【作者】 何友兰；

【导师】 马祥庆；

【作者基本信息】 福建农林大学 ， 生态学， 2009， 硕士

【摘要】 磷是植物生长发育的必需元素,是许多生物分子(核酸,磷脂,磷酸糖,催化辅酶)的结构组成物质,在细胞膜结构、物质代谢及酶活性调节等方面均起着极为重要作用。但土壤中可利用磷的含量却很少能满足植物的需求,目前世界绝大部分土壤均严重缺磷,我国缺磷土壤面积约有6.72×107 hm2,特别是我国南方大面积的红壤分布区,高温多雨,土壤风化强烈,强烈的淋溶作用使土壤成酸性,富铝化作用明显,对土壤磷的固定作用强。然而在磷胁迫环境下生长的植物通过长期的适应,形成了一系列适应磷胁迫的反应,如调整根生长模式以增加磷的吸收,溢泌低分子量有机酸螯合解毒铝离子并增加磷可利用性等,这为进行磷高效利用植物的筛选提供了可能。马尾松是我国南方重要的乡土造林树种,具有速生、耐瘠薄、适应性强、纤维优良等特性,是林产工业和造纸工业的重要原料。马尾松分布遍及南方15个省(区),分布区内地理环境存在极大差异。在长期的自然选择和生殖隔离下,马尾松存在着丰富的种内遗传变异,特别是对南方低磷土壤环境表现出很强的适应能力。因此进行南方磷高效利用马尾松基因型的筛选及其适应土壤磷胁迫的生理生态学机制是提高马尾松产量的有效途径,具有重要的理论意义和应用价值。有鉴于此,本文根据植物营养遗传学、根系生物学和胁迫植物学的原理和方法,以福建漳平五一国有林场从全国各地收集的11个马尾松优良半同胞家系为研究对象,通过构建均一性施加Al-P和Fe-P磷胁迫砂培模拟试验,测定不同马尾松家系在磷胁迫下生理学过程和根系分泌物指标,分析不同马尾松家系应对酸性土壤磷胁迫的形态学和生理学过程的差异,比较马尾松在酸性土壤基质下活化利用难溶性磷源的能力,探讨马尾松对酸性土壤磷胁迫的适应机制;同时对不同马尾松家系的磷吸收利用效率进行评价,据此筛选耐低磷土壤的马尾松优良家系,为从机理水平上揭示马尾松对南方土壤潜在难溶性磷的利用途径提供科学依据。主要研究结果如下:1.在磷胁迫条件下不同马尾松家系的细胞抗氧化能力和酶活性存在显著差异。335号、474号和388号马尾松家系在磷胁迫条件下的脯氨酸含量较高,其维持细胞压力势和保持细胞内环境稳态的能力较强。2号家系丙二醛含量较高,脯氨酸含量和CAT活性较低,表明该家系在磷胁迫条件下细胞膜结构的受损程度较深,在逆境下的活性氧清除能力较弱。335号、568号、242号和658号家系的CAT活性整体上较高,对H202的清除能力强,抗氧化性强。2.在磷胁迫条件下马尾松通过提高根系和针叶的APase活性,进一步活化吸收根际有机磷,并多次重复利用植株体内有限磷素。本研究中,P0处理条件下587号、474号和388号家系针叶的APase活性较高,568号、326号、659号和388号家系根系的APase活性较高。马尾松针叶的APase活性显著高于根系的APase活性,施加难溶性磷处理的马尾松针叶APase活性高于P0处理,根系APase活性则随难溶性磷的施入而降低。3.在土壤磷胁迫条件下,马尾松幼苗的可溶性蛋白含量随难溶性磷的施入量而发生变化。相对于P0处理,施入低量难溶性磷的P5处理提高了马尾松幼苗的可溶性蛋白含量,有利于其体内蛋白质合成;而在P20处理下,由于酸性基质中增加的大量铝离子对植物细胞代谢的抑制作用,马尾松各家系根据自身的抗逆能力出现或增或减的可溶性蛋白含量变化。4.马尾松根系分泌物对土壤难溶性Al-P和Fe-P具有显著的活化作用。施入难溶性磷后,不同马尾松家系均能吸收大量的磷,使体内磷的积累量显著增加。施入难溶性磷后马尾松分泌出更多有机酸阴离子,使根际pH值上升,钝化毒性Al3+离子,改善了根际磷的有效性。474号和568号家系根分泌的有机酸总量最高,且其根分泌物对磷的活化量较大。5.综合各指标评价,马尾松474号家系具有较高的细胞抗氧化代谢活性,且磷利用效率较高,因此是较理想的耐低磷遗传种源。2号和242号家系的磷素利用效率也较高,但其细胞抗氧化能力较弱,对土壤的铝浓度较为敏感。335号、568号和658号家系对施入的难溶性磷利用效率变化较平稳,可能与这三个家系的细胞均具有较强的活性氧清除能力有关,因此这三个家系也是适于南方贫瘠红壤上生长的马尾松理想家系。更多还原

