Melatonin and dopamine alleviate waterlogging stress in apples by recruiting beneficial endophytes to enhance physiological resilience

Melatonin and dopamine can potentially prevent waterlogging stress in apples.The current study investigated the mechanism by which melatonin and dopamine alleviate apple waterlogging stress.This study demonstrated that melatonin and dopamine alleviated waterlogging by removing reactive oxygen species(ROS),and that the nitric oxide(NO)content and nitrate reductase(NR)activity were significantly correlated.Melatonin and dopamine were also found to recruit different candidate beneficial endophytes(melatonin:Novosphingobium,Propionivibrio,and Cellvibrio;dopamine:Hydrogenophaga,Simplicispira,Methyloversatilis,Candidatus_Kaiserbacteria,and Humicola),and these endophytes were significantly and positively correlated with plant growth.Network analyses showed that melatonin and dopamine significantly affected the endophytic bacterial and fungal communities under waterlogging stress.The metabolomic results showed that melatonin and dopamine led to waterlogging resistance by upregulating the abundance of beneficial substances such as amino acids,flavonoids,coumarins,and organic acids.In addition,melatonin and dopamine regulated the physicochemical properties of the soil,which altered the endophyte community and affected plant growth.The co-occurrence network demonstrated close and complex relationships among endophytes,metabolites,soil,and the plants.Our results demonstrate that melatonin and dopamine alleviate waterlogging stress in apples by recruiting beneficial endophytes to enhance physiological resilience.This study provides new insights into how melatonin and dopamine alleviate stress and a theoretical basis for synergistic beneficial microbial resistance to waterlogging stress.

Dopamine improves apple replant disease resistance by regulating physiological resilience and rhizosphere microbial community structure

Apple replant disease(ARD)is a complex agricultural problem caused by multiple stressors that can lead to increased reactive oxygen species(ROS)levels and limited nutrient utilization in plants.However,existing countermeasures cannot effectively address this challenge.Here,we used Malus hupehensis as a test organism to investigate whether the pleiotropic molecule dopamine can alleviate ARD using pot experiments.Exogenous application of 100μmol L-1 dopamine significantly promoted the growth of apple seedlings in the replanted soil,with a relative growth rate increase of 17.44%.Our results revealed two major pathways by which dopamine regulates ARD resistance in apple trees.First,dopamine effectively reduces the level of ROS and activates the expression of genes related to nitrogen(N)transport and metabolism.Among those genes,MdNLP5,MdNRT1.1,MdNLP2,MdNRT2.5,MdNLP3,MdNRT2.4,MdNADH-GAGOT,and MdFd-GAGOT were strongly regulated by dopamine.These regulatory effects promoted the uptake and utilization of soil N by the plants.Second,dopamine improved the physical and chemical properties,enhanced microbial community diversity,and promoted mutual cooperation between microbial communities in the soil.Furthermore,dopamine altered the microbial structure of rhizosphere soil(upregulating Clostridiales,Gaiellales,Sordariales and Mortierellales;downregulating Micrococcales,Longimicrobiales,Hypocreales and Cystobasidiales).Notably,dopamine significantly upregulated the abundances of Gaiella and Mortierella,both of which were positively correlated with soil urease activity,soil available N content,plant growth and N uptake.Dopamine also significantly downregulated the abundance of the plant pathogen Gibberella(by 11.71-fold)in replant soil.Our results provide insights into the mechanisms by which dopamine promotes ARD resistance,and can promote the sustainable development of the apple industry.

Dopamine alleviates cadmium stress in apple trees by recruiting beneficial microorganisms to enhance the physiological resilience revealed by high-throughput sequencing and soil metabolomics

Dopamine has demonstrated promise as a stress-relief substance.However,the function of dopamine in Cd tolerance and its mechanism remains largely unknown.The current study was performed to investigate the mechanism of dopamine on alleviating apple Cd stress through regular application of CdCl2 and dopamine solution to potting soil.The results indicated that dopamine significantly reduced reactive oxygen species(ROS)and Cd accumulation and alleviated the inhibitory effect of Cd stress on the growth of apple plants through activation of the antioxidant system,enhancement of photosynthetic capacity,and regulation of gene expression related to Cd absorption and detoxification.The richness of the rhizosphere microbial community increased,and community composition and assembly were affected by dopamine treatment.Network analysis of microbial communities showed that the numbers of nodes and total links increased significantly after dopamine treatment,while the keystone species shifted.Linear discriminant analysis effect size indicated that some biomarkers were significantly enriched after dopamine treatment,suggesting that dopamine induced plants to recruit potentially beneficial microorganisms(Pseudoxanthomonas,Aeromicrobium,Bradyrhizobium,Frankia,Saccharimonadales,Novosphingobium,and Streptomyces)to resist Cd stress.The co-occurrence network showed several metabolites that were positively correlated with relative growth rate and negatively correlated with Cd accumulation,suggesting that potentially beneficial microorganisms may be attracted by several metabolites(L-threonic acid,profenamine,juniperic acid and(3β,5ξ,9ξ)-3,6,19-trihydroxyurs-12-en-28-oic acid).Our results demonstrate that dopamine alleviates Cd stress in apple trees by recruiting beneficial microorganisms to enhance the physiological resilience revealed.This study provides an effective means to reduce the harm to agricultural production caused by heavy metals.

Correlates of Sexual Lifestyles Among Older Adults Living With HIV in China: Findings From the Sexual Well-being (SWELL) Study

Sexual lifestyles are closely related to overall human health and well-being.Few studies have focused on sexual lifestyles among older adults living with HIV(OALHIV),especially in low-and middle-income countries.This study is a part of the sexual well-being among older adults in China(SWELL)study,which is a multicenter cross-sectional study focused on sexual health among older adults aged 50 years and older.Participants were 680 OALHIV(≥50 years old)from the SWELL study conducted from June 2020 to December 2022.Data were collected through one-on-one interviews.We used logistic regression to assess the correlates of sexual activity and sexual satis-faction.Among all participants,37.1%were sexually active.Being older,male,in a steady relationship and employed were associated with being sexually active.The prevalence of sexual satisfaction was 69.8%among sexually active OALHIV.Being homosexual and reporting a better general health status were associated with sexual satisfaction.The OALHIV who have depressive symptoms were less likely to report sexual satisfaction.To support holistic healthy aging among OALHIV,it is important for healthcare providers to be educated about the importance of enquiring about sexual activity,satisfaction and problems and addressing concerns while conveying sex-positive attitudes during clinical reviews,as these are still critical aspects of their health and well-being.

Multi-block electret-based mechanical antenna model for low frequency communication

In an LF/VLF transmission system,the performance of the antenna is of great importance to the entire system.Currently,the electret-based mechanical LF/VLF antenna uses mechanical movement to accelerate electret charges to produce LF/VLF electromagnetic waves,and the frequency of these electromagnetic waves is limited by the rotation speed of the actuating motor.Based on research that addressed the relationship between antenna structure and electromagnetic wave frequency,this paper—in order to increase the frequency of electromagnetic waves—alters the charge distribution mode of the mechanical antenna while keeping the motor’s rotational speed constant to realize an increase of transmission signal frequency.The effectiveness of this method was verified by model simulation.