Mechanism Involved In Formation Of Adventitious Root Regulating By Ethylene And Auxin In Lotus Root (Nelumbo Nucifera Gaertn.)

Lotus root(Nelumbo nucifera Gaertn),a member of the family Nymphaeaceae,is an aquatic herb vegetable,and it has been widely cultivated in China for multiple purposes.The products of lotus root,lotus seeds and lotus root starch are very popular in the daily diet because of its richness in nutrients such as starch,protein,vitamin and mineral nutrition.Ethylene and auxin plays an important role in plant growth and development,and it also participates in the formation of adventitious roots.The effects of ethylene and auxin on the formation of adventitious root of lotus root and the formation of adventitious root were documented in this study.The mechanism involved in formation of adventitious root regulating by ethylene and auxin in was lotus root summarized,we obtained following results:1.Increased number of adventitious root in lotus root significantly enhanced the petiole height,leaf diameter,number of stolons underground and number of buds.Our result showed that the number of adventitious roots had positively correlated with the growth and development of lotus root.2.Microstructure of internodes of lotus seedlings was studied by paraffin section technique.It was showed that the adventitious root of lotus root was the original root of latent root.3.The results showed that 10 μmol/L,50 μmol/L and 100 μmol/L IAA promoted adventitious root formation,while 150 μmol/L IAA inhibited the adventitious roots formation in lotus seedlings.The emergence of adventitious root was delayed by 5 μmol/L,10 μmol/L and 15μmol/L TIBA treatment.Among which,the effect of 15 μmol/L TIB A in inhibiting formation of adventitious root was better than that of other two concentrations.In addition,200 mg/L and 300 mg/L ethylene significantly promoted the formation of adventitious roots,while 100 mg/L of ethylene could not changed occurance of adventitious roots.It was also showed that 200 mg/L and 200 mg/L 1-MCP significantly inhibited the number and the incidence of adventitious shoots.4.It was found that the content of endogengous auxin in seedling increased,and then decreased after treatment with 10 μmol IAA.Endogenous IAA reached highest content after 4 d treatment.However,the content of endogenous IAA treated by IAA was significantly lower than control plant.The tendency of endogenous auxin content treated by 200 mg/L ethylene was similar with IAA treatment.The contents of auxin in lotus root seedlings maintained at almost the same level as dry seeds(M)after treatment with 15 μmol/L TIB A and 200 mg/L 1-MCP.10 μmol/L IAA and 15 μmol/L TIB A had no effect on endogenous ethylene content,while 200 mg/L ethylene and 1-MCP could promote or decreased the content of ethylene in the plant respectively.5、The activity of POD was first increased,and then decreased in 24 h after treatment with IAA,TIB A,ethylene and 1-MCP.The activity of POD was in the order of 1-MCP>IAA,TIBA,Ethylene>CK after 12 h treatment.However,this order was changed with TIB A>1-MCP and CK>Ethylene>IAA after treatment for 24 h.At 36 h,the POD activity of ethylene was significantly higher than that of control,and the POD activity of IAA was significantly higher than that of control,while the POD activity of TIB A and 1-MCP was not significantly different from the control.6.Leaf cuttings could promote the adventitious root formation of seedlings.In addition,it was also found that the number of adventitious roots formed by leaf cutting + IAA(10 μmol/L)and leaf cutting + ethylene(200 mg/L)treatment was higher than that of control.The content of endogenous auxin and ethylene in leaf cuttings was significantly lower than that of control plants after treatment for 0 d to 6 d.Thence,ethylene and auxin play an important role in formation of lotus root.IAA was required in formation of adventitious root affecting by ethylene and leaf cuttings.