【作者】 吴沙沙；

【导师】 吕英民；

【作者基本信息】 北京林业大学 ， 园林植物与观赏园艺， 2012， 博士

【摘要】 百合(Lilium spp.)鳞茎作为多年生地下贮藏器官,是由鳞片、根、芽和鳞茎盘组成,前三者都是通过鳞茎盘彼此联系。百合鳞茎在生长发育过程中经历了营养物质的积累,分解和再积累等过程,成为研究源-库转换的模式植物。本研究以东方百合‘索邦’为试材,研究了百合鳞茎发育过程中源-库关系转变的一系列生理指标的变化,包括淀粉、蔗糖、总可溶性糖等碳水化合物,还有与蔗糖和淀粉代谢相关的7种酶的活性变化及4中激素含量的变化,同时利用光学显微镜和透视电子显微镜对鳞片和鳞茎盘的显微及超微结构进行系统的研究,还将免疫胶体金定位技术和透射电子显微镜观察相结合,对百合鳞片及鳞茎盘内p-淀粉酶的亚细胞定位进行了研究。为探明百合鳞茎源-库转换过程中不同部位的作用,尤其是鳞茎的源-库功能转换,利用羧基荧光素系统研究了百合鳞茎及植株内同化物的运输方向。主要结果及结论如下：1百合鳞茎发育过程中并非仅仅只是单纯地作为源或库进行同化物的供应或积累,而是存在一个源*库复合体的状态,源*库复合体的存在是由于不同部位鳞片(外层、中层鳞片)作为源或库在时间上的差异而造成的。2百合鳞茎单纯作为源的时期为自栽种起至花蕾发育到1cm时,由源转变为源*库复合体发生在花蕾1cm到3cm之间的发育过程中,发育到盛花期前鳞茎已经完成了由源*库复合体向单纯积累同化物的库的转变,之后鳞茎就成为整个植株的库进行同化物的积累而为下一生长季做准备。3百合鳞茎作为源或库的功能可以以淀粉作为主要参考指标,而与淀粉合成密切相关的腺苷二磷酸葡萄糖焦磷酸化酶(AGPase)、淀粉合成酶(可溶性淀粉合成酶SSS和结合型淀粉合成酶GBSS)也可以作为百合鳞茎源或库功能的重要参考指标,其中SSS和GBSS对于库强的决定作用最明显。4鳞茎盘中碳水化合物含量明显低于鳞片,其内的激素含量高于(ABA和IAA)或接近于(GA3和ZR)鳞片中激素的含量,说明鳞茎盘在鳞茎中具有重要的作用。作为短缩地下茎的鳞茎盘的显微及超微结构表明其结构为分布在大量薄壁细胞中的维管束,短缩的维管束连接着鳞片和地上部分；CFDA荧光示踪结果表明鳞茎作为源-库复合体时,鳞茎盘中韧皮部内同化物的运输方向为双向运输。5β-淀粉酶在百合鳞片细胞中主要定位在淀粉粒上,且表示β-淀粉酶的免疫胶体金颗粒的分布密度呈现出先增多后下降的趋势,与用生理方法测定的β-淀粉酶的活性变化趋势一致。β-淀粉酶在鳞茎盘中主要定位于淀粉粒上,但也观察到筛板、筛分子P-型质体内有少量金颗粒的分布,说明了鳞茎盘中β-淀粉酶可能的主要功能是防止淀粉粒的积累而不是分解淀粉。6鳞片中同化物是通过共质体途径由韧皮部卸载到韧皮部薄壁细胞中,再通过薄壁细胞之间的胞间连丝运输到贮藏薄壁细胞中,在显微结构上表现为远离韧皮部淀粉的分布密度越高,在生理方面形成糖卸载的浓度梯度。贮藏薄壁细胞之间除了通过胞间连丝这种共质体途径进行物质和信息的交换外,还可能通过细胞间隙和细胞壁等质外体途径进行物质交换。本研究首次对百合鳞茎生长发育过程中源-库关系的转换进行了系统的研究,明确了鳞茎在单纯作为源或库的发育过程之间,存在一个源-库复合体的时期,该时期可以成为优质百合鳞茎生产调控的关键时期。更多还原

