Aquatic angiosperms represent an important but underexplored lineage for understanding genome evolution,particularly in species with exceptionally large genomes.Here,we present a chromosome-scale genome assembly of th...Aquatic angiosperms represent an important but underexplored lineage for understanding genome evolution,particularly in species with exceptionally large genomes.Here,we present a chromosome-scale genome assembly of the endangered aquatic monocot Ottelia songmingensis(~10.8 Gb),providing a valuable genomic resource for studying genome gigantism and conservation.Using ONT and Hi-C technologies,we anchored 87.7%of the assembly to 11 pseudochromosomes and predicted 35362 protein-coding genes.Comparative genomics revealed two whole-genome duplication events,including a more recent duplication and an ancestral triplication shared within Alismatidae.Repetitive elements constitute 94.3%of the genome,with long terminal repeat retrotransposons alone accounting for over 90%.A recent burst of LTR activity(~6 Mya)combined with a low solo-to-intact ratio(0.61)suggests inefficient transposon removal as a driver of genome expansion.Whole-genome bisulfite sequencing showed globally high DNA methylation levels(CG~85%,CHG~78%),particularly enriched in transposable element-rich regions,highlighting the role of epigenetic regulation in stabilizing large genomes.Population resequencing further indicated extremely low nucleotide diversity(π=5.31×10⁻⁴)and a long-term decline in effective population size since the Middle Pleistocene.Together,these resources provide a genomic foundation for exploring the evolutionary forces underlying genome gigantism and for guiding conservation genomics in endangered aquatic plants.展开更多
Otteacumienes G-K(1-5),five pairs of enantiomeric diarylheptanoids,along with one undescribed diarylhepta-noid glycoside and one new lignan,were isolated from Ottelia acuminata var.acuminata.Compounds 1-5 were identif...Otteacumienes G-K(1-5),five pairs of enantiomeric diarylheptanoids,along with one undescribed diarylhepta-noid glycoside and one new lignan,were isolated from Ottelia acuminata var.acuminata.Compounds 1-5 were identified as five pairs of enantiomers and their structural configurations were determined through a combination of spectroscopic analysis,X-ray crystallography,and ECD calculation.Notably,compound 6 was the first diarylhep-tanoid glycoside isolated from this aquatic species,and its absolute configuration was unequivocally established through semi-synthesis.Biological evaluation demonstrated that compound 1 exhibited α-glucosidase inhibitory activity,with an inhibition ratio of 38.97%(acarbose as the positive control,inhibition ratio=13.52%).展开更多
Mimicry of non-rewarding flowers to rewarding flowers has been accepted as a strategy to improve pollination success in angiosperms.It has been proposed that this mechanism depends on whether potential pollinators can...Mimicry of non-rewarding flowers to rewarding flowers has been accepted as a strategy to improve pollination success in angiosperms.It has been proposed that this mechanism depends on whether potential pollinators can discriminate between the flowers.In this study,the intersexual mimicry and deceit pollination were studied in a threatened dioecious aquatic herb,Ottelia acuminata.Its female flowers resemble male flowers in morphology and odor compounds,to avoid discrimination by pollinators and outcompete male flowers in attracting the pollinators using stronger scents and bigger flowers.However,an obvious visit bias of its pollinator(Apis cerana)to male flowers was detected,suggesting that bees can distinguish the rewarding males from non-rewarding females.Although the deceit was not successful,pollination was not seriously undermined because pollen limitation was found to be low in the sampled natural population.We speculate that,due to“accidental”visits on female flowers and“mistake”pollinations,pollen limitation could be mitigated by a high frequency of pollen donors,and is correlated with the size and sex ratio of a population.Ottelia acuminata is a threatened dioecious aquatic herb.We suggest that developing multi-stakeholder coalitions should be encouraged to save the threatened edible and ornamental plant species in China.We hope this study could provide new insights into understanding of the role of intersexual mimicry in other flowering plants.展开更多
Diabetes is an urgent health issue characterized by ethnic and regional variations,and is inseparable from the differ-ent dietary habits.It is worthy to note that the incidence of diabetes in Bai nationality has been ...Diabetes is an urgent health issue characterized by ethnic and regional variations,and is inseparable from the differ-ent dietary habits.It is worthy to note that the incidence of diabetes in Bai nationality has been reported to be much lower than Han in China.As a daily vegetable of Bai,the phytochemical and antidiabetic study of Ottelia acuminata var.acuminata had not been carried out.In this study,41 metabolites with diverse diarylheptanoid(six new ones,Otteacumienes A-F),flavone,sesquiterpenoid,coumarin,lignan,polyacetylene,and alkaloid skeletons were charac-terized from O.acuminata var.acuminata.Among them,the racemic nature of 3 was characterized by chiral resolution and calculated ECD methods.The biological study revealed diarylheptanoids showed significantα-glucosidase inhibi-tory activities with 5 as the most effective one(60-fold stronger than acarbose).Molecular docking studies indicated that these structures have different binding cavities with acarbose.This study demonstrated that O.acuminata var.acuminata might correlated with the low incidence diabetes of Bai and the diarylheptanoids may have potential therapeutic value for diabetes mellitus.展开更多
