Diverse morphological and cytogenetic variation and differentiation of the two subspecies in <Emphasis Type="Italic">Aegilops geniculata</Emphasis> Roth,a wild relative of wheat

Aegilops geniculata Roth, a wild relative of wheat (2n = 4x = 28, genome UUMM), is distributed over the Mediterranean basin and nearby areas. The species consists of two subspecies, subsp. geniculata and subsp. gibberosa (Zhuk.) Hammer. The former is distributed over the whole species area and has been genetically analyzed, and the latter is endemic to Spain and North Africa and has not been genetically evaluated. In this study, to clarify the genetic variation and delineation of the two subspecies from a biosystematic viewpoint, morphological variation among 23 accessions of subsp. geniculata and three of subsp. gibberosa and chromosome pairing at meiosis and fertility in their intra- and inter-subspecific F₁ hybrids were examined. A principal component analysis based on the 11 spike characteristics clearly divided the 26 accessions into two groups representing the two subspecies. The inter-subspecific F₁ hybrids showed significantly lower frequencies of chromosome pairing, significantly higher frequencies of multivalents, and significantly lower fertilities relative to those of the intra-subspecific F₁ hybrids. It was concluded that wide-ranging cytogenetic variation is included in subsp. geniculata, that subsp. gibberosa, the intra-subspecific variation of which is small, is morphologically and cytogenetically differentiated from subsp. geniculata beyond the range of the intra-subspecific variation of subsp. geniculata, and that the two subspecies are effectively isolated reproductively by hybrid sterility. The results strongly suggested that western North Africa is one of the important diversity centers of Ae. geniculata, where two subspecies were differentiated in the past and grow together in the present.     

Morphological variation related with environmental factors in endemic and threatened <Emphasis Type="Italic">Jatropha</Emphasis> species of Tehuacan-Cuicatlan,Mexico

Jatropha spp. from Mexico includes high species richness and endemism; five species inhabit in the Tehuacan-Cuicatlan Biosphere Reserve (TCBR), and they are important resources as food, medicine and biofuel. The assessment of morphological and agronomic characteristics is essential to identify, use and maintain plant genetic resources. Given the lack of information on the morphological variability of Jatropha species in relation to environment, the objective was to analyze the influence of physiographic, climatic, and anthropogenic factors in the morphological variability of the species: Jatropha neopauciflora and J. rzedowskii, both not-endangered; J. oaxacana, special protection; J. ciliata and J. rufescens, both endangered in the Reserve. Twelve quantitative morphological variables were measured in 24 populations of these species; 14 environmental variables were registered, and the disturbance index in the sites was estimated. The information was analyzed with Principal Components Analysis (PCA), Cluster Analysis and Canonical Correspondence Analysis (CCA). PCA detected interspecific variation: J. ciliata and J. rufescens have longer and broader leaves and longer flowers, while the other three species have smaller leaves and flowers. J. oaxacana population has intermediate size of leaves, fruits and seeds, compared with those of J. neopauciflora and J. rzedowskii. CCA detected intra-specific variation among the populations of J. neopauciflora and J. rzedowskii, which were separated in two groups due to fruit and seed size. Axis 1 of CCA correlated positively with altitude and annual temperature range, and negatively with mean annual temperature; at the intra-specific level, both species are adapted to variations of temperature and altitude.     

<Emphasis Type="Italic">Arnica montana</Emphasis> subsp. <Emphasis Type="Italic">atlantica</Emphasis>: Really a subspecies?

