无患子硬枝扦插进程插穗内源激素和多酚类物质含量变化

Content changes of endogenous hormone and polyphenols during hardwood cuttage progress in Sapindus mukorossi

为了解无患子硬枝扦插生根机制,以1年生无患子硬枝作为扦插材料,在扦插第0—80天调查愈伤组织发育和根系形成情况,测定插穗的腋芽(嫩叶)以及基部2cm长度的韧皮部内源激素和多酚类物质的含量。结果表明,无患子硬枝扦插第10天开始出现愈伤组织,第50天愈伤率达到最高值83.33%;第40天开始出现生根插穗,生根率为6.67%,随后不定根数量迅速增加,第70天生根率达到86.67%,此时平均有5.33条。之后生根数量不变,根系仍然在生长,且扦插后根系效果指数持续增高。插穗韧皮部内源激素含量变化较复杂。整体来看,高含量赤霉素(GA3)抑制愈伤组织和不定根形成,且在根原基发生期和不定根形成关键期达到峰值,在不定根速生期持续下降;高含量生长素(IAA)促进不定根的形成,且在扦插后第20天,即根原基发生期,达到峰值(92.7μg/g);玉米素核苷(ZR)对无患子硬枝扦插过程的生理作用较复杂,低含量的ZR有利于根原基的发生和不定根速生,但高含量的ZR促进不定根形成。韧皮部ZR/IAA在扦插后第20—40天呈下降趋势,第40—60天快速上升,促进不定根生长;GA3/IAA整体呈现抛物线形下降趋势,特别是在根原基发生期和不定根速生期,下降速率更快,以促进不定根的生长。无患子硬枝插穗生根进程中,多数多酚类物质对愈伤组织形成、根原基发生及不定根形成有极显著抑制作用,没食子酸抑制效果稍弱;插穗内多种激素和多酚类物质的含量均发生了变化,且对插穗生根产生重大影响。总之,插穗根原基发生和不定根形成等关键时期,IAA含量升高,GA3、ZR以及多酚类物质含量降低,植物体内多种内源物质此消彼长,达到动态平衡,共同促进插穗生根。

In order to learn rooting mechanism of hardwood cuttage in Sapindus mukorossi, we used one-year hardwood in S. mukorossias cutting materials, investigated status of callus growth and root formation in 80 days, and measured contents of endogenous hormones and polyphenolsin axillary bud (tender leaf) and phloem at 2 cm length inthe base of cuttings. The results showed that callus began to produce on the 10th day of hardwood cuttage in S. mukorossi, and callus rate reached the highest value (83.33%) on the 50th day. Cutting began rooting on the 40th day, and rooting rate was 6.67%. And then, adventitious root number was rapidly increased, and rooting rate reached 86.67% and root number was 5.33 on the 70th day. Later, rootnumber remained unchanged, roots still grew, and root effect index continued to be increased after cutting. Changes of endogenous hormone contents in phloem of cuttings were complex. On the whole, GA3 at higher content inhibited formation of calluses and adventitious roots, GA3 contentreached peak values at root primordia generation stage and critical stage of adventitious root formation, and it continued to decline in rapid growth stage of adventitious roots. IAA at higher content promoted formation of adventitious roots, and IAA content reached the peak value (92.7 μg/g) on the 20th day after cutting, which was the root primordia generation stage. Physiological effect of ZR on hardwood cuttage in S. mukorossi was complex. Low ZR content was beneficial to generation of root primordia and rapid growth of adventitious roots, while high ZR content promoted formation of adventitious roots. Value of ZR/IAA in phloem was decreased from the 20th to the 40th day after cutting, and was rapidly increased from the 40th to the 60th day, which promoting adventitious root growth. Value of GA3/IAA showed a parabolic downward trend, especially at root primordia generation stage and adventitious root rapid growth stage, decline was faster for promoting adventitious root growth. During rooting process of hardwood cuttage, most polyphenols had very significant inhibitory effects on callus formation, root primordia generation and adventitious root formation, only gallic acid had slightly weaker inhibitory effect. Contents of various hormones and polyphenols in cuttings changed, and had a great influence on rooting of cuttings. In general, IAA content was increased, and contents of GA3, ZR and polyphenols were decreased at critical stages of root primordia generation stage and adventitious root formation. Various endogenous substances in plant went up and down, achieving a dynamic balance and jointly promoting rooting of cuttings.