Sediment properties have a crucial effect on the growth and recovery of aquatic plants in lakes.Addition of various chemical substances has been proposed to reinforce the recovery of plants after a nutrient loading re...Sediment properties have a crucial effect on the growth and recovery of aquatic plants in lakes.Addition of various chemical substances has been proposed to reinforce the recovery of plants after a nutrient loading reduction.However,the effects of such sediment amendments on plant growth,especially those from rhizosphere microorganisms,is limited.We added Kaolin clay to sediments in different concentrations to explore its impact on the growth of Vallisneria natans and Ottelia acuminate and the concurrent shift in rhizosphere microorganisms using high-throughput sequencing technology.We found that the addition of low doses(10%and 20%in mass ratio)of Kaolin significantly modified sediment conditions(oxidation reduction potential and pH),with implications also for the composition,diversity,and stability of rhizosphere microorganisms.LEfSe analysis revealed that low-dose addition of Kaolin increased the abundances of functional microbial groups that benefit plant nutrient absorption and enhance plant stress resistance,such as Spirillaceae,Rhodocyclaceae,and Burkholderiales.Moreover,low doses of Kaolin significantly promoted the photosynthesis and nutrient absorption of submerged macrophytes,thereby facilitating plant growth.A structural equation model(SEM)indicated that the direct impact of Kaolin on the growth of submerged plants was relatively minor,while the indirect effect through modulation of rhizosphere microorganisms was important.Our study suggests that low doses of Kaolin may be used to promote the growth of submerged macrophytes when lakes with a high organic content in the sediment are recovering after nutrient loading reduction.展开更多
基金supported by grants from the National Natural Science Foundation of China(32120103002,32070253,and 32100186)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB31000000)the National Key R&D Program of China(2024YFF1307400).
摘要Aquatic angiosperms represent an important but underexplored lineage for understanding genome evolution,particularly in species with exceptionally large genomes.Here,we present a chromosome-scale genome assembly of the endangered aquatic monocot Ottelia songmingensis(~10.8 Gb),providing a valuable genomic resource for studying genome gigantism and conservation.Using ONT and Hi-C technologies,we anchored 87.7%of the assembly to 11 pseudochromosomes and predicted 35362 protein-coding genes.Comparative genomics revealed two whole-genome duplication events,including a more recent duplication and an ancestral triplication shared within Alismatidae.Repetitive elements constitute 94.3%of the genome,with long terminal repeat retrotransposons alone accounting for over 90%.A recent burst of LTR activity(~6 Mya)combined with a low solo-to-intact ratio(0.61)suggests inefficient transposon removal as a driver of genome expansion.Whole-genome bisulfite sequencing showed globally high DNA methylation levels(CG~85%,CHG~78%),particularly enriched in transposable element-rich regions,highlighting the role of epigenetic regulation in stabilizing large genomes.Population resequencing further indicated extremely low nucleotide diversity(π=5.31×10⁻⁴)and a long-term decline in effective population size since the Middle Pleistocene.Together,these resources provide a genomic foundation for exploring the evolutionary forces underlying genome gigantism and for guiding conservation genomics in endangered aquatic plants.
基金supported financially by Yunnan Key Laboratory Screening and Research on Anti-pathogenic Plant Resources from Western Yunnan(APR202301)Yunnan Revitalization Talent Support Program“Innovation Team”Project(202305AS350014)Foundation of DR.PLANT.
摘要Otteacumienes G-K(1-5),five pairs of enantiomeric diarylheptanoids,along with one undescribed diarylhepta-noid glycoside and one new lignan,were isolated from Ottelia acuminata var.acuminata.Compounds 1-5 were identified as five pairs of enantiomers and their structural configurations were determined through a combination of spectroscopic analysis,X-ray crystallography,and ECD calculation.Notably,compound 6 was the first diarylhep-tanoid glycoside isolated from this aquatic species,and its absolute configuration was unequivocally established through semi-synthesis.Biological evaluation demonstrated that compound 1 exhibited α-glucosidase inhibitory activity,with an inhibition ratio of 38.97%(acarbose as the positive control,inhibition ratio=13.52%).
