<Emphasis Type="Italic">Angelica sinensi</Emphasis>s (Oliv.) Diels in China: distribution,cultivation, utilization and variation

Angelica sinensis (Oliv.) Diels has been cultivated and used in China for more than 2000 years. Its root is an important traditional Chinese medicine mainly used for tonifying blood and for treatment of anemia, rheumatism, and menstrual problems. Cultivated populations of this crop are distributed in the Gansu, Yunnan, Sichuan, Shaanxi, and Hubei provinces of China. Today it is used not only for its medicinal properties, but also as a health food product, a dietary supplement, and in cosmetics. Cultivated A. sinensis can be divided into green-stemmed and purple-stemmed phenotypes according to morphological traits. The classification of the two phenotypes was supported by AFLP data. Analysis of molecular variance (AMOVA) showed that genetic diversity was greater within populations (80.53%) than among populations (19.47%).     

Genetic diversity and spatial structure in a new distinct <Emphasis Type="Italic">Theobroma cacao</Emphasis> L. population in Bolivia

Cacao (Theobroma cacao L.) is an important economic crop in the Bolivian Amazon. Bolivian farmers both cultivate cacao, and extract fruits from wild stands in the Beni River region and in valleys of the Andes foothills. The germplasm group traditionally used is presently referred to as “Cacao Nacional Boliviano” (CNB). Using DNA fingerprinting technology based on microsatellite markers, we genotyped 164 Bolivian cacao accessions, including both cultivated and wild CNB accessions sampled from the Amazonian regions of La Paz and Beni, and compared their SSR profiles with 78 reference Forastero accessions from Amazonian cacao populations, including germplasm from the Ucayali region of Peru. Results of multivariate ordination and analysis of molecular variance show that CNB cacao has a unique genetic profile that is significantly different from the known cacao germplasm groups in South America. The results also show that cultivated CNB and wild CNB populations in the Beni River share a similar genetic profile, suggesting that the cultivated CNB is of indigenous origin in Bolivia. The level of genetic diversity, measured by allele richness and gene diversity in the Bolivian cacao, is moderately high, but was significantly lower than gene diversity in the other Amazonian cacao populations. Significant spatial genetic structure was detected in the wild CNB population, using analysis of autocorrelation (rc = 0.232; P < 0.001) and Mantel tests (Rxy = 0.276; P < 0.001). This finding is also highly valuable to support in situ conservation and sustainable use of CNB genetic diversity in Bolivia.     

Genetic diversity and differentiation of cultivated ginseng (<Emphasis Type="Italic">Panax ginseng</Emphasis> C. A. Meyer) populations in North-east China revealed by inter-simple sequence repeat (ISSR) markers

Panax ginseng C. A. Meyer is a medicinally important herb with a long history of cultivation, and includes three cultivated types, viz. garden ginseng (GGS), forest ginseng (FGS) and transplanted wild ginseng (TGS). In the present study, inter-simple sequence repeat (ISSR) markers were employed to investigate the genetic variability in 282 individuals, which corresponded to 16 cultivated ginseng populations. Genetic diversity was high at the species level (h = 0.2886; I = 0.4382; PPB = 98.96%), but relatively lower at the cultivated-type level (GGS: h = 0.2294, I = 0.3590, PPB = 85.42%; FGS: h = 0.1702, I = 0.2559, PPB = 57.29%; TGS: h = 0.2021, I = 0.3125, PPB = 76.04%). The hierarchical analysis of molecular variance (AMOVA) revealed pronounced genetic differentiation among populations (Φ _ST = 53.94%), which was confirmed by the gene differentiation coefficient (G _ST = 0.4910) and low gene flow (N _m = 0.5184). Both Principal Coordinates Analysis (PCoA) and UPGMA cluster analysis supported the clustering of all 16 populations into three groups, corresponding to the three cultivated types, among which there occurred remarkable genetic differentiation (Φ _ST = 37.43%). Pronounced genetic differentiation was also detected among populations within the three cultivated types (GGS: Φ _ST = 40.83%, G _ST = 0.3187, N _m = 1.0691; FGS: Φ _ST = 22.85%, G _ST = 0.2328, N _m = 1.6480; TGS: Φ _ST = 30.68%, G _ST = 0.2540, N _m = 1.4686). Mantel test indicated no significant correlation between geographic and genetic distances at both species and cultivated-type levels (P > 0.05). These findings have profound implications for the sustainable utilization of this precious medicinal herb.     

