本文選題：硅 + 養(yǎng)分運(yùn)輸��； 參考：《華中農(nóng)業(yè)大學(xué)》2017年碩士論文

【摘要】：硅在土壤中的豐度位列第二,且有益于植物的生長。水稻(Oryza sativa)是一種典型的喜硅植物,在其體內(nèi)積累了大量的硅,其中地上部分干重高達(dá)10%。這些硅主要以無定型的二氧化硅沉積在莖和葉的特化細(xì)胞內(nèi)或細(xì)胞壁上,只有微量硅與細(xì)胞壁交聯(lián)形成硅-細(xì)胞壁復(fù)合物(有機(jī)硅)。大量的研究表明硅營養(yǎng)能夠幫助水稻緩解環(huán)境脅迫和調(diào)節(jié)養(yǎng)分運(yùn)輸,然而硅的生物學(xué)功能與其相對應(yīng)的分子機(jī)制尚未完全清楚。為了排除組織、器官和植株水平上多因子作用的復(fù)雜性,我們選用遺傳背景和發(fā)育階段完全一致的水稻懸浮細(xì)胞作為研究對象,采用非損傷微測技術(shù)(NMT)、同位素標(biāo)記相對和絕對定量的蛋白質(zhì)組學(xué)技術(shù)(iTRAQ)以及其它化學(xué)與生物的手段,在細(xì)胞水平系統(tǒng)地研究硅與養(yǎng)分運(yùn)輸和蛋白表達(dá)的關(guān)系。同時(shí)利用原子力顯微鏡(AFM)模擬了不同細(xì)胞壁組分對二氧化硅沉積的影響。主要結(jié)果總結(jié)如下:1、硅-細(xì)胞壁有機(jī)復(fù)合物提高了細(xì)胞壁的機(jī)械性質(zhì),進(jìn)而有利于細(xì)胞膜的穩(wěn)定,從而促進(jìn)了水稻懸浮細(xì)胞對銨態(tài)氮(NH_4~+)的吸收在正常狀態(tài)和1%聚乙二醇6000(PEG 6000)處理的條件下,借助NMT測得加硅(+Si)細(xì)胞NH_4~+的平均內(nèi)流速率大于缺硅(-Si)細(xì)胞的速率�？俁NA和總蛋白的測定,發(fā)現(xiàn)兩者的濃度均是+Si細(xì)胞高于-Si細(xì)胞,說明硅的添加提高了單細(xì)胞的氮代謝水平。XPS和AFM分析可知,硅是以有機(jī)硅的形式存在于細(xì)胞壁上,而且提高了細(xì)胞壁的致密程度和力學(xué)性質(zhì)。細(xì)胞壁的機(jī)械性質(zhì)與膜穩(wěn)定性緊密相關(guān),不同條件下,其它的離子流的監(jiān)測、電解質(zhì)滲漏的測定和熒光染料DiBAC4(3)標(biāo)記的膜電勢變化均表明+Si細(xì)胞的質(zhì)膜要更加穩(wěn)定。2、硅營養(yǎng)能夠引起水稻懸浮細(xì)胞蛋白的差異性表達(dá)在無脅迫的條件下,iTRAQ結(jié)果表明,硅營養(yǎng)調(diào)控了74蛋白的表達(dá),其中下調(diào)和上調(diào)的蛋白分別為51和23個(gè)。分析可知,硅營養(yǎng)的缺失使得細(xì)胞壁存在缺陷,因此-Si細(xì)胞遭受各種環(huán)境脅迫,引起蛋白的差異性表達(dá)。這些蛋白主要是與細(xì)胞壁合成相關(guān)的酶以及抗逆蛋白。3、不同細(xì)胞壁組分對植物體內(nèi)二氧化硅(SiO_2)沉積的誘導(dǎo)能力不同,且半纖維素為主要的誘導(dǎo)因子運(yùn)用原子力顯微鏡,以不同細(xì)胞壁組分修飾的云母為基底,在體外模擬了二氧化硅在植物體內(nèi)的沉積,結(jié)果表明半纖維素的主要成分木聚糖比果膠更容易誘導(dǎo)SiO_2成核。
[Abstract]:Silicon is the second most abundant in the soil and beneficial to plant growth. Rice (Oryza sativa) is a typical silicon-loving plant, which accumulates a large amount of silicon in its body, in which the dry weight of the aboveground part is as high as 10%. These silicon is mainly deposited in the specialized cell or cell wall of stem and leaf by amorphous silica. Only a trace of silicon is cross-linked with the cell wall to form a silicon-cell wall complex (organosilicon). A large number of studies have shown that silicon nutrition can help rice alleviate environmental stress and regulate nutrient transport. However, the biological function of silicon and its corresponding molecular mechanism have not been fully understood. In order to eliminate the complexity of multifactorial action at the tissue, organ and plant levels, we chose rice suspended cells with identical genetic background and developmental stage as the research objects. The relationship between silicon and nutrient transport and protein expression at the cellular level was systematically studied at the cellular level by using noninvasive microassay, relative and absolute quantitative proteomics techniques with isotopic labeling and other chemical and biological methods. At the same time, AFM was used to simulate the effect of different cell wall components on the deposition of silica. The main results are summarized as follows: 1. The silicon-cell wall organic complex improves the mechanical properties of the cell wall and contributes to the stability of the cell membrane. Thus, the absorption of ammonium nitrogen by rice suspension cells under normal condition and 1% polyethylene glycol (6000(PEG) treatment was promoted. The average inflow rate of Si-added cells was higher than that of Si-deficient cells by means of NMT. The concentrations of total RNA and total protein were both higher in Si cells than in -Si cells, indicating that the addition of silicon increased the nitrogen metabolism level of single cells. XPS and AFM analysis showed that silicon existed in the form of organosilicon on the cell wall. Moreover, the density and mechanical properties of the cell wall were improved. The mechanical properties of the cell wall are closely related to the stability of the membrane, and other ion currents are monitored under different conditions. The measurement of electrolyte leakage and the change of membrane potential labeled by fluorescent dye DiBAC4C3 indicated that the plasma membrane of Si cells should be more stable, and silicon nutrition could induce the differential expression of protein in rice suspension cells under the condition of no stress. Silicon nutrition regulated the expression of 74 protein, of which the downregulation and upregulation were 51 and 23, respectively. The results showed that the cell wall was deficient due to the lack of silicon nutrition, so that the -Si cells were subjected to various environmental stresses, which led to the differential expression of protein. These proteins are mainly enzymes associated with cell wall synthesis and stress-resistant proteins. Different cell wall components have different inductive effects on the deposition of SiO-2) in plants, and hemicellulose is the main inducer using atomic force microscopy (AFM). The deposition of silicon dioxide in plant was simulated in vitro on the base of mica modified by different cell wall components. The results showed that xylan, the main component of hemicellulose, was easier to induce SiO_2 nucleation than pectin.
【學(xué)位授予單位】：華中農(nóng)業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：S511

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