立枯丝核菌毒素对马铃薯幼苗细胞结构及抗性生理的影响

发布时间：2017-12-31 03:02

本文关键词：立枯丝核菌毒素对马铃薯幼苗细胞结构及抗性生理的影响　出处：《甘肃农业大学》2017年硕士论文　论文类型：学位论文

【摘要】：由立枯丝核菌(Rhizoctonia solani)引起的马铃薯茎溃疡病(黑痣病)已成为影响甘肃省马铃薯产业发展的主要限制因子,严重影响马铃薯块茎的产量和品质。立枯丝核菌产生的毒素可能是其致病的关键因子,探明立枯丝核菌毒素在植株发病过程中的作用,对防治马铃薯茎溃疡病具有重要意义。本研究通过水培试验,采用透射电镜等技术,结合生理生化指标的测定,研究立枯丝核菌毒素对马铃薯幼苗细胞结构及其抗性生理的影响,主要试验结果如下:1.立枯丝核菌毒素的作用位点不仅仅表现在质膜上,而是作用于整个膜系统;立枯丝核菌毒素可对线粒体、叶绿体、细胞核和内质网等多个细胞器的结构造成损失;不同器官对毒素处理的敏感程度不尽相同,这种破坏作用首先发生在根系细胞的细胞壁和质膜上,其次是茎基部和叶片细胞超微结构的破坏。与对照相比,经立枯丝核菌毒素处理后,根系细胞在毒素处理48 h后即发生质壁分离,且细胞壁出现变形、断裂,细胞膜局部破损,核仁消失,线粒体嵴不见,随试验时间的延长,细胞核溶解;随着毒素向地上器官的运输,茎基部细胞的显微结构也表现出细胞壁部分缺损,内质网肿胀、变形,叶绿体片层结构消失,在处理96 h后可观察到细胞壁断裂,细胞膜破损,线粒体嵴消失,淀粉粒数量减少;叶细胞则表现为叶绿体基粒片层结构不规则、膜局部溶解,线粒体结构变形,嵴消失。2.立枯丝核菌毒素可使细胞膜严重受损,膜透性增加,细胞内电解质外渗,导致质外体汁液电导率增加;在一定时间范围内,立枯丝核菌毒素也能够活化细胞膜H~+-ATPase活性,而随试验时间的延长,毒素可抑制细胞膜H~+-ATPase活性,而不同器官对毒素的敏感程度不同,根系最为敏感,其次为茎基部和叶片。3.立枯丝核菌毒素能显著降低马铃薯幼苗叶片叶绿素的含量,且叶绿素b对立枯丝核菌毒素更加敏感,从而更容易降解。4.立枯丝核菌毒素可使马铃薯幼苗中储藏的淀粉水解转化为糖类,导致可溶性糖含量升高,而淀粉含量的的变化趋势恰恰验证了可溶性糖的变化结果;随试验时间的延长,达到峰值之后的可溶性糖含量下降,是由于植株体内可溶性糖进入糖酵解途径参与合成了某些抗性物质,抵抗毒素的伤害作用。5.立枯丝核菌毒素可诱导寄主产生一些抗性功能蛋白,有助于提高植株的抗性。随试验时间的延长,立枯丝核菌毒素破坏了蛋白代谢平衡,使大量可溶性蛋白被分解。然而,叶片中可溶性蛋白含量最高,然后是茎基部,根系中含量最低。6.立枯丝核菌毒素导致马铃薯幼苗根系、茎基部、叶片中游离脯氨酸含量均大幅增加,但不同器官之间游离脯氨酸含量不同,并且增加幅度各有差异。说明立枯丝核菌毒素可引起马铃薯细胞内游离脯氨酸含量的升高,对植物起到保护的作用。7.立枯丝核菌毒素可引起马铃薯幼苗根系、茎基部、叶片内防御酶PAL活性改变,可激活幼苗体内PAL活性,引起一系列防御反应,从而降低立枯丝核菌毒素对马铃薯幼苗的毒害作用。然而,马铃薯幼苗不同器官PAL活性变化幅度不尽相同,且达到酶活高峰的时间也不一致。
[Abstract]:By Rhizoctonia solani (Rhizoctonia solani) of potato stem canker caused (Rhizoctonia solani) has become a major limiting factor affecting the development of potato industry in Gansu Province, seriously affect the yield and quality of potato tubers produced. Rhizoctonia solani toxin may be the key factor for the disease, proven Rhizoctonia solani plant toxins in the pathogenesis of the role, is of great significance to the prevention and control of potato stem canker. This study by hydroponic experiment using transmission electron microscopy, combined with the determination of physiological and biochemical indexes of Rhizoctonia solani toxin effect on potato seedling cell structure and physiological resistance. The main results are as follows: 1. sites of action Rhizoctonia solani toxin not only in the plasma membrane, but on the whole membrane system; Rhizoctonia solani toxin on chloroplast, mitochondria, nucleus and endoplasmic reticulum and other organelles The structure damage; different organs is more sensitive to the toxin treatment is not the same, the damage occurs first in the cell wall of root cells and plasma membrane, followed by stem and leaf cell ultrastructure damage. Compared with the control, the toxin of Rhizoctonia solani treatment, root cell 48 h after plasmolysis in toxin, cell wall and cell membrane deformation, fracture, local damage, nucleolus and mitochondria cristae disappeared, with prolonging test time, the nucleus dissolved; with the toxin to the ground organs of transportation, the microstructure of stem cells also