外源生长素对杜梨组培不定芽生根及相关氧化酶的影响

Effects of exogenous auxin on adventitious bud rooting and related oxidases in tissue culture of Pyrus betulifolia

【目的】为了解生长素诱导杜梨不定根发生效应,明确不定根诱导过程与氧化酶活性间的关系,从而为杜梨等难生根植物的生根研究提供理论指导和技术借鉴。【方法】以连续继代培养的杜梨不定芽为材料,调查了不同种类(NAA、IBA和IAA)和浓度(0.1、0.5、1.0、2.0 mg·L^(-1))的生长素对不定芽生根的影响情况,分别在生根诱导0、4、8、12、16 d后观察不定根发育的内外组织形态,测定并分析相关酶活性的变化情况。【结果】外源生长素均能促进不定芽不定根的发生,在相同种类的生长素处理下,浓度分别为0.1和2.0 mg·L^(-1)处理的各项生根指标均显著低于浓度分别为0.5和1.0 mg·L^(-1)处理的。以NAA诱导产生的愈伤组织较大且松软易脱落,不利于其后期的移栽成活;以IBA处理的生根率显著高于NAA和IAA处理的,其中以浓度为0.5 mg·L^(-1)的IBA处理的各项生根指标均最优。对其组织形态的观察结果表明,杜梨不定根发生类型属于诱生根原基,经IBA处理4 d后,其茎基部表皮颜色变红,内部根原基发生于韧皮部和维管束形成层交界处,诱导8 d后茎段外部出现了愈伤组织且组织内部根原基已形成,诱导12 d后不定根突破表皮向外生长。在杜梨不定芽生根过程中,SOD和PPO活性在诱导的0~4 d内均快速上升,在诱导的4~12 d内均下降,而在诱导的12~16 d内均呈现缓慢上升的变化趋势;IAAO活性总体呈现先下降后上升的趋势,且每个时期的活性均显著高于对照组;POD活性呈现出上升→下降→上升→下降的变化趋势,2个峰值分别出现在诱导4 和12 d之时。【结论】0.5 mg·L^(-1)的IBA可有效促进连续继代培养的杜梨不定芽的生根,其不定根的形成过程与氧化酶有密切的关系。

【Objective】In order to clarify effect of auxin on adventitious root formation in Pyrus betulifolia,to learn relationship between adventitious root induction process and oxidase activity,and to provied some references for researches on P.betulifolia rooting.【Method】Adventitious buds in continuous subculture were used as materials,effects of different types(NAA,IBA and IAA)and concentrations(0.1,0.5,1.0 and 2.0 mg·L-1)of auxin on adventitious root induction were investigated.Internal and external tissue morphologies of adventitious roots were observed and changes of related enzyme activities were determined and analyzed,after rooting induction for 0,4,8,12,and 16 days,respectively.【Result】Exogenous auxins can promote formation of adventitious roots.In the same type of auxin treatment,rooting indexes at concentrations of 0.1 and 2.0 mg·L-1 are significantly lower than those of 0.5 and 1.0 mg·L-1.Callus induced by NAA is large,soft and easy to fall off,which is not conducive to survival in later transplanting.Rooting rates in IBA treatments are significantly higher than thoes in NAA and IAA treatments,and each rooting index is the best in 0.5 mg·L-1 IBA treatment.The results of histomorphology observation shows that formation type of adventitious roots in P.betulifolia belongs to inducing root primordium.In IBA treatment,epidermis color at the base of stem turns red,and inner root primordium occurs at junction of phloem and vascular bundle cambiuma after 4 days,calli appear in external tissue of stem segment and internal root primordia form after 8 days,and adventitious roots break through epidermis and grow outward after 12 days.In the process of adventitious bud rooting,activities of SOD and PPO are increased rapidly in 0-4 d,decreased in 4-12 d and increased slowly in 12-16 d.IAAO activity is decreased first and then increased in general and activity at each period is significantly higher than that of CK.POD activity shows a trend of increasing→decreasing→increasing→decreasing,and two peaks appear after 4 d and 12 d,respectively.【Conclusion】In continuous subculture,0.5 mg·L-1 IBA can effectively promote adventitious bud rooting in P.betulifolia.Formation process of adventitious root is closely related to oxidases.