Fly-pollinated Pleurothallis (Orchidaceae) species have high genetic variability: evidence from isozyme markers

2001 ◽  
Vol 88 (3) ◽  
pp. 419-428 ◽  
Author(s):  
Eduardo L. Borba ◽  
Juliana M. Felix ◽  
Vera N. Solferini ◽  
João Semir
Keyword(s):  
Genetic Variability ◽  
Isozyme Markers ◽  
High Genetic Variability

scholarly journals High genetic variability of Alexandrium catenella directly detected in environmental samples from the Southern Austral Ecosystem of Chile

2018 ◽  
Vol 127 ◽  
pp. 437-444 ◽  
Author(s):  
Fernando A. Cruzat ◽  
Christian Muñoz ◽  
Rodrigo R. González-Saldía ◽  
Agar Inostroza ◽  
Karl B. Andree
Keyword(s):  
Genetic Variability ◽  
Environmental Samples ◽  
Alexandrium Catenella ◽  
High Genetic Variability

Cynodon dactylon (Bermuda grass).

2021 ◽  
Author(s):  
Julissa Rojas-Sandoval ◽  
Pedro Acevedo-Rodríguez
Keyword(s):  
Genetic Variability ◽  
Inbreeding Depression ◽  
Germination Rate ◽  
Forage Yield ◽  
Bermuda Grass ◽  
Total Biomass ◽  
Forage Production ◽  
Perennial Weed ◽  
High Genetic Variability ◽  
Biomass Partition

Abstract Genetics: The chromosome number reported for C. dactylon varies from 2n = 18 to 2n = 36 with diploid and polyploid populations (Cook et al., 2005). Ramakrishan and Singh (1966) and Sarandon (1991) have found differences in total biomass and biomass partition according to the origin of the population. Sarandon (1991) points out that characters are highly heritable, which means that high genetic variability for biomass production and variable architecture allows an ample base for selection, which in most cases is induced by herbicides, mechanical control or forage production. Reproductive Biology: C. dactylon is wind-pollinated and generally self-incompatible, suffering from inbreeding depression when genotypes are self-pollinated. Quantitative traits such as seed yield and forage yield can be dramatically negatively affected by inbreeding depression (Cook et al., 2005). In diploid populations, caryopses are formed after zygote formation. In polyploids, which are sterile, caryopses may be apomictic. Physiology: This C4 plant (Kissmann, 1991) has high rates of accumulation under adequate irradiance, water and nutrient supply and may consume 75 kg of N, 20 kg of P and more than 1,500,000 litres of water for 5000 kg/ha of biomass dry matter (Fernandez, 1991). In the south of Santa Fe province, Argentina, a maximum biomass of 8000 kg/ha may be generated under a summer crop of maize or sunflower with >75% located in the first 10 cm of the soil profile (Lombardo, 1973), whereas in Balcarce (Argentina) about 5000 kg/ha is commonly found in maize or sunflower stubble. Phenology: A photoperiod of 13 hours induces flowering. Low night temperatures coupled with high diurnal temperatures induces blooming (Nir and Koller, 1976). A reduction in irradiance drastically decreases inflorescence production (Moreira, 1975). In North America, annual plants reproduce during spring and perennial plants reproduce all year long (USDA-NRCS, 2014). Longevity: C. dactylon grows as both an annual and perennial grass. The annual growth-form becomes dormant and turns brown when nighttime temperatures fall below freezing or average daytime temperatures are below 10°C (Cook et al., 2005). Activity Patterns: Seeds may be the route of invasion in weed-free fields through the faeces of cows (Rodriguez, personal communication). Rhizome biomass exhibits an annual cyclic pattern and, as with any perennial weed, low temperatures reduce biomass and viability is lost as a consequence of the consumption of materials due to respiration and maintenance. The digestibility of stocked material is severely decreased, implying a loss in forage quality (Vaz Martins, 1989). This is a character that has largely improved in cultivated varieties. Each node has a physiological self-governing structure in relation to the apex, but is highly dependent on substances from other plant parts. The mother plant determines the runner growth pattern on the soil surface according to the sugar-gibberellin balance (Montaldi 1970). Node disconnection may be caused by natural decay and cultivation and produces damage in the breakdown zone and changes in hormone and nutrient relationships. It is widely demonstrated that rhizome or runner fragmentation induces the activation of buds. The proportion of activated buds increases as the number of buds per segment decreases (Moreira, 1980; Kigel and Koller, 1985; Fernandez and Bedmar, 1992). The cultivation method is mainly responsible for vegetative propagation fragmentation. The higher the cultivation intensity, the smaller the segments produced (Kigel and Koller, 1985). Population Size and Structure This weed produces an enormous number of small seeds (0.25-0.30 mg), the viability and dormancy of which are highly variable according to genotype and the conditions when formed. The seed is important because it confers high genetic variability on the population. Perez et al. (1995) recorded a very low germination rate. Uygur et al. (1985) obtained up to 15% germination at constant temperatures of 35-40°C, and 50% at temperatures alternating between 20 and 30°C. Moreira (1975) obtained up to 80% germination with the help of nitrate, chilling and alternating temperatures, and Elias (1986) recorded up to 96% germination from heavier samples of seed. Seeds remain viable in the soil for at least 2 years (Caixinhas et al., 1988). As a rule, cultivars have relatively high viability. Osmo-conditioning of Bermuda grass seeds with PEG followed by immediate sowing improved seed germination and seedling growth under saline conditions (Al-Humaid 2002). The probability of emergence and successful establishment of C. dactylon decreases with the depth of the fragment, but increases with the weight of the node and internode (Perez et al., 1998). Growth from plants originated from a runner may exhibit a different biomass partition than that from plants originated from a rhizome (Fernandez, 1986). From sprouting onwards, weed growth is controlled mainly by temperature (optimum 25-30°C) and radiation, but also by humidity and soil fertility. The efficiency of carbohydrate reserve usage during sprout growth is highly dependent on temperature and the type of vegetative structure; it is maximum at 20°C and is higher for rhizomes than for stolons (Satorre et al., 1996). Runners and rhizome growth begins 30 days after growth but only if soil temperature is >15°C. Rates of 15 g/g/day have been recorded in Argentina (Lescano de Ríos, 1982).

