本文選題：桉樹(shù) + 砷��； 參考：《廣西大學(xué)》2017年碩士論文

【摘要】：本文以桉樹(shù)為實(shí)驗(yàn)材料,通過(guò)水培實(shí)驗(yàn),研究了不同濃度砷脅迫對(duì)桉樹(shù)生物量、葉綠素和丙二醛(MDA)含量,以及對(duì)桉樹(shù)抗氧化酶系統(tǒng)(超氧化物岐化酶(SOD)、過(guò)氧化氫酶(CAT)和過(guò)氧化物酶(POD))和部分巰基物質(zhì)(非蛋白巰基(NPT)、谷胱甘肽(GSH)和植物螯合素(PCs))含量的影響;研究了砷在桉樹(shù)根和葉中的亞細(xì)胞分布和化學(xué)形態(tài),并從砷的亞細(xì)胞分布和化學(xué)形態(tài),以及桉樹(shù)的抗氧化酶系統(tǒng)和巰基物質(zhì)的螯合作用等方面探討了桉樹(shù)對(duì)砷的解毒機(jī)制。論文主要研究結(jié)果如下:(1)高濃度砷能顯著抑制桉樹(shù)生長(zhǎng),使桉樹(shù)受到較強(qiáng)的氧化性損傷。低濃度砷(5 mg/L和10 mg/L)脅迫7 d和14 d時(shí),桉樹(shù)根、莖和葉的生物量及根和葉中MDA含量較對(duì)照無(wú)顯著性差異,表明低濃度砷脅迫對(duì)桉樹(shù)沒(méi)有明顯的毒害作用。高濃度砷(20 mg/L和30 mg/L)脅迫時(shí),桉樹(shù)生物量和葉綠素含量減少,MDA含量顯著性增加,高濃度砷能抑制桉樹(shù)生長(zhǎng),使桉樹(shù)遭受較強(qiáng)的氧化損傷。(2)根部對(duì)砷的滯留作用及限制吸收作用是桉樹(shù)解砷毒的重要機(jī)制。砷脅迫時(shí),桉樹(shù)各部位砷的積累量順序?yàn)?根莖葉,大部分砷存儲(chǔ)在根部(76.9%-88.9%),砷從根部向地上部的轉(zhuǎn)運(yùn)受到限制,能減輕砷對(duì)桉樹(shù)地上部的毒害。砷脅迫時(shí),隨砷濃度的增加桉樹(shù)根中砷積累量先增加后基本保持不變,表現(xiàn)出一定的限制吸收作用。(3)可溶組分對(duì)砷的區(qū)室化作用、細(xì)胞壁組分對(duì)砷的固定作用及根中部分砷轉(zhuǎn)變?yōu)槁然c提取態(tài)是桉樹(shù)解砷毒的重要機(jī)制。砷脅迫時(shí),桉樹(shù)根和葉中的砷主要分布在可溶組分(分布比例分別為66.3%-79.9%和50.6%-53.8%),其次是細(xì)胞壁組分(分布比例分別為14.6%-23.2%和35.6%-39.9%)。砷脅迫時(shí),根部砷的主要存在形態(tài)是乙醇提取態(tài)(29.5%-40.00%)、去離子水提取態(tài)(28.3%-32.3%)和氯化鈉提取態(tài)(24.1%-33.8%)。隨砷脅迫濃度的增加,乙醇提取態(tài)的砷的比例先基本不變后減少,去離子水提取態(tài)的比例先增加后保持不變,氯化鈉提取態(tài)的比例先減少后增加。根中部分砷與果膠酸鹽或蛋白質(zhì)的結(jié)合,增加了氯化鈉提取態(tài)的比例,能在一定程度上降低砷對(duì)桉樹(shù)的毒害。另一方面,大量的砷未能向更穩(wěn)定的化學(xué)形態(tài)轉(zhuǎn)變,說(shuō)明桉樹(shù)較易受到砷的毒害。(4)低濃度砷脅迫時(shí),桉樹(shù)的抗氧化酶系統(tǒng)和疏基物質(zhì)的螯合作用能緩解砷對(duì)桉樹(shù)的毒害作用。低濃度砷脅迫7 d時(shí),桉樹(shù)根中抗氧化酶SOD、CAT和POD活性增加,減緩過(guò)氧化物積累,緩解膜脂過(guò)氧化程度。高濃度砷脅迫時(shí),根中SOD和CAT活性較最高值顯著性降低,葉中CAT和POD活性較對(duì)照顯著性降低,大量過(guò)氧化物積累,抗氧化酶系統(tǒng)對(duì)氧化損傷的緩解作用大大降低。低濃度砷脅迫時(shí),桉樹(shù)根和葉中巰基物質(zhì)NPT、GSH和PCs含量增加,巰基物質(zhì)的螯合作用對(duì)桉樹(shù)抵抗砷脅迫的毒害有重要意義。砷脅迫14 d時(shí),隨砷脅迫濃度的增加根中PCs含量顯著性減少,PCs對(duì)砷的螯合作用和解毒能力降低。
[Abstract]:In this paper, eucalyptus was used as experimental material to study the effects of arsenic stress on biomass, chlorophyll and malondialdehyde (MDA) content in eucalyptus. The contents of antioxidant enzyme system (superoxide dismutase (SOD), catalase (catalase) and peroxidase (POD), some sulfhydryl substances (non-protein mercapto (NPT), glutathione (GSH) and plant chelate (PCS) in eucalyptus (Eucalyptus) were also affected. The distribution and chemical forms of arsenic in the roots and leaves of eucalyptus were studied. The detoxification mechanism of arsenic in eucalyptus was discussed from the subcellular distribution and chemical form of arsenic, as well as the antioxidant enzyme system and the chelation of sulfhydryl substances in eucalyptus. The main results are as follows: (1) the high concentration of arsenic can significantly inhibit the growth of eucalyptus and cause strong oxidative damage to eucalyptus. The biomass of root, stem and leaf of eucalyptus and the content of MDA in root and leaf of eucalyptus under 5 mg/L and 10 mg / L low concentration of arsenic stress were not significantly different from those of the control, indicating that the low concentration of arsenic stress had no obvious toxic effect on eucalyptus. Under the stress of 20 mg/L and 30 mg / L, the