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The physiological transition to spores has also been implicated in mass export events following diatom blooms due to their heavily silicified, thick frustules that facilitate rapid sinking (Salter et al., 2012 Rynearson et al., 2013 Rembauville et al., 2016). In diatoms, resting spores play an important role in community structure and population dynamics, acting as ‘seed banks’ and allowing species to subsist under sub-optimal conditions until more favourable environments return. The formation of resting stages has been linked to the onset of adverse environmental conditions such as lack of nutrients, changes in temperature or day length (Kuwata et al., 1993 Kremp et al., 2009), or food limitation for heterotrophic and mixotrophic species (Tillmann & Hoppenrath, 2013).
Spore formation series#
Their distinctive features include the inability to reproduce (undergo binary fission), and a series of morphological and physiological traits such as thick cell walls, high concentrations of lipids and carbohydrates, and low metabolic activity, all of which allow for dormancy or quiescence for extended periods of time (Ellegaard & Ribeiro, 2018). Resting stages are present in the life cycles of numerous species, and these species are widely distributed over the broad phylogenetic diversity of microalgae. Heteromorphic life cycles can increase the range of conditions in which a species can survive or act as a defense strategy against predators and/or pathogens (Pančić & Kiørboe, 2018). Examples include organisms that have a haplo-diplobiontic life cycle (von Dassow et al., 2009), can form multi-cellular colonies or chains (Peperzak & Gäbler-Schwarz, 2012), or have the capability to form quiescent or dormant stages such as resting cysts, spores, or akinetes (Ellegaard & Ribeiro, 2018). Many unicellular eukaryotes are characterized by heteromorphic life histories that include different morphological and physiological stages. They provide a possible mechanistic link between viral infection, bloom termination, and mass carbon export events and highlight an unappreciated role of viruses in regulating diatom life cycle transitions and ecological success. These results demonstrate that diatom spore formation is an effective defense strategy against viral-mediated mortality.‘Infected’ spores were capable of germinating, but did not propagate or transmit infectious viruses. Although viral RNA was detected within spores, mature virions were not observed.We show that viral infection of the bloom-forming, planktonic diatom Chaetoceros socialis induces the mass formation of resting spores, a heavily silicified life cycle stage associated with carbon export due to rapid sinking.Although viral infection has been described as a primary mechanism of phytoplankton mortality, little is known about host defense responses. Algal viruses are important contributors to carbon cycling, recycling nutrients and organic material through host lysis.*Parent plants with diseases transfer their diseases to the offspring. *Vegetatively propagated plants cannot be cultivated on a large scale. *The wood of vegetatively produced plants are small in size hence is not costly. *Plants produced by asexual reproduction are short lived than the plants produced by sexual reproduction. Vegetative propagation takes place by different methods like Leaf propagation, Root propagation, Underground stem propagation etc. Roots, stems and leaves are called the vegetative parts of a plant. Vegetative propagation is the production of new plants from the vegetative parts of the plant. *The organism forming spores can propagate its species by protecting the future individual in a hard thick covering called as spore. *Spores can also be carried away easily by agents like wind water etc. Under favourable conditions, spores can germinate into new individuals *A spore can withstand adverse conditions like high temperature, low moisture etc without getting spoiled. Some organisms like ferns, some groups of fungi reproduce by spore formation. Spore germinates on a substratum under favourable conditions. Spore formation is the method of developing new individuals by forming reproductive structures called spores.Ī spore is a small spherical or oval structure which protects the future individual in a thick protective covering.