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Macro-Morphological and Ecological Variation in Rosa sericea Complex
No full textTaxon delimitation and identification are important in many areas of biology, especially in taxonomy and conservation. Taxonomic treatment is required to establish and justify recommendations in conservation biology for the group being considered. Imperfect and controversial taxonomy can undermine conservation assessment. We studied 71 populations; 665 individuals corresponding to the morphology of the Rosa sericea complex (including six taxa, one of which has extremely narrow distributions) were collected from sympatric, parapatric, and allopatric populations distributed in China. This study aims to investigate whether the complex species are macromorphologically different species and evaluate the rare taxa of the complex for conservation priority. The morphological characters and principal component analysis (PCA) of the R. sericea complex showed that the complex species have overlapping characters but can distinguish morphologically. The species of R. sericea complex systematics status based on previous DNA sequencing is controversial. The ecological habitat's current morphological characters only delimit the R. morrisonensis (in Taiwan). To evade mistakes in species conservation, we recommend that taxonomical knowledge be needed to ensure success in protecting target species. Thus, the complementarity of systemic and conservation assurance makes conservation actions more necessary for the complex's rare taxa. The ecological niche modelling (ENM) results showed that habitats of these conspecific taxa would be shrunken. With the presence of snapshots in time, the geography of taxa might decrease rapidly in representative entirely of the Geographic space (G-space) and Environmental space (E-space) that such taxa are bright to inhabit. So far, the significant inferences meant for the niche occupy the most incredible comparative research, taking the impermanent nature of taxa distributions and undertaking that such species are at a state of stability. If the artificially identified species (rarely distributed) are based on morphological identification, they must be conserved
Transcriptomic and physio-biochemical features in rice (Oryza sativa L.) in response to mercury stress
No full textMercury (Hg) is a toxic and nonessential element for organisms, and its contamination in the environment is a global concern. Previous research has shown that Hg stress may cause severe damage to rice roots; however, the transcriptomic changes in roots and physio-biochemical responses in leaves to different levels of Hg stress are not fully understood. In the present study, rice seedlings were exposed to 20, 80, and 160 mu M HgCl2 for three days in hydroponic experiments. The results showed that the majority of Hg was accumulated in rice roots after Hg exposure, and the 80-and 160-mu M Hg stresses significantly increased the root-to-shoot translocation factors relative to 20-mu M Hg stress, resulting in elevated Hg concentrations in rice shoots. Only the 160-mu M Hg stress significantly inhibited root growth compared with the control, while photosynthesis capacity in leaves was significantly reduced under Hg stress. RNA transcriptome sequencing analyses of the roots showed that common responsive differentially expressed genes were strongly associated with glutathione metabolism, amino acid biosynthesis, and secondary metabolite metabolism, which may play significant roles in Hg accumulation by rice plants. Nine crucial genes identified by protein-protein interaction network analysis may be used as candidate target genes for further investigation of the detoxification mechanism, encoding proteins involved in jasmonic acid synthesis, sugar metabolism, allene oxide synthase, glutathione peroxidase, dismutase, and catalase. Furthermore, physio-biochemical analyses of the leaves indicated that higher production of reactive oxygen species was induced by Hg stress, while glutathione and antioxidant enzymes may play crucial roles in Hg detoxification. Our findings provide transcriptomic and physio-biochemical features of rice roots and shoots, which advance our understanding of the responsive and detoxification mechanisms in rice under different levels of Hg stress
The prokaryotic and fungal communities of oat rhizosphere responded contrastingly to different irrigation regimes at pre- and post-anthesis stages
No full textThe transition from the vegetative stage to reproductive stage of plants and variations in soil water regimes can alter the community feedbacks of rhizosphere microbiomes by affecting the partitioning of photosynthates to roots. However, little is known about how different rhizosphere microbiota respond to the growth stages of drought-resistant crops under different irrigation regimes. To address these issues, we investigated the effects of irrigation regimes on the rhizosphere prokaryotic and fungal communities at the pre-and post-anthesis stages of oats in a semi-arid region of northeastern China. The prokaryotic and fungal community traits of the oat rhizosphere were characterized by Illumina high-throughput sequencing. The results revealed that the pro-karyotic diversity was primarily regulated by oat growth stage, while the fungal diversity was mainly increased by irrigation regimes. Similarly, all prokaryotic phyla responded significantly to oat growth stages rather than irrigation regimes, while the composition of the fungal taxa was largely regulated by irrigation regimes. Approximately 2-3-fold higher proportions of the predominating pathogenic Fusarium genus were identified under dryland farming conditions than under irrigation treatment. In addition, functional predictions suggested that the contrasting responsive traits of prokaryotes and fungi were attributed to their functional guilds, which were related to oat growth stages and soil water conditions. However, the properties of the prokaryotic networks mainly responded to irrigation regimes while the fungal networks were regulated by oat growth, implying distinct determination mechanisms for microbial diversity and community stability. Our results indicate that rhizosphere prokaryotic and fungal communities differentially responded to oat growth stages and soil water history, highlighting the significance of irrigation in manipulating rhizosphere microbes in semi-arid regions
