Cytogenetic and systematic analyses of Kengyilia gobicola, K. zhaosuensis and K. batalinii var. nana (Poaceae)

Kengyilia batalinii var. nana J.L. Yang, Yen et Baum, K. gobicola Yen et J.L. Yang, K. zhaosuensis J.L. Yang, Yen et Baum are short-lived perennial grasses of the family Triticeae distributed throughout the upper and middle mountain ranges of west China. They were cytogenetically studied with testers R. kamoji Ohwi (StStHHYY) and K. hirsuta (Keng) J. L. Yang, Yen et Baum (PPStStYY). Analysis of metaphase I pairing configurations in the F₁ indicate that K. batalinii var. nana, K. gobicola, K. zhaosuensis possess the P, St, and Y genomes, with o nly minor structural rearrangements. These results showed that the three target taxa are good species in the genus Kengyilia.     

Markers associated with altitude and ecological factors in hexaploid Campeiostachys nutans (Griseb.) J. L. Yang,B. R. Baum et C. Yen and tetraploid Roegeneria nutans (Keng) Keng

The genetic basis of adaptation can be unraveled directly at the genome level, without regard to selectively advantageous genes or traits. Genetic variation and adaptation of polyploidy in the evolution of plants is becoming an area of intense interest. Whether hexaploid wheatgrass species has higher adaptability to altitude than tetraploid or not needs to be proofed by population genomic data. A fluorescence-based AFLP technique was used to investigate the allele share of hexaploid Campeiostachys nutans (Griseb.) J. L. Yang, B. R. Baum et C. Yen and tetraploid Roegeneria nutans (Keng) Keng as well as the genetic variation and natural selection in 22 natural populations and their association with ecological factors. Of all the AFLP bands, 84.29 % were found in common between two different ploidy wheatgrasses. In addition, we found that hexapoid C. nutans had 1.45 times the allelic frequency and more large-sized bands than tetraploid R. nutans. After genetic analyses, the next factor examined should be the effect of altitude on genetic variation. There were no significant inter-population genetic differentiations, suggesting that distance did not contribute to spatial isolation. Altitude and soil nutrient availability might play an important role in maintaining the genetic diversity. A certain percentage of positive selection loci were discovered in total genome allele. Hexaploid wheatgrass with higher ploidy numbers can show strong genetic adaptability to adverse high-altitude condition because of its complex genomic background with an additional H genome, which supports our hypothesis. Though this evolutionary process is believed to be the driving force behind sympatric speciation, we cannot forecast that hexaploid wheatgrass species will diversify into two species in the long term, but believe that diversification under local selection helps to increase the adaptability to the changes in altitude.     

Cytogenetic relationships between Avena insularis (2n=28) and both A. strigosa (2n=14) and A. murphyi (2n=28)

The newly discovered tetraploid oat Avena insularis was crossed with the diploid A. strigosa and the tetraploid A. murphyi. Considerably reduced chromosome association at meiosis and a low average number of chiasmata per cell of the A. strigosa × A. insularis hybrids indicated that the diploid A. strigosa did not participate in the creation of A. insularis. From A. murphyi, A. insularis differed by four chromosomal rearrangements and the hybrids between them were sterile. The tetraploids A. magna, A. murphyi and A. insularis share the two to four floret large diaspore, which is adapted to heavy alluvial soil. They all, however, diverge from one another by four chromosomal rearrangements. At this point it is not possible to determine whether they have diverged from a single tetraploid progenitor, or developed from different diploid species.     

Levels and distribution of allozyme and RAPD variation in populations of Elymus fibrosus (Schrenk) Tzvel. (Poaceae)