Maintenance of Squash (<Emphasis Type="Italic">Cucurbita</Emphasis> spp.) Landrace Diversity by Farmers' Activities in Mexico

Squash (Cucurbita spp.) is a common component in traditional cropping systems in Mexico, mainly in the agroecosystem known as the “milpa”, in which squash is cultivated in association with maize (Zea mays), the main crop. Using a questionnaire, 80 farmers were interviewed about crop production and selection practices in order to understand how these factors affect genetic diversity of local squash populations. We found that the most of the farmers who cultivate squash were elderly 59.8 ± 14.5 (mean ± SD; n = 78) years old. Squash varieties in the area were exclusively locally adapted landraces, and had not been replaced by modern squash cultivars. Two cultivated squash species, C. argyrosperma ssp. argyrosperma and C. moschata, had been grown intercropped with maize by 97.5% of the interviewed farmers, but only 50.0% were still producing squash at the time of the study. Farmers recognize typical characteristics of particular varieties within each of the local cultivated squash species, and selection is directed to maintain their identity. Nearly two thirds of the farmers (62.0%) had exchanged seeds of squash for planting, a practice that serves to increase genetic variability in the populations. All of the interviewed farmers were conscious of the possible hybridization between the wild gourd (C. argyrosperma ssp. sororia) and their cultivated squash. Despite various natural and human managed factors identified as contributing to enhancement of genetic diversity in these populations, results of the study show that genetic erosion of Cucurbita is likely in the region in the near future.     

Nutritional composition of Sanchi (Panax notoginseng) seed and its potential for industrial use

Sanchi (Panax notoginseng) root has been widely used as traditional herb to stanch blood, disperse gore and reduce pain in China for centuries. However, the nutritional information about its seed was unknown. Sanchi seeds obtained from Yunnan Province were analyzed for their nutritional composition, fatty acid, amino acid profile and sugar contents. Sanchi seeds were abundant in fats (46.35 %) and proteins (23.90 %). Notably, seven fatty acid compositions were determined and abundant in unsaturated fatty acid (99.56 %), containing 95.71 % oleic acid. Sanchi seed proteins were rich in glutenin, globulin and albumin (28.63, 27.83 and 26.81 %, respectively). Sanchi seed contain 17 kinds of amino acids, of which nine were essential amino acids, accounting for 41.30 %. These nutritional compositions indicate that Sanchi seed has the potentiality to be exploited as human edible oil, industrial use, new medicine or healthcare products for diabetes patients due to low sugar content.     

Effect of difference between day and night temperature on tomato (Lycopersicon esculentum Mill.) root activity and low molecular weight organic acid secretion

The difference between day and night temperature (DIF) is a major environmental factor affecting crop growth, but the mechanisms are not fully understood. We investigated crop performance, root activity and concentrations of low molecular weight organic acids (LMWOAs) secreted by tomato (Lycopersicon esculentum Mill.) root under different DIF conditions. A fixed daily temperature of 25°C and five DIF treatments (?12, ?6, 0, 6 and 12°C) were used to grow tomato in a climate chamber. Root/shoot ratio; leaf maximum photosynthetic rate (P_max); root activity; total nitrogen (N), phosphorus (P) and potassium (K) concentrations in roots; and types and concentrations of LMWOAs were measured at different growth stages. Results showed that positive and negative DIFs inhibited the dry matter accumulation of aerial parts, while 0°C DIF was conducive to the accumulation. Compared to 0°C DIF, positive DIFs significantly increased root dry weight, P_max, root activity and total N, P and K concentrations in roots, while negative DIFs had contrary effects. During the whole growth period, tomato root activity decreased in the order of fruit setting stage, mature stage and flowering stage. Tomato roots secreted oxalic acid, formic acid, malic acid, malonic acid, lactic acid, acetic acid, citric acid, succinic acid and propionic acid under positive DIFs, while acetic acid was not detected in the negative DIF treatments. Oxalic acid concentration was significantly higher than other LMWOAs. Furthermore, in the same growth stage, positive DIFs caused more LMWOA secretion than negative DIFs and 0°C DIF. There were significant positive correlations between the total LMWOA concentration and root activity, root/shoot ratio, P_max and total N, P and K concentrations in roots. Based on the results, more attention should be paid to the potential effect on tomato growth posed by DIFs, positive DIFs have higher positive influence than negative DIFs, and 6°C DIF is best for greenhouse tomato growth.     