Genetic variability of Tunisian wild strawberry tree (Arbutus unedo L.) populations interfered from isozyme markers

2012 ◽  
Vol 146 ◽  
pp. 92-98 ◽  
Author(s):  
Malek Mhamdi Takrouni ◽  
Imen Ben El Haj Ali ◽  
Chokri Messaoued ◽  
Mohamed Boussaid
Keyword(s):  
Genetic Variability ◽  
Isozyme Markers ◽  
Arbutus Unedo ◽  
Strawberry Tree ◽  
Wild Strawberry

scholarly journals High genetic variability and polychromatism in Pachycoris torridus (Heteroptera: Scutelleridae)

2015 ◽  
Vol 14 (4) ◽  
pp. 14300-14307
Author(s):  
T.S. Souza-Firmino ◽  
K.C.C. Alevi ◽  
L.L.V. Pereira ◽  
E.R.S. Souza ◽  
F.C.S. Júnior ◽  
...  
Keyword(s):  
Genetic Variability ◽  
High Genetic Variability

Genomic identification of Anisakis simplex isolates

1997 ◽  
Vol 71 (1) ◽  
pp. 73-75 ◽  
Author(s):  
M. Siles ◽  
C. Cuéllar ◽  
M.J. Perteguer
Keyword(s):  
Genetic Variability ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Anisakis Simplex ◽  
Merluccius Merluccius ◽  
High Genetic Variability ◽  
The North ◽  
The North Atlantic ◽  
Two Populations ◽  
Conger Conger

AbstractRAPD technique was used to differentiate individuals of Anisakis simplex obtained from Merluccius merluccius, Phycis blennoides, Conger conger and Lepidorhombus boscii, from the North Atlantic Ocean. The amplification patterns of the host DNA controls were markedly different from those obtained for the parasitic material. No variation within the same host was detected. The amplification patterns for larvae obtained from fish of the same genus were somewhat different. The amplification patterns of A. simplex isolates from M. merluccius, P. blennoides, C. conger and L. boscii, were different. These results suggest the possible existence of two populations with a considerable high genetic variability and a different adaptation to different host species.

Multiple introductions and efficient propagule dispersion can lead to high genetic variability in an invasive clonal species

2019 ◽  
Vol 21 (11) ◽  
pp. 3427-3438
Author(s):  
Cristiana Barbosa ◽  
Rafael Trevisan ◽  
Tairine Freisleben Estevinho ◽  
Tânia Tarabini Castellani ◽  
Viviane Silva-Pereira
Keyword(s):  
Genetic Variability ◽  
High Genetic Variability ◽  
Multiple Introductions ◽  
Clonal Species

Κοροναϊός του σκύλου: ένας όχι ‘αθώος’ ιός

2017 ◽  
Vol 64 (1) ◽  
pp. 57
Author(s):  
V. NTAFIS (Β. ΝΤΑΦΗΣ) ◽  
M. PAPANASTASSOPOULOU (Μ. ΠΑΠΑΝΑΣΤΑΣΟΠΟΥΛΟΥ) ◽  
E. XYLOURI (E.ΞΥΛΟΥΡΗ)
Keyword(s):  
Genetic Variability ◽  
Protective Efficacy ◽  
Clinical Signs ◽  
Acute Diarrhoea ◽  
Systemic Infection ◽  
Transmissible Gastroenteritis Virus ◽  
Mixed Infections ◽  
Type I ◽  
Type Ii ◽  
High Genetic Variability

Canine coronavirus (CCoV) is a significant aetiologic agent of acute diarrhoea in dogs, specially in puppies. An important characteristic of coronaviruses is their high genetic variability, due to increased mutation frequency and sporadic recombination events. Due to this genetic variability, CCoV is classified in two distinct types, type I and II. CCoV type I strains share increased genetic similarity with Feline coronavirus strains, while CCoV type II consists of the typical reference CCoVs. Moreover, type II strains are classified into one of two subtypes, which include the classical strains (CCoV-IIa) and the new strains (CCoV-IIb), which emerged as a result of recombination among CCoV and Porcine transmissible gastroenteritis virus. Typical disease signs of CCoV infection are anorexia, depression, lethargy, as well as vomiting and diarrhoea. Mortality rate is low, especially in adult dogs with no infection signs. Most dogs recover within 7-10 days. Mixed infections with other viruses, bacteria or parasites may lead to more severe clinical disease. Currently, CCoV appears to have spread worldwide and has been related to mild, acute diarrhoea. However, during the last years, novel CCoV strains associated with outbreaks of lethal gastroenteritis have been detected in Australia and Europe. Genome analysis revealed that these strains shared low similarity with prototype reference strains of CCoV, suggesting that atypical, divergent strains may be related to more severe clinical signs. In addition, over the past decade, strains with an ability to trespass the intestinal tract, leading to lethal systemic infection, have also been isolated. These strains have attracted scientific interest, with research focusing on experimental infections, identification of genetic markers and prophylaxis. Pantropic CCoV strains have been detected across Europe, suggesting that the new, highly pathogenic biotype is circulating among canine population. The high genetic variability of CCoV, the severe mixed infections  and the antigenic differences among CCoV types and subtypes raise questions regarding the protective efficacy of the currently commercially available vaccines.

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