Evolution of chloroplast retrograde signaling facilitates green plant adaptation to land

Chloroplast retrograde signaling networks are vital for chloroplast biogenesis, operation, and signaling, including excess light and drought stress signaling. To date, retrograde signaling has been considered in the context of land plant adaptation, but not regarding the origin and evolution of signaling cascades linking chloroplast function to stomatal regulation. We show that key elements of the chloroplast retrograde signaling process, the nucleotide phosphatase (SAL1) and 3'-phosphoadenosine-5'-phosphate (PAP) metabolism, evolved in streptophyte algae-the algal ancestors of land plants. We discover an early evolution of SAL1-PAP chloroplast retrograde signaling in stomatal regulation based on conserved gene and protein structure, function, and enzyme activity and transit peptides of SAL1s in species including flowering plants, the fern Ceratopteris richardii, and the moss Physcomitrella patens. Moreover, we demonstrate that PAP regulates stomatal closure via secondary messengers and ion transport in guard cells of these diverse lineages. The origin of stomata facilitated gas exchange in the earliest land plants. Our findings suggest that the conquest of land by plants was enabled by rapid response to drought stress through the deployment of an ancestral SAL1-PAP signaling pathway, intersecting with the core abscisic acid signaling in stomatal guard cells

Evolution of chloroplast retrograde signaling facilitates green plant adaptation to land

Chloroplast retrograde signaling networks are vital for chloroplast biogenesis, operation, and signaling, including excess light and drought stress signaling. To date, retrograde signaling has been considered in the context of land plant adaptation, but not regarding the origin and evolution of signaling cascades linking chloroplast function to stomatal regulation. We show that key elements of the chloroplast retrograde signaling process, the nucleotide phosphatase (SAL1) and 3'-phosphoadenosine-5'-phosphate (PAP) metabolism, evolved in streptophyte algae-the algal ancestors of land plants. We discover an early evolution of SAL1-PAP chloroplast retrograde signaling in stomatal regulation based on conserved gene and protein structure, function, and enzyme activity and transit peptides of SAL1s in species including flowering plants, the fern Ceratopteris richardii, and the moss Physcomitrella patens Moreover, we demonstrate that PAP regulates stomatal closure via secondary messengers and ion transport in guard cells of these diverse lineages. The origin of stomata facilitated gas exchange in the earliest land plants. Our findings suggest that the conquest of land by plants was enabled by rapid response to drought stress through the deployment of an ancestral SAL1-PAP signaling pathway, intersecting with the core abscisic acid signaling in stomatal guard cells

Petrogenesis of the Ultramafic Zone of the Stillwater Complex in North America: constraints from mineral chemistry and stable isotopes of Li and O

To investigate the petrogenesis of cyclic units in layered intrusions, we examined chromitite, dunite, poikilitic harzburgite and bronzitite from the Ultramaic Zone of the Stillwater Complex and measured stable isotopes of Li and O in their major minerals. The Li isotopes in olivine range from 4 to 26\u2030 in \u3b47Li with uniform Li contents of 1\u20133 ppm, whereas orthopyroxene and clinopyroxene have Li contents of 0.5\u20135 ppm and 4\u20138 ppm, and \u3b47Li ranges of 1213 to 7\u2030 and 1214 to 126\u2030, respectively. The \u3b418O values vary from 4.91 to 5.72\u2030 in olivine, from 5.11 to 5.87\u2030 in orthopyroxene, and from 4.64 to 5.86\u2030 in clinopyroxene. For a given sample, olivine displays more variable and higher \u3b47Li but lower \u3b418O values than orthopyroxene, indicating that olivine experienced more extensive compositional modiication after crystallization relative to orthopyroxene. The general Li and O isotopic compositions are interpreted as the result of re-equilibration between interstitial liquids, from which pyroxenes crystallized, and cumulus minerals. The inter-mineral and inter-sample isotopic variations correlate with mineral assemblages, crystal sizes and major and trace element compositions, revealing that the interstitial liquids varied compositionally mainly due to mixing between fractionated magma and newly injected primitive magma. Abrupt mineralogical and geochemical changes from silicate rocks to chromitites imply that hydrous luids, which collected on chromite surface and were later released from chromite seams, played an additional, critical medium of chemical exchange between minerals in the chromitites

