Plant-microbial interactions inspired the discovery of novel sesquiterpenoid dimeric skeletons of hidden natural products from Hibiscus tiliaceus

Hidden natural products are representative of defensive strategies produced in vivo in diseased plants,a process that is induced by the plant immune system.The first transcriptome library of uninfected and pathogen infected Hibiscus tiliaceus stems was constructed by transcriptome sequencing technology,genes related to cadinene-type sesquiterpenoid biosynthesis were screened and combined with ultra-performance liquid chromatography-quadrupole-time of flight mass spectrometry(UPLC-QTOF-MS)analysis data,which indicated pathological tissue had potential to produce novel carbon skeletons of cadinane sesquiterpenoid dimers.Successfully,two cadinane-derived sesquiterpenoid dimers with unprecedented carbon skeletons,hibisceusanols A(1)and B(2)were isolated for the first time from the stems of H.tiliaceus induced by plant-microbial interactions.Their structures and absolute configurations were unambiguously established by spectroscopy,advanced chemistry development(ACD)and electronic circular dichroism(ECD)methods.Compounds 1 and 2 exhibited significant antitumor activity in vitro with half maximal inhibitory concentration(IC_(5)0)values of 2.3–7.2μmol/L.The anticancer effect was generated via the induction of Hep G2 cell apoptosis by inhibiting the phosphatidylinositol 3-kinase(PI3K)pathway.

Responses of plant diversity and soil microorganism diversity to nitrogen addition in the desert steppe,China

Nitrogen(N)deposition is a significant aspect of global change and poses a threat to terrestrial biodiversity.The impact of plant-soil microbe relationships to N deposition has recently attracted considerable attention.Soil microorganisms have been proven to provide nutrients for specific plant growth,especially in nutrient-poor desert steppe ecosystems.However,the effects of N deposition on plant-soil microbial community interactions in such ecosystems remain poorly understood.To investigate these effects,we conducted a 6-year N-addition field experiment in a Stipa breviflora Griseb.desert steppe in Inner Mongolia Autonomous Region,China.Four N treatment levels(N0,N30,N50,and N100,corresponding to 0,30,50,and 100 kg N/(hm2•a),respectively)were applied to simulate atmospheric N deposition.The results showed that N deposition did not significantly affect the aboveground biomass of desert steppe plants.N deposition did not significantly reduce the alfa-diversity of plant and microbial communities in the desert steppe,and low and mediate N additions(N30 and N50)had a promoting effect on them.The variation pattern of plant Shannon index was consistent with that of the soil bacterial Chao1 index.N deposition significantly affected the beta-diversity of plants and soil bacteria,but did not significantly affect fungal communities.In conclusion,N deposition led to co-evolution between desert steppe plants and soil bacterial communities,while fungal communities exhibited strong stability and did not undergo significant changes.These findings help clarify atmospheric N deposition effects on the ecological health and function of the desert steppe.

The Removal and Remediation of Phenanthrene and Pyrene in Soil by Mixed Cropping of Alfalfa and Rape

The mechanisms and efficiencies of the removal and remediation of polycyclic aromatic hydrocarbons （PAHs） in soils by different planting patterns with rape （Brassica campestris） and alfalfa （Medicago sativa） were studied by pot experiments in a greenhouse. Results showed that the remediation efficiencies under mixed cropping of alfalfa and rape significantly exceeded those under single cropping when the initial concentrations of phenanthrene and pyrene were at 20.05-322.06 mg kg^-1 and 20.24-321.42 mg kg^-1, respectively. After 70 days plantation of crops, the contents of extractable PAHs in soils under mixed cropping were much lower than those under single cropping. About 65.17-83.52% of phenanthrene and 60.09%- 75.34% ofpyrene was removed from the soils under mixed cropping, respectively, which were averagely 43.26 and 40.38% for phenanthrene, and 11.03 and 16.29% for pyren higher than those under single cropping. Alfalfa or rape did absorb and accumulate PAHs from the soils apparently; the PAHs concentrations in plants monotonically increased with the increase of initial PAHs concentrations in soil; the accumulations of PAHs in plants showed following sequence as roots 〉 above parts, phenanthrene 〉 pyrene and single cropping 〉 mixed cropping at same contamination level. Despite the presence of vegetation significantly enhanced the remediation of PAHs in soils, contributions of abiotic loss, plant uptake, accumulation and microbial degradation was much lower than those of plant-microbial interactions in the process of phytoremediation. Thus plant-microbial interactions are the main mechanisms for the remediation enhancement of soil PAHs pollution under mixed cropping models. Results suggested a feasibility of the establishment of multi-species phytoremediation for the improvement of remediation efficiencies of PAHs, which may decrease accumulations of PAHs in crops and thus reduce their risks.

Neotyphodium fungal endophyte in tall fescue (Schedonorus phoenix): a comparison of three Northern European wild populations and the cultivar Kentucky-31

Pooideae grasses may be colonized by systemic fungal endophytes.The fitness of endophyte depends entirely on resources and seed transmission from the host plant,while colonized plants may gain increased survival,growth,and reproduction relative to their uncolonized conspecifics.Most research of endophyte-grass interactions have been carried out on few cultivars of tall fescue(Schedonorus phoenix)and their symbiont Neotyphodium coenophialum.Lack of studies using wild populations of tall fescue across the species natural distribution range,however,limits the understanding of the ecological and evolutionary role of the symbiosis in nature.We performed a common garden experiment in Southern Finland with three wild,tall fescue populations from northern Europe and the forage cultivar Kentucky-31(KY-31).For each population,we used naturally endophyte-colonized,naturally endophytecolonized but endophyte removed(decolonized),and naturally uncolonized plants to separate effects due to the host genotype from the endophyte.We evaluated growth variables and survival in four environmental treatments of varying water and nutrients.Supply of water and nutrients increased plant biomass and reproductive effort in all populations.This effect was higher for KY-31 plants which produced on average 55%more seeds than wild plants,indicating better adaptation to high resource environments.However,the higher incidence of Claviceps sp.and the low winter survival indicated KY-31 tall fescue is mal-adapted to Northern European conditions.Naturally colonized plants had greater plant biomass(≈12%),reproductive effort(≈22%)and seed mass(≈29%)than naturally uncolonized and decolonized plants.Nonetheless,endophyte colonization did not affect plant survival,and the effects of endophyte colonization on tiller number,panicle/tiller ratio and Claviceps sp.incidence depended on the population origin.In the wild populations,endophyte removal only reduced the number of tillers(≈29%lower),while the difference between naturally colonized and naturally uncolonized plants was not significant.Our results show that endophyte symbiont increases tall fescue performance in general,but the differences between wild populations and cultivars indicate adaptation to local habitats and agronomic management,respectively.The comparison of naturally endophyte-colonized and decolonized plants suggests certain plant genotype-endophyte combinations found within populations result from local selection pressures.