To study the magnitude and nature of genetic variation in E. fibrosus, the levels and distribution of allozyme and RAPD variations were investigated in populations collected from Finland and Russia. The results obtained from the allozyme and RAPD studies were compared to each other in 10 of the populations. The allozyme analysis showed that 6 of 12 presumed loci (50%) were polymorphic within the species, while the mean number of polymorphic loci within populations was 4.8%. The mean number of allele per locus for the species was 1.5 and 1.05 across the populations. Genetic diversity at the species level was low (H _es = 0.025), and the mean population genetic diversity was even lower (H _ep = 0.007). Both these values were much lower than the average for other Elymus and self-fertilising species. The largest proportion of the total allozyme diversity was found among, rather than within the populations (G _ST = 0.70). The allozyme genetic distances between the populations did not reflect geographic distances. Cluster and principal coordinates analyses revealed the same allozyme relationship patterns among the populations. A comparison of allozyme and RAPD variation in 10 of the populations showed differences in the amount of genetic variation. The RAPD analysis revealed higher levels of variation (A _p = 1.19, P _p = 20.3 and H _ep = 0.09) than the allozyme one) A _p = 1.06, P _p = 5.8 and H _ep = 0.008). For both markers, the largest proportion of the total gene diversity was found among the populations studied (G _st = 0.63 for RAPDs and G _st = 0.65 for allozyme). In contrast to the allozyme analysis, the RAPD based genetic distances did reflect geographic distances. The cluster and principal coordinates analyses showed different grouping of populations for each data set. There was a positive, but not significant, correlation (r = 0.41) between the genetic distance matrices resulting from these markers. Regional comparison revealed that the Finnish populations had a higher diversity than the Russian ones. Generally, this study indicates that E. fibrosus contains low genetic variation in its populations. The results are discussed in the context of conservation of the species.     

The genus Amygdalus L. (Rosaceae): Species relationships, distribution and evolution under domestication

Summary The paper reviews the taxonomic relationships, morphological distinction, geographical distribution and ecological specificities of the twenty six species recognized (by us) in Amygdalus L. It also surveys the intra-genetic structure in this genus stressing the fact that they fall into five groups of closely related vicarious species: (i) Communis group (9 species), (ii) Orientalis group (6 species), (iii) Sect. Chamaeamygdalus (4 species), (iv) Sect. Spartioides (2 species), and (v) Subgenus Dodecandara (5 species). Within each group, species are separated from one another geographically (in few cases by altitude). The only major exception to such allopatric distribution is found in A. communis L., and this is interpreted as an outcome of domestication. Interspecific sterility barriers are absent, or only weakly developed in Amygdalus, and numerous inter-specific hybrids (particularly between the crop and various wild almond species) have been detected. Therefore most (may be all) wild almond species constitute the primary gene-pool of the cultivated nut crop.The combined botanical and archaeological evidene points to the Levant countries as the place where the almond was taken into cultivation. Wild forms of A. communis are very likely native only to this area. Also the earliest archaeological signs of almond domestication come from this area.     

Conservation of the genetic variation of Triticum tauschii (Coss.) Schmalh. (Aegilops squarrosa auct. non L.) in synthetic hexaploid wheats (T. turgidum L. s.lat. x T. tauschii; 2n=6x=42, AABBDD) and its potential utilization for wheat improvement

Triticum tauschii (Coss.) Schmalh. (Aegilops squarrosa auct. non L., 2n=2x=14, DD genome) with its diverse range of accessions and distribution provides a unique opportunity for exploiting novel genetic variability for wheat (T. aestivum L.) improvement associated with biotic/abiotic stress factors. From our working collection of 490 T. tauschii accessions we have so far produced 430 different synthetic hexaploids (2n=6x=42, AABBDD) resulting from the chromosome doubling of Triticum turgidum L. s. lat. x T. tauschii F₁ hybrids (each synthetic involving a different T. tauschii accession). We present here our results on hybrid production, plantlet regeneration, cytology, colchicine induced doubling of the 2n=3x=21 chromosome F1 hybrids, seed increase of the doubled progeny and screening for a biotic stress; Cochliobolus sativus Ito and Kuribay (syn. Helminthosporium sativum Pamm. King and Bakke); of 250 of these synthetic hexaploid (2n=6x=42) amphiploids. Application of the direct crossing methodology involving susceptible T. aestivum cultivars with resistant T. tauschii accessions is also alluded to.     

Application of random amplified polymorphic DNA to study genetic diversity in Paspalum scrobiculatum L. (Kodo millet, Poaceae)

Summary Genetic diversity and patterns of geographic variation among collections of Paspalum scrobiculatum (kodo millet) and P. polystachyum were studied using molecular markers generated through the random amplified polymorphic DNA (RAPD) method. A high level of polymorphism in RAPD markers was observed among the individual accessions, demonstrating the high genetic diversity of the crop. The markers obtained from the RAPD method were analyzed with the cluster analysis, principal coordinates and minimum spanning tree methods. Three major groups were resolved, one representing the African accessions, and two for the Indian accessions. The accessions of the north African kodo millet and P. polystachyum (considered conspecific with P. scrobiculatum) were quite distinct. The Australian kodo millet showed higher affinity to the African types. The study demonstrated that the RAPD technique can be applied to resolving degrees and patterns of genetic variation at the population and species levels, identifying cultivars, and defining gene pools of this crop.     

