“51 genes showed evidence for positive selection in seagrass branches indicating that photosynthesis, a few metabolic pathways, and ribosomes have strongly diverged after the split of the common ancestor of seagrasses from terrestrial monocots.” https://t.
“Consequently, the current dataset of orthologous gene clusters for 10 angiosperm species is biased and limited in size.“ https://t.co/WF2bAZEkSF
“Only genes that were contained in the available seagrass EST collections could be analyzed in this study.“ https://t.co/WF2bAZEkSF
Seagrass metabolic adjustments to low light, “including down-regulation of RuBisCO, enhanced proteolysis and putative changes in the antenna complex.” https://t.co/WF2bAZEkSF
“Finally, seagrasses are able to activate different mechanisms to cope with conditions of light-limitation and shifted light spectrum through long-lasting metabolic adjustments.” https://t.co/WF2bAZEkSF
Seagrasses: “physiological measurements have gathered indications that several seagrass species, including Z. marina, are C3-C4 intermediates or have various carbon-concentrating mechanisms to aid the RuBisCO enzyme in carbon acquisition.” https://t.co/WF2
“Seagrasses have long been regarded as C3 plants.” https://t.co/WF2bAZEkSF
“The two seagrass species under investigation, Z. marina and P. oceanica, are known to utilize bicarbonate (HCO−3) as a major source of inorganic carbon as a major source of inorganic carbon for photosynthesis.” https://t.co/WF2bAZEkSF
“Factors contributing to slow CO2 diffusion in aquatic plants (and especially in seagrasses) are thick boundary layers around the leaves that are sometimes amplified by the presence of unicellular or multicellular photosynthetic epiphytes.” https://t.co/WF
“While CO2 can readily diffuse from the air through the stomata to the mesophyll cells in terrestrial plants, aquatic plants often have limited CO2 diffusion rates.” https://t.co/WF2bAZEkSF
“Fixation of CO2 is expected to be more difficult for seagrasses since seawater contains very little dissolved carbon dioxide.” https://t.co/WF2bAZEkSF
“Seven PSGs were related to the photosynthetic pathway and may reflect adaptations to new conditions of carbon fixation and photosynthesis that seagrasses had to face after their split from a terrestrial ancestor.” (PSG = positively selected genes). https:
“In A. thaliana, on average four gene copies encode for any of the approximately 80 different ribosomal proteins. This redundancy may reflect the importance of maintaining highly productive translation and protein synthesis.” https://t.co/WF2bAZEkSF
From an evolutionary point of view, translation is an ancient cellular process, and high selection pressure is expected to act against deleterious mutations, as ribosome functioning affects virtually all cellular processes.” https://t.co/WF2bAZEkSF
“Ten PSGs were found to be ribosomal proteins involved in translation.” (PSG = positively selected genes). https://t.co/WF2bAZEkSF
“Hence, the positive selection of these three glycolysis genes may be associated with seagrass-specific adaptation to anaerobiosis.” https://t.co/WF2bAZEkSF
“In darkness, seagrasses can even be forced to switch to fermentative metabolism. In P. oceanica, malate has previously been shown to accumulate as a consequence of anoxic conditions.” https://t.co/WF2bAZEkSF
“This observation may be particularly significant due to the challenges imposed by the O2 sink created by the reductive sediment leading to compensation by internal transport of oxygen from shoot to root tissues during the day cycle.” https://t.co/WF2bAZEk
“With two fructose-bisphosphate aldolase enzymes and a malate dehydrogenase, the list of PSGs contains three enzymes of the glycolysis pathway.” (PSG = positively selected genes). https://t.co/WF2bAZEkSF
“Genes that are known to facilitate salt tolerance such as the SOS pathway were absent from the orthologous gene clusters and could therefore not be investigated." https://t.co/WF2bAZEkSF
“In general, salt-tolerant plants compensate osmotic and ionic imbalances with increased K+ import and the accumulation of compatible solutes.” https://t.co/WF2bAZEkSF
“Seagrasses have been found to harbor increased intracellular levels of Na+ and K+ as compared to terrestrial angiosperm species as well as to other aquatic angiosperms." https://t.co/WF2bAZEkSF
“One of the questions that has to remain open is how exactly do seagrasses deal with the high salinity of the ocean.“ https://t.co/WF2bAZEkSF
“Physiologically, however, seagrasses must cope with high ion concentrations, inefficient carbon uptake and other physical coping mechanisms that are still poorly understood." https://t.co/WF2bAZEkSF
The morphological features shared by hydrophytes and seagrasses: “the presence of a diffusive boundary layer around the leaves, a photosynthetic epidermis, loss of stomata and the development of aerenchyma." https://t.co/WF2bAZEkSF