Effectiveness of Air,N<Subscript>2</Subscript> (gas), Fe<Superscript>+3</Superscript> and Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> Nanoparticles on the Sonication of Less and More Hydrophobic Polycyclic Aromatic Hydrocarbons (PAHs) and Toxicity

In this study, the effects of 1 h aeration, nitrogen gas N₂(g) sparging (15 and 30 min) and increasing ferric ions (Fe⁺³) as FeSO₄ (10, 20 and 50 mg L⁻¹) and Fe₃O₄ nanoparticles (1, 2 and 4 g L⁻¹) concentrations on three less hydrophobic and three more hydrophobic polycyclic aromatic hydrocarbons (PAHs) and toxicity removals from a petrochemical industry in Izmir (Turkey) were investigated in a sonicator with a power of 650 W and an ultrasound frequency of 35 kHz; 1 h aeration increased the yields in benzo[b]fluoranthene, benzo[k]fluoranthene and benzo[a]pyrene PAHs (less hydrophobic) from 62% to 67% to around 95–97% after 150 min sonication at 60°C. However, 1 h aeration did not contribute to the yields of more hydrophobic PAHs (indeno[1,2,3-cd]pyrene, dibenz[a,h]anthracene, benzo[g,h,i]perylene). The maximum yields were obtained at acidic and alkaline pH for more and less hydrophobic PAHs, respectively, after 60 and 120 min sonication at 30°C; 30 min N₂(g) sparging, 50 mg L⁻¹ Fe⁺³ increased the yields of less hydropobic PAHs after 150 min sonication at 60°C. Two milligrams per liter of Fe₃O₄ nanoparticles increased both less (87–88%) and more (96–98%) hydrophobic PAH yields. The Daphnia magna acute toxicity test showed that the toxicity decreased significantly with an hour aeration, 30 min N₂(g) sparging, 50 mg L⁻¹ Fe⁺³ and 2 g L⁻¹ Fe₃O₄ nanoparticles at 60°C after 120 and 150 min sonications. Vibrio fischeri was found to be more resistant to the sonicated samples than D. magna. Significant correlations were found between the physicochemical properties of sonicated PAHs and acute toxicities both organisms.     

Collection and conservation of ‘Morado de Huetor’ Spanish tetraploid asparagus landrace

A cultivated tetraploid asparagus landrace ‘Morado de Huetor’ growing in the South of Spain has been collected and conserved ex situ in two experimental plots. This landrace has been reported to have an interspecific hybrid origin (A. officinalis × A. maritimus). A 59% of the total farmer plots cultivated in the region were visited and ripe fruits collected from 10 female plants per plot. Fruits from a total of 300 plants were collected and two half sibs descendents from each one were sown separate in two plots. Of the 88 farmer plots visited, the landrace was growing only in 34, in the rest the crop had been removed. Hence, ‘Morado de Huetor’ is in a very high risk of disappearing. Now this landrace is conserved ex situ in two experimental plots with sufficient number of plants to represent their maximum variability in order to be used in plant breeding.     

Diversity of Paenibacillus polymyxa populations in the rhizosphereof wheat (Triticum durum) in Algerian soils

The diversity of Paenibacillus polymyxa populations associated with the rhizosphere of durum wheat was investigated in Algerian soils sampled in regions where wheat had been cultivated for 5 and 26 years (Hamiz, H5 and Z26), 70 years (Algiers, D70), and more than 2 000 years (Tiaret, T2000 and K2000). A total of 111 strains were isolated by immunotrapping and identified as P. polymyxa using an API50CHB kit and restriction analysis of the amplified 16S rDNA gene. The phenotypic characteristics of the P. polymyxa populations were compared and the strains found not to cluster according to their origin. The longer the history of wheat cultivation, the lower the phenotypic diversity and the higher the frequency of nitrogen-fixing strains. Population genetic diversity, evaluated by ERIC-PCR, showed the same trends as phenotypic diversity. The distribution of ERIC genotypes among the different populations studied were compared using Pearson’s Chi-squared test. The strains isolated in D70, Z26, and H5 derived from soil populations sharing the same genetic structure, but those isolated in T2000 and K2000 each stemmed from a population with a specific genetic structure. These data suggest that the genetic structure of P. polymyxa populations has been affected by long-term wheat cultivation.     