Geomorphic features of a badland (biancane) area (Central Italy): characterisation, distribution and quantitative spatial analysis

The biancana landscapes, rather common in several Italian areas, have a very complex morphology. Different geomorphic features often occur along the same hillslope. From a morphological survey of an experimental site in southern Tuscany, the forms were classified, and their distribution analysed. Spatial analysis of the biancane provided insights into the range of forces responsible for their formation and evolution. The results confirm an evolutionary trend from an original gently sloping surface to a complex biancana landform, emphasising a trend from the taller bean forms to the terminal soufflé-like and cone forms. The presence of scarp and sliding forms in the most sloping areas and along the residual surfaces supports the hypothesis of a process influenced by base level, acting initially by small mass movements. Spatial analysis did not reveal any systematic trend in the variability of the erosional features along the slopes. Variographic analysis showed that selected morphological attributes are spatially auto-correlated over a short range, suggesting that the erosive processes responsible for morphogenic evolution of biancane act mostly on a local scale. The strong geometric anisotropy detected in directions parallel to the main jointing systems also indicated a broader scale tectonic control of biancane evolution, probably in an early stage of their formation.     

Multivariate analysis of morphological variation in sorghum (Sorghum bicolor (L.) Moench) germplasm from Ethiopia and Eritrea

Multivariate methods, including principal component, cluster and discriminant analyses, were used to assess the patterns of morphological variation and to group 415 sorghum accessions for 15 quantitative characters. The first five principal components explained 79% of the total variation with plant height and days to 50% flowering being the most important characters in the first principal component. Cluster analysis grouped the accessions into ten clusters. A greater proportion of accessions of similar adaptation zones and accessions from regions of origin with similar agro-climatic conditions were grouped together. Moreover, discrimination of accessions was more pronounced when discriminant analysis was based on zone of adaptation rather than regions of origin. Based on the observed patterns of variation, it is concluded that the morphological variation in the material studied is structured by environmental factors. The implications of the results for plant breeding and germplasm conservation programmes arediscussed.     

Development and characterization of microsatellite markers,genetic diversity and population structure analysis in Sapota (Manilkara zapota (L.) P. Royen)

Genetic Resources and Crop Evolution - Manilkara zapota (L.) P. Royen, a widely adapted and popular tree meant for its appetizing fruits in tropics with no genomic resources like microsatellite...     

A phylogenetic analysis of the genus Carica L. (Caricaceae) based on restriction fragment length variation in a cpDNA intergenic spacer region

The phylogenetic relationships among twelve wild and cultivated species of Carica (Caricaceae) were analyzed using restriction fragment length variation in a 3.2-kb PCR amplified intergenic spacer region of the chloroplast DNA. A total of 138 fragments representing 137 restriction sites accounting for 5.8% of the amplified region were examined. Both parsimony and neighbor joining cluster analyses confirmed the close association among South American wild Carica species. However, cpDNA data did not support the traditional monophyly hypothesis for the evolution of Carica. Further, cpDNA analyses showed two basic evolutionary lineages within the genus Carica, one defined by cultivated C. papaya and another consisting of the remaining wild species from South America in a well resolved but poorly supported monophyletic assemblage. This evolutionary split in Carica strongly suggests that C. papaya diverged from the rest of the species early in the evolution of the genus and evolved in isolation, probably in Central America.     

Gene isolation, analysis of expression, and in vitro synthesis of glutathione S-transferase from orange fruit [Citrus sinensis L. (Osbeck)