【Abstract】 Phosphorus is an essential element for plant growth, and is the structural composition material of many kinds of biomolecule (nucleic acid, phospholipid, phosphoric acid, glucose, catalytic coenzyme), therefore plays a crucial role in stabilizing the cellular membrane structure, improving the efficiency of material metabolism and regulating enzyme activity. However, the bioavailable phosphorus in the soil seldom meets the needs of plant growth. At present, most of the soil around the world is in bad lack of phosphorus. The area of aphosphagenic soil in China is approximately 6.72×107 ha, especially in the large distribution area of red soil in southern China, which belongs to subtropical monsoon climate zone, where the soil weathering is intensely, and by the proccess of stronger eluviation, the soil is distinct desilisification and allitization, has strong effect on phosphorus-fixation. After a long period of acclimation under stress environment, plant had evolved their own adaptive mechanism. For example, adjusting the growth pattern of roots to avoid soil patches that contain toxic Al3+, or exudate low molecular weight organic acids to chelate Al3+ and increase the availability of P. In recent years, in order to establishing a high efficiency, low waste sustainable production system of agriculture and forestry, scientists in the field of plant nutrition had devoted to introduce and select plant genotypes that can grow and develop well on the acid soil by genetic breeding.Masson pine is an Chinese special local tree species as well as an important industrial material wood in subtropical zone of China, possesses excellent characteristics such as fast growing, high yield, good comprehensive utilization and fine fiber quality, therefore, is an important pillar for forest industry, papermaking industry and forest product industry. Masson pine is widely distributed in China and has strong adaptability, spreads over 15 provinces, where exist many high mountains and big rivers throughout its entire distribution area, and the geographical environment is always changeable. Under the long-term natural selection and reproductive isolation, there is considerable genetic variation within the sample of masson pine, and reflects its great capability of adapting to low-phosphorus red soil. Therefore, development of genetic resources, screening and cultivating acid-tolerance P-efficient genotypes of masson pine provides a new way to ensure the sustainable production of plantation, while understanding the low-P tolerance mechanism of masson pine is required. For this reason, the further study of low-P tolerance mechanism of masson pine is of important theoretical significance and practical value. Based on this background, this research was carries out with eleven superior families of Pinus massoniana, which were provided by Wuyi forest farm of Zhangping county, Fujian, and sand culture experiment at four P levels were conducted to observe and explore their differences in utilizing the insoluble phosphate. The activated adaptation mechanism for insoluble phosphate in acid soils and genetics of P efficiency were expatiated primarily, and five families were screened out as ideal family to plant widely on acid red soil of south China. The main results are as follows:1. Sand pot experiments indicated that the 11 families of masson pine had a significant variation in cellular antioxidation capacity and enzymatic activity. The free proline concentrations in the leaves of No.335, No.474 and No.388 was relatively high, therefore these three families had greater capabilities for maintaining the cell pressure potential, keeping the cell’s internal environment in steady-state. No.2 had relatively higher content of MDA, lower content of Pro and CAT, therefore, indicated that its cellular membrane structure was damaged in deep degree, and its ability in scavenging active oxygen was poor. No.335, No.568, No.242 and No.658 had relatively higher content of CAT, indicated that they hadremarkable scavenging effects against H2O2. 2. Under phosphorus stress, masson pine promotes the activity of Apase in the roots and leaves to activate and absorb organic phosphorus in the rhizosphere soil and multiple reuse the limited P inside plant tissues. Results of this study show that the activity of Apase in the leaves was significantly greater than that in the roots. When applying hard-soluble P, the activity of Apase in the leaves of masson pine was raised, while the activity in the roots was reduced.3. Under adversity stress, the gene expression of masson pine was changed and some induced proteins were produced in plants. P5 treatment had increased the soluble protein content of masson pine, while under P20 treatment, the inceasing Al3+ in the sand had toxic effects on plants, therefore each family had encountered more or less reducing of soluble protein.4. The root exudates of masson pine had certain ability to mobilize insoluble Fe-P and Al-P. After applying sparingly soluble phosphate into soils with low available phosphorus, each fimily can absorbed large amounts of phophorus, making P accumulation in vivo increase significantly. Masson pine secreted much more oganic acid, and its root exudates increased the pH value of the rhizosphere, chelating the toxic Al3+, therefore inproving the availability of phosphorus in the rhizosphere.5. Among the 11 tested masson pine families, No.474 has high cellular antioxidation capacity, and moreover, its phosphorus use efficiency is relatively high, therefore is an ideal provenancethat can tolerance low phosphorus. No.2 also has relatively high phosphorus use efficiency, while its cellular antioxidation capacity is relatively poor. Therefore under the single P stress, its growth performance maybe is a great satisfaction. But if it met complex Al-P stress, that the result may have potential risk. No.335, No.568 and No.658 have stationary utilization efficiency of insoluble phosphates, attributed to their relatively high decomposing capacity of activated oxygen, therefore these three family could grow and develop well on the strong weathered soil with rich aluminum and effect of phosphorus fixation.更多还原