scholarly journals The polyploid nature of Cenchrus ciliaris L. (Poaceae) has been overlooked: new insights for the conservation and invasion biology of this species – a review

2014 ◽  
Vol 36 (1) ◽  
pp. 11 ◽  
Author(s):  
Amina Kharrat-Souissi ◽  
Sonja Siljak-Yakovlev ◽  
Spencer C. Brown ◽  
Alex Baumel ◽  
Franck Torre ◽  
...  
Keyword(s):  
Perennial Grass ◽  
Invasion Biology ◽  
Molecular Data ◽  
Grazing Pressure ◽  
Arid Ecosystems ◽  
Evolutionary Development ◽  
Cenchrus Ciliaris ◽  
Ploidy Levels ◽  
Western Asia ◽  
Genetic Mechanisms

Climate change, associated with increased aridity, and high grazing pressure by livestock results in the scarcity and loss of perennial Poaceae in arid ecosystems. The species threatened by this include Cenchrus ciliaris L., a native perennial grass of the tropical and sub-tropical arid rangelands of Africa and Western Asia and now introduced in Central and South America, and Australia. This species reproduces predominantly through aposporous apomixis although sexual individuals have been occasionally identified. Cenchrus ciliaris is characterised by a significant, heritable, phenotypic polymorphism and three ploidy levels including tetraploids (2n = 4x = 36), pentaploids (2n = 5x = 45) and hexaploids (2n = 6x = 54). Under water-deficit conditions, C. ciliaris shows plasticity in growth characteristics and aboveground biomass. This phenotypic plasticity has led to the identification of genotypic-associated responses conferring more productivity. This underlines the importance of conserving the genetic diversity of C. ciliaris in order to ensure the persistence of the vegetation cover in the arid ecosystems in which it occurs. Observations from cytogenetic and molecular data converge to underline the possibility of sexual reproduction, recombination and gene flow within and between populations of C. ciliaris. Genetic mechanisms, such as polyploidy, hybridisation between ploidy levels and apomixes, are generating and then maintaining the diversity of C. ciliaris. This review emphasises the role of polyploidy in the evolutionary development of C. ciliaris and how it may be a crucial factor for its conservation in some countries and its weedy nature in others.

New insights into the polyploid complex Cenchrus ciliaris L. (Poaceae) show its capacity for gene flow and recombination processes despite its apomictic nature

2011 ◽  
Vol 59 (6) ◽  
pp. 543 ◽  
Author(s):  
Amina Kharrat-Souissi ◽  
Alex Baumel ◽  
Franck Torre ◽  
Marianick Juin ◽  
Sonja Siljak-Yakovlev ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
Perennial Grass ◽  
Common Garden ◽  
Aflp Markers ◽  
Phenotypic Traits ◽  
Cenchrus Ciliaris ◽  
Ploidy Levels ◽  
Recombination Processes

Cenchrus ciliaris L. is a C4 perennial grass of arid lands which is under the focus of different ecological issues such as response to desertification, quality of forage grass and impacts of invasions. Here, molecular and morphological analyses of the genetic diversity of several Tunisian provenances of C. ciliaris were performed to better understand the phenotypic polymorphism of this agamospermous and polyploid grass. Ten phenotypic traits associated with productivity were measured in a common garden environment. Amplified Fragment Length Polymorphism (AFLP) markers were developed to investigate the structure of genetic diversity among and within provenances and between the three ploidy levels. Heritable phenotypic traits showed considerable differences within provenances. Surprisingly, AFLP markers revealed the existence of genotypic variations between individuals of the same sibship and a high G/N value (0.55). A neighbour-joining tree based on AFLP markers revealed three major groups; tetraploid, pentaploid and a mix of pentaploid and hexaploids. These groups do not correspond completely to the geographical origin of samples. The results underline the possibility of sexual reproduction, recombination and gene flow within and between populations of C. ciliaris. In respect with the well known dynamic nature of polyploid genomes, these results should have strong consequences for the future management of this grass for both conservation and invasion issues.

