【作者】 史国安；

【导师】 包满珠；

【作者基本信息】 华中农业大学 ， 植物学， 2010， 博士

【摘要】 牡丹是原产中国的特有花卉,属于芍药属牡丹组植物。由于牡丹花大色艳,广泛的用于园艺观赏。近些年,牡丹作为新型切花受到广泛的重视。然而,人们对牡丹开花和衰老的生理生化机制的研究尚不够深入。本研究围绕牡丹开花和衰老过程中糖代谢、抗氧化代谢和内源激素变化,以及保鲜剂对切花衰老的调节效应进行了探索,为延长牡丹切花的瓶插寿命与贮藏技术提供了理论与实践依据。现将研究结果报告如下：1.在牡丹品种‘洛阳红’和‘胡红’花开放和衰老过程中伴随花瓣的迅速扩张生长,总可溶性糖呈现迅速增加的趋势,特别是己糖(葡萄糖和果糖)含量显著增加,盛开后己糖水平达到最高,而蔗糖含量呈现逐渐下降的变化。己糖和蔗糖降解指数(SDI)与花枝重呈现极显著的正相关；‘洛阳红’和‘胡红’花瓣的酸性转化酶(AI)活性维持较高水平,开花过程中AI活性逐渐升高,开放后逐渐下降。经主成份回归分析,可溶性糖的代谢依赖于酸性转化酶、中性转化酶(NI)、蔗糖合成酶(SS)和蔗糖磷酸合成酶(SPS)四种酶的共同作用。结果表明,花瓣中己糖的积累在牡丹花开放和衰老过程中起着重要作用。2.牡丹开花和衰老过程中,花瓣中MDA显著积累导致细胞膜透性持续升高,2个牡丹品种花瓣脂质过氧化代谢有一定差异。‘洛阳红’花瓣中O2-、H2O2含量与MDA含量呈极显著的正相关,‘胡红’花瓣中O2-含量与MDA呈显著正相关。O2-对MDA含量有较大的正向直接效应,而H2O2、AsA-POD、CAT和PPO在2个牡丹品种中的效应表现不同。牡丹开花和衰老的过程,是膜脂过氧化加剧引起细胞膜损伤的过程,O2-是影响牡丹开花和衰老过程中花瓣内膜脂过氧化作用的最主要因素。3.牡丹花瓣提取液能显著降低DPPH的吸光值、抑制O3-介导的氮兰四唑(NBT)光化学还原和·OH作用下的水杨酸羟基化作用,显著抑制卵黄组织匀浆的脂质过氧化作用,其中牡丹花瓣提取液清除DPPH自由基的活性高于200μg·mL-1 BHT但低于80μg·mL-1 Vc。6个试样在四种测定系统中均具有一定程度的抗氧化能力,水提取液的抗氧化活性略高于50%乙醇提取液,深色花瓣提取液对不同自由基的清除能力较强。4.牡丹花瓣富含多酚、类黄酮与花色素苷,牡丹开花和衰老过程中花瓣总酚含量呈下降趋势。开花前期的花瓣提取液维持较高的抗氧化活性和自由基清除能力,开花后抗氧化活性和自由基清除能力明显下降。牡丹花瓣多酚含量与清除DPPH自由基活性之间呈现显著的正相关。提示花瓣多酚类功能成分减少与清除自由基的能力显著降低是导致牡丹花衰老的重要生理原因。营养上从初开期到盛开期是牡丹花的适宜采收期。5.‘洛阳红’和‘胡红’呼吸速率均呈现典型的跃变特征,呼吸峰分别出现在盛开期和半开期。牡丹开花和衰老过程中内源IAA、ZR和GA3含量降低,内源ABA含量上升,‘洛阳红’属于类似乙烯跃变型花卉,‘胡红’属于类似乙烯末期上升型花卉；而花瓣ACO活性随花朵的开放逐渐下降,ACO活性变化与内源乙烯的释放不相关。结果提示,牡丹开花和衰老过程中花瓣内源激素代谢失衡是导致花瓣衰老的重要原因。6.花朵衰老时花托、雄蕊和花瓣是乙烯释放的主要部位,雄蕊在初开期有—明显的乙烯峰,花朵的乙烯主要来自于花瓣；‘胡红’开放过程中花瓣的ACC含量缓慢减少,进入衰老期ACC含量又有快速上升的趋势;而茎的ACC含量一直处于下降趋势；叶柄和叶片的ACC含量在花朵的整个开放过程中变化不大。结果提示器官之间乙烯和ACC梯度在‘胡红’花朵开放和衰老前后起着重要调节作用,而乙烯和ACC在花器不同部位间的运输及分配上有差异。7.瓶插试验结果表明,随着切花开放级别的升高,瓶插寿命和最佳观赏期相应缩短,保鲜液能够延长牡丹切花的瓶插寿命和最佳观赏期,提高最大花径和花枝鲜样质量；牡丹切花瓶插期间花枝吸水量和失水量持续下降,水分平衡值在瓶插1d达到最大,保鲜液能够提高花枝的吸水量和失水量,延迟水分平衡值趋于0的时间,牡丹切花瓶插期水分平衡值降为零的时间与瓶插寿命呈显著的正相关。牡丹切花的适宜采收期为绽口期到初开期,保鲜液能够改善切花的品质。更多还原

