【作者】 何玲；

【导师】 孙红梅；

【作者基本信息】 沈阳农业大学 ， 观赏园艺学， 2011， 硕士

【摘要】 蔗糖是高等植物光合作用的主要产物,是百合植株碳水化合物长距离运输至鳞茎的主要形态,系统研究蔗糖代谢机制对于明确百合鳞茎发育机理、生产优质种球具有重要意义。本试验研究了不同缓冲液、pH值、时间及温度对百合鳞茎中SAI(可溶性酸性转化酶)活性的影响；研究了不同规格亚洲百合‘穿梭’鳞茎生长发育及低温贮藏过程的蔗糖代谢。主要研究结果如下：首次建立了百合鳞茎SAI活性检测体系。以百合外层鳞片为试材,研究了不同提取及反应缓冲液、pH值和反应时间、温度对百合鳞茎中SAI活性的影响。结果表明,最适提取缓冲液为pH 8.0的Hepes-NaOH;最佳反应缓冲液为pH 4.8的HAc-K3PO4,最适反应温度为40℃,最适反应时间为30 min。该结果与其他植物中的SAI活性检测方法有所不同,说明不同植物的SAI对外界因素的敏感度不同,也进一步表明了建立百合鳞茎SAI活性检测体系的重要性。不同规格的百合鳞茎发育进程不同。对鳞茎Ⅰ[m=(15±1)g]而言,鳞茎体积的膨大和重量的增加是从现蕾期开始的,植株现蕾期至花后20 d为其快速生长期；而鳞茎Ⅱ[m=(4.5-4-1)g]体积的膨大和重量的增加则是从出苗后20 d开始,其快速生长期为出苗后20 d至80 d且鳞茎Ⅱ迅速增长时期较鳞茎Ⅰ早。在百合鳞茎生长发育过程中,鳞茎Ⅰ和鳞茎Ⅱ的淀粉、蔗糖含量变化趋势基本一致。在发育前期(鳞茎Ⅰ栽种期至开花期,鳞茎Ⅱ栽种期至出苗后60 d)淀粉降解,蔗糖总体呈下降趋势；鳞茎发育后期(鳞茎Ⅰ开花期至枯萎期,鳞茎Ⅱ出苗后60 d至枯萎期)蔗糖上升,淀粉含量上升,说明淀粉与蔗糖代谢密切相关。SAI和SuSy(蔗糖合成酶)是百合鳞茎蔗糖代谢关键酶。在鳞茎发育期间,SuSy分解方向的活性远远小于合成方向的活性,说明SuSy主要起到分解蔗糖的作用。SAI活性变化趋势与SuSy分解方向活性变化趋势基本一致,但其活性显著高于SuSy活性,一方面说明在百合鳞茎发育过程中SAI在蔗糖分解代谢上起主要作用,另外可以看出鳞茎中蔗糖代谢的分解酶类具有相同的变化趋势,协同作用参与蔗糖代谢过程。在鳞茎发育后期鳞茎中SAI和SuSy活性均呈上升趋势,促进鳞茎中的蔗糖降解为己糖,使鳞茎与地上器官之间形成蔗糖浓度梯度,促使地上部分的蔗糖向地下部分转移,分解成还原糖进而合成淀粉。低温贮藏过程中,百合种球中SuSy仍然主要起分解蔗糖的作用,SuSy合成方向活性较低,但在整个过程中其变化趋势与蔗糖的含量变化基本一致,说明其在蔗糖合成过程中起一定作用。顶芽中SuSy分解方向维持较高的酶活性,从冷藏20 d开始SAI活性呈持续上升的趋势,且在40～60 d这一阶段,SAI活性上升速度较快,说明顶芽的萌发与高活性的SAI有关,高活性的蔗糖分解酶可促使顶芽中的蔗糖分解为可直接利用的还原糖,进而供顶芽萌发所需。低温贮藏过程中,种球鳞片中淀粉含量持续下降,与外层鳞片相比,中层鳞片淀粉含量较高,且其下降幅度要大于外层鳞片,在冷藏第0 d开始,中层鳞片下部淀粉含量就开始急剧下降,说明中层鳞片内部物质代谢启动较早、快。种球鳞片中蔗糖含量显著上升,均在冷藏60 d达到高峰,但整个贮藏过程中,中层鳞片蔗糖含量要高于外层鳞片,说明中层鳞片是更为重要的蔗糖积累部位。不管是外层鳞片还是中层鳞片,与上部鳞片相比,中、下部鳞片有较高的淀粉和蔗糖含量、蔗糖合成酶合成方向活性和较低的蔗糖分解酶活性,说明中、下部鳞片是蔗糖积累和转运的重要部位。更多还原