Genetic differentiation of the dominant perennial grass Cenchrus ciliaris L. contributes to response to water deficit in arid lands

2012 ◽  
Vol 34 (1) ◽  
pp. 55 ◽  
Author(s):  
Amina Kharrat-Souissi ◽  
Alex Baumel ◽  
Franck Torre ◽  
Mohamed Chaieb
Keyword(s):  
Water Deficit ◽  
Aboveground Biomass ◽  
Vegetation Cover ◽  
Stomatal Density ◽  
Perennial Grass ◽  
Arid Lands ◽  
Arid Ecosystems ◽  
Cenchrus Ciliaris ◽  
Response To Water ◽  
The Impact

Perennial herbaceous plants are a key element of the vegetation cover in arid lands, during a long period of the year, but their persistence depends on their ability to cope with acute drought. This characteristic could become very important with the predicted climatic changes in arid lands because the persistence of perennial plants will be a key element countering the process of desertification. The aim of the present study was to compare experimentally the response to water deficit of different genotypes of the perennial grass Cenchrus ciliaris L. (buffelgrass). We analysed the impact of water deficit on productivity, time span of the vegetative growth and leaf traits. Overall, there was highly heritable variation in the responses to applied water deficit for the measured attributes, and five different groups of genotypes responded differently to water deficit. These groups of genotypes differently invested their energy to alter their phenotype in response to water deficit. Consequently, some genotypes were more strongly affected by the water deficit and their aboveground biomass showed the largest decrease. The group of genotypes which showed the smallest decrease of their aboveground biomass was characterised by less increase of leaf hairiness, a strong decrease of leaf area and also the strongest decrease of stomatal density on the abaxial epidermis. The current study provides evidence that the capacity of C. ciliaris to regulate its growth as an adaptive mechanism under water deficit is dependent on strong genetic variation that could affect its productivity and in consequence the vegetation cover of arid ecosystems.

Comparative morphological, anatomical, micromorphological, and palynological studies on the genera Opopanax and Crenosciadium (Apiaceae)

Phytotaxa ◽  
2018 ◽  
Vol 372 (1) ◽  
pp. 35 ◽  
Author(s):  
ÖZLEM ÇETIN ◽  
MUSTAFA ÇELIK
Keyword(s):  
Cross Sections ◽  
Mediterranean Region ◽  
Pollen Morphology ◽  
Pollen Grains ◽  
Molecular Data ◽  
Monotypic Genus ◽  
Western Asia ◽  
The Family ◽  
Surface Ornamentation ◽  
Fruit Surface

In the present study, morphological, micromorphological, palynological and anatomical characteristics of the genera Opopanax and Crenosciadium are reviewed and compared. The genus Opopanax is distributed in southern Europe, the Mediterranean region and Western Asia, and it is represented by three species in Turkey. Crenosciadium is a poorly known monotypic genus from Turkey, recently treated as synonym in Opopanax. Expanded descriptions, phenology, geographic distributions, and images of habitus of Opopanax and Crenosciadium are given. The differences between the two genera are discussed. The pollen morphology of Opopanax and Crenosciadium is studied by SEM and LM. The palynological results confirmed the stenopalynous characteristic of the family Apiaceae, and revealed that the pollen grains of both genera are perprolate in shape. Also fruit surface ornamentation of both genera is typically striate, and epidermal cells are polygonal or elongated in one direction. Cross-sections of mature fruits are examined and a detailed anatomical description is presented. Mericarp shape and width are very useful characters for discrimination between Opopanax and Crenosciadium; mericarp ribs are also very significant characteristics to discriminate both genera. Our findings, together with previous molecular data, clearly indicate that Crenosciadium differs considerably from Opopanax, and therefore it should be accepted at genus rank.

scholarly journals Estimation of Molecular Pairwise Relatedness in Autopolyploid Crops

2020 ◽  
Vol 10 (12) ◽  
pp. 4579-4589 ◽  
Author(s):  
Rodrigo R. Amadeu ◽  
Leticia A. C. Lara ◽  
Patricio Munoz ◽  
Antonio A. F. Garcia
Keyword(s):  
Molecular Markers ◽  
Molecular Marker ◽  
Close Relationships ◽  
R Package ◽  
Molecular Data ◽  
Genetic Studies ◽  
Ploidy Levels ◽  
Lower Performance

A suitable pairwise relatedness estimation is key to genetic studies. Several methods are proposed to compute relatedness in autopolyploids based on molecular data. However, unlike diploids, autopolyploids still need further studies considering scenarios with many linked molecular markers with known dosage. In this study, we provide guidelines for plant geneticists and breeders to access trustworthy pairwise relatedness estimates. To this end, we simulated populations considering different ploidy levels, meiotic pairings patterns, number of loci and alleles, and inbreeding levels. Analysis were performed to access the accuracy of distinct methods and to demonstrate the usefulness of molecular marker in practical situations. Overall, our results suggest that at least 100 effective biallelic molecular markers are required to have good pairwise relatedness estimation if methods based on correlation is used. For this number of loci, current methods based on multiallelic markers show lower performance than biallelic ones. To estimate relatedness in cases of inbreeding or close relationships (as parent-offspring, full-sibs, or half-sibs) is more challenging. Methods to estimate pairwise relatedness based on molecular markers, for different ploidy levels or pedigrees were implemented in the AGHmatrix R package.