Phenotypic diversity in wild barley (<Emphasis Type="Italic">Hordeum vulgare</Emphasis> L. ssp. <Emphasis Type="Italic">spontaneum</Emphasis> (C. Koch) Thell.) accessions collected in Jordan

Wild barley, Hordeum vulgare L. ssp. spontaneum (C. Koch) Thell., is the progenitor of cultivated barley. Almost unanimously the center of diversity is considered to be in the Fertile Crescent of the Near East, where wild barley grows under a wide range of environmental and climatic conditions. Jordanian wild barley is expected to harbor genes useful for the improvement of cultivated barley, particularly those associated with tolerance to drought. This study evaluated 103 wild barley accessions collected from different areas of Jordan along with 29 cultivated barley genotypes for several morphological and agronomical traits. The Hordeum vulgare ssp. spontaneum C. Koch accessions were grouped into six populations according to the longitude, latitude, altitude, and rainfall zone of the collection site, and the cultivated barley in one population. The evaluation was conducted during the 2004–2005 growing season under field conditions in three locations in Jordan; namely, Khanasri, Ramtha, and Maru with 123.0, 222.9, and 429.2 mm annual rainfall, respectively. We used an unreplicated design with two systematic checks (the cultivars Rum and Mu’ta) each repeated 15 times. The results showed the existence of high variability among the Hordeum vulgare ssp. spontaneum C. Koch accessions for most of the traits, especially for plant height, tiller number, days to heading, days to anthesis, peduncle length, and peduncle extrusion. Plant height, earliness, peduncle length, and peduncle extrusion were found to be adaptive traits under drought conditions and several superior genotypes for each trait were identified. Genetic variation within population was much higher than between populations. Clustering of populations was according to their ecological geographical pattern.     

Variability and selection on different <Emphasis Type="Italic">Argyrolobium roseum</Emphasis> accessions for morphological traits and yield

Variability studies were carried out among different accessions of Argyrolobium roseum for 12 metric traits under natural and cultivated conditions. Almost all characters showed higher values in cultivated than natural population. Leaf breadth recorded highest CV (30.59%). Highest percentage of vitexin and D-pinitol (0.208 and 0.773% dwb) was observed in RAR-7 and RAR-6, respectively, under cultivated conditions. Phenotypic coefficient was higher than genotypic coefficient of variation. The association analysis revealed that root yield had positive significant correlation with 100 seed weight (r=0.839) biomass yield (r=0.601), where biomass yield had a positive significant correlation with leaf length, single pod weight. High heritability (97.4–99.8%) coupled with moderate genetic advance ranged between (49–67%) as a percent of mean was observed for leaf breadth, pod length, total foliage biomass yield and total root yield/plant. This suggests that direct selection for these traits is suitable for the improvement of this crop.     

Corn growth and nitrogen nutrition after additions of biochars with varying properties to a temperate soil

