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韧皮部环割对骆驼刺生理生态特征的影响
唐钢梁
学位类型硕士
导师李向义
2015
学位授予单位中国科学院大学
学位授予地点北京
学位专业生态学
关键词骆驼刺 叶绿素荧光 韧皮部环割 叶片衰老 水分状况
摘要环割是指去除韧皮部的一圈,由此导致叶片产生的碳水化合物通过韧皮部向下的极性运输受阻,使得碳水化合物在环割口上部的积累以及环割口下部的降低。作为植物学中一个经典的模型,环割很容易操控碳水化合物在不同器官的比例,韧皮部环割对植物生理生态的影响方面的研究已经被报道很多。然而,环割对植物叶片水分状况以及叶片衰老机制方面的研究还并不多见,我们的研究旨在补充这方面理论的不足。本研究选用荒漠植物疏叶骆驼刺(Alhagi Sparsifolia)为研究材料,对骆驼刺主茎基部进行环割处理,通过对骆驼刺叶片可溶性糖含量,淀粉含量,相对含水量,水势,气孔导度,光合速率,蒸腾速率,水分利用效率,脱落酸含量,叶绿素含量,类胡萝卜素含量,脯氨酸含量,丙二醛含量,叶绿素荧光,根系可溶性糖含量,根系淀粉含量以及根呼吸速率测定,以期对骆驼刺韧皮部环割诱导下的叶片水分状况,叶片衰老进程以及衰老过程中的叶绿素荧光特性进行研究,研究结果如下: 1. 韧皮部环割首先影响ABA在叶片的积累并且由此导致叶片气孔导度和蒸腾速率的降低,使得叶片水分状况得到改善。随后由于碳水化合物在叶片的积累,以及植物根系碳水化合物的减少和根呼吸速率的降低,由此导致的植物根系水分吸收的减少最终共同导致了植物叶片相对含水量和水势的降低。 2. 韧皮部环割不仅能够诱导骆驼刺叶片衰老,还能加剧叶片衰老的自然过程。在自然衰老和环割诱导的衰老过程中,叶绿素含量,类胡萝卜素含量,光合速率降低。其中光合速率在环割叶片的降低首先是因为气孔限制,从第11天开始就是通过气孔导度,光合终产物的反馈抑制,叶片水分胁迫等多种因素起作用。骆驼刺的自然衰老是一种受到严格调控的过程,表现为衰老过程中光合机构活性的维持。而在韧皮部环割诱导下,叶片衰老过程无法得到有效控制,表现为叶绿素a/b的大幅降低以及光系统II(PSII)供体侧放氧复合体的损伤和最大光化学效率的降低。 3. 在骆驼刺叶片自然衰老和环割诱导的衰老过程中,PSII 反应中心受体侧PQ库大小(Sm)降低,导致反应中心吸收的光能中用于电子传递的比率(φEo)的降低,以及有活性的反应中心的开放程度(ψo)降低,使得更多的光能被用来还原QA,由此导致PSII的整体性能和活性(PIabs)降低。在衰老过程中,单位面积有活性的反应中心数目(RC/CS)减少,导致单位反应中心吸收的光能(ABS/RC)增加。但是随着PSII活性的降低,被反应中心捕获(TRo/RC)的能量以及用于电子传递的能量(ETo/RC)反而降低,导致更多的能量通过荧光和热能的形式耗散,显示为DIo/RC的降低。非光化学淬灭的增加导致了光能胁迫,使得活性氧在衰老过程中增加,并且由此导致了膜脂过氧化以及丙二醛的产生。植物在衰老过程中通过保留更多的类胡萝卜素(Car),吸收更多的过剩光能,淬灭在衰老过程中产生的活性氧,防止膜脂过氧化,保持细胞质膜的通透性。相比于自然衰老,在环割诱导的衰老过程中,PSII反应中心的变化更为剧烈,这表明相比于缓慢进行的自然衰老,环割诱导下的衰老是一个较为剧烈的过程。 简言之,韧皮部环割先能够改善骆驼刺叶片的水分状况,随后骆驼刺的水分状况会恶化。韧皮部环割诱导骆驼刺叶片的衰老,衰老过程中,被反应中心吸收的能量增加,但是大部分光能用于热耗散,导致光系统II产生应激压,形成光胁迫。
其他摘要Girdling is defined as the removal of a ring of bark or phloem, mainly around the trunk or branch, which has the immediate effect of blocking the phloem transport pathway, thereby causing the accumulation of carbohydrates above the girdle and reduction of carbohydrates below the girdle. As a classic model in botany, girdling is easy to manipulate carbohydrate ratio in different organs. The research of effect of phloem girdling on plant physiological and ecological had been reported in many previous studies. However, studies of girdling on leaf water status and the mechanism of leaf senescence were rare, and the objective of our study was to provide data and basis for in this field. In this study, we chose desert plant Alhagi sparsifolia as our study materials, and we performed girdling at the base of A. sparsifolia. The aims of this study was to investigate the leaf water status and the process of leaf senescence which induced by phloem girdling, and to illustrate the chlorophyll fluorescence characteristics during senescence. Several correlated parameters of A. sparsifolia were measured, including soluble sugar content, starch content, relative water content, water potential, stomatal conductance, photosynthetic rate, transpiration rate, water use efficiency, abscisic acid content, chlorophyll content, carotenoid content, proline content, malondialdehyde content, chlorophyll fluorescence, root soluble sugar content, root starch content and root respiration rate. The results are as follows: 1. Phloem girdling first affected the accumulation of ABA in leaves and thus led to the reduction in stomatal conductance and transpiration rate, which subsequently resulted in the improvement of leaf water status. Phloem girdling then led to the accumulation of carbohydrate in the leaf and the reduction in carbohydrate in the leaves and thus resulted in the decline of root respiration rate. The decrease of water absorption by root and the accumulation of carbohydrate in leaves together may be the reason for decline of leaf water content and leaf water potential in girdled plants. 