“A number of terrestrial lineages of plants have evolved into aquatic-freshwater hydrophytes and a number of morphological features are shared by both hydrophytes and seagrasses.” https://t.co/WF2bAZEkSF
ESTs = expressed sequence tags. https://t.co/WF2bAZEkSF
“Since orthologous clusters include only ESTs from both seagrasses, the presented dataset is not an unbiased sample of the genome and is probably enriched for genes that show significant expression levels in both seagrass species." https://t.co/WF2bAZEkSF
“The available dataset allowed only for the investigation of 189 orthologous clusters, equivalent to ~1% of the A. thaliana genome.” https://t.co/WF2bAZEkSF
Na+ toxicity which seagrasses have experienced.”To this respect, molecular adaptation of key cellular processes known to be sensitive towards increased ionic levels such as photosynthesis, translation, and selected metabolic enzymes are expected." https://
“These adaptations are possibly associated to the above mentioned Na+ toxicity which seagrasses have likely experienced during their evolution towards the marine environment.” https://t.co/WF2bAZEkSF
“In the present analysis, many of the identified PSGs are involved in the central biological pathways of translation, photosynthesis, and glycolysis." (PSGs= positively selected genes). https://t.co/WF2bAZEkSF
“Positive selection for 51 genes was detected after the split from terrestrial monocots based on a maximum likelihood approach.” https://t.co/WF2bAZEkSF
Sub-aqueous pollination in seagrasses. “This adaptation to a marine habitat is thus an example of morphological parallel evolution." https://t.co/WF2bAZEkSF
“Except for the genus Enhalus with above-surface pollination, all of the 60 seagrass species exhibit true sub-aqueous pollination by means of filiforme pollen (hydrophily).” https://t.co/WF2bAZEkSF
“Seagrasses have been found to share morphological traits that distinguish them from terrestrial plants such as reduced stamen and corolla, and elongated pollen without exine walls." https://t.co/WF2bAZEkSF
“Most seagrass species share a secondarily simplified morphology which includes horizontal rhizomes and strap-like leaves originating from a basal meristem." https://t.co/WF2bAZEkSF
Seagrasses. “This indicates that the aquatic habitat imposes novel selection forces that can lead to parallel evolution." https://t.co/WF2bAZEkSF
“Strikingly, despite their independent evolutionary routes, seagrasses from the three different lineages have evolved many similar morphologies, life history strategies, and breeding systems.“ https://t.co/WF2bAZEkSF
Seagrasses returning to the sea. “Moreover, detrimental effects can propagate from the cytoplasmic compartment into the chloroplasts, leading to a decreased efficiency of photosynthesis which in turn impairs growth." https://t.co/WF2bAZEkSF
K+ as a co-factor for plants. “An increased level of Na+ creates a competing environment for K+ binding sites and thus decreases efficiency of these processes.“ https://t.co/WF2bAZEkSF
Seagrasses. “Key metabolic processes in the cytoplasm such as enzymatic reactions, protein synthesis, and ribosome functions rely on K+ as a co-factor.” https://t.co/WF2bAZEkSF
Return of seagrasses to the sea. “Increased levels of sodium (Na+) are known to be toxic, partly due to the fact that both Na+ and potassium (K+) have very similar physicochemical properties." https://t.co/WF2bAZEkSF
“Specific to marine environments, seagrasses are often exposed to high salt levels and short-term salinity fluctuations in the coastal and estuarine system." https://t.co/WF2bAZEkSF
“Consequently, seagrasses have evolved to propagate via hydrophilous pollination and rely on carbonic acid and bicarbonate instead of CO2." https://t.co/WF2bAZEkSF
“Submergence also exposes organisms to the forces of wave action and tidal currents that effects reproductive functions and reduces the availability of carbon dioxide (CO2).“ https://t.co/WF2bAZEkSF
“When the internal transport of oxygen from shoot to root tissues is not sufficient, seagrasses can be forced to resort to fermentative metabolism." https://t.co/WF2bAZEkSF
“One factor contributing to these high light requirements is the reducing sediments to which seagrasses are rooted. These sediments challenge seagrass root tissues with anaerobic conditions since marine sediments are often oxygen deficient.“ https://t.co/W
“The overall light intensity is decreased and the wavelength composition of sunlight reaching underwater plants is different. Accordingly, seagrasses have one of the highest light requirements among angiosperms." https://t.co/WF2bAZEkSF
“The photosynthetic apparatus needs to be modulated to accommodate the changes in light attenuation through the water depth.“ https://t.co/WF2bAZEkSF