In Arnica montana L. (Asteraceae) two subspecies are described, A. montana subsp. atlantica (AMA), present only on the Iberian Peninsula and A. montana subsp. montana (AMM) with a very wide distribution area. The morphological differences between the two subspecies are small and variable. Therefore, this concept is sometimes questioned. To establish the genetic background of the two subspecies, populations of AMA and AMM together with herbarium samples and DNA Bank material of AMM were tested with 12 microsatellite markers. A. montana propagates by seeds or by clonal propagation of its rhizome. In AMA, clonality was frequent while in AMM only one case of clonality could be identified. Therefore, further results were clone-corrected. Genetically, AMA separated very well from AMM with a G_ST between the subspecies of 0.81, genetically justifying the subspecies concept of A. montana. Genetic variability in AMA (H_exp?=?0.28) was lower than in the AMM populations (H_exp?=?0.70). A somewhat higher fixation index of AMA (F_ST?=?0.17, compared to an F_ST?=?0.08 for AMM) may indicate that geneflow in AMA is a bit more restricted than in alpine AMM. However, the fixation index of AMA is not deviating from Hardy–Weinberg equilibrium. No inbreeding was observed for AMA (F_IS?=?0.10) and AMM (F_IS?=?0.08).     

Polymorphism of gliadins in <Emphasis Type="Italic">Aegilops tauschii</Emphasis> Coss. local populations in two primary habitats in Dagestan

Polymorphism of gliadins was investigated in Aegilops tauschii from primary habitats “4”, near Hily, and “6”, near Rukel, in Dagestan, Russia 205 individual plants were analysed (53/50 and 54/48 plants of subsp. tauschii/subsp. strangulata from the habitats “4” and “6”, respectively) and 1/7 and 18/14 different haplotypes were found among the plants of subsp. tauschii/subsp. strangulata from the habitats “4” and “6”, respectively. No direct evidences of cross-pollination were pointed out, although gliadins electrophoretic phenotypes obtained allowed to suggest that it occur in Ae. tauschii with very low frequency. The data obtained revealed that during Ae. tauschii evolutionary history a local habitat could be populated many times by different phylogenetic lineages of the species. It was found that in Dagestan, at the very edge of the species area, several different lineages belonging to different subspecies could for a long time co-exist together in a local habit, and in such case a very high level of genetic variation in Ae. tauschii could be accumulated on a square of less than one hectare. The further studies of genetic variation in Ae. tauschii local populations, based on molecular genetic methods seems to be very prospective for understanding of peculiarities of the species evolution.     

Polymorphism of <Emphasis Type="Italic">Got2</Emphasis> DNA sequences sheds light on <Emphasis Type="Italic">Aegilops tauschii</Emphasis> Coss. intraspecies divergence and origin of <Emphasis Type="Italic">Triticum aestivum</Emphasis> L.

DNA sequences of nuclear gene Got2 was studied in 60 accessions of Aegilops tauschii, 29 of subsp. tauschii and 31 of subsp. strangulata. It was found that Got2 allozyme polymorphism in Ae. tauschii is due to a single, unique, mutation which led to replacement of glutamic acid by isoleucine in residue 256 of the enzyme molecule, encoded by Got2. As revealed by Got2 DNA sequences variation, initially in its history Ae. tauschii was presented by subsp. strangulata, and among phylogenetic lineages of subsp. strangulata, the lineage “t-9¹s” (TauL3) is the most ancient, a relict one. Subspecies tauschii is relatively “young”. Initially it was presented by the lineage marked by combination of allozyme alleles Got2 ¹⁰⁵ and Acph1 ¹⁰⁰. In the past it inhabited the Continental area from Caucasia to Pakistan, but later on it was forced out by newly originated, now—a major lineage of subsp. tauschii, marked by Got2 ¹⁰⁰. This lineage extended the Continental area of the species up to Kirgizstan, but actually failed to penetrate into pre-Caspian area, occupied by subsp. strangulata. These results essentially differ from those obtained previously, using chloroplast DNA (cpDNA) sequences polymorphism. As revealed by cpDNA, the major, “usual”, subsp. strangulata (TauL2) is “younger” than subsp. tauschii, which resided on phylogenetic tree between relict lineage “t-9¹s”of subsp. strangulata—and major subsp. strangulata. But both cpDNA and Got2 DNA sequences indicate that the level of genetic variation in subsp. tauschii is much lower than in subsp. strangulata. According to Got2 DNA sequences variation, it was Ae. tauschii subsp. strangulata lineage “k-109″ which donated genome D to Triticum aestivum L. This lineage includes accessions: k-109 from South-Eastern Precaspian Azerbaijan; KU-2105, KU-2159 from Western Precaspian Iran; KU-2080 from Eastern Precaspian Iran.     