The Influence of Recent Grazing Pressure and Landscape Position on Grass Recruitment in a Semi-Arid Woodland of Eastern Australia.

1996 ◽  
Vol 18 (1) ◽  
pp. 3 ◽  
Author(s):  
VJ Anderson ◽  
KC Hodgkinson ◽  
AC Grice
Keyword(s):  
Seedling Emergence ◽  
Perennial Grass ◽  
Soil Surface ◽  
Grazing Pressure ◽  
Perennial Grasses ◽  
Run Off ◽  
Eastern Australia ◽  
Annual Grasses ◽  
History Of ◽  
Semi Arid

This study examined the effects of previous grazing pressure, position in the landscape and apparent seed trapping capability of soil surface micro-sites on recruitment of the perennial grass Monachather paradoxa (mulga oats) in a semi-arid woodland. Seedling emergence was counted on small plots which had been kept moist for one month. The plots were on bare ground, or at grass tussocks, or at log mounds, sited in the run-off, interception and run-on zones of paddocks that had been grazed for six years at 0.3 and 0.8 sheep equivalent/ha. Few naturally occurring perennial grass seedlings emerged on any of the sites. The level of previous grazing pressure influenced the recruitment of grasses from natural sources as well as from seed of M. paradoxa broadcast on the soil surface; significantly more grass seedlings recruited in paddocks stocked at 0.3 than at 0.8 sheep/ha. Emergence of the sown grass did not differ significantly between the three zones in the landscape, but trends in the data suggest the interception zone may have been the most favourable. Recruitment from in situ grass seed was highest in the mulga grove (run-on) zone. Most seedlings of the sown grass emerged around the bases of existing perennial grass tussocks, but recruitment of volunteer perennial and annual grasses was more evenly distributed between the mulga log-mounds and perennial grass tussocks. It is concluded that very low levels of readily germinable seed of perennial grasses remained in the soil at the end of the drought and that areas with a history of high grazing pressure have less probability of grass recruitment when suitable rain occurs.

Response to selection for grazing tolerance in winter-active populations of phalaris (Phalaris aquatica L.). 1. Persistence under grazing in three environments

2009 ◽  
Vol 60 (11) ◽  
pp. 1097 ◽  
Author(s):  
R. A. Culvenor ◽  
S. P. Boschma ◽  
K. F. M. Reed
Keyword(s):  
Linear Response ◽  
Perennial Grass ◽  
Grazing Pressure ◽  
Response To Selection ◽  
North West ◽  
Phalaris Aquatica ◽  
Grazing Tolerance ◽  
The North ◽  
Breeding Populations ◽  
Selection For

Forage grass cultivars must have adequate grazing tolerance for use in the grazing systems for which they are intended. Response to 2 cycles of selection for persistence under heavy grazing pressure was examined in 3 winter-active breeding populations of the productive perennial grass, phalaris (Phalaris aquatica L.), from 2000 to 2003, at Bulart in western Victoria and Rye Park on the Southern Tablelands and Tamworth on the North-West Slopes of New South Wales. There was one continuously grazed and one rotationally grazed set of plots at Bulart to examine the effect of grazing management. All sites were affected by drought in later years but drought stress was most severe at Tamworth. A strongly positive linear response to selection was observed in an analysis of persistence measured as frequency of phalaris plant base across the 3 sites (excluding the rotational treatment at Bulart), but response interacted with site. By 2003, linear response averaged 14% frequency units or 34–40% proportional response per cycle at Rye Park and the continuously grazed plots at Bulart, sites that were environmentally suited to survival of phalaris. In contrast, response to selection was absent or slightly negative at Tamworth where conditions were drier and hotter. Populations responded similarly in analyses across all 3 sites but 1 population was less responsive when analyses were restricted to Bulart and Rye Park. Herbage mass measurements in 2001 at Bulart and 2002 at Rye Park indicated positive responses to selection, which were increasingly linked to frequency over time. Rotationally grazed plots at Bulart displayed higher frequency than continuously grazed plots after 3 years of grazing. The experiment showed that grazing tolerance was a heritable trait in the populations tested when environmental constraints were not limiting and that useful improvements in persistence had been obtained compared with existing cultivars.

Black-fruited hawthorns of western North America — one or more agamic complexes?This paper is one of a selection of papers published in the Special Issue on Systematics Research.This paper is dedicated to the memory of the University of Idaho botanist who got us thinking about the complexities of Northwest hawthorns: the late Steven J. Brunsfeld.