Sustainability challenges for the social-environmental systems across the Asian Drylands Belt
No full textThis paper synthesizes the contemporary challenges for the sustainability of the social-environmental system (SES) across a geographically, environmentally, and geopolitically diverse region-the Asian Drylands Belt (ADB). This region includes 18 political entities, covering 10.3% of global land area and 30% of total global drylands. At the present time, the ADB is confronted with a unique set of environmental and socioeconomic changes including water shortage-related environmental challenges and dramatic institutional changes since the collapse of the Union of Soviet Socialist Republics. The SES of the ADB is assessed using a conceptual framework rooted in the three pillars of sustainability science: social, economic, and ecological systems. The complex dynamics are explored with biophysical, socioeconomic, institutional, and local context-dependent mechanisms with a focus on institutions and land use and land cover change (LULCC) as important drivers of SES dynamics. This paper also discusses the following five pressing, practical challenges for the sustainability of the ADB SES: (a) reduced water quantity and quality under warming, drying, and escalating extreme events, (b) continued, if not intensifying, geopolitical conflicts, (c) volatile, uncertain, and shifting socioeconomic structures, (d) globalization and cross-country influences, and (e) intensification and shifts in LULCC. To meet the varied challenges across the region, place-based, context-dependent transdisciplinary approaches are needed to focus on the human-environment interactions within and between regional landscapes with explicit consideration of specific forcings and regulatory mechanisms. Future work focused on this region should also assess the role of the following mechanisms that may moderate SES dynamics: socioeconomic regulating mechanisms, biophysical regulating mechanisms, regional and national institutional regulating mechanisms, and localized institutional regulating mechanisms
Hurricanes Substantially Reduce the Nutrients in Tropical Forested Watersheds in Puerto Rico
No full textBecause nutrients including nitrogen and phosphorus are generally limited in tropical forest ecosystems in Puerto Rico, a quantitative understanding of the nutrient budget at a watershed scale is required to assess vegetation growth and predict forest carbon dynamics. Hurricanes are the most frequent disturbance in Puerto Rico and play an important role in regulating lateral nitrogen and phosphorus exports from the forested watershed. In this study, we selected seven watersheds in Puerto Rico to examine the immediate and lagged effects of hurricanes on nitrogen and phosphorous exports. Our results suggest that immediate surges of heavy precipitation associated with hurricanes accelerate nitrogen and phosphorus exports as much as 297 +/- 113 and 306 +/- 70 times than the long-term average, respectively. In addition, we estimated that it requires approximately one year for post-hurricane riverine nitrogen and phosphorus concentrations to recover to pre-hurricane levels. During the recovery period, the riverine nitrogen and phosphorus concentrations are 30 +/- 6% and 28 +/- 5% higher than the pre-hurricane concentrations on average
Molecular Characterization of Bacterial Isolates from Soil Samples and Evaluation of their Antibacterial Potential against MDRS
No full textSome soil microbes, with their diverse inhabitance, biologically active metabolites, and endospore formation, gave them characteristic predominance and recognition among other microbial communities. The present study collected ten soil samples from green land, agricultural and marshy soil sites of Khyber Pakhtunkhwa, Pakistan. After culturing on described media, the bacterial isolates were identified through phenotypic, biochemical and phylogenetic analysis. Our phylogenetic analysis revealed three bacterial isolates, A6S7, A1S6, and A1S10, showing 99% nucleotides sequence similarity with Brevibacillus formosus, Bacillus Subtilis and Paenibacillus dendritiformis. The crude extract was prepared from bacterial isolates to assess the anti-bacterial potential against various targeted multidrug-resistant strains (MDRS), including Acinetobacter baumannii (ATCC 19606), Methicillin-resistant Staphylococcus aureus (MRSA) (BAA-1683), Klebsiella pneumoniae (ATCC 13883), Pseudomonas aeruginosa (BAA-2108), Staphylococcus aureus (ATCC 292013), Escherichia coli (ATCC25922) and Salmonella typhi (ATCC 14028). Our analysis revealed that all bacterial extracts possess activity against Gram-negative and Gram-positive bacteria at a concentration of 5 mg/mL, efficiently restricting the growth of E. coli compared with positive control ciprofloxacin. The study concluded that the identified species have the potential to produce antimicrobial compounds which can be used to control different microbial infections, especially MDRS. Moreover, the analysis of the bacterial extracts through GC-MS indicated the presence of different antimicrobial compounds such as propanoic acid, oxalic acid, phenol and hexadecanoic acid
Phylogenetic analysis and character evolution of tribe Arethuseae (Orchidaceae) reveal a new genus Mengzia
