Mulberry (morus) From The Establishment Of The Regeneration System And The Physiological And Biochemical Research

Leaves, cotyledon, and winter buds of 25 mulberry cultivars were employed as explants in this experiment. Under different treatment, difference of plant regeneration and callus initiation between them was compared. In this paper, regeneration system was established and variation of endogenous hormone, SOD and POD was studied during in vitro culture. It may be usefull in efficiently controlling in vitro morphopoiesis of mulberry and lay foundation for its genetic transformation. The main resuls were as follows: 1. Establishment of in vitro regeneration system.1.1 The effects of explants on in vitro culture.Cultured on medium containing 0.5mg/L NAA and 0.5mg/L BA, seedlings of the 25 materials were obtained with rate range from 0% to 87%. Basal portion of mulberry branch gave the best results. The seedling rate of winter buds taken in January are higher than that of taken in Feberuary and December.1.2 Induction of callus and advertious shootOrthnnormal test showed that 68% induction rate of leaves was observed with medium containing 0.5mg/L NAA, 0.5mg/L BA, 30% fructose, 8p vitamins and 500mg/L CH .Induction rate between different parts of leaves was significantly different.1.3 Propagation and rooting of seedlingsMaxium propagation coefficient (4.67) of seedlings was reached after cultured on medium containing 3.0mg/LBA and 0.5mg/L IAA for 10 days. Quarter strength MS medium supplemented with 0.5mg/L IBA and 300-600mg/L inose was better used for rooting.with light intensity of 2000Lx. 2 Studies of physiology and biochemistry2.1 Variation of endogeious hormoneConcentration of endgenous hormone in mulberry leaves varied with the culture time. Concentration of ABA increases till to reach peak value after 16 days culture. Concentration of iPA, ZR and DHZR reach peak value in the eighth day respectively and decrease thereafter.Two peaks was observed with IAA in the sixth and sixteenth day respectively.2.2 Analysis of SOD and PODConcentration of SOD and POD and their enzyme activity varied rhythmical during in vitro culture. Some bands of SOD isoenzyme disappear when adventitous shoots were initiated and two novel bands appeared when adventitous roots were initiated. For POD, one band disappeared when shoots were initiated. Two enzyme activity peak of SOD and POD were observed in the eighth and sixteenth cuture day respectively.2.3 Effects of AgNO3 on physiological variation of mulberry in vitro.Concentration of ABA, IAA and iPA was decreased when AgNO3 was added to the culture medium. Increasing the ratio of cytokinin and auxin, differentiation of bud was promoted and rooting was inhibited. Enzy activity of isoenzyme SOD and POD were increased when differentiation of bud was promoted and were reduced during the period of root morphoresis.