Botany ◽  
2008 ◽  
Vol 86 (8) ◽  
pp. 846-865 ◽  
Author(s):  
Timothy A. Dickinson ◽  
Eugenia Y.Y. Lo ◽  
Nadia Talent ◽  
Rhoda M. Love
Keyword(s):  
North America ◽  
Leaf Shape ◽  
Molecular Data ◽  
Ploidy Levels ◽  
Gametophytic Apomixis ◽  
Single Clade ◽  
Self Compatibility ◽  
Distribution And Ecology ◽  
Taxonomic Groups ◽  
The University

Black-fruited hawthorns in North America comprise two taxonomic groups within the genus Crataegus , section Brevispinae and section Douglasianae. The first of these has recently been shown to be monospecific, consisting of the blueberry haw, Crataegus brachyacantha Sarg. & Engelm., of Louisiana and Texas. Crataegus section Douglasianae, however, comprises several taxa in a single clade that is not closely related to section Brevispinae, and that is now one of the best-studied groups of hawthorns at least in North America. Most taxa in the group are found in, or west of, the Rocky Mountains. They include diploids, triploids, and tetraploids that can be ascribed to four or more species that differ in distribution and ecology, thorn morphology, leaf shape, and floral architecture. Diploids are self-incompatible, whereas polyploidy is associated with pseudogamous, gametophytic apomixis and self compatibility. Molecular data suggest that polyploids have arisen repeatedly, both within and from crosses between ploidy levels. We suggest that Crataegus section Douglasianae represents at least two agamic complexes that may serve as models for understanding the biology of, the relationships within, and the appropriate taxonomic treatment of other such groups that may make up much of the rest of the genus.

scholarly journals Genetics of hairy cell leukemia

2011 ◽  
pp. 189-194
Author(s):  
Jorge J. Nieva
Keyword(s):  
Hairy Cell Leukemia ◽  
Expression Profiling ◽  
Molecular Data ◽  
Hairy Cell ◽  
Cell Leukemia ◽  
Bone Marrow Fibrosis ◽  
Genetic Event ◽  
Molecular Events ◽  
Purine Analog ◽  
Genetic Mechanisms

Hairy cell leukemia (HCL) is a chronic B-cell lymphoproliferative disorder characterized by cytopenias, splenomegaly, and bone marrow fibrosis associated with an infiltrate of B-lymphocytes. Although in the majority of cases diagnosis and treatment of the disease is relatively straightforward, there is a lack of clinical and molecular data on its genetic mechanisms. Recent advances in gene expression profiling have identified a number of proteins that are specific to the HCL phenotype. However, these data are only the first step in identifying the genetic event responsible for development of the disease. Because of the success of purine analog therapy in treating the disease, there has so far been little interest within the scientific community in gaining a greater understanding of the genetics that drive the neoplastic clone in this strikingly homogeneous and well characterized clinical entity. This review describes the epidemiological genetic and molecular events associated with HCL.

Changes in the Quantitative Floristics in Some Astrebla Spp. (Mitchell Grass) Communities in South-Western Queensland in Relation to Trends in Seasonal Rainfall

1981 ◽  
Vol 29 (5) ◽  
pp. 533 ◽  
Author(s):  
DM Orr
Keyword(s):  
Relative Abundance ◽  
Perennial Grass ◽  
Grazing Pressure ◽  
Perennial Grasses ◽  
Seasonal Rainfall ◽  
Individual Species ◽  
Botanical Composition ◽  
Basal Cover ◽  
Wide Range ◽  
Annual Grasses

Seasonal changes in the quantitative floristics at a wide range of Astrebla grassland sites in south-western Queensland were monitored between 1972 and 1980 with a wheel point apparatus. Changes in the floristics were measured in terms of both relative abundance and basal cover. A large increase in the relative abundance of perennial grasses, particularly Aristida latifolia, Astrebla spp. and Dichanthium sericeum, occurred between 1972 and 1976. This increase was at the expense of annual grasses and forbs which declined in both relative abundance and number of genera present. The relative abundance of perennial grasses declined between 1978 and 1980 and this was associated with a large increase in the forbs such as Daucus glochidiatus and Plantago spp., particularly at southern sites. The contribution of annual grasses to botanical composition remained low throughout the period. Total basal cover differed between years although these differences were not significant. As perennial grass, particularly Astrebla spp., was the major vegetation component of total basal cover, changes in the latter were associated mainly with changes in the basal cover of Astrebla spp. Changes in the contribution of individual species to total basal cover were related to changes in the relative abundance of those species. Changes in botanical composition in Astrebla grassland may be influenced more by trends in seasonal rainfall than by grazing pressure.

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