The effects of biochar properties on crop growth are little understood. Therefore, biochar was produced from eight feedstocks and pyrolyzed at four temperatures (300°C, 400°C, 500°C, 600°C) using slow pyrolysis. Corn was grown for 46 days in a greenhouse pot trial on a temperate and moderately fertile Alfisol amended with the biochar at application rates of 0.0%, 0.2%, 0.5%, 2.0%, and 7.0% (w/w) (equivalent to 0.0, 2.6, 6.5, 26, and 91 t biochar ha⁻¹) and full recommended fertilization. Animal manure biochars increased biomass by up to 43% and corn stover biochar by up to 30%, while food waste biochar decreased biomass by up to 92% in relation to similarly fertilized controls (all P < 0.05). Increasing the pyrolysis temperature from 300°C to 600°C decreased the negative effect of food waste as well as paper sludge biochars. On average, plant growth was the highest with additions of biochar produced at a pyrolysis temperature of 500°C (P < 0.05), but feedstock type caused eight times more variation in growth than pyrolysis temperature. Biochar application rates above 2.0% (w/w) (equivalent to 26 t ha⁻¹) did generally not improve corn growth and rather decreased growth when biochars produced from dairy manure, paper sludge, or food waste were applied. Crop N uptake was 15% greater than the fully fertilized control (P < 0.05, average at 300°C) at a biochar application rate of 0.2% but decreased with greater application to 16% below the N uptake of the control at an application rate of 7%. Volatile matter or ash content in biochar did not correlate with crop growth or N uptake (P > 0.05), and greater pH had only a weak positive relationship with growth at intermediate application rates. Greater nutrient contents (N, P, K, Mg) improved growth at low application rates of 0.2% and 0.5%, but Na reduced growth at high application rates of 2.0% and 7.0% in the studied fertile Alfisol.     

Cultivation of lotus (<Emphasis Type="Italic">Nelumbo nucifera</Emphasis> Gaertn. ssp. <Emphasis Type="Italic">nucifera</Emphasis>) and its utilization in China

Lotus (Nelumbo nucifera Gaertn. ssp. nucifera), one of 12 aquatic species used as vegetable, has been cultivated for more than 2,000 years, and now has been widely cultivated in almost all provinces in China. The largest area under cultivation of lotus is located in the regions surrounding mid-down Yangtse River, including Hubei, Jiangsu, Zhejiang, Anhui, Jiangxi and Hunan provinces. According to different purposes or morphological differences, the Chinese lotus (N. nucifera ssp. nucifera) is usually classified into three types: rhizome lotus, seed lotus and flower lotus. Rhizome lotus is mainly cultivated in Hubei, Jiangsu, Anhui and Zhejiang provinces; Seed lotus in Jiangxi, Fujian and Hunan, and flower lotus in Wuhan, Hubei province, and Beijing. Up to the year 2002, a total of 572 lotus accessions (including landraces, cultivars and breeding lines) were conserved in National Garden of Aquatic Vegetable, Wuhan, Hubei province, including those collections from 153 counties in 18 provinces, and lines bred by breeders. Out of these accessions, 310 were rhizome lotus which contains 201 landraces and 109 breeding lines; 229 were flower lotus including 172 cultivars and 57 breeding lines; and the rest 33 were seed lotus with 18 cultivars.     

A study of genetic diversity of sesame (<Emphasis Type="Italic">Sesamum indicum</Emphasis> L.) in Vietnam and Cambodia estimated by RAPD markers

Sesame (Sesamum indicum L.) is a traditional oil crop cultivated throughout South East Asia. To estimate the genetic diversity of this crop in parts at the region, 22 sesame accessions collected in Vietnam and Cambodia were analyzed using 10 RAPD markers. The 10 primers generated 107 amplification products of which 88 were polymorphic fragments (83%). Genetic diversity of all populations was H_t = 0.34 when estimated by Nei’s genetic diversity and species diversity was H′_sp = 0.513 when estimated by Shannon diversity index. Genetic distance ranged from 0.03 to 0.43, with a mean genetic distance of 0.23. The unweighted pair group method with arithmetic averages (UPGMA) cluster analysis for the 22 accessions divided the material in four groups. The dendrogram revealed a clear division among the sesame accessions based on their geographical region. Interestingly, some geographically distant accessions clustered in the same group, which might indicate the human factor involved in the spreading of sesame varieties. The high level of polymorphism shown suggests that RAPD techniques can also be useful for the selection of parents in sesame (Sesamum indicum L.) breeding program and for cultivar differentiation.     

