Ameliorating Effects Of Applied Salicylic Acid And Jasmonie Acid On Perilla Frutescens(L.) Britt. Exposing To Cadmium Stress Condition

Phytoremediation for the soils polluted by heavy metals with plants is a low-cost and effective strategy.Screening of hyperaccumulators,plants that with high accumulation of heavy metals,is prerequisite for the technique.Perilla frutescens(L.)Britt.,which has been widely cultivated in China,Japan,South Korea and other countries,also has a very intense enrichment capacity for Cd and act as a promising hyperaccumulator of Cd in environment.Salicylic acid(SA)and Jasmonic acid(JA),plant hormone,play important roles in plant resistance to adverse environment,and alleviate adversity generated damage to plant.However,the ameliorating effect of SA and JA on Prilla treated by Cd has not been reported.Based on the laboratory experiments,the effects of SA and JA on plant physiological respone,microstructure,metal element uptake and Cd compartmentalization attributes in the plants exposed to cadmium(Cd)stress conditon was conducted in the present study,and Cd resisting mechanism of different hormones has been discussed.These all are to build the foundation for solving the questions which exist in the cultivation pratices of Perilla under for phytoremediation in field.Main results of this study are as follows:1)Contrasted to the control(treated without hormone),SA allayed the adverse effects of Cd on the growth and photosynthesis rate of the plants,while the inhibitory effect of Cd on the activities of SOD and CAT were further promoted due to SA treatment.The content of Cd in different organs,H2O2 and phenol content in leaves were increased.The effect of JA on Perilla under Cd stress showed the same results.Under 5 mg·kg-1 Cd stress,JA mitigated the Cd-induced inhibition in the growth of Perilla by increasing the activity of SOD and CAT,vigor of root,content of soluble protein,decreasing the content of MDA and O2-.This means that the alleviation of S A on Cd treated plant can be accomplished by improving phenol metabolism,and the alleviation can be finished by modifying the activity of SOD and CAT.2)The influence of SA and JA on stem and leaf anatomy of Perilla,revealed that the increasing concentrations of Cd led to changed thickness of leaves,midvein thickness,xylem conduit area,xylem conduit tangential length,xylem conduit radial length,xylem thickness,vascular bundle group thickness,vascular bundle group length,downside epidermal thickness,upside epidermal thickness,lamina thickness,and stem diameter,epidermal thickness,collenchyma thickness,phloem tissue thickness,parenchymataous pith thickness,xylem tissue thickness,hollow pith diameter.The principal component analysis(PCA)showed that foliar application with SA induced prominent increase in stem diameter,xylem thickness,which could attribute to the induced adaption to Cd stress.Also by increasing the thickness of both leaves and phloem tissue in stem,the tolerance of Preilla to Cd stress could be stimulated by spraying JA.3)With the increase of Cd concentration,the concentration of Ca and Fe content in leaves of Perilla were significantly decreased,the soncentration of Zn increased first and then decreased,while no significant differences were detected in Mg concentration.Moreover,the application of SA,induced the higher accumulation of Ca,Mg and Zn than the seedlings feed with ddH2O under same Cd concentration,and the reverse is ture for Fe element.To the Perilla leaves treated without hormones under same Cd stress,the application of JA decrease the concentration of Ca,Zn and Fe,increase Mg concentration.These results suggested that application of exogenous SA and JA enhanced Cd tolerance of the plant by reducing the concentration of Fe,which induced the up-regulate expression of ZIP and NRAMP.4)Concentration and accumulation of Cd in sub-cellular has positive correlation with Cd concentration in hydroponic solutions.The accumulation of Cd showed in the order of cytoplasm>cell wall>vacuole.The application of SA on the leaves of Perilla seedlings,under Cd stress condition,increased the concentration of Cd in cytoplasm,with the decrease in cell wall and vacuole.While,after the application of JA,Cd concentration decreased in cell wall and vacuole,no significant change was found in Cd concentration in cytoplasm.Indicated that the plant could adapt stress condition rapidly through inducing the expression of phytochelatins and MTs to bind Cd under SA treatment.However,the alleviation of JA on Cd treated Perilla seedlings were realized by enhancing the cell wall immobilization and vacuolar compartmentalization.