甘蔗无根试管苗光合自养生根过程中叶片生理生化特征的变化

摘要

甘蔗光合自养生根技术是一种新型的试管苗生根方法,比传统的培养基异养生根法有显著优势.为了揭示甘蔗生根的生理生化机理,为完善其生根技术提供理论依据.本研究以甘蔗栽培品种桂糖44号无根试管苗为材料,喷施ABT2号生根粉溶液后移栽于沙土混合基质中,在普通日光温室进行自养生根.在生根过程中连续采样调查试管苗生根率和生长状态,检测叶片中总叶绿素、碳水化合物(蔗糖、可溶性糖)、三大内源激素(IAA、ABA、CTK)含量和过氧化物酶(POD)活性.结果表明,由于环境改变,试管苗受到环境胁迫,致使叶片先微黄后转绿,7d后老叶变黄衰老,新叶开始长出,并与日俱增;第一批不定根在处理后第5天突破表皮,至第9天100％的试管苗完成不定根的再生.叶绿素含量先减少后增加而后下降,9d后跳跃上升;蔗糖、可溶性糖含量先是呈波动上升后急剧下降再跳跃上升;ABA含量和POD活性先上升后下降;IAA和CTK含量则相反,先下降后上升.从试管苗生长状态和生理生化指标变化规律分析,本研究发现甘蔗试管苗光合自养生根过程分为3个阶段,第一阶段在0～7 d,为试管苗适应期;第二阶段在7～9 d,为试管苗异养自养切换期;第三阶段在9～15 d,为试管苗自养能力恢复期,试管苗成功过渡到自养阶段是试管苗获得高存活率的必要条件.%Photoautotrophic rooting technique is newly developed for in vitro sugarcane plantlets,which has a significant advantage over the conventional heterotrophic rooting technique.The purpose of this study is to reveal the physiological and biochemical mechanism of the new rooting technique,and ultimately to provide a theoretical basis for improving the technology.In this study,the sugarcane cultivar GT44 was used as the explant,and the in vitro sugarcane plantlets were transplanted in the mixed sandy soil substrate for photoautotrophic rooting in the sunlight greenhouse after sprayed with ABT 2 rooting powder solution and hardened for 24 h.During the rooting process,samples were taken continuously to investigate the rooting rate and growth status,the total chlorophyll,carbohydrates (sucrose,soluble sugars),three types of endogenous hormones (IAA,ABA,CTK) contents and peroxidase (POD) activity in the leaves were detected.The results showed that the plantlets were stressed and got yellow slightly in the leaves due to environmental changes,then turned green.Seven days later the older leaves turned yellow and aging,but more new leaves appeared.The first signed adventitious roots broke through the epidermis at 5 d and 100％ of plantlets completed their regeneration of adventitious roots before 9 d.The chlorophyll content decreased firstly then increased and decreased,but jumped up after 9 d.The sucrose and soluble sugar contents at first steadily increased then drastically declined from day 7 to day 9 and later jumped up.The ABA content and POD activity increased at first and then decreased.The contents of IAA and CTK were declined at first and then increased,which was in opposite to that of ABA.The findings of the study suggested that photoautotrophic rooting of sugarcane in vitro plantlets was divided into three phases:the first was the adaptation phase from 0 d to 7 d,the second was the heterotrophic-autotrophic switching phase from 7 d to 9 d,and the third was the autotrophic function recovery phase from 9 d to 15 d.Successful recovery of the autotrophic function was essential for high survival of sugarcane plantlets.