Lithium elemental and isotopic variations in rock-melt interaction

International audienceDespite the occurrence of highly variable lithium (Li) elemental distribution and isotopic fractionation in mantle mineral, the mechanism of Li heterogeneity and fractionation remains a controversial issue. We measured Li contents and isotopic compositions of olivine and clinopyroxene xenocrysts and phenocrysts from kamafugite host lavas, as well as minerals in melt pockets occurring as metasomatic products in peridotite xenoliths from the Western Qinling, central China. The olivine xenocrysts in the kamafugites show compositional zonation. The cores have high Mg# (100 × Mg/(Mg+Fe); 91.0–92.2) and Li abundances (5.63–21.7 ppm), low CaO contents (≤0.12 wt%) and low δ7Li values (−39.6 to −6.76‰), which overlap with the compositional ranges of the olivines in the melt pockets as well as those in peridotite xenoliths. The rims of the olivine xenocrysts display relatively low Mg# (85.9–88.2), high CaO contents (0.19–0.38 wt%) and high δ7Li values (18.3–26.9‰), which are comparable to the olivine phenocrysts (Mg#: 86.4–87.1; CaO: 0.20–0.28 wt%; Li: 12.4–36.8 ppm; δ7Li: 18.1–26.0‰) and the silicate-melt metasomatized olivines. The clinopyroxene phenocrysts and clinopyroxenes in the melt pockets have no distinct characteristics with respect to the Li abundances and δ7Li values, but show higher and lower CaO contents, respectively, than the clinopyroxenes from silicate and carbonatite metasomatized samples. These features indicate that Li concentration and isotopic signatures of the cores of the xenocrysts recorded carbonatite melt-peridotite reaction (carbonatite metasomatism) at mantle depth, and the variations in the rims probably resulted from xenocryst–host magma interaction during ascent. Our results reveal that the interaction with carbonatite and silicate melts gave rise to an increase in Li abundance in minerals of peridotite xenoliths at mantle depth or during transportation. In terms of δ7Li, the carbonatite and silicate melts produced remarkably contrasting δ7Li variations in olivine. Based on the systematic variations of Li abundances and Li isotopes in olivines, we suggest that the δ7Li value of olivine is a more important indicator than that of clinopyroxene in discriminating carbonatite and silicate melt interaction agents with peridotites

U-Pb geochronology of zircons from river sediments in Sri Lanka: Implications on early Archean to late Cambrian magmatism and episodic crustal growth

Geochronology of zircons from river-sediments in Sri Lanka has never been attempted. Here we present Rare Earth Elements (REE) and U-Pb isotopes of -700 zircon grains by laser ablation ICP-MS technique, from sediments of the major rivers in the Sri Lankan basement (rivers of Mahaweli, Kelani, Kalu, Walawe, Maduru Oya and Maha Oya). Most of the studied zircons display oscillatory zoning and Th/U > 0.1, confirming their igneous origin. U-Pb age distribution of these river-sand zircons exhibits two major populations depicting Mesoproterozoic to Archean ( similar to 30%; > 1100-3100 Ma) and Neoproterozoic to late Cambrian ( similar to 70%; > 430-1000 Ma) magmatism. The two populations could be further resolved into intensive and episodic magmatic peaks at 480-680 Ma, 680-1000 Ma, 1100-1300 Ma, 1300-1700 Ma, 1700-1900 Ma, 2100-2300 Ma, 2300-2600 Ma and 2600-3100 Ma. These river-sediment-zircon data are consistent with the principal episodes of global continental crustal growth and the recognized U-Pb ages of magmatism are mostly correlative with those obtained from basement rocks by previous studies of Sri Lanka. The older zircons found in this study may have mainly originated from reworked/recycled ancient (Palaoproterozoic to Archean) crust. A younger zircon group of 450-700 Ma with homogenous core-rim zoning texture and Th/U ratios < 0.1 were inferred to be of metamorphic origin, indicating their possible crystallization at late Neoproterozoic metamorphic events, associated with the final assembly of the Gondwana Supercontinent. Thus, our data imply that the present-day continental crust of Sri Lanka may have predominantly formed and grown in the Neoproterozoic, while there is evidence that crustal growth began at least in the Paleoproterozoic. Further, the Mesoproterozoic peaks of the frequency distribution of U-Pb ages of river-sand zircons at similar to 1.6 Ga and similar to 1.1 Ga might reflect triggering of subduction in a paleo tectonic setting forming the Wanni and Vijayan dual arc systems, respectively