Genetic variation for phenolic acids concentration and composition in a tetraploid wheat (<Emphasis Type="Italic">Triticum turgidum</Emphasis> L.) collection

Phenolic acid intake through the consumption of whole-wheat foods provides important health benefits associated with reduced risks of cardiovascular diseases and colon cancer. The genetic variation for phenolic acids was extensively studied in common wheat, but a comprehensive survey in tetraploid wheat is lacking. In this study we evaluated the genetic variability for individual and total phenolic acids concentration existing in a large collection of tetraploid wheat (Triticum turgidum L.). A 2-year evaluation was undertaken on the whole-meal flour of 111 genotypes belonging to seven T. turgidum subspecies including cultivars, landraces and wild accessions. Durum cultivars [T. turgidum subsp. durum (Desf.) MacKey], had the highest average concentration of total phenolic acids (828.7 μg g^?1 dm in 2012; 834.5 μg g^?1 dm in 2013) with amounts varying from 550.9 μg g^?1 dm to 1701.2 μg g^?1 dm, indicating a variation of greater than threefold fold. The lowest concentration of phenolic acids was found in T. turgidum subsp. dicoccum (Schrank ex Schübler) Thell. Rivet wheat (T. turgidum L. subsp. turgidum) had phenolic acid concentrations similar to those in durum, but less variation was noted among the accessions. On the other hand, the accessions of the four remaining subspecies showed lower phenolic acid concentrations and variation among the accessions as compared to durum. A total of six phenolic acids were identified across the wheat genotypes. The effects of genotype, year and year × genotype were estimated by ANOVA and resulted significant for all phenolic acids. The ratio of genotypic variance to total variance suggested the possibility of improving phenolic acid content in elite wheat germplasm through appropriate breeding programs. Moreover, significant correlations between phenolic acids and other quality characteristics of the grain were detected.     

Genotyping-by-sequencing reveals the origin of the Tunisian relatives of cultivated carrot (<Emphasis Type="Italic">Daucus carota</Emphasis>)

Tunisia, other countries in northwestern Africa, and the Iberian Peninsula, represent a center of diversity of Daucus. The genus traditionally has included about 20–25 species worldwide, but a recent molecular study redefined and expanded Daucus to include representatives from nine other genera. By this classification, Daucus now contains about 40 species, with some of them having winged fruits in addition to its traditionally recognized spiny fruits. The taxonomy of Daucus in Tunisia has recently been studied with morphological data, concluding that D. carota subsp. capillifolius is a subspecies that co-occurs and crosses with subsp. carota. The present study extends these findings with additional data from Genotyping-by-Sequencing (GBS) from 33 Tunisian accessions of D. carota (93 individuals with two to three replicates per accession), including the first collections of subsp. gummifer from Tunisia. Placed in the context of additional GBS data, D. carota subsp. gummifer has separate origins from other collections of subsp. carota in Tunisia and/or immediately adjacent areas to the north in Italy or its surrounding islands. Our results add support to the utility of large SNP datasets for species-level phylogenetic studies in Daucus.     

Complete chloroplast DNA sequences of Georgian indigenous polyploid wheats (<Emphasis Type="Italic">Triticum</Emphasis> spp.) and B plasmon evolution

Three types of plasmon (A, B and G) are present for genus Triticum. Plasmon B is detected in polyploid species - Triticum turgidum L. and Triticum aestivum L. By now, 21 complete sequences of chloroplast DNA of the genus Triticum is published by different authors. Many inaccuracies can be detected in the sequenced chloroplast DNAs. Therefore, we found it necessary to study of plasmon B evolution to use only those sequences obtained by our method in our laboratory. Complete nucleotide sequences of chloroplast DNA of 11 representatives of Georgian wheat polyploid species were determined. Chloroplast DNA sequencing was performed on an Illumina MiSeq platform. Chloroplast DNA molecules were assembled using the SOAPdenovo computer program. Using T. aestivum L. subsp. macha var. palaeocolchicum as a reference, 5 SNPs were identified in chloroplast DNA of Georgian indigenous polyploid wheats. 38 and 56 bp inversions were observed in paleocolchicum subspecies. The phylogeny tree shows that subspecies macha, durum, carthlicum and palaeocolchicum occupy different positions. According the simplified scheme based on SNP and indel data the ancestral, female parent of all studied polyploid wheats is an unknown X predecesor, from which four lines were formed.     