2. Phloem girdling not only induced leaf senescence of A. sparsifolia, but also accelerated the senescence process in the natural senescent leaves. In both natural senescence process and girdling induced senescence process, chlorophyll content, carotenoid content and photosynthetic rate decreased. One of the reasons for the decline of photosynthetic rate in girdled leaf may be the stomatal limitation, but from the 11th day, it was result from reduction in stomatal conductance, end-product feedback inhibition and leaf water stress. Natural senescence of A. sparsifolia was a tightly regulated process, which performed as the maintenance of activity of photosynthetic apparatus. However, when induced by phloem girdling, the process of leaf senescence cannot be effectively controlled, which was showed as the significant decline of chlorophyll a/b, the damage of oxygen-evolving complex in the donor side of photosystem II(PSII), and the significant reduction of maximum photochemical efficiency of PSII. 3. In the process of natural leaf senescence and girdling induced leaf senescence process, PQ sink which was in the acceptor side of PSII reaction centers (Sm) reduced, and then resulted in the ratio of the energy absorbed in the reaction center used for electron transfer (φEo) reduced. In addition, the degree of open access in the active reaction centers (ψo) reduced, which led to more light was used to restore QA, thereby resulted in overall performance and activity of PSII (PIabs) decreased. In the senescence process, the number of active reaction center in unit area (RC/CS) reduced, which resulted in the absorption of light energy in per reaction center (ABS/RC) increased. However, with the reduction of PSII activity, the energy which captured by reaction (TRo/RC) and the energy used for transfer of electron (ETo/RC) reduced, which led to more energy dissipated as the form of fluorescence and heat, shown as decline of DIo/RC. The increase of non-photochemical quenching leads to energy stress, which resulted in the increase of reactive oxygen species during senescence, and thus leads to membrane lipid peroxidation and production of malondialdehyde. During senescence, plants retain more carotenoids (Car) to absorb more surplus energy and quench reactive oxygen species so that prevent cells from membrane lipid peroxidation and maintain permeability of cell membrane. Compared to natural senescence, changes of PSII reaction centers appeared to be more severe in the girdling-induced senescence process. This result suggested that compared to the slowly conducted natural senescence process, girdling induced senescence is a more severe process. In short, phloem girdling first improved the water status in A. sparsifolia leaves, and then the water status will decline. Girdling can induce A. sparsifolia leaf senescence, and in the process of leaf senescence, the energy absorbed by reaction center increased, however, most of the energy was used for heat dissipation, which resulted in a stress pressure and light stress in photosystem II.
学科领域生态学
语种中文
文献类型学位论文
条目标识符http://ir.xjlas.org/handle/365004/14669
专题研究系统_荒漠环境研究室
作者单位中科院新疆生态与地理研究所
推荐引用方式
GB/T 7714
唐钢梁. 韧皮部环割对骆驼刺生理生态特征的影响[D]. 北京. 中国科学院大学,2015.
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