基金Support for this study was provided through grants from the NSFC-Yunnan joint fund to support key projects(U1602264)the Yunnan Science and Technology Innovation Team Program(2019HC015)+1 种基金National Key R&D Program of China(2017YFC0505200)Yunnan Ten Thousand Talents Plan Young&Elite Talents Project.
摘要Mimicry of non-rewarding flowers to rewarding flowers has been accepted as a strategy to improve pollination success in angiosperms.It has been proposed that this mechanism depends on whether potential pollinators can discriminate between the flowers.In this study,the intersexual mimicry and deceit pollination were studied in a threatened dioecious aquatic herb,Ottelia acuminata.Its female flowers resemble male flowers in morphology and odor compounds,to avoid discrimination by pollinators and outcompete male flowers in attracting the pollinators using stronger scents and bigger flowers.However,an obvious visit bias of its pollinator(Apis cerana)to male flowers was detected,suggesting that bees can distinguish the rewarding males from non-rewarding females.Although the deceit was not successful,pollination was not seriously undermined because pollen limitation was found to be low in the sampled natural population.We speculate that,due to“accidental”visits on female flowers and“mistake”pollinations,pollen limitation could be mitigated by a high frequency of pollen donors,and is correlated with the size and sex ratio of a population.Ottelia acuminata is a threatened dioecious aquatic herb.We suggest that developing multi-stakeholder coalitions should be encouraged to save the threatened edible and ornamental plant species in China.We hope this study could provide new insights into understanding of the role of intersexual mimicry in other flowering plants.
基金supported financially by the Second Tibetan Plateau Scientific Expedition and Research program (2019QZKK0502)State Key Laboratory of Phytochemistry and Plant Resources in West China (E0230211Z1 and P2019-ZZ05).
摘要Diabetes is an urgent health issue characterized by ethnic and regional variations,and is inseparable from the differ-ent dietary habits.It is worthy to note that the incidence of diabetes in Bai nationality has been reported to be much lower than Han in China.As a daily vegetable of Bai,the phytochemical and antidiabetic study of Ottelia acuminata var.acuminata had not been carried out.In this study,41 metabolites with diverse diarylheptanoid(six new ones,Otteacumienes A-F),flavone,sesquiterpenoid,coumarin,lignan,polyacetylene,and alkaloid skeletons were charac-terized from O.acuminata var.acuminata.Among them,the racemic nature of 3 was characterized by chiral resolution and calculated ECD methods.The biological study revealed diarylheptanoids showed significantα-glucosidase inhibi-tory activities with 5 as the most effective one(60-fold stronger than acarbose).Molecular docking studies indicated that these structures have different binding cavities with acarbose.This study demonstrated that O.acuminata var.acuminata might correlated with the low incidence diabetes of Bai and the diarylheptanoids may have potential therapeutic value for diabetes mellitus.
基金supported by the National Natural Science Foundation of China(Nos.U23A20153,and 32101319).
摘要Sediment properties have a crucial effect on the growth and recovery of aquatic plants in lakes.Addition of various chemical substances has been proposed to reinforce the recovery of plants after a nutrient loading reduction.However,the effects of such sediment amendments on plant growth,especially those from rhizosphere microorganisms,is limited.We added Kaolin clay to sediments in different concentrations to explore its impact on the growth of Vallisneria natans and Ottelia acuminate and the concurrent shift in rhizosphere microorganisms using high-throughput sequencing technology.We found that the addition of low doses(10%and 20%in mass ratio)of Kaolin significantly modified sediment conditions(oxidation reduction potential and pH),with implications also for the composition,diversity,and stability of rhizosphere microorganisms.LEfSe analysis revealed that low-dose addition of Kaolin increased the abundances of functional microbial groups that benefit plant nutrient absorption and enhance plant stress resistance,such as Spirillaceae,Rhodocyclaceae,and Burkholderiales.Moreover,low doses of Kaolin significantly promoted the photosynthesis and nutrient absorption of submerged macrophytes,thereby facilitating plant growth.A structural equation model(SEM)indicated that the direct impact of Kaolin on the growth of submerged plants was relatively minor,while the indirect effect through modulation of rhizosphere microorganisms was important.Our study suggests that low doses of Kaolin may be used to promote the growth of submerged macrophytes when lakes with a high organic content in the sediment are recovering after nutrient loading reduction.