| Zoysia matrella,which is also called manilagrass,is a perennial herbaceous plant of Gramineae chloridoideae Zoysia.Zoyasia matrella is a kind of very good warm season turfgrass,which has the characteristics of fine leaf,green color and long green period.Also,it has good drought tolerance,saline-alkaline resistance and shade tolerance.Therefore,it is a turfgrass of high quality which is widely used in parks,recreational square and golf courses in most region of southern China.Zoysia matrella is breeding by stolon in nature,so it is difficult to use traditional method such as the cross breeding in the process of genetic improvement.Under this circumstances,a simple method for somaclonal variation is an effective breeding approach for screening resistant plants for Zoysia matrella.Iron is one of the essential elements for normal growth of plants.It is also an essential element for synthesis of chlorophyll and a component of some enzymes.In the condition of iron deficiency,the leaves turn yellow.Therefore,it is important to explore the correlation between the content of iron in the plant and the green period.In this experiment,8 generations of embryogenic callus of Zoysia matrella were used as experimental materials to the responses to iron stress and the physiological characteristics of leaves and roots of regeneration plant,to explore in vitro screening whether the iron resistance plants has long green period under field conditions.The different concentrations of iron we set in callus culture were 100.0?200.0?500.0 and 1000.0?M.For further screening of iron tolerance in callus culture,the concentration of iron were 100.0?200.0?550.0?650.0?750.0?850.0 and 950.0?M.The callus were taken into the regeneration medium after iron screening.After 16 weeks,we got a small amount of iron resistance plants.Physiological and biochemical analysis and determination of iron content of plant were taken on the plant.The main results are as follows:1.After treatment with different concentrations of iron,the average diameter and the growth rate of fresh weight of callus of Zoysia matrella were the highest at the iron concentration of 200.0?M.The average diameter of callus and the growth rate of fresh weight decreased significantly at 850.0?M.Therefore,the ultimate limit of resistance of the callus was about 850.0?M.Besides,we could change the concentration of iron in MS a little higher in which way the callus of Zoysia matrella culture will be better.2.After the callus cultured in regeneration medium with iron stress,the regeneration plant grow better under the concentration of 500.0?M,while it can't be generate under the concentration of 750.0?M.Therefore,the ultimate limit of resistance of regeneration was between 650.0-750.0?M.3.The activities of CAT?POD?SOD and the contents of MDA of callus were the lowest at the concentration of 200.0?M.The activity of antioxidant enzymes and the contents of MDA continued to increased until 850.0?M,and they showed a downward trend later.4.The activities of CAT?POD?SOD and the contents of MDA of leaves and roots were the lowest at the concentration of 500.0?M,and the content of chlorophyll was the highest.What's more,the antioxidant enzyme activities and the contents of MDA in roots was much lower than it was in leaves.5.The contents of iron in callus,leaves and roots all increased,with the increase of the concentration of iron in the culture medium.What is more,we found in this study that compared with the regenerated plants,callus had stronger ability of resisting iron stress,and iron accumulation in roots was much higher than that in leaves.6.The results showed that there was resistance to iron in the callus of Zoysia matrella.It is most suitable for callus subculture and preservation when the concentration of iron was 200.0?M.The regenerated plant grow better when the concentration of iron in the medium was 500.0?M,whose content of chlorophyll was the highest.However,whether or not it could be mass cultured to prolong the green period of Zoysia matrella when transplanted to field experiment,still need more study in the future. |
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