Genetic structure and differentiation among oregano [<Emphasis Type="Italic">Origanum vulgare</Emphasis> subsp. <Emphasis Type="Italic">glandulosum</Emphasis> (Desf.) Ietswaart] provenances from North Africa: bioinformatic approaches cause systematic bias

Thirteen simple sequence repeat (SSR) markers developed from expressed sequence tags (ESTs) of essential oil glands of Origanum vulgare were previously evaluated. These EST-SSR loci were analyzed to study the genetic diversity and differentiation of Origanum vulgare subsp. glandulosum, an endemic species of Tunisia. The study was performed on five natural populations from the Maghreb regions (North Africa) from northern Tunisia (Sejnane, Krib, Bargou, Zaghouan and Nefza). Two other subspecies of O. vulgare were used as out-group. These are O. vulgare subsp. hirtum (from USA) and O. vulgare subsp. vulgare (from Italy). A total of 60 alleles were detected in the seven populations studied. The number of alleles per locus ranged from 2 to 9. This analysis revealed that the unbiased expected heterozygosity (0.327) is higher than the observed heterozygosity (0.242), reflecting a deficit in heterozygosity in the total population. Only the Sejnane population has an excess of heterozygosity. The differentiation between Tunisian populations is highly significant and indicates the presence of a structure between these populations. However, the indexes of genetic differentiation (FST) values are low and vary between 0.048 and 0.115 which indicate the presence of a weak structure. The value of the FST between Nefza and Krib is not significant, reflecting the absence of genetic structure between them. The value of gene flow between these two populations is the most important (27.34), showing a substantial exchange of genes or genomic regions between them. The migration of genes is less important among the other Tunisian populations. Genetic structuring according to the geographical origin of Tunisian populations is low but still exists, which allows concluding the presence of a single complex gene pool.     

Prediction of the effects of climate change on <Emphasis Type="Italic">Sechium edule</Emphasis> (Jacq.) Swartz varietal groups in Mexico

Climate change has significant impacts on biodiversity and, particularly, on agriculture. In this study, the impact of climate change on five varietal groups of Sechium edule, up to the year 2050, was determined through the application of the HadGEM2-CC model based on bioclimate layers. The varietal groups, nigrum minor, albus dulcis and nigrum xalapensis, will lose more than 50 % of their potential current distribution due to a high impact in both the rcp 45 and the rcp 85 scenarios. These two varietal groups also have a limited distribution, which makes them highly susceptible. In the case of nigrum spinosum, a loss under 50 % is predicted with scenario rcp 45. The varietal group that increases its distribution in 11 % is virens levis. The model forecasts significant impacts up to the year 2050; however, the groups evaluated present high genetic diversity and phenotypic plasticity which allow adapting to new conditions that may contribute to mitigating the effects of climate change.     

The impact of adsorption on the exposure assessment of <Emphasis Type="Italic">Bacillus thuringiensis</Emphasis> in the water-sediment system: a mathematical model approach

A model to assess the environmental fate of bacteria to be used as plant protection products or biocides is presented. The model, based on a black-box approach, takes into account the bacterial cell adsorption on the sediment phase and the degradation kinetics and allows the calculation of the expected environmental density of bacterial cells and the predicted environmental concentration of bacterial toxins in the water-sediment system. An example of calculation results is reported for the study cases of Bacillus thuringiensis subsp. aizawai strain GC-91, B. thuringiensis subsp. kurstaki strain ABTS-351, and B. thuringiensis subsp. tenebrionis strain NB 176, used as plant protection products, and B. thuringiensis subsp. israelensis strains AM 65–52 and SA3A, used as biocides. The calculation of expected environmental density and predicted environmental concentration for bacteria in soil-water systems allows to achieve an appropriate risk assessment of the environmental fate and of the impact of bacterial pest control agents or bacterial biocides on non-target organisms.     

