Different Physiological Responses And Chloroplast Proteomics Analysis Between Male And Female Populus×euramericana Exposed To Manganese Stress

With the development of the global economy and the acceleration of industrialization as well as the influence of human and environmental factors,the heavy metals in the region and the world have increased sharply.The excessive manganese concentration in the soil not only causes great damage to plants,but also affects the sustainable development of agroforestry seriously.After farming in contaminated farmland,heavy metals may be rich in agricultural products,which affects human health eventually.At present,proteomics researches have been carried out in various plants,and proteomics methods have been well used for analysis.To date,the differences in physiological responses and proteomics of dioecious poplars under abiotic stress have been well confirmed.The physiological and protein response mechanisms of poplars identified by previous studies also have gender differences under the manganese stress.However,the differences in physiological responses and protein response mechanisms of manganese stress in male and female siblings P.euramericana have not been reported yet.In this paper,the artificially cultivated male and female siblings,the P.euramericana,namely Nanlin-895?female?and Nanlin-1388?male?,were used as materials to study the physiological and chloroplast proteomics changes under manganese stress.For the first time,the changes of protein components under manganese stress were researched from the perspective of chloroplast proteomics.The changes of chlorophyll a,chlorophyll b,carotenoid content,net photosynthetic rate and specific leaf weight of the leaves of male and female poplar under stress?0.5mMol/L MnCl₂ treatment?and control conditions?deionized water irrigation?were determined.The results showed that the leaves of both males and females showed corresponding stress symptoms and the damage of females was greater than that of males under manganese stress.The net photosynthetic rate and carotenoid content of the females were reduced significantly,but they were not decreased obviously in males.The content of chlorophyll a,chlorophyll b and specific leaf weight of females and males were significantly reduced,but they were decreased more in females.The different stress symptoms and physiological responses of males and females indicated that the manganese resistance of males were greater than that of females under manganese stress.Besides,iTRAQ-based quantitative proteome analysis was performed in female and male P.euramericana.A total of 2773 proteins were identified,with 174 chloroplast proteins defined as differentially expressed proteins?DEPs?.Among of these,8 and 6DEPs were decreased and 15 and 11 DEPs were increased under manganese stress in females and males,respectively.A bioinformatics analysis categorized the differential protein classification of males and females responses to manganese stress.Proteins of significantly up-regulated in males were related to carbohydrate and energy metabolism processes,translation/transcription/post-transcriptional modification,and stress responses,while the down-regulated proteins were mainly related to photosynthesis,transportation processes,cell membrane synthesis,and other biological processes.Proteins of significantly up-regulated in males were mainly involved in carbohydrate and energy metabolism,chlorophyll metabolism,translation/transcription/post-transcriptional modification,and signal transduction,while the down-regulated proteins were mainly involved in biological processes such as RNA biosynthesis,amino acid synthesis,photosynthesis,regulation of gene expression,molecular function,regulation of catabolic activity and so on.This study provides proteomic profiles that females mainly increase the response proteins to improve the ability to scavenge reactive oxygen species under manganese stress.Males mainly adapt to stress by signal transduction and other processes.Post-transcriptional regulation and post-translational modification play an important role in both males and females to adapt manganese stress condition.We found that the photosynthesis protein and membrane protein synthesis of female P.euramericana were blocked under the manganese stress,which indicates that the females suffer damage.The up-regulated expression proteins of females were involved in the stress response process,indicating that it mainly enhances the ability to scavenge reactive oxygen species by increasing the response proteins under manganese stress.However,the males were adapted to stress by the process of chlorophyll catabolism and signal transduction.The photosynthesis proteins of males were also down-regulated under stress,but they were less suppressed than that of females.Post-transcriptional regulation and post-translational modification play an important role in the adaptation of both male and female P.euramericana to manganese stress.