Programmed Cell Death Induced In Japanese Lawngrass(Zoysia Japonica Steud.) By H₂O₂ And Preliminary Studies On Alleviated Effects Of Gibberellin Acid (GA3)

Zoysiagrass(Zoysia japonica Steud.) is a type of turfgrass with good quality,however,as the deteriorating external environment,the living environment which they live had been destroyed.Environmental stress on plant cell damage was largely due to the increased concentration of reactive oxyen species,reactive oxyen species had become an important signal molecule which induced programmed cell death by environmental stress.Japanese lawngrass(Zoysia japonica Steud.) cells were uesd as material,through added exogennous reactive oxyen species-H₂O₂ to investigate whether the cell death under H₂O₂ stress was programmed cell death.In additon,added exogenous GA3 into H₂O₂ to explore the role of GA3 in the process,in order to provide theoretical and practical basis for studying zoysiagrass resistance mechanism. Conclusions showed as follows:(1)Through the adding of different concentrations of H₂O₂,the cell growth coditions were determined by packed cell volume.H₂O₂ sress could inhibit the growth of the cells and japanese lawngrass cells could no longer grow after 2 days of H₂O₂ sress.Evans blue staining detected cell death dynamics,the results showed the nummber of cell death would increased with higher H₂O₂ concentration and longer treatment time.(2) The results of microscopic observation:trypan blue staining indicated that low level of H₂O₂ (5mmol/L) would not damaged the membrance strcture,,and cells would not stained.With higher concentration,cells stained under 30mmol/L H₂O₂,the membrance strcture were damaged.The results of DAPI stained nuclei indicated there were morphological characteristics of programmed cell death in the process of japanese lawngrass cell death inducd by H₂O₂, such as protoplast shrinkaged,chromation condensed,nuclei shringkaged,and had some apoptosis bodies.DNA content analysis displayed that cell death was increased after 12 hours H₂O₂ disposal,a large number of DNA degraded after 24 hours.(3) Antioxidant enzyme activity as SOD,POD,CAT decreased in the process of cell death induced by H₂O₂ demonstrated that they might play different role in the process of activity oxyen metabolism..Antioxidant enzyme activity trends to smooth after 24 hours.(4) After exogenous application of GA3,the results of DAB staining showed that oxidative damage was initiated in the early stage of stress,and released less amount of activity oxyen.The results of cell death dynamics indicated there were little effct on cell growth and low cell death rate treating with 10mmol/L GA3.After added GA3 into H₂O₂,decreased the number of cell death.After exogenous application of GA3,enhanced activity of SOD,POD,CAT indicated that GA3 play an important role in alleviating cells death inducing by H₂O2 in Japanese lawngrass.