Characterization of wild Beta populations in and adjacent to sugar beet fields in the Imperial Valley,California

Populations of wild Beta L. species exist as weeds in commercial sugar beet (Beta vulgaris L. subspecies vulgaris) fields in the Imperial Valley, California. Significant losses to sugar yield and quality result if these wild plants are not removed. In cases of extreme infestation, fields are abandoned without harvest. No selective chemicals are available to differentiate conventional sugar beet from wild relatives and hand removal is labor intensive and expensive. Planting sugar beet varieties with tolerance to glyphosate is a potential solution for infested fields, but risk of gene flow to adjacent wild relatives must be determined. Previous research identified these populations as either Beta vulgaris L. subspecies maritima (L.) Arcang. or Beta macrocarpa Guss. This distinction is critical because B. v. subsp. maritima will readily cross hybridize with cultivated sugar beet while B. macrocarpa rarely will. In April 2011, we collected herbarium samples, mature seed, and leaf tissue from wild Beta populations in 25 infested sugar beet fields throughout the Imperial Valley. Bolting cultivated beets were identified at two locations. Taxonomy of whole plant herbarium samples was unclear due to wild beet stem elongation when under competition with sugar beet plants for canopy light. Morphology of plants from collected seed grown in non-competitive conditions assigned taxonomy of these populations to B. macrocarpa. We used molecular tools to determine the genetic structure of wild Beta populations throughout the Imperial Valley. Extracted DNA was genotyped with 22 simple sequence repeat molecular markers and evaluated for population structure. The bolting beet samples were clearly separated from the majority of B. macrocarpa samples, except for two. The remaining wild populations were further divided into two subgroups suggesting exchange of genetic information or a common ancestor.     

Morphological and genetic diversity of shea tree (<Emphasis Type="Italic">Vitellaria paradoxa</Emphasis>) in the savannah regions of Ghana

Vitellaria paradoxa C. F. Gaertn., commonly known as shea tree or Vitellaria, is ranked the most important tree species of the savannah regions in the most African countries due to its ecological and economic importance for livelihoods and national economies. However, the savannah regions are the most vulnerable areas to the global climate change. Moreover, the Vitellaria populations on farmlands are threatened by the dominance of old trees with low or lack of regeneration. In this study both morphological and genetic diversity were assessed using several phenotypic traits and 10 microsatellite markers, respectively, to assess the impact of land use and agro-ecozone types on Vitellaria in Ghana. The land use types were forests and farmlands, and the agro-ecozone types included the Transitional, Guinea, and Sudan savannah zones. The mean values of morphological traits, such as diameter at breast height (DBH) and canopy diameter (CD), were statistically different between forest (DBH = 22.20, CD = 5.37) and farmland (DBH = 39.85 CD = 7.49) populations (P < 0.00001). The Sudan savannah zone with mean petiole length of 4.96 cm showed significant difference from the other zones, likely as a result of adaptation to drier climate conditions. Genetic data analysis was based on 10 microsatellite markers and revealed high genetic diversity of Vitellaria in Ghana: mean expected heterozygosity, H _e was 0.667, and allelic richness, measured as number of effective alleles A _e , was 4.066. Both farmlands and forests were very diverse indicating lack of negative influence of farmer’s selection on genetic diversity. Fixation index was positive for all populations (mean F _IS = 0.136) with farmlands recording relatively higher values than forests in all ecological zone types studied, probably indicating less gene flow in the farmlands. Moderate differentiation (F′ _ST = 0.113) was comparable to other similar tree species. Both land use and ecological zone types influenced genetic differentiation of Vitellaria at varying levels. The species was spatially structured across three ecozones and following climatic gradient. The forest reserves are used in situ conservation for Vitellaria in Ghana. High diversity observed in the most arid zones provides opportunity to find and use appropriate plant materials for breeding climate change resilient trees.     

