Study On Physiological And Biochemical Characteristics Of Rice Callus During The Course Of Plant Differentiation Under Desiccation And AgNO₃ Treatment

In this experiment, with A-28, Bo-b(maintainer lines) and 253(restoring line) asmaterials, which were widely used in Guangxi province, Physiological and Biochemicalcharacteristics of rice callus during the course of plant differentiation under desiccationand AgNO₃ treatment were studied in order to explain impact factors of rice callusdifferentiation and enrich the knowledge for the mechanism of plant cell morphogenesis..The results are as follows.(1) Suitable concentration of 2,4-D and 6-BA could improve the inductionpercentage of rice callus, 2,4-D 2mg·L^-1 and 6-BA 0.5mg·L^-1 had best effect, and thecallus induction percentage of A-28, Bob and 253 was 48.1ï¼…,92.8ï¼…,62.1ï¼…, respectively.Rice genotype had high effect on callus induction percentage, Bo-b was easy induced toform callus, and its callus had good growth state.Desiccation and AgNO₃ treatment improved callus differentiation rate, 3ddesiccation and AgNO₃ at 5μmol·L^-1 had highest callus differentiation rate.(2) During the course of plant differentiation of rice callus, callus O₂^·- content ishigher under desiccation treatment or AgNO₃ treatment compared with no desiccationtreatment, but they were similar after 4thd or 7thd in differentiation medium. CallusH₂O₂ content decreased and had not significant difference among 3 rice cultivars anddifferent treatments during callus differentiation course. CAT activity of callus with desiccation treatment was higher than that of no desiccation callus in earlydifferentiation stage. SOD activity of callus increased after desiccation treatment.During callus differentiation course, SOD activity of callus in differentiation mediumwith AgNO₃ was higher than that of callus in no AgNO₃ differentiation medium, highSOD activity maybe in favor of callus differentiation.(3) Desiccation treatment could increase the amylase activity of rice callus, AgNO₃could increase more callus amylase activity, and then improved rice callusdifferentiation and bud growth. There was a positive relationship between amylaseactivity and callus differentiation.Amylum content changes were similar between desiccation treated callus and nodesiccation treated callus in differentiation medium with no AgNO₃, and had a decreasechanges. Callus in differentiation medium with AgNO₃ kept high amylum content,AgNO₃ improved rice callus to form more amylum.(4) The content of endogenous polyamines of rice callus from high to low wasspermine, putrescine, spermdine and cadaverine. Callus with no desiccation treatmenthad highest endogenous polyamines content, then callus with desiccation treatment only,and callus with desiccation treatment added by AgNO₃.Compared with the control, spermine and spermdine contents of callus withdesiccation treatment decreased significantly. Spm content of callus with desiccationtreatment was lower than that of callus with no desiccation treatment during callusdifferentiation course. Spd content of desiccation treated callus had not district changesin differentiation medium with no AgNO₃, but it decreased in 1std in differentiationmedium with AgNO₃, and then had not great changes. AgNO₃ decreased Spd content ofcallus.Cad content of callus with 3d desiccation treatment was lower than that of calluswith no desiccation treatment. Compared with the control, Cad contents decreasedsignificantly under desiccation treatment and desiccation treatment added by AgNO₃,especially in desiccation treatment added by AgNO₃. During callus differentiation course,compared with the control, callus Put content decreased under desiccation treatmentand desiccation treatment added by AgNO₃, especially in desiccation treatment added by AgNO₃.Low endogenous polyamines were benefit for rice callus differentiation.