【作者】 尹冬梅；

【导师】 陈发棣；

【作者基本信息】 南京农业大学 ， 观赏园艺， 2011， 博士

【摘要】 菊花(Chrysanthemum morifolium)是我国十大名花和世界四大切花之一,因其很高的观赏价值和独特的文化内涵,在世界范围内被广泛应用。菊花最忌水湿,耐涝新品种培育已成为菊花育种的重要目标。野生种质资源携带栽培物种缺乏的某些抗逆性基因,是抗性育种的重要基础材料。本文对57份菊花近缘种属植物耐涝性进行了评价,发掘优异耐涝种质资源,探讨菊花耐涝生理生化及形态解剖学机理,以及乙烯对涝渍胁迫下其根系通气组织形成及乙醇发酵的影响进行了系统研究。为推动菊花耐涝种质创新和新品种选育奠定了基础。主要研究结果如下：1.建立了菊花近缘种属植物苗期耐涝性评价体系。根据盆栽淹水处理过程菊花近缘种属植物的表型变化,将涝害指数划分为7级；采用叶色、叶形态、茎色、茎形态4个外观形态指标,并将其定量分级,制定等级得分标准及评价方案,然后以各指标得分的总和对耐涝性进行综合评价,建立评价体系。并对57个菊花近缘种属植物进行了苗期耐涝性鉴定,结果表明,耐涝性鉴定时间以淹水6天为宜；菊花近缘种属植物对水涝较为敏感,大部分材料属于较不耐涝级,同种不同种源存在耐涝性差异；初步筛选出8份耐涝性强的菊花优异种质。2.对5种菊花近缘种属植物的根系活力、叶绿素含量和光合生理特性以及涝渍胁迫后的形态表现进行了研究和观察,初步评价、比较了其耐涝能力。结果表明：涝渍胁迫下,5种菊花近缘种属植物根系活力急剧下降,但紫花野菊在胁迫初期表现出强的根系活力；5种植物叶绿素含量总体呈现先升后降的趋势；涝渍胁迫15d时纪伊潮菊、泡黄金菊的光合强度明显降低,cO2同化作用下降,并出现负值,叶片已丧失光合作用能力,其次是大岛野路菊和那贺川野菊,而紫花野菊维持了一定水平的净光合速率。3.以耐涝性具有明显差异的2个菊花品种为试材,研究涝渍胁迫对菊花表观形态和无氧呼吸酶、抗氧化酶活性及内源乙烯生成量的影响。结果表明,耐涝性弱的菊花品种‘05(13)-13’涝害症状严重,胁迫4天时即出现叶片萎蔫、近水面叶片失绿发黄等涝害症状,而耐涝性较强的‘05(53)-4’在胁迫的8天之内没有明显的涝害症状,20天时,淹水处茎出现大量气生根,而‘05(13)-13’仅有少量的气生根增生。涝渍胁迫下,与‘05(13)-13’相比,耐涝品种‘05(53)-4’根系无氧呼吸酶ADH、LDH和PDC活性增幅不显著,叶片抗氧化酶SOD、CAT、APX活性增幅显著。‘05(13)-13’MDA含量增加幅度显著高于‘05(53)-4’,2个品种茎基部内源乙烯水平都有所增加,但耐涝品种‘05(53)-4’的乙烯峰值比‘05(13)-13’提前2天出现,且其生成量是‘05(13)-13’的3倍。表明较高的抗氧化酶系SOD、CAT、APX活性和较低的无氧呼吸酶活性有利于增强菊花植株的耐涝能力,推测2个菊花品种茎基部内源乙烯水平的差异可能与不定根形成的差异有关。4.对耐涝性的紫花野菊(C. zawadskii)和涝敏感的菊花脑(C. nankingense) 2种菊属植物在涝胁迫下的形态解剖学和生理生化指标进行了观察和测定。结果表明,气生根增生和通气组织的形成是菊属植物耐涝的重要机制。耐涝性强的紫花野菊通过形态解剖结构的改变,积极适应低氧逆境,无氧呼吸的主要途径为乙醇发酵,能保持较高水平的抗氧化酶活性和光合性能,而菊花脑在低氧胁迫下无氧呼吸的主要途径为乳酸发酵,这是2者耐涝性差异的重要原因。外源乙烯参与菊属植物根系通气组织形成及乙醇发酵的调节：乙烯通过调控根系PCD促进通气组织形成以避免低氧逆境,减少发酵代谢产物的积累,从而提高菊属植物的耐涝性。更多还原