Relationships among <Emphasis Type="Italic">Crataegus</Emphasis> accessions sampled from Hatay,Turkey, as assessed by fruit characteristics and RAPD

The genus Crataegus known as hawthorns, is the largest genus among the Maloideae, which comprises 265 species. Turkey is one of the genetic centers of Crataegus and there are more than 20 species found in Turkey. The fruits of Crataegus are used as food and have high flavonoid, vitamin C, glycoside, anthocyanidin, saponin, tannin, and antioxidant levels. In this study, we attempted to characterize 15 Crataegus accessions sampled from Hatay, located in Eastern Mediterranean region of Turkey. The accessions belonged to several species; C. aronia (L.) DC. var. aronia, C. aronia var. dentata Browicz, C. aronia var. minuta Browicz, C. monogyna Jacq. subsp. azarella (Griseb.) Franco, and C. orientalis Pall. ex M. Bieb. var. orientalis. Fruit characteristics of the accessions exhibited considerable variation. The multivariate, principle component and cluster analyses indicated that the accessions belonged to three groups: (1) C. aronia var. arona accessions; (2) C. aronia var. dentata accessions; and, (3) C. monogyna subsp. azarella and C. orientalis var. orientalis accessions. The principle component analysis results also revealed that the first three components explained 46, 21, and 14% of the variation, comprising a total of 81%. The fruit length and width, leaf area, and soluble solids contents were highly correlated characteristics for the first three components. The 19 RAPD primers generated a total of 107 bands, where 76 of these were polymorphic. The molecular data analyses by principle coordinate and clustering showed similar results to those of pomological characteristics. There were three groups, (1) C. aronia var. arona accessions; (2) C. aronia var. dentata accession; and, (3) C. monogyna subsp. azarella. C. orientalis var. orientalis accession grouped with C. aronia var. arona accessions. Therefore, it can be concluded that, overall, the diversity patterns of pomological and molecular data, generated by RAPD, for Crataegus are in good agreement and the accessions of C. aronia var. aronia, C. aronia var. minuta, C. monogyna subsp. azarella and C. orientalis var. orientalis accessions.     

Population genetic analysis of hyacinth bean (<Emphasis Type="Italic">Lablab purpureus</Emphasis> (L.) Sweet,Leguminosae) indicates an East African origin and variation in drought tolerance

Population genetic studies are effective ways of researching the origin of, and genetic variation within, crop species, with a view to breeding for increased tolerances or novel traits. This is particularly important now that we are facing climate change and an increasing global population. Lablab purpureus (L.) Sweet (hyacinth bean) is an underutilised legume that has the potential of being an important crop species in the future due to its enhanced environmental tolerances relative to other legumes. It is farmed extensively, but locally, throughout Africa and Asia, however limited research and development of the crop has been undertaken so far, hence an investigation into its origin and diversity is warranted. Our microsatellite analysis suggests an East African origin of Lablab because of the genetic similarities between East African lines and the wild subspecies, subsp. uncinatus. The East African lines were also more genetically diverse. Two chloroplast DNA haplotypes were resolved and Africa was the only continent where both were present, again suggesting an African origin followed by the dissemination of lines outside of Africa coupled with a reduction in genetic diversity. Variation in tolerance to drought was recorded, with some lines able to tolerate 14 days without watering. In sum, we propose an East African origin of Lablab and have identified potential adaptive diversity for future crop breeding attempts.     

Characteristics of the root system in the diploid genome donors of hexaploid wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.)

Wild crop relatives are of considerable interest in plant breeding and significant efforts have been made to transfer their genetic variation into modern crops. Of the three diploid progenitors of bread wheat (Triticum aestivum L.), only Aegilops tauschii Coss. has been explored and exploited and only for some above ground characteristics. The three wild progenitors (Aegilops speltoides Tausch., Triticum urartu Tumanian ex Gandilyan, and Aegilops tauschii) have never been assayed for root traits. Here we report such a root study, and include Triticum monococcum L. subsp. boeoticum (Boiss.) Hayek and T. turgidum L. subsp. dicoccoides (Koern. ex Asch. et Graebn.) Thell. Fifteen accessions were selected from the above wild species and tested in the presence of one bread wheat cultivar Pavon F76. Significant variation was observed between and within the taxa. Of all accessions tested, cv. Pavon F76 had the smallest root system at maturity while A. speltoides had the largest root system. Moreover, Aegilops spp. had larger mean values for root biomass when compared with Triticum spp. These results suggest there is significant unexplored potential for the use of wheat wild relatives in wheat breeding to improve the root system, or to develop synthetic mapping populations to study root traits.     