Anthropogenic and natural causes influencing population genetic structure of <Emphasis Type="Italic">Juniperus procera</Emphasis> Hochst. ex Endl. in the Ethiopian highlands

Juniperus procera is economically highly important but threatened tree species. It is the only species among 67 taxa in the genus Juniperus that naturally grows in Africa and south of the equator extending up to 18°S in Zimbabwe. Ethiopia is assumed to host the largest J. procera populations, which are also believed to have high genetic variation owing to their wide ecological amplitude. This study assessed genetic variation at AFLPs of J. procera populations in the Ethiopian highlands. In the study six populations, namely Chilimo, Goba, Menagesha-Suba, Wef-Washa, Yabelo and Ziquala were included. A total of 20–24 trees from each population were investigated based on 128 AFLP band positions. AMOVA revealed that most of the variation (94%) resided within populations of J. procera suggesting extensive gene flow among populations which is attributable to the outcrossing mating system and effective gene transport mechanisms of the species. However, genetic differentiation among populations was still significant (P < 0.05), and the differentiation was significantly (P < 0.05) correlated with geographic distance. All population pairs were significantly (P < 0.05) differentiated except for Menagesha-Suba and Wef-Washa. These two populations also showed the highest gene diversity (H _j = 0.301 and H _j = 0.297, respectively). These results are in accordance with historical records that claim the establishment of the Menagesha-Suba juniper population as plantation of seedlings from Wef-Washa back in fifteenth century.     

Genetic relationships among wild and cultivated populations of peach palm (<Emphasis Type="Italic">Bactris gasipaes</Emphasis> Kunth,Palmae): evidence for multiple independent domestication events

We studied the genetic relationship among four wild and ten cultivated populations of peach palm (Bactris gasipaes Kunth) using five microsatellite markers. Peach palm populations were grouped into two major complexes based on morphological traits (see Mora-Urpí 1984, 1993): the Occidental group, including populations found north and west of the Andes Mountains, and the Oriental group, including populations in the Amazon Basin. The Oriental group is further divided into two subgroups, the upper and eastern Amazonia. We also studied two wild relatives of peach palm from the Maracaibo basin in Venezuela. All microsatellite loci were polymorphic and the total number of alleles across all loci was 64. The number of alleles observed per locus ranged from 9 (Bg51) to 16 (Bg63; Average = 12.8 ± 2.8 alleles per locus), while the average number of alleles per population was 31.8 ± 7.3. Our data also revealed that some alleles were common to populations from the same geographical region. A dendrogram based on Rogers and Tanimoto’s similarity coefficient revealed three main branches. The first branch is divided into two nodes and includes all populations from Occidental and Upper Amazonia groups; the second branch includes both populations from Eastern Amazonia, and the third branch includes both wild relatives from Maracaibo. All populations included in each node are neighbors within a geographic region, indicating that populations were finely clustered into their respective geographic groups. We propose that this clustering supports the hypothesis of several independent domestication events on both sides of the Andes, as proposed by Mora-Urpí (1993).     

Nitrogen release from differently aged Raphanus sativus L. nitrate catch crops during mineralization at autumn temperatures

In temperate climates with surplus precipitation and low temperatures during autumn and winter, nitrate catch crops have become crucial in reducing nitrate leaching losses. Preferably, the N retained by the catch crop should remain in the soil and become available to the next main crop. Fodder radish (Raphanus sativus, L.) has emerged as a promising nitrate catch crop in cereal cropping, although the course of remineralization of residue N following termination of this frost‐sensitive crucifer remains obscured. We incubated radish residues of different age (different planting and harvest dates) with a loamy sand soil; mineralization of residue N was determined after 1, 2, 4 and 7 months of incubation at 2 °C and 10 °C. Incubations with soil only and with residues of white mustard (Sinapis alba, L) and perennial ryegrass (Lolium perenne, L.) were included as references. Using linear regression, net N release was fitted to plant chemical characteristics (initial concentrations of N, fibre fractions, lignin and C/N ratio). Residue C/N ratio (ranging from 10 to 25) and N concentration (ranging from 17 to 40 mg N/g dry matter) showed superior fits to net N release at both temperatures (r², 0.64–0.94) while fibre analyses provided inferior fits (r², 0.12–0.64). This was true across planting date and plant age. Net N release after 7 months of incubation at 2 °C and 10 °C accounted for up to 40% and 50% of residue N, respectively. During most of the incubation period, nitrate dominated the mineral N pool at both temperatures. The N mineralization and nitrification potential at these low soil temperatures suggest that a considerable fraction of the N captured by nitrate catch crops may be remineralized, nitrified and thus available for plant uptake but also for loss by leaching and denitrification.     

