Search results for "Dormancy"
showing 10 items of 39 documents
Sex Allocation Theory for Facultatively Sexual Organisms Inhabiting Seasonal Environments: The Importance of Bet Hedging
2018
Adaptive explanations for dormancy often invoke bet hedging, where reduced mean fitness can be adaptive if it associates with reduced fitness variance. Sex allocation theory typically ignores variance effects and focuses on mean fitness. For many cyclical parthenogens, these themes become linked, as only sexually produced eggs undergo the dormancy needed to survive harsh conditions. We ask how sex allocation and the timing of sex evolve when this constraint exists in the form of a trade-off between asexual reproduction and sexual production of dormant eggs-the former being crucial for within-season success and the latter for survival across seasons. We show that male production can be tempo…
Opportunistic Germination Behaviour of Gypsophila (Caryophyllaceae) in Two Priority Habitats from Semi-arid Mediterranean Steppes
2011
Gypsophila tomentosa and G. struthium are closely related species, characteristic of two European priority habitats, salt and gypsum inland steppes, respectively. Germination strategies of the two taxa were investigated in plants from two nearby populations, growing under the same climatic conditions but on different types of soil, and belonging to different plant communities. Their germination patterns were studied at five constant temperatures in darkness: 5oC, 10oC, 15oC, 20oC and 25oC, and the base temperature and the thermal time requirement were calculated. As the distribution area of both species is subjected to a Mediterranean continental climate with significant differences between…
LisRK is required for optimal fitness ofListeria monocytogenesin soil
2020
ABSTRACTListeria monocytogenes is a food-borne pathogen responsible for the disease listeriosis. It is ubiquitously found in the environment and soil is one of its natural habitats. Listeria monocytogenes is highly capable of coping with various stressful conditions. We hypothesized that stress-responsive two-component systems such as LisRK might contribute to the adaptation of L. monocytogenes to the soil environment. Indeed, investigations of the population dynamics of wild-type and mutant strains suggest an important role of LisRK for optimal fitness of L. monocytogenes in sterile soil. Results from non-sterile soil showed that the parental strain was capable of surviving longer than mut…
Sex Loss in Monogonont Rotifers
2009
Monogonont rotifers are small, aquatic invertebrates capable of asexual and sexual reproduction. Sexual reproduction is required to produce diapausing eggs, which are able to survive adverse periods that typically occur every year. Their cyclically parthenogenetic life-cycle is believed to retain the advantages of recombination while minimizing the cost of sex. However, this life cycle is also thought to be unstable due to periodic loss of sexual reproduction by directional selection. Explaining the evolutionary dynamics of the monogonont rotifer life cycle is important for understanding how cyclical parthenogenesis is maintained, and for comparing monogononts with their close relatives, th…
Can the Caper (Capparis spinosa L.) Still Be Considered a Difficult-to-Propagate Crop?
2021
As a perennial xerophytic shrub, characterized by plesiomorphic features, the caper (Capparis spinosa L.) is naturally spread throughout the Mediterranean basin and occupies an important ecological role, as well as an economic one, in traditional and specialized systems for commercial production. This species, in spite of its wide diffusion, is currently considered at risk of genetic erosion, mainly due to overgrazing and overharvesting for domestic uses and for trade. This situation is made more serious because of the lack of efficient propagation techniques, determining the caper as a “difficult-to-propagate species”. In this review, we report the main available sexual and vegetative prop…
Effect of Gibberellin on Mature Euonymus europaeus L. Seeds
1992
The release from dormancy of Euonymus europaeus L. embryos by a brief treatment with GA 3 has been studied. During 48 h incubation of dormant embryos in GA-free medium, phospholipid levels increased at first, then declined sharply over the last 6 h. When the embryos were placed in GA, medium during this 6 h period levels of total phospholipids as well as of phosphatidylethanolamine increased whilst phosphatidylinositol and phosphatidylcholine declined slightly
Ultrastructural Studies on Development in Mature Seeds; Embryos ofEuonymus europaeaL. Dormant or Cultured at +25 °C
1989
Ultrastructural observations on naturally dispersed and dehydrated seeds of Euonymus europaea L. were performed. It was shown that during the culture of isolated embryos at 25 °C for 7 d the maturation of protein bodies continued; the initial juvenile form (single protein body per cell with dispersed contents) was developing into a more advanced form (single body split to form several sub-units with condensed contents). Parallel biochemical determinations pointed to an increase in insoluble protein levels. There were no changes in other storage organelles, lipid bodies, either in the fine structure or in the level of triacylglycerols. Deterioration of cellular membranes (in mitochondria, pr…
Seed germination of six coastal plant species of the Baltic region: effect of salinity and dormancy-breaking treatments
2008
AbstractSeed salinity tolerance and dormancy play important roles in germination behaviour. The effects of NaCl concentration and different dormancy-breaking treatments on germination were determined for six species growing on the coasts of the Baltic Sea or the Gulf of Riga: Juncus balticus, Triglochin maritima, Triglochin palustre, Anthyllis maritima, Linaria vulgaris and Linaria loeselii. Germination percentages were significantly reduced at NaCl concentrations >100 mM. Germination of J. balticus, T. maritima and T. palustre, but not that of A. maritima and L. vulgaris, recovered after seeds were rinsed with distilled water. Seeds of J. balticus were non-dormant; those of A. maritima …
Use of phenoclimatic models to estimate the chill and heat requirements of four sweet cherry cultivars in Italy
2017
During their dormant period, fruit trees require a certain amount of relatively low temperatures to complete bud differentiation processes and regularly resume growth the following spring. Unsatisfied chilling needs can result in delayed foliation, severe yield and fruit quality losses. There is a need for a method to estimate accurately the chilling requirement of a cultivar. This is especially important in those areas where the potential of chill accumulation in winter is low and for those crops, such as sweet cherry, which generally have a high chilling requirement. Historical temperature records and blooming dates of four sweet cherry cultivars widely cultivated in Italy - 'Burlat', 'Sw…
Mutant ACCase alleles endowing herbicide resistance have a direct effect on seed germination
2013
Germination and emergence dynamics and herbicide resistance are adaptive traits crucial for weed persistence in arable fields. Herbicide resistance alleles can have pleiotropic effects on other traits. We investigated the pleiotropic effects of acetyl-coenzyme A carboxylase (ACCase) alleles L1781, N2041 or G2078 on seed germination and seedling emergence in the grass weed Alopecurus myosuroides (black-grass). We used black-grass populations with homogenised genetic backgrounds that segregated for L1781, N2041 or G2078 ACCase alleles. In two series of experiments, germination dynamics and seedling growth were compared among seeds containing embryos carrying no, one or two copies of a given m…