EBL Regulates The Growth And Regeneration Of Callus Of Zoysia Matrella Under 4℃ Stress And After Recovery

Low temperature is one of the main stress factors of warm season turfgrasses.In order to improve the cold resistance of Zoysia matrella(L.),the selection and genetic improvement of new varieties using somatic clonal mutation technology is a major research direction.However,the research on the improvement of cold resistance of callus and the selection of cold resistant regenerated plants of Zoysia matrella is still blank.So this paper aims to test and discuss how to improve the cold resistance of Zoysia matrella through somatic clonal selection,combined with the current research progress.Brassinolides(BRs)are widely used in plant growth regulation and improvement of stress resistance.Combined with BR treatment,we can further understand the regulation effects of BR on the antioxidant enzyme system of callus.In this experiment,the physiological and apparent indexes of callus and regenerated plants under various concentrations of EBL were measured and analyzed,and the effects of EBL on cold tolerance of Zoysia matrella callus was studied systematically.The main results are as follows:(1)Low temperature stress at 4 ℃ obviously inhibits the growth and regeneration of Zoysia matrella callus and reduces its biomass growth.(2)The callus of Zoysia matrella has certain cold tolerance.The callus in the early stage of stress responds rapidly to the low temperature environment,and its protective enzyme activity and malondialdehyde(MDA)content have obvious dynamic changes.In the early stage of subculture stress,the activities of catalase(CAT)and superoxide dismutase(SOD)first decrease and then increase,showing consistency,while peroxidase(POD)activity continues to decline and MDA content continues to rise.At the early stage of stress on regeneration culture,CAT,POD and SOD activity decrease first and then increase;MDA content continues to increase.(3)During the cold stress recovery period,the antioxidant enzymes in callus increase rapidly and MDA content decreases continuously.As the recovery continues,the antioxidant enzyme activity begins to decline,and the plant enters the normal growth and development stage.(4)EBL relieves stress damage by regulating the antioxidant enzyme system of Zoysia matrella callus.EBL in a certain concentration range(0.01-0 mg/L)significantly increases the activity of CAT,POD and SOD of callus,reducing the content of MDA,promoting the growth trend of callus subculture and regeneration.(5)EBL regulates the recovery of Zoysia matrella callus after stress by regulating its antioxidant enzyme system,promoting the recovery of subculture proliferation and regeneration of callus.EBL treatment with a concentration range of0.01-0.1 mg/L significantly improves the callus subculture recovery,increasing fresh weight and diameter growth,while 0.5 mg/L EBL has an inhibitory effect;EBL treatment with a concentration range of 0.01-0.05 mg/L significantly improves callus regeneration,increasing regeneration rate and reducing browning rate.Among them,0.05 mg/L EBL is the optimal concentration to improve regeneration recovery,while EBL at a concentration of 0.1 mg/L and above has a negative effect on the recovery of callus regeneration.