【Abstract】 Tree peony (Paeonia suffruticosa Andr.), originating in China, belongs to the section Moutan in genus Paeonia of the Paeoniaceae famliy. It is widely used as an ornamental plant because of its large showy flowers and ornamental foliage. Little was known by human being to the mechanism of bloosming and senescence of tree peony. To deeping the acknownlage of the mechanism in florescence and flower senescence, we investigated sucrose metabolism, antioxidative activity and endogenous hormones in two tree peony (Paeonia suffruticosa) petal and its chemical regulations, which will be very useful to establish a solid theretical and practical foudation for prolonging vase life and storage period of the cut flowers. The results showed as follow:1. The results showed that total soluble sugar content was ripidly increasing in company with cell enlargement of two peony petal of florescence and flower senescence. The contents of hexose (glucose and fructose) were markedly increased in florescence period and get highest level at full-opening, whereas the content of sucrose was reduction in different developmental stages. The hexose content and sucrose degration index (SDI) were postively correlated with the fresh weight of flower. The activity for acid invertase (AI) increased in florescence and decreased after flower opening and remained at high levels during development periods. The soluble sugars metabolism rely on the 4 enzymes activities of acid invertase(AI), neutral invertase(NI), sucrose synthase(SS) and sucrose phosphate synthase (SPS), which was deduced from principal component analysis. Our results suggest that hexose accumulation might be important for florescence and flower senescence of some tree peony cultivars.2. The results showed that a ripid accmulation of MDA content lead to the continuous increase of petal cell membrance permeability during florescence and flower senescence. There were some differences of lipid peroxidation metabolisam in ’Luoyanghong’ and ’Huhong’. There was significantly positive correlation between O2- production and H2O2 and MDA content in ’Luoyanghong’, samely there was significantly positive correlation between O2- production and MDA content in ’Huhong’. O2- production has positively and significantly direct effect to MDA content, but others of main factors as H2O2, AsA-POD, CAT and PPO have different effect in two tree peony. The active oxygen turned into imbalance in lipid peroxidation during during florescence and flower senescence of two tree peony. It implied that O2- production was the key factor affecting the membrane lipid peroxidation metabolism in two tree peony during florescence and flower senescence.3. The extracts from 6 peonies petals were isolated using water and 50% ethanol. Their antioxidation activities were detected and evaluated by four systems of DPPH, O2-,·OH and PUFA with controls for Vc and BHT. Based on the generating and detecting systems of DPPH radical、hydroxyl radical (·OH)、superoxide radical (O2-) and PUFA peroxidation of yolk lipoprotein, water or 50% ethanol extracts of 6 peonies petals were investigated for the competitive abilities to active reactions. The results indicated that the water or 50% ethanol extracts from tree peonies petals could reduce light absorption of DPPH and·OH initiated hydroxylation of salicylate, and inhibit O2- mediated light chemical reduction of nitroblue tetrazolium (NBT) effectively. Both have significant inhibitions to lipid peroxidation of polyunsaturated fatty from yolk lipoprotein, in which DPPH scavenging activities of 6 peonies water extracts were higher than that of 200μg·mL-1 BHT, but lower than 80μg·mL-1 Vc. In 4 kinds of detecting systems of antioxidation, the peroxidation activity of deep colored flowers of tree peonies was higher than that of light colored flowers of tree peonies.4. There were rich with total phenolics, flavonoids and anthocyanin of petal in ’Luoyanghong’ and ’Huhong’, while the content of total phenolics decreased in petal during florescence and flower senescence of tree peonies. The antioxidative activity and secavenging ridical ability were keeping at a high level during florescence and declined ripidly after blooming. Significantly positive correlation existed between content of total phenolics and IC50 of DPPH secavenging ability in both the tree peony cultivars. It was proposed that decrease of content of poly phenolics and antioxidative activity was a main reason for petal senescence of tree peonies. Tree peonies flowers, from early bloom to full opening, were confirmed to be the optional stage in view of the nutritional consideration.5. The respiration changes in ’Luoyanghong’ and ’Huhong’ have those characterstics of a typical respiratory climacteric type in the flower opening and natural senescence in tree peonies. The peaks of respiratory climacteric were at full-opening stages and middle-opening stage, respectively. With florescence and senescence in tree peonies, the contents of endogenous IAA, ZR and GA3 decreased and the content of endogenous ABA accumulated in petal. The change pattern of ethylene production in ’Luoyanghong’ was consistent to an ethylene climacteric of cut flower, but ’Huhong’ behaved a like increase during later stage cut flower. The activities of ACO in tree peonies petal declined slowly, while ACO activity has uncorrlated to ethylene production. It suggested that the tree peonies petal senescence is caused by unbalance of endogenous hormones levels during florescence and flower senescence.6. The production of ethylene over senescent stage mainly results from receptacle, stamens and petals, whereas the most part of ethylene production in intact flowers depended on petals. Peak of ethylene production from stamen occurred at initial bloom stage. ACC content of petals decreased slowly over flowering and increased rapidly at senscent stage. ACC content of stem fell continuingly over flowering and senscence. ACC content of petiole and leaf remained virtually unchanged in flowering process. Those results indicated that the difference in ethylene and ACC content in various parts of flower played an key role in regulation of inflorescence and senscence, and difference in transporttion and distribution of ethylene and ACC was present among organs of tree peony flower.7. The vase life and the optimum ornamental period of cut tree peony flowers are relatively short when kept in distilled water (control) with the flower opening index change. The vase life could be prolonged when kept in the floral preservative, which could raise the max flower diameter and the fresh weight of flowering branches. In vase period, the water absorption and loss of flowering branches decreased continuously, and the water balance value reached the maximum at 1 day of inserting in distilled water condition. However, fresh-keeping solution could improve water status, and delay the time of hydrologic balance value from positive to 0, which showed significantly positive correlation to vase life. It is therefore proposed that the optimum harvesting period of cut tree peony flowers is from soft bud to the beginning of opening, and the floral preservative could improve the quality of cut tree peony flowers in vase-holding.更多还原