Agro-morphological traits of <Emphasis Type="Italic">Cicer reticulatum</Emphasis> Ladizinsky in comparison to <Emphasis Type="Italic">C. echinospermum</Emphasis> P.H. Davis in terms of potential to improve cultivated chickpea (<Emphasis Type="Italic">C. arietinum</Emphasis> L.)

Germplasm collections of C. reticulatum and C. echinospermum are limited, while both species face threats from over-grazing and habitat change in their natural environments. Recently many new accessions of C. reticulatum and C. echinospermum were collected in east and south-east Anatolia (Turkey) but they have not yet been evaluated for agro-morphological traits. Therefore, the current study investigated agro-morphological traits of new germplasm sources of C. reticulatum and C. echinospermum and evaluated resistance to biotic and abiotic stresses for chickpea improvement. The most attractive agro-morphological traits were canopy width, number of stems and pods per plant and biological yield. The most productive accessions of C. reticulatum and C. echinospermum had 712 and 625 pods per plant, respectively. Two distinct seed, flower and leaf shapes were found in accessions of C. echinospermum. Path analyses indicated that biological yield and harvest index had the most direct influence on seed yield in both species. Factor analyses showed that high seed yield in C. reticulatum depended on high biological yield and number of pods per plant, whereas high seed yield in C. echinospermum depended on harvest index. It was concluded that most accessions of C. reticulatum and C. echinospermum were not only resistant to some biotic and abiotic stresses but also had hidden alleles that could produce transgressive segregation in crosses to cultivated material.     

Assessment of artificial selection in maize (<Emphasis Type="Italic">Zea mays</Emphasis> L.) and Asian rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.) using QTL data

Maize (Zea mays L.) and Asian rice (Oryza sativa L.), two most important cereals for human nutrition, have undergone strong artificial selection during a long period of time. Currently, a number of genes with stronger signals of selection have been identified through combining genomic and population genetic approach, but research on artificial selection of maize and Asian rice is scarcely done from the perspective of phenotypic difference of a number of agronomic traits. In this study, such an investigation was carried out on the basis of 179 published studies about phenotypic quantitative trait locus (QTL) mapping of Zea and Oryza species via QTL sign test. At the overall level, the proportions of antagonistic QTLs of Zea and Oryza species were 0.2446 and 0.2382 respectively, deviating significantly from neutrality. It indicated that these two genera have undergone similar selection strength during their evolutionary process. A previous study showed that 4 traits undergoing the directional selection during domestication were identified in Asian rice via QTL sign test, and 16 individual traits in Asian rice and 38 ones in maize that newly detected in this study deviated significantly from neutrality as well, demonstrating the dominant influence of artificial selection on them. Moreover, analysis of different categories of cross type including O. sativa × Oryza rufipogon (perennial and annual forms) crosses, maize × teosinte (Zea mays subsp. parviglumis) crosses, O. sativa × O. sativa crosses, and maize × maize crosses showed that their proportions of antagonistic QTLs were 0.1869, 0.1467, 0.2649, and 0.2618 respectively. These results revealed that selection strength of domestication is significantly stronger than that of modern genetic improvement. However, interestingly, the proportion of antagonistic QTLs (0.1591) in maize × maize with long-term selection was very similar to that (0.1467) in the maize × teosinte (Zea mays subsp. parviglumis) crosses. It suggested that some favorable traits could be cultivated within a few decades if we carry out strong selection. In addition, the proportions of antagonistic QTLs of the widely cultivated hybrids of rice (Minghui 63 × Zhenshan 97) and maize (Zheng 58 × Chang 7-2) in China were 0.309 and 0.3472 respectively. It suggested that selection during modern genetic improvement has significantly acted on them.