biomass and chlorophyll content of eucalyptus decreased significantly, and the high concentration of arsenic inhibited the growth of eucalyptus. It is an important mechanism of arsenic detoxification for eucalyptus to retain arsenic in roots and limit the absorption of arsenic to eucalyptus. Under arsenic stress, the order of arsenic accumulation in eucalyptus was as follows: root, stem and leaf, and most of arsenic was stored in root, 76.9-88.9. the transport of arsenic from root to shoot was restricted, which could reduce the toxicity of arsenic to eucalyptus. Under arsenic stress, the arsenic accumulation in eucalyptus roots increased first and then remained unchanged with the increase of arsenic concentration. The immobilization of cell wall components to arsenic and the transformation of some arsenic from root to sodium chloride are the important mechanisms of arsenic detoxification in eucalyptus. Under arsenic stress, arsenic in roots and leaves of eucalyptus was mainly distributed in soluble components (66.3-79.9% and 50.6-53.8%, respectively), followed by cell wall components (14.6-23.2% and 35.6-39.9%, respectively). Under arsenic stress, the main forms of arsenic in the root were ethanol extract (29.5-40.00g), deionized water (28.3- 32.3um) and sodium chloride (24.1- 33.8g). With the increase of arsenic stress concentration, the ratio of arsenic in ethanol was first unchanged and then decreased, the proportion of deionized water first increased and then remained unchanged, and the proportion of sodium chloride first decreased and then increased. The combination of some arsenic in roots with pectin or protein increased the ratio of sodium chloride extract and reduced the toxicity of arsenic to eucalyptus to some extent. On the other hand, a large amount of arsenic could not change to a more stable chemical form, which indicated that the antioxidation enzyme system and chelation of the basic substances in eucalyptus could alleviate the toxicity of arsenic to eucalyptus under low concentration arsenic stress. The activities of cat and POD in root of eucalyptus increased after 7 days of low concentration arsenic stress, which slowed down the accumulation of peroxide and alleviated the degree of membrane lipid peroxidation. Under high arsenic stress, the activities of SOD and CAT in roots were significantly lower than those in the highest values, the activities of CAT and POD in leaves were significantly lower than those in the control, the accumulation of a large amount of peroxide, and the protective effect of antioxidant enzyme system on oxidative damage was greatly reduced. Under low concentration of arsenic, the contents of sulfhydryl substance (NPTGSH and PCs) in roots and leaves of eucalyptus increased, and the chelation of sulfhydryl compounds was of great significance to the resistance of eucalyptus to arsenic stress. Under arsenic stress for 14 days, the content of PCs in roots decreased significantly with the increase of arsenic stress concentration.
【學(xué)位授予單位】：廣西大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類(lèi)號(hào)】：X173;S792.39

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