Glutathione S-transferases (GSTs) (EC 2.5.1.18) are ubiquitous enzymes that have a defined role in xenobiotic detoxification, but a deeper knowledge of their function in endogenous metabolism is still lacking. In this work, we isolated the cDNAs as well as the genomic clones of orange GSTs. Having considered gene organization and homology data, we suggest that the isolated GST gene is probably involved in the vacuolar import of anthocyanins. We also found that the blood and blond orange GSTs shared the same nucleotide sequences, but as expected, the GST expression in the nonpigmented orange cultivar [Citrus sinensis L. (Osbeck)] (Navel and Ovale) was strongly reduced as compared to that of the pigmented orange (Tarocco). Interestingly, in the crude extracts of pigmented orange fruits, the GST activity was reproducibly detected by providing either 1-chloro-2,4 dinitrobenzene (CDNB) or cyanidin-3-O-glucoside (C-3-G) as substrates; moreover, we have shown that cyanidin-3-O-glucoside acted as a powerful competitive inhibitor of 1-chloro-2,4 dinitrobenzene conjugation to reduced glutathione (GSH) in the pigmented orange, confirming that this molecule might easily bind to the active site of the enzyme and functions as a putative substrate. In addition, we have reported here the successful in vitro expression of orange GST cDNAs leading to a GST enzyme that is active against cyanidin-3-O-glucoside, thus suggesting the probable involvement of the isolated gene in the tagging of anthocyanins for vacuolar import. This last result will help to study the kinetic and structural properties of orange fruit GST avoiding time-consuming protein purification procedures.     

Artemisia dracunculus L. (tarragon): a critical review of its traditional use, chemical composition, pharmacology, and safety

Artemisia dracunculus L. (tarragon) has a long history of use as a spice and remedy. Two well-described "cultivars" (Russian and French) are used widely and differ in ploidy level, morphology, and chemistry. Key biologically active secondary metabolites are essential oils (0.15-3.1%), coumarins (>1%), flavonoids, and phenolcarbonic acids. In vivo studies mainly in rodents, particularly from Russian sources, highlight potential anti-inflammatory, hepatoprotective, and antihyperglycemic effects. Despite concerns about the toxic effects of two of its main constituents, estragole (up to 82%) and methyleugenol (up to 39%), no acute toxicity or mutagenic activity has been reported at doses relevant for human consumption. Water extracts of A. dracunculus contain very low amounts of estragole and methyleugenol and, therefore, are considered to pose a very limited risk. Overall, a stronger focus on clinical studies and precise taxonomic and phytochemical definition of the source material will be essential for future research efforts.     

Time of seed collection and germination in rocket, Erucavesicaria (L.) Cav. (Brassicaceae)

The increasing importance of rocket Erucaspp. as a leaf and oil crop, and especially as a Fourth Generationvegetable, calls for a better understanding of several basic aspectsof its biology. Knowledge on seed germination behaviour is necessaryto optimize the management of the plant in the field and inseedbanks. Seed germination of several samples of rocket was assayedin the laboratory under different incubation conditions. Germinationin the two studied populations was fairly high, ranging from68% to 96%. However, remarkable variation was foundwithin one of them according to the date of collection of the sample,ranging from 78–96% for those collected in summer(LG1 and LG2) to 21–29% for that collected inautumn (LG3). Neither time of storage nor GA₃treatments had any significant effect on this low percentage, whichcould only be significantly improved with scarification, up to47% by dry heat and up to 66% by immersion in liquidnitrogen. Dormancy and low seed viability probably originating fromeffects of environmental factors during seed formation and maturationseem to play a role in the low germination percentage of sampleLG3.     

Path analysis and percentage contribution of different growth characters to pod yield of groundnut (Arachis hypogaea L.) at Kadawa,Sudan savanna,Nigeria

Irrigated trials were conducted during the dry seasons of 2004, 2005 and 2006 at the Irrigation Research Station of the Institute for Agricultural Research (IAR), Nigeria, to study the performance of three groundnut (Arachis hypogaea L.) varieties as affected by basin size and plant population. Treatments consisting of three basin sizes (3 × 3, 3 × 4 and 3 × 5 m), three plant populations (50,000, 100,000 and 200,000 plants ha^?1) and three varieties (Samnut 11, Samnut 21 and Samnut 23), were laid out in a split-plot design with factorial combination of population and variety assigned to the main plots and basin sizes to the subplots. Plant height exhibited the highest positive (p ≤ 0.05) effect of 0.3993, 0.5124, 0.6296 and 0.5897, followed by total dry matter (0.2339, 0.3329, 0.4040 and 0.4197) and number of branches (0.1118, 0.0181, 0.0416 and 0.1541) in the three years and when combined. Path coefficient analysis revealed that among the growth characters selected, plant height made the highest positive contribution of 34.77% to pod yield of groundnut, followed by total dry matter with a positive contribution of 17.46%, suggesting plant height was the most critical growth parameter for determining yield of groundnut under irrigation.