in microsatellite loci using Bayesian methods, PCoA and Neighbour-joining tree identified 32 F1 hybrids. These F1 hybrids, described here as C. paradoxum Mandák, formed a cluster between well-differentiated parental species, combining the morphological characters of both their parents. Moreover, genetic analyses also recognized several F2 or backcross hybrids, whose delimitation, mainly from C. suecicum and F1 hybrids, based on morphological characters, is problematic.     

Molecular characteristics of two new <Emphasis Type="Italic">waxy</Emphasis> mutations in China waxy maize

The waxy gene mutation causes waxy maize grain to have a sticky quality. China has numerous waxy maize landraces and is thought to be the place of origin of waxy maize. The most abundant waxy maize resources in China are located in the Yunnan province and its surrounding areas. We collected 57 waxy maize landraces from Yunnan province and cloned and sequenced the waxy gene from its fourth to eighth exon. Two new waxy gene mutations, named wx-Cin4 and wx-124, were identified. The wx-Cin4 mutation is a 466-bp retrotransposon inserted into exon six. The wx-124 mutation is a 116-bp miniature inverted-repeat transposable element inserted into exon seven. This is the first time a 124-type mutation has been found in a maize waxy gene. The discovery of the two specific waxy mutations from landraces collected in Yunnan province provides new evidence supporting the hypothesis that China is the origin area for waxy maize.