| Phosphorus,rely on phosphate transporter(PHT)carrier to absorb and utilize from soil,is the key nutrient element necessary for plant growth and development,but it is often difficult to be absorbed and utilized for the poor mobility in soil.Therefore,even if it is applied to enough,plants not only can't absorb,but will lead to plant phosphorus poisoning,soil phosphorus waste and environmental pollution.Moreover,the lack of phosphorus resources is a global challenge currently facing.In recent years,a kind of "biological fertilizer"--arbuscular mycorrhizal(AM)fungi,which can improve the state of phosphorus deficiency,is found in nature.One of its main functions is to improve the mineral nutrition status of the host plant,especially the phosphorus.These mycorrhizal fungi can form a mutually beneficial mycorrhizal symbiosis with most plants,to carry out nutrient exchange,energy flow and information transmission,and have an important potential to maintain the regeneration,diversity and system stability of the ecosystem.Salvia miltiorrhiza is a perennial herb of Lamiaceae plants.It is not only a recognized model medicinal plant,but also a large supply of medicinal herbs in the market.Both the dry roots and rhizomes have the traditional efficacy of activating blood and removing stasis,relieving pain and clearing the heart and tranquilizing the mind.Moreover,it have significant effects on diseases of cardiovascular and cerebrovascular system in modern medicine.However,due to the cultivation area is widespread and dispersal,it is difficult to form a standard of standard cultivation.There are many problems such as serious degradation of germplasm,uneven quality and continuous cropping obstacle,which hinders the production of high-yield and high-quality Radix Salvia Miltiorrhizae.The current research tends to directly understand the effect of phosphorus application on the accumulation of active components of Salvia miltiorrhiza,but neglects the primary metabolism of phosphorus nutrition.In this study,on the one hand,the in-situ detection of Salvia miltiorrhiza roots under natural growth conditions was performed,on the other hand,the effect of inoculation of indigenous AM Fungi—glomus formosanum Wu&Chen(GF),by using potted controlled experiments,on Phosphorus Metabolism of Salvia miltiorrhiza is explore at three different levels of appearance,physiology,biochemistry and molecular biology.A total of the following results have been achieved:1.The growth and development of Salvia miltiorrhiza plant and its root system in the natural environment.There is an interesting phenomenon,Salvia miltiorrhiza has two periods of vegetative growth and reproductive development within one year,but mainly focus on the second times.The effect of the change of the aerial part of Salvia miltiorrhiza on the root is not obvious.The color of its root will undergo a process "white?red?purple brown",and the red color will last for 2 to 3 months.According to the quantity,size and color of the root comprehensively,it is suggested that the best harvest time of Radix Salviae Miltiorrhizae should be selected about 5th to 6th months after the seedling transplanting.2.Effects of AM fungi on the appearance and morphological characteristics of Salvia miltiorrhiza under different phosphorus supply.Low phosphorus stress can inhibit the growth and development of Salvia miltiorrhiza,and AM fungi can improve its poor growth state caused by phosphorus deficiency.It can not only promote the growth(increase plant height,enlargement of stem diameter)and the accumulation of biomass(aboveground and underground)of Salvia miltiorrhiza;also change its morphological characteristics of root,that is increase the root length,projected area,surface area,volume,average diameter,root tip number.3.Effects of AM fungi on the appearance and morphological characteristics of Salvia miltiorrhiza in physiological and biochemical aspects under different phosphorus supply.The symbiotic dependence of AM fungi on Salvia miltiorrhiza is different when it under the different P concentration,the low phosphorus environment will increase the infection rate of mycorrhiza.With the increase of phosphorus concentration,the symbiosis is inhibited and the dependence of AM fungi on Salvia miltiorrhiza is reduced.The formation of AM symbiotic system will reduce the available nitrogen in the rhizosphere soil of Salvia miltiorrhiza The concentration of available phosphorus,available potassium and the content of organic matter;AM fungi can also promote the absorption and utilization of phosphorus in Salvia miltiorrhiza plants,especially the utilization efficiency of Salvia miltiorrhiza on Phosphorus in the low phosphorus environment,which can significantly increase the phosphorus content both ground and underground of Salvia miltiorrhiza,the total phosphorus content can be increased by 5.33 times.AM symbiotic system will also improve the leaf cause of Salvia miltiorrhiza The inhibition of photosynthesis caused by low phosphorus is to increase the net Pn,Gs and Tr of the leaves of Salvia miltiorrhiza,and decrease the Ci of leaves.4.The PHT1 gene family of Salvia miltiorrhiza was excavated and its mycorrhizal markers were screened.A total of 12 new PHT1 candidate genes were excavated from the Salvia miltiorrhiza genome,the member of Sm1 is the reported gene Smpht1.All members were highly conserved and the homology between them was as high as 74.34%,and the members were annotated.Among the family genes,the 3 pairs of Smpht1&Sm1,Sm4&Sm6 and Sm5&Sm11 may belong to the co-evolution of the same functional genes;5 members of Sm1,Sm3,Sm5,Sm7 and Sm11 will be expressed in the root of Salvia miltiorrhiza Except for Sm7 and Sm3 influenced by phosphorus deficiency factors,the other 4 members may all belong to phosphorus-induced enhanced expression genes,which in turn may play an important role in phosphorus absorption of Salvia miltiorrhiza In addition,Sm7 and Sm16 may also be found in the floral organs of Salvia miltiorrhiza Sm14 is likely to be a specific phosphorous transport gene induced by mycorrhizal induced specific expression.5.Effects of AM fungi on the expression of phosphorus related genes in Salvia miltiorrhiza under different phosphorus nutrition conditions.We further studied the tissue-specific expression of Sm1 and Sm14,and preliminarily verified their related functions to phosphorus transport.By Real Time PCR technique.The results show that their expression were detected in root,stem and leaf of Salvia miltiorrhiza,and the most content in the root,stem and leaf was less than 10% of root.Sm1 gene could be detected in all samples of this experiment,and it is significantly up-regulated in low phosphorus concentration,but decreased with the increase of phosphorus concentration,and is less affected by AM,so the mycorrhizal effect is not obvious.Sm14 could also be detected in all samples,its expression is not only affected by the concentration of phosphorus which decreased with the increase of phosphorus concentration,but also strongly induced by AM fungi,compared with the control group,it increased by 3.7 times.So the Sm14 is belongs to the PHT1 family of Salvia miltiorrhiza,which is a marker gene for AM symbiotic phosphorus metabolism pathway.To sum up,the research of this subject has certain innovation in both content and method.(1)On the premise of not damaging the plant body,the root system of Salvia miltiorrhiza which was grown under natural environment was firstly monitored by the micro-root canal method,and the developmental dynamics of different stages of growth were known preliminarily.(2)We,for the first time,used the method of native AM species from Salvia miltiorrhiza root,to investigate the effects of AM fungi on the phosphorus metabolism at three levels of apparent morphology,physiological biochemistry and molecular biology.In addition,three different genetic backgrounds(Sichuan,Henan and Shandong)of Salvia miltiorrhiza were was also investigated,Through the comparison and analysis of various indexes,it was found that the overall mycorrhizal effect of Salvia miltiorrhiza from Sichuan and Henan was good,and the salvia miltiorrhiza plants from Shandong would be in the dormancy state during the test period.So the corresponding experimental results were not obtained. |
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