“Living submerged in an aqueous environment poses many challenges requiring physiological and morphological adaptations that are distinctive from terrestrial angiosperms." https://t.co/WF2bAZEkSF
Seagrasses. “The return into the sea occurred at least three times independently through parallel evolution from a common aquatic-freshwater ancestor of terrestrial origin." https://t.co/WF2bAZEkSF
Seagrasses. “Phylogenetic analysis of members of the entire order, based on the plastid gene encoding for RuBisCO large subunit, indicates that the return into the sea occurred at least three times independently.” https://t.co/WF2bAZEkSF
Seagrasses. “The marine families include the Posidoniaceae, Zosteraceae, Hydrocharitaceae, and Cymodoceaceae, and have originated in the Cretaceous period." https://t.co/WF2bAZEkSF
“Seagrasses belong to the order of Alismatales which includes 11 families of aquatic-freshwater species and 4 families that are fully marine.“ https://t.co/WF2bAZEkSF
“At least three independent seagrass lineages, but no other angiosperm species, have evolved to a life in the marine environment." https://t.co/WF2bAZEkSF
“The monocotyledonous seagrasses represent, in fact, a polyphyletic group of plants that can live underwater in fully marine environments.“ https://t.co/WF2bAZEkSF
“Aquatic angiosperms are perhaps comparable to whales: They returned to the water, preserving some features of terrestrial organisms.” https://t.co/WF2bAZEkSF
“51 genes showed evidence for positive selection in seagrass branches indicating that photosynthesis, a few metabolic pathways, and ribosomes have strongly diverged after the split of the common ancestor of seagrasses from terrestrial monocots.” https://t.
Seagrass study. “Only genes that were contained in the available seagrass EST collections could be analyzed in this study. Consequently, the current dataset of orthologous gene clusters for 10 angiosperm species is biased and limited in size.“ https://t.co
Seagrass light-limitation and shifted light spectrum adaptations “through long-lasting metabolic adjustments including down-regulation of RuBisCO, enhanced proteolysis and putative changes in the antenna complex.” https://t.co/WF2bAZEkSF
“Seagrasses are able to activate different mechanisms to cope with conditions of light-limitation and shifted light spectrum.” https://t.co/WF2bAZEkSF
“Seagrasses have long been regarded as C3 plants, but...several seagrass species, including Z. marina, are C3-C4 intermediates or have various carbon-concentrating mechanisms to aid the RuBisCO enzyme in carbon acquisition.” https://t.co/WF2bAZEkSF
“The two seagrass species under investigation, Z. marina and P. oceanica, are known to utilize bicarbonate (HCO−3) as a major source of inorganic carbon as a major source of inorganic carbon for photosynthesis.” https://t.co/WF2bAZEkSF
“Factors contributing to slow CO2 diffusion in aquatic plants (and especially in seagrasses) are thick boundary layers around the leaves that are sometimes amplified by the presence of unicellular or multicellular photosynthetic epiphytes.” https://t.co/WF
“While CO2 can readily diffuse from the air through the stomata to the mesophyll cells in terrestrial plants, aquatic plants often have limited CO2 diffusion rates.“ https://t.co/WF2bAZEkSF
“Fixation of CO2 is expected to be more difficult for seagrasses since seawater contains very little dissolved carbon dioxide.” https://t.co/WF2bAZEkSF
Seagrasses. “Seven PSGs were related to the photosynthetic pathway and may reflect adaptations to new conditions of carbon fixation and photosynthesis that seagrasses had to face after their split from a terrestrial ancestor.” https://t.co/WF2bAZEkSF
Seagrasses. “In A. thaliana, on average four gene copies encode for any of the approximately 80 different ribosomal proteins. This redundancy may reflect the importance of maintaining highly productive translation and protein synthesis.” https://t.co/WF2bA
“From an evolutionary point of view, translation is an ancient cellular process, and high selection pressure is expected to act against deleterious mutations, as ribosome functioning affects virtually all cellular processes.” https://t.co/WF2bAZEkSF
Seagrasses. “Ten PSGs were found to be ribosomal proteins involved in translation.” (PSGs= positively selected genes). https://t.co/WF2bAZEkSF
“Hence, the positive selection of these three glycolysis genes may be associated with seagrass-specific adaptation to anaerobiosis.” https://t.co/WF2bAZEkSF
“In darkness, seagrasses can even be forced to switch to fermentative metabolism. In P. oceanica, malate has previously been shown to accumulate as a consequence of anoxic conditions.” https://t.co/WF2bAZEkSF
Seagrasses. “This observation may be particularly significant due to the challenges imposed by the O2 sink created by the reductive sediment leading to compensation by internal transport of oxygen from shoot to root tissues during the day cycle.” https://t