exhibit a defect in cell wall, endoplasmic reticulum swelling, deformation, disappearance of chloroplast grana lamellae, in the treatment of 96 h could be observed after cell wall rupture, cell membrane damage, mitochondrial cristae disappeared, the number of starch grains decreased; the leaf cells showed the chloroplast grana lamellae structure irregular membrane Partial dissolution, mitochondrial cristae structure deformation,.2. toxin of Rhizoctonia solani can cause serious injury of cell membrane, membrane permeability increased, cell electrolyte leakage, resulting in the increase of apoplastic SAP conductivity; within a certain time, Rhizoctonia solani toxin also can activate H~+-ATPase activity in cell membrane, and with the extension of the test time, the toxin could inhibit the activity of H~+-ATPase in the cell membrane, and the sensitivity of different organs of different toxins, root was the most sensitive, followed by stem and leaf.3. of Rhizoctonia solani toxin can significantly reduce the content of potato seedling leaf chlorophyll, chlorophyll b and Rhizoctonia solani toxin more sensitive thus, more prone to degradation of.4. toxin of Rhizoctonia solani can make the storage of potato seedlings in the hydrolysis of starch into sugar, resulting in increased soluble sugar content, but on the change trend of starch content verification of soluble sugar The change of results; with prolonging test time, soluble sugar content decreased after the peak, is due to plant soluble sugar into the glycolytic pathway involved in the synthesis of some resistant material, resist the damage effects of.5. toxin of Rhizoctonia solani toxin can induce the host to produce some resistance proteins and helps to improve the plant resistance. With prolonging test time, Rhizoctonia solani toxin destroys the balance of protein metabolism, so that a large number of soluble protein was resolved. However, the content of soluble protein in leaves were highest, and then the stem base, the root was the lowest in the.6. toxin of Rhizoctonia solani to potato seedling root, stem base, sharp the increase of free proline content in leaves, but the content of free proline in different organs, and the increase rate is different. Rhizoctonia solani toxin can cause potato intracellular free proline Increased acid content of plants, play a role in the protection of.7. toxin of Rhizoctonia solani can cause potato seedling root, stem base, changes of defense enzyme activity of leaf PAL, seedlings can activate PAL activity, cause a series of defensive reactions, thereby reducing the toxicity of toxin of Rhizoctonia solani on potato seedlings. However, changes of PAL activity in different organs of potato seedlings are not the same, and reached the peak of enzyme activity time is not consistent.

【学位授予单位】：甘肃农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S435.32

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