Distinctive calcium isotopic composition of mice organs and fluids: implications for biological research

The stable calcium (Ca) isotopes offer a minimally invasive method for assessing Ca balance in the body, providing a new avenue for research and clinical applications. In this study, we measured the Ca isotopic composition of soft tissues (brain, muscle, liver, and kidney), mineralized tissue (bone), and blood (plasma) from 10 mice (5 females and 5 males) with three different genetic backgrounds and same age (3 months old). The results reveal a distinctive Ca isotopic composition in different body compartments of mice, primally controlled by each compartment’s unique Ca metabolism and genetic background, independent of sex. The bones are enriched in the lighter Ca isotopes (δ44/40Cabone = − 0.10 ± 0.55 ‰) compared to blood and other soft tissues, reflecting the preferential incorporation of lighter Ca isotopes through bone formation, while heavier Ca isotopes remain preferentially in blood. The brain and muscle are enriched in lighter Ca isotopes (δ44/40Cabrain = − 0.10 ± 0.53 ‰; δ44/40Camuscle = 0.19 ± 0.41 ‰) relative to blood and other soft tissues, making the brain the isotopically lightest soft tissues of the mouse body. In contrast, the kidney is enriched in heavier isotopes (δ44/40Cakidney = 0.86 ± 0.31 ‰) reflecting filtration and reabsorption by the kidney. This study provides important insight into the Ca isotopic composition of various body compartments and fluids. Graphical Abstract: [Figure not available: see fulltext.

Syn-mineralization hydrous fluid activity in giant Jinchuan magmatic Ni-Cu sulfide deposit in North China Craton

Giant magmatic Ni-Cu sulfide deposits in the world are hosted mainly in pristine gabbro-dolerite sills (e.g., the first largest in the Noril'sk region) and norite bodies (e.g., the second largest in Sudbury, Duluth, and Voisey's Bay), implying the petrogenic relationship between the giant deposits and anhydrous parental magmas. In contrast, the third largest Jinchuan deposit is hosted in dunite- and lherzolite-dominated peridotite bodies and characterized by the presence of hydrous minerals (e.g., hornblende and phlogopite) and intensive serpentinization of olivine. The role of water in the formation of the magmatic Ni-Cu sulfide deposit remains unclear. To reveal the potential linkage between sulfide mineralization and ‘water’ (i.e., hydrous minerals), a detailed petrographic investigation of the Jinchuan deposit and the associated mineral chemistry analyses have been conducted in this study. The distribution of serpentinization of olivine in the Jinchuan deposit is unevenly, being more pervasive in the sulfide-bearing rocks compared to sulfide-free rocks. The degree of serpentinization decreases systematically in general sequence outwardly from the core net-textured dunite to the outer disseminated lherzolite at orebody-scale. In the sulfide-bearing rocks, the serpentinization is more intensively observed in the sulfide-rich portions compared to the sulfide-poor portions at thin section-scale. We consider sulfide content-dependent serpentinization as ‘selective alteration’, which is distinct from post-magmatic modifications and should have occurred coevally with sulfide liquid emplacement and sulfide crystallization. The selective alteration with dependence on sulfide contents is caused by hydrous fluids released from sulfide crystallization, because the crystallized sulfides cannot structurally accommodate hydrous components which previous latching onto the sulfide liquid. The olivine grains in sulfide-bearing rocks are reversely zoned with respect to Ni (Ni-poor cores, Ni-rich rims) and Co (Co-rich cores, Co-poor rims) which can be interpreted by stages of sulfide liquid-olivine Ni-Co exchange and Fe-Ni exchange. Comparison of intra-grain elemental distributions of olivine grains shows that hydrous fluid activity enhanced elemental exchange between olivine and sulfide liquid. Interestingly, the presence of hydrous minerals, protects olivine from selective alteration, suggesting that the hydrous minerals were formed during syn-mineralization fluid activity. These features are linkage between the inferred fluids compounded with sulfide droplets in previous experiments and their transfer and fate in natural magmatic sulfide deposits. The selective alteration proposed here, formed during the syn-mineralization stage and indicate that the fluid activity is instrumental in the formation of magmatic sulfide ores. The selective alteration may be a common characteristic in ultramafic rock-hosted magmatic sulfide deposits and a pathfinder for mineral exploration