【作者】 王冰；

【导师】 刘文哲；

【作者基本信息】 西北大学 ， 植物学， 2014， 硕士

【摘要】 植食性动物对植物叶子的采食或者其他外在环境因素造成植物叶子量的降低,进一步影响植物的光合作用产物,减少了植物的可用资源总量,从而影响植物的营养性状和繁殖性状的表现。雄全同株植物喜树(Camptotheca acuminata),隶属于蓝果树科(Nyssaceae)喜树属,是我国特有的落叶阔叶乔木,广泛分布于长江流域和西南诸省,由于其大部分器官中都含有一种生物碱(喜树碱,具有显著的抗癌和抗逆转录病毒作用),深受植物学界和医药学界的关注。目前,国内外的学者针对喜树的分类学研究、地理分布、药理学研究、生殖生物学、引种栽培等方面已经进行了大量研究工作。研究大多集中于其药用价值上,对于喜树花序内的性别表达及半自主性整合生理单元(IPU)内的资源配置的研究还比较缺乏。喜树花序着生于每年新形成的短枝顶端,由1-13个头状花序组成聚伞花序,头状花序的个数因植株营养状况以及开花年份的不同而不同。在聚伞花序内,早期的头状花序主要由两性花组成,花序直径较大、坐果率较高；晚期的头状花序(在顶端花序开放后约一周开始开花)性别表达逐渐倾向于雄性,花序直径较小,雌蕊发育程度较低,坐果率较低或不座果。通常同一植株上的同一级头状花序开花时间大致相同,同一个头状花序内的小花同步开放,且表现为雄蕊先熟,同一花序内雌雄功能有着时间上的隔离。所以本文探讨的主要问题包括：(1)自然条件下不同开花年份的喜树植株聚伞花序内头状花序个数的变化规律及影响因素。(2)通过比较人工补充异交花粉与自然授粉的坐果率,评估是否存在花粉限制。(3)在雄全同株喜树上,通过选取着生着由4～5个头状花序组成的聚伞花序的短枝,以每个短枝为一个半自主性整合生理单元(IPU),进行三种处理：摘除100%(High),50%(Low),0%(Control)叶子,分析摘叶处理后营养性状(叶子生物量,光合作用效率,IPU直径等)与繁殖性状(雄性繁殖相关性状、雌性繁殖相关性状、繁殖成功、第二性征及花序性状)的变化。结果表明：(1)初次开花的喜树植株通常只有一级花序,而开花两三年后,二级花序以及三级花序以及更多的次级花序便会逐渐产生,通常开花四年后头状花序的数目趋于稳定；开花一至三年的喜树花序内头状花序数与IPU直径和长度有很强的相关性。(2)人工补充异交花粉后,坐果率和果实重量提升不明显,没有发现花粉限制的影响。(3)摘叶处理后,可用资源总量的减少对营养性状与繁殖性状产生不同程度的影响。同时,由于雄全同株喜树聚伞花序存在着特殊的花序结构和开花时序,使得摘叶处理在不同的头状花序位置所产生的影响程度有所不同,其中二、三级头状花序所受到的影响程度要比一级头状花序位置更剧烈一些。在摘叶处理后,IPU内没有产生新的叶子,但剩余叶子的光合作用能力有所提高。令人惊讶的是,其中一种雄性繁殖性状：花粉,在不同的聚伞花序位置呈现出不同的变化模式,而雌性繁殖特征：雌蕊始终是降低的。综上所述,资源限制(可用资源量)与位置效应(花序结构)共同决定了雄全同株喜树IPU内(尤其是聚伞花序内)的资源配置。更多还原

【Abstract】 The reduction of leaves will reduce the amount of photosynthesis production, further reducing the amount of resources available to the plants, thus affecting the vegetative and/or reproductive performance of plants. C. acuminate, endemic species of China, of which various organs contains an alkaloid Camptothecin (CPT, have significant anti-tumor activity and unique anticancer mechanism), caught the attention of many people. Camptotheca acuminate (Nyssaceae) is a perennial woody plant distributed in the Yangtze River and Southwest provinces of China. At present, taxonomic studies, geographic distribution, pharmacology studies, reproductive biology, the introduction and cultivation and other aspects of Camptotheca acuminate has been carried out extensive research by the domestic and international scholars. Most studies concentrate on its medicinal value, the allocation of resources for gender expression and semi-autonomous integrated physiological unit (IPU) in C. acuminata inflorescence within the research is still relatively scarce.The C. acuminate inflorescence, which is composed of1-13(generally4/5)capitula, was born in the apex of annually-formed short shoot. Due to the nutritional status and the first flowering year, Capitulum number of C. acuminate individualsis different. Within the cyme of C. acuminata, the early capitulais composed of hermaphrodite flowers, with large capitulum in diameter and high fruit set; the late capitulum (begin to blossom after the primary capitulum open for about a week) sex expression tend to male, with small capitulum in diameter and low fruit set or no fruit. Usually the same level capitulum, in which all the flowers of same capitulum synchronous blossom and showed protandrous, almost blossom at the same time. Male and female function in the same capitulum has an isolation of time. The main issues we addressed are:(1) Under natural conditions, variation and influencing factors of capitulum numbers within Cymes of C. acuminate individuals in different flowering years.(2) Pollen limitations were tested by comparing fruit set and infructescence mass between natural pollination group and supplementary outcrossing pollen group.(3) we regard the annually-formed short shoot of C. acuminata as an IPU, three levels of defoliation treatments were applied:100%(high),50%(low) or0%(control) on IPU, and examined the resulting impact on vegetative traits (such as the numbers of leaves, maximum photosynthetic rate, etc.) and reproductive traits (male reproductive traits and female reproductive traits, reproductive success, secondary sexual characteristics and characters, etc.).The results are as follows:(1) First flowering plants usually have only one inflorescence, and after two or three years, secondary and tertiary inflorescence and even more will gradually produce; Typically, after about three years the state of reproductive physiology time C. acuminata begin to stabilize, and the number of capitulum within cyme becomes fixed. And during the first three years of flowering, Capitulum number within cyme has a strong correlation with the diameter and length of IPU.(2)After the supplement of out-crossing pollen, the fruit set and infructescence mass was not significantly increased, thus the pollen limitation was not found(3)After defoliation treatment, the reduction of the total amount of available resources produced different degrees of impact on the vegetative traits and reproductive traits. Meanwhile, due to the inherent inflorescence structure and flowering time sequence of cyme, making defoliation in different capitulum position has generated diversity, of which secondary and tertiary suffered larger impact than the tertiary capitulum position. After defoliation, there are no leaves produced within IPU, but photosynthetic capacity of the remaining leaves was enhanced. Surprisingly, pollen numbers, one of the male reproductive characteristics, showing different degrees of change reduced model at different positions of cyme, while female reproductive traits is always decreased.In conclusion, resource limitations and architectural effects together determine the resource allocation of integrated physiological units in an andromonoecy C. acuminate.更多还原