【Abstract】 The bulb of the genus Lilium is composed of scales, roots, shoots, and a basal plate (a compressed stem), among which the former three organs are connected through the basal plate. Scales go through the accumulation, decomposition and re-accumulation of nutrients processes during the growth and development stages, which provides an excellent model to study the source-sink relationship. Oriental hybrid lily’Sorbonne’was used as the subject material to study the series of physiology changes such as the contents of starch, sucrose, soluble sugars, the activities of seven enzymes catalyzing metabolism of sucrose and starch, and the changes of four kinds of endogenous hormones. Besides, the microscopic structure and ultrastructure of scales and basal plate were investigated by optical microscope and transmission electron microscope (TEM). Furthermore, the immunogold electron-microscopy technique was used to determine the subcellular localization ofβ-amylase, one of the key enzymes catalyzing starch breakdown, in scales and basal plate during the growth and development stages. To understand the function of lily bulb especially the relationship of source-sink of lily bulb, the 6(5)-carboxyfluorescein diacetate (CFDA) was applied to study the transport direction of assimilates among the bulb and the aboveground parts. The main results and conclusions are as follows:1 The function of lily bulb is not only serving as source or sink simply to supply or accumulate assimilates during the growth and development. Due to the discrepancy of outer and middle scales serving as source or sink at the same time, the bulb has a state of complex of source and sink between it serving as source and sink merely.2 The lily bulb simply serves as the source to supply nutrients for the growth and development of the shoots after planting to the flower buds developing to 1cm in length. The function transformation of bulb from source to complex of source and sink occurs from the flower buds developing from lcm to 3cm in length. Before anthesis, the bulb has already finished the transformation from a complex of source and sink to sink of the whole plant. After that the bulb only accumulates assimilates for the next growth cycle.3 Starch can be defined as one of the main factors to judge the function of lily bulb as a source or sink during the growth and development stages. Furthermore, the enzymes synthesizing starch, i.e. ADP-glucose pyrophosphorylase (AGPase), soluble starch synthase (SSS) and granule-bound starch synthase (GBSS), especially the latter tow enzymes, also have a close relationship to the sink strength of bulb to accumulate assimilates from the leaves and stem.4 The contents of carbohydrates of basal plate is quite lower than those of scales, but the contents of endogenous hormones in basal plate are higher (ABA and IAA) or close to (GA3 and ZR) those in scales, which means that the basal plate plays an important role in the metabolism among scales and the aboveground parts. As a compressed stem, the basal plate have many vascular bundles distributed among parenchyma cells with a quite complex pattern, which can be seen from the presence of transverse and longitudinal sections of vascular bundles in the same plane. The 6(5)-carboxyfluorescein (CF) observation results show that the transportation direction of assimilate in the phloem of basal plate is bidirectional during the bulb serves as the complex of source and sink.5 The result of immunogold subcellular localization in this study with the polyconalβ-amylase antiserum indicates thatβ-amylase in the scale of lily bulb is mainly distributed in starch granules. The subcellular localization also displays the seasonal changes in quantities ofβ-amylase that essentially increased progressively after planting then reached the maximum at anthesis and dropped to a low density at senescence. The result is in line with the activity changes ofβ-amylase determined by 3, 5-dinitrosalicylic acid method. It also shows thatβ-amylase in the basal plate is mainly localized in starch granules. Besides, there are fewβ-amylase in the sieve plate and P-type plastids as well, indicating that the main function of P-amylase could be preventing the accumulation of starch grains rather than decomposition of starch.6 Assimilates in the scales of lily bulb is unloaded to the phloem parenchyma cells through symplastic pathway, and then transported to the storage parenchyma cells through plasmodesmata between the parenchyma cells, which can be shown by the fact that farther from the phloem higher the density of starch distribution, which forms a concentration gradient of sugar unloading. The exchange of substances and information between the parenchyma cells can not only through plasmodesmata which are symplastic pathways, but also can through cell wall and intercellular spaces which are apoplastic pathways.It is the first study focusing on the source-sink exchange of lily bulb during the growth and development stages. The key conclusion is that between the lily bulb serves as source or sink merely, there is a state of complex as source and sink, which can be used as the key regulation phase for the high quality of lily bulb production.更多还原