【Abstract】 Sucrose is the main photosynthesis product of higher plants and the main form of the carbohydrate long-distance transport between the bulblet and aerial part of lily. The study of sucrose metabolic mechanism is significant for definituding development mechanism and producing high quality bulb. In present study, we explore the effects of different buffers, pH values, durations and temperatures on SAI activity, and research the sucrose metabolic mechanism of lily bulb during bulb development and cooling storage. The main results are as follow.SAI activity detection system was established for the first time. The exterior scales of lily bulb were used in present study to explore the effects of different buffers, pH values, durations and temperatures on SAI activity. The results indicated that the optimal extraction and reaction buffers were Hepes-NaOH(pH 8.0) and HAc-K3PO4(pH 4.8), respectively. And SAI has an optimum reaction duration and temperature of 30 min and 40℃. These were different from other plants. SAI has different sensitive to external influence in different plants. It is important to activity establish the detection system for soluble acid invertase in lily bulb.The development of different size was varied. At flower bub stage, bulb I became bigger and heavier, but bulbⅡwas at 20 days after emergence. Bulb I had a rapid growth between flower bub and 20 days after anthesis, and a rapid growth of bulbⅡwas between 20 days after emergence and 80 days after emergence.During bulb development, bulb I and II had the similar trend of changes in starch and sucrose content. In early stage, there were a net breakdown of starch and a decline of sucrose; in later developmental stage, both starch and sucrose increased. Starch was closely related to sucrose metabolism.SAI and SuSy are the key enzymes of sucrose metabolism in lily bulb. During bulb development, cleavage activity of SuSy was far less than synthetic activity, it indicated that cleavage activity plays a major role. SAI activity and SuSy cleavage direction had a similar trend, but SAI had a higher activity than SuSy cleavage direction. SAI plays a leading role and sucrose lysosomal enzymes work together in sucrose metabolism during bulb development. The activity of SAI and SuSy increased, which results in the significant decrease of sucrose in later developmental stage. It formed a sucrose concentration gradient bettween bulb and aerial part, which promoted sucrose moving to bulb and provid the carbon skeleton for starch synthesis.During cooling storage, SuSy cleavage activity still plays a major role in SuSy. SuSy had a low activity in synthetic direction and the change trend was consistent with sucrose basically. It illustrated SuSy synthetic direction has a certain influence on formation of sucrose. The SuSy cleavage direction acticity kept a high level in apical bud. SAI activity rised sustaining after 20 days cooling storage. Moreover, it rised sharply during 40-60 days. It resulted that the sprout of buds was related to the higher activity of SAI. The sucrose lysosomal enzymes at a high level promoted that sucrose resolve into reducing sugar which could boost the buds sprouting.Starch content in bulb scales was continue to decline during cooling storage. Compared with exterior scales, starch content of middle scales is higher and the descending range is larger, starch content is have shown a sharp decline at the beginning of cooling storage. This indicated that nutrient metabolism started earlier and more quickly. Sucrose content in scales increased significantly and reached a peak after 60 days, sucrose content of middle scales is higher than exterior scales, it indicated that middle scales was more important position of sucrose accumulation. No matter exterior scales or middle scales, compared with apical parts, central and basal part have higher starch and sucrose content, SuSy synthetic activity and lower sucrose lysosomal enzymes, it shows that central and basal part are the important position of sucrose accumulation and transshipment.更多还原