Natural hybrids between cultivated and wild sunflowers (<Emphasis Type="Italic">Helianthus</Emphasis> spp.) in Argentina

Two introduced wild species Helianthus annuus L. and H. petiolaris Nutt. have become widespread in central Argentina and overlap the sunflower crop region. Intermediate off-type plants between the wild and cultivated species are often found, which is of concern because of the recent release of imidazolinone resistant varieties and the likely use of genetically modified sunflower cultivars. The progeny of 33 off-type plants obtained from 14 representative sites of the diffusion area were studied to confirm hybrid origin. Germination, survival, morphological traits and days to flowering confirmed hybridization between crop and both wild species, when compared to eight accessions of typical wild plants. Some progenies were presumably crop–wild H. annuus hybrids, some originated from the cross of cultivated plants and H. petiolaris, and two were the advanced generation of a cultivated hybrid. Hence, morphological traits are a good clue for the identification of spontaneous hybrid plants at field. The results indicate that crop–wild hybridization and introgression occur at various places in central Argentina. This fact may represent a way to herbicide resistance escape and future transgene escape if GM sunflower cultivars are released for commercial use.     

Diversity of Paenibacillus polymyxa populations in the rhizosphereof wheat (Triticum durum) in Algerian soils

The diversity of Paenibacillus polymyxa populations associated with the rhizosphere of durum wheat was investigated in Algerian soils sampled in regions where wheat had been cultivated for 5 and 26 years (Hamiz, H5 and Z26), 70 years (Algiers, D70), and more than 2 000 years (Tiaret, T2000 and K2000). A total of 111 strains were isolated by immunotrapping and identified as P. polymyxa using an API50CHB kit and restriction analysis of the amplified 16S rDNA gene. The phenotypic characteristics of the P. polymyxa populations were compared and the strains found not to cluster according to their origin. The longer the history of wheat cultivation, the lower the phenotypic diversity and the higher the frequency of nitrogen-fixing strains. Population genetic diversity, evaluated by ERIC-PCR, showed the same trends as phenotypic diversity. The distribution of ERIC genotypes among the different populations studied were compared using Pearson’s Chi-squared test. The strains isolated in D70, Z26, and H5 derived from soil populations sharing the same genetic structure, but those isolated in T2000 and K2000 each stemmed from a population with a specific genetic structure. These data suggest that the genetic structure of P. polymyxa populations has been affected by long-term wheat cultivation.     

Diversity analysis of <Emphasis Type="Italic">Acacia tortilis</Emphasis> (Forsk.) Hayne ssp. <Emphasis Type="Italic">raddiana</Emphasis> (Savi) Brenan (Mimosaceae) using phenotypic traits,chromosome counting and DNA content approaches

Acacia tortilis (Forsk.) Hayne ssp. raddiana (Savi) Brenan (Family Fabaceae; subfamily Mimosoideae) is a pioneer tree of dry areas. In spite of its several uses, there are no any published studies which deal with genetic diversity of Acacia tortilis (Forsk.) Hayne ssp. raddiana (Savi) Brenan in Tunisia. For this reason, here we study its genetic diversity with morphometric (only in Tunisian populations), chromosome counting, and cytometric (in Tunisian and Ziambabwean populations) approaches. Morphological field studies of four Tunisian populations (Bouhedma, Haddej, Hajeb and Gtar, respectively, designated as A, B, C, D) of A. tortilis (Forsk.) Hayne ssp. raddiana (Savi) Brenan using a general linear model (ANOVA) revealed statistically highly-significant differences between populations for all examined characters (P < 0.0001). Significant differences were found also between genotypes for the majority of morphological traits (P < 0.0001) except the width of 10 pods (laP), weight of 10 pods (Wt) and seed number of 10 pods (Sn) (P ≥ 0.110). The variability in the tree, pod and seed characters can be exploited for agro-industrial purposes. The DNA amount and chromosome numbers of populations Umguza and Gwaii River from Ziambabwe and of Tunisian populations A, B, C and D were determined. Tunisian populations had 2C nuclear DNA contents of 2.95–3.03 pg, and were shown to be tetraploid (2n = 4x = 52), whilst the two Ziambabwean populations had 1.39–1.40 pg and were diploid (2n = 2x = 26). It is suggested that the Tunisian populations are paleotetraploids, adapted to the more-arid local conditions.