Seagrasses. “With two fructose-bisphosphate aldolase enzymes and a malate dehydrogenase, the list of PSGs contains three enzymes of the glycolysis pathway.” (PSGs= positively selected genes). https://t.co/WF2bAZEkSF
Seagrasses. “However, genes that are known to facilitate salt tolerance such as the SOS pathway were absent from the orthologous gene clusters and could therefore not be investigated." https://t.co/WF2bAZEkSF
“In general, salt-tolerant plants compensate osmotic and ionic imbalances with increased K+ import and the accumulation of compatible solutes.“ https://t.co/WF2bAZEkSF
“Seagrasses have been found to harbor increased intracellular levels of Na+ and K+ as compared to terrestrial angiosperm species as well as to other aquatic angiosperms." https://t.co/WF2bAZEkSF
“One of the questions that has to remain open is how exactly do seagrasses deal with the high salinity of the ocean.“ https://t.co/WF2bAZEkSF
“Physiologically, however, seagrasses must cope with high ion concentrations, inefficient carbon uptake and other physical coping mechanisms that are still poorly understood." https://t.co/WF2bAZEkSF
Shared features by both hydrophytes and seagrasses, “e.g., the presence of a diffusive boundary layer around the leaves, a photosynthetic epidermis, loss of stomata and the development of aerenchyma." https://t.co/WF2bAZEkSF
“A number of terrestrial lineages of plants have evolved into aquatic-freshwater hydrophytes and a number of morphological features are shared by both hydrophytes and seagrasses.” https://t.co/WF2bAZEkSF
Seagrasses. “The presented dataset is not an unbiased sample of the genome and is probably enriched for genes that show significant expression levels in both seagrass species." (ESTs = expressed sequence tags). https://t.co/WF2bAZEkSF
Seagrasses. “Since orthologous clusters include only ESTs from both seagrasses, the presented dataset is not an unbiased sample of the genome.” https://t.co/WF2bAZEkSF
Seagrasses. “The available dataset allowed only for the investigation of 189 orthologous clusters, equivalent to ~1% of the A. thaliana genome.“ https://t.co/WF2bAZEkSF
Seagrasses. “To this respect, molecular adaptation of key cellular processes known to be sensitive towards increased ionic levels such as photosynthesis, translation, and selected metabolic enzymes are expected." https://t.co/WF2bAZEkSF
Seagrasses. “These adaptations are possibly associated to the above mentioned Na+ toxicity which seagrasses have likely experienced during their evolution towards the marine environment.“ https://t.co/WF2bAZEkSF
“In the present analysis, many of the identified PSGs are involved in the central biological pathways of translation, photosynthesis, and glycolysis." (PSGs= positively selected genes). https://t.co/WF2bAZEkSF
“Positive selection for 51 genes was detected after the split from terrestrial monocots based on a maximum likelihood approach.” https://t.co/WF2bAZEkSF
Seagrasses. “This adaptation to a marine habitat is thus an example of morphological parallel evolution." https://t.co/WF2bAZEkSF
“Except for the genus Enhalus with above-surface pollination, all of the 60 seagrass species exhibit true sub-aqueous pollination by means of filiforme pollen (hydrophily).“ https://t.co/WF2bAZEkSF
“Seagrasses have been found to share morphological traits that distinguish them from terrestrial plants such as reduced stamen and corolla, and elongated pollen without exine walls.“ https://t.co/WF2bAZEkSF
“Most seagrass species share a secondarily simplified morphology which includes horizontal rhizomes and strap-like leaves originating from a basal meristem." https://t.co/WF2bAZEkSF
“This indicates that the aquatic habitat imposes novel selection forces that can lead to parallel evolution." https://t.co/WF2bAZEkSF
“Strikingly, despite their independent evolutionary routes, seagrasses from the three different lineages have evolved many similar morphologies, life history strategies, and breeding systems.” https://t.co/WF2bAZEkSF
“Moreover, detrimental effects can propagate from the cytoplasmic compartment into the chloroplasts, leading to a decreased efficiency of photosynthesis which in turn impairs growth." https://t.co/WF2bAZEkSF
“An increased level of Na+ creates a competing environment for K+ binding sites and thus decreases efficiency of these processes.“ https://t.co/WF2bAZEkSF
“Key metabolic processes in the cytoplasm such as enzymatic reactions, protein synthesis, and ribosome functions rely on K+ as a co-factor.“ https://t.co/WF2bAZEkSF
“Increased levels of sodium (Na+) are known to be toxic, partly due to the fact that both Na+ and potassium (K+) have very similar physicochemical properties." https://t.co/WF2bAZmJu5
“Specific to marine environments, seagrasses are often exposed to high salt levels and short-term salinity fluctuations in the coastal and estuarine system.“ https://t.co/WF2bAZmJu5