No full textDelimitation of the tribe Arethuseae has varied considerably since it was first defined. The relationships within Arethuseae, particularly within the subtribe Arethusinae, remain poorly elucidated. In this study, we reconstructed the phylogeny of Arethuseae, using six plastid markers (matK, ycf1, rbcL rpoc1, rpl32-trnL and trnL-F) from 83 taxa. The ancestral state reconstruction of 11 selected morphological characters was also conducted to identify synapomorphies and assess potential evolutionary transitions. Morphological character comparision between the distinct species Bletilla foliosa and other species are conducted. Our results unequivocally supported the monophyly of Arethuseae, which included highly supported clades and a clear synapomorphy of nontrichome-like lamellae. Furthermore, B. foliosa formed a separate clade in the subtribe Arethusinae, instead of clustering with the other Bletilla species in the subtribe Coelogyninae. The morphological characters comparision further showed that the B. foliosa clade could be distinguished from other genera in Arethuseae by multiple characters, including presence of lateral inflorescence, three lamellae with trichome-like apex and four pollinia. In light of these molecular and morphological evidences, we propose Mengzia as a new genus to accommodate B. foliosa and accordingly provide descriptions of this new genus and combination
Early Domestication History of Asian Rice Revealed by Mutations and Genome-Wide Analysis of Gene Genealogies
No full textBackground: Asian rice (Oryza sativa L.) has been a model plant but its cultivation history is inadequately understood, and its origin still under debate. Several enigmas remain, including how this annual crop shifted its growth habit from its perennial ancestor, O. rufipogon, why genetic divergence between indica and japonica appears older than the history of human domestication, and why some domestication genes do not show signals of introgression between subgroups. Addressing these issues may benefit both basic research and rice breeding. Results: Gene genealogy-based mutation (GGM) analysis shows that history of Asian rice is divided into two phases (Phase I and II) of about equal lengths. Mutations occurred earlier than the partition of indica and japonica to Os genome mark Phase-I period. We diagnosed 91 such mutations among 101 genes sampled across 12 chromosomes of Asian rice and its wild relatives. Positive selection, detected more at 5' regions than at coding regions of some of the genes, involved 22 loci (e.g., An-1, SH4, Rc, Hd3a, GL3.2, OsMYB3, OsDFR, and OsMYB15), which affected traits from easy harvesting, grain color, flowering time, productivity, to likely taste and tolerance. Phase-I mutations of OsMYB3, OsHd3a and OsDFR were experimentally tested and all caused enhanced functions of the genes in vivo. Phase-II period features separate cultivations, lineage-specific selection, and expanded domestication to more genes. Further genomic analysis, along with phenotypic comparisons, indicates that O. sativa is hybrid progeny of O. rufipogon and O. nivara, inherited slightly more genes of O. rufipogon. Congruently, modern alleles of the sampled genes are approximately 6% ancient, 38% uni-specific, 40% bi-specific (mixed), and 15% new after accumulating significant mutations. Results of sequencing surveys across modern cultivars/landraces indicate locus-specific usages of various alleles while confirming the associated mutations. Conclusions: Asian rice was initially domesticated as one crop and later separate selection mediated by human resulted in its major subgroups. This history and the hybrid origin well explain previous puzzles. Positive selection, particularly in 5' regions, was the major force underlying trait domestication. Locus-specific domestication can be characterized and the result may facilitate breeders in developing better rice varieties in future
Active water management brings possibility restoration to degraded lakes in dryland regions: a case study of Lop Nur, China
No full textProtecting and restoring the degraded arid lakes are globally urgent issues. We document a potential recovery of the dried salt-lake, Lop Nur called the Sea of Death which is located at the terminus of the largest inland basin in China, the Tarim River Basin. The changes and relationship of surface water with climate parameters and groundwater in the basin over the last 30 years are analyzed, by using satellite remote sensing and land data assimilation products. We find that with increased surface water in the basin, the groundwater level in Lop Nur began to show an obvious positive response in 2015; and the rate of decline of the groundwater level is slowing down. We argue that after a balance is achieved between regional groundwater recharge and evapotranspiration, the Lop Nur ecosystem will gradually recover. This study shows an encouraging case for the protection and restoration of degraded lakes in dryland regions around the world
A comprehensive checklist of the deciduous photinia genus Pourthiaea (Maleae, Rosaceae), with emphasis on their validity and typification
No full textDue to the complicated evolutionary history in Pourthiaea, ninety-seven taxa have been described since 1784, and ninety-one of them are validly published taxa, five are naked names, and one is an invalid name. After a comprehensive and critical evaluation, 213 names have been published, including new combinations, new status, and new names; this may be due to the controversial taxonomic position of Pourthiaea in the apple tribe, Maleae. We herewith provide a taxonomic checklist of Pourthiaea for further taxonomic and evolutionary studies. We also lectotypify two taxa: Photinia amphidoxa var. stylosa and P. glabra var. fokienensis