【Abstract】 Chrysanthemum (Chrysanthemum morifolium) is one of the ten traditional Chinese famous flowers and of four important cut flowers all over the world, which is widely used as its high ornamental value and unique culture, and plays an important role in flower producing. Chrysanthemum is very sensitive to waterlogging. Waterlogging inhibits crop growth and yield, primarily through initiation of hypoxia conditions. The serious impact of waterlogging on chrysanthemum production and quality has made breeding new tolerant varieties as an important goal. Wild species of Chrysanthemum and its relative genera often carry important resistance genes and are important resource for resistant breeding materials. To identify the sources of waterlogging tolerant germplasm in Chrysanthemum and explore the mechanism of waterlogging, to promote innovation and laid the foundation for breeding new varieties, the waterlogging tolerance was identified in 57 taxa of Chrysanthemum and its related genera. The main results are as follows:1. An evaluation system for waterlogging-tolerance of chrysanthemum was established. Pot plants were exposed to mimicked waterlogging treatment. In terms of the morphological changes under the waterlogging treatment, the level of waterlogging damage was classified into 7 grades. Four morphological criteria i.e., leaf color, leaf morphology, stem color and stem morphology, were quantified via grading and scoring. The waterlogging tolerance was identified by the comprehensive scores of the four criteria, then the evaluation system was established. And the waterlogging tolerance was identified in 57 taxa of Chrysanthemum and its related genera as well. The results showed that the 6th day after submergence (waterlogging) was critical day to identify the waterlogging tolerance. The most of the related genera of Chrysanthemum are more susceptible to waterlogging, which belongs to less tolerant class. Different tolerance to waterlogging was observed in different populations of the same taxa. Eight materials showing highly waterlogging tolerance were screened out.2. The Effects of waterlogging on root vigor, chlorophyll content, photosynthetic characteristics and morphological changes in five related species of Chrysanthemum were studied. The waterlogging was mimicked by treating pot plants with flooding (2-3 cm in depth). Waterlogging tolerance of five species was evaluated. The results showed that the root vigor of five species all declined significantly under waterlogging, except that Chrysanthemum zawadskii showed high root vigor in the early stage of waterlogging stress.The chlorophyll contents of the five species increased during the early stages of stress and then decreased afterwards; After flooding treatment for 15d, in Ajania shiwogiku Kitam. var. kinokuniense and Chrysanthemum boreale, the net photosynthetic rate declined significantly, CO2 assimilation declined as well and even decreased to negative value which suggests that photosynthetic capacity was lost. Obvious decrease in photosynthetic rate was also observed in Chrysanthemum crassum and Chrysanthemum yoshinaganthum. However, Chrysanthemum zawadskii maintained higher net photosynthetic rate under the stress.3. Responses to waterlogging of a tolerant chrysanthemum cultivar (’05 (53)-4’) were compared with those of a susceptible one (’05 (13)-13’). Just four days of waterlogging were enough to induce wilting and leaf chlorosis in’05 (13)-13’, but there was no visual damage to the leaves of’05 (53)-4’after eight days of treatment. After 20 days, only a small number of adventitious roots had emerged from’05 (13)-13’stems, but many vigorous adventitious roots had formed in’05 (53)-4’. Waterlogging induced increases in the activity of alcohol dehydrogenase (EC 1.1.1.1), pyruvate decarboxylase (EC 4.1.1.1) and lactate dehydrogenase (EC 1.1.1.27) in both cultivars, but the increases in’05 (13)-13’were more pronounced than in’05 (53)-4’. On the other hand, the activities of superoxide dismutase (EC 1.15.1.1), ascorbate peroxidase (EC 1.11.1.11) and catalase (EC 1.11.1.6) were higher in’05 (53)-4’ thanin ’05 (13)-13’. Leaves of’05 (13)-13’had a higher content of malondialdehyde, and the amount of this stress indicator in’05 (53)-4’was stable throughout the waterlogging period. Ethylene production was enhanced by waterlogging in both cultivars, but peak ethylene production occurred two days earlier in the tolerant cultivar, and was three fold higher than in the susceptible one.4. Sensitive (C. nankingense) and tolerant (C. zawadskii) wild species were compared to determine the mechanism of waterlogging tolerance. Although the stress induced wilting and leaf chlorosis in both species, symptoms were more apparent and appeared earlier in the intolerant C. nankingense. In the more tolerant C. zawadskii, adventitious roots formed above the flooding level, and aerenchyma developed in the root, stem and leaf. The C. zawadskii palisade parenchyma was thicker, and larger intercellular spaces developed in the spongy mesophyll. The activities of alcohol dehydrogenase, pyruvate decarboxylase and lactate dehydrogenase were enhanced in roots of both species following the imposition of stress. In C. zawadskii the rise in ADH activity was more pronounced, while C. nankingense showed a significantly higher LDH activity. The activities of superoxide dismutase, ascorbate peroxidase and catalase were all higher in the leaves of C. zawadskii than in C. nankingense, and the leaves of C. nankingense showed a higher content of malondialdehyde throughout the period of waterlogging. Photosynthesis was decreased in both species, and there was a significant fall in the intercellular CO2 concentration in C. zawadskii. These data suggested that the greater relative waterlogging tolerance of C. zawadskii appears to depend on a combination of metabolic and morpho-anatomical responses. Ethylene as a gaseous hormone, its role in hypoxic signaling remains controversial and is uncertain in non-wetland species. Chrysanthemum species contrasting for their hypoxia tolerance were treated with ethylene and inhibitor of ethylene action to determine the ethylene signalling in hypoxia-induced aerenchyma formation and ethanolic fermentation. Ethylene appears to signal an acceleration of PCD and aerenchyma formation, and to alleviate ethanolic fermentation in tolerant species, while in sensitive one it activates fermentation and increases the toxic fermentation by-products responsible for hypoxia injury.更多还原