野生大麥和栽培大麥氮利用效率差異的生理與分子機(jī)理
發(fā)布時間：2018-09-04 11:23
【摘要】：氮(N)在植物生長和發(fā)育中具有重要作用,因為它是DNA、RNA蛋白質(zhì)以及其它大分子化合物,包括酶、葉綠素、ATP、生長素和細(xì)胞分裂素等主要成分。大麥(Hordeum vulgare)是全球廣泛種植的第四大糧食作物,用途多樣,主要用于啤酒、飼料生產(chǎn)及人類食用。氮的吸收、運(yùn)輸和積累以及氮素利用效率(NUE)遺傳差異已經(jīng)有大量研究,但有關(guān)大麥基因型差異的機(jī)制尚未完全揭示與明確。因此,為了發(fā)掘耐低氮或氮素高效利用作物資源與品種,必須深入研究低氮耐性的機(jī)制。本研究評價了野生大麥和栽培大麥對低氮脅迫響應(yīng)的生理、生化和分子差異,并研究了不同耐低氮大麥基因型在低氮脅迫下與氮素吸收和代謝相關(guān)基因表達(dá)水平。取得的主要結(jié)果總結(jié)如下：培育與推廣耐低氮或氮素高效利用作物品種是促進(jìn)農(nóng)業(yè)可持續(xù)發(fā)展的重要目標(biāo),其實現(xiàn)則依賴于優(yōu)異種質(zhì)資源的開發(fā)與利用。本研究以實驗室前期鑒定到的4個氮肥利用效率(NUE)不同的大麥基因型(二個西藏野生大麥,兩個栽培大麥)為材料,設(shè)置正常供氮和低氮處理,研究它們對低氮脅迫的生長與生理反應(yīng)�；蛐蚙D9(栽培品種)和XZ149(野生基因型)具有較高的NUE,表現(xiàn)為地上部干重和各項光合參數(shù)在低氮脅迫下降低較少,同時具有較高的抗氧化酶活性、組織N濃度和較大的積累量。研究結(jié)果顯示,低氮耐性大麥基因型之間差異明顯,野生大麥種質(zhì)中具有低氮耐性表現(xiàn)獨特的基因型,可以為改良栽培大麥NUE提供有用的遺傳資源及相關(guān)基因。在溫室利用水培試驗研究了不同施氮水平(0,0.2和2 mM)對低氮耐性不同的大麥基因型的超微結(jié)構(gòu)、無機(jī)營養(yǎng)濃度和氮代謝相關(guān)酶的影響,供試大麥基因型4個,其中栽培品種和野生基因型各2個。高NUE基因型ZD9(栽培品種)和XZ149(野生基因型)在低氮水平下植株葉面積、葉綠素含量和光系統(tǒng)Ⅱ的最大光化學(xué)效率等參數(shù),與對照相比變化相對較�。桓逳水平下,植物組織的營養(yǎng)元素(包括磷、鉀、鈣、鐵、銅和錳)濃度明顯高于低氮水平,且N高效基因型ZD9和XZ149在低氮水平下這些元素的下降相對較少。透射電子顯微鏡觀察顯示,低氮下葉綠體結(jié)構(gòu)嚴(yán)重受損,但兩個氮高效基因型相對影響較小。5種氮代謝相關(guān)的酶,即硝酸還原酶(NR)、谷氨酰胺合成酶(GS)、亞硝酸鹽還原酶(NIR)、谷氨酸合酶(GOGAT)和谷氨酸脫氫酶(GDH)的活性都表現(xiàn)在高氮水平下較高,低氮脅迫抑制這些酶活性的程度基因型之間差異顯著,兩個氮高效基因型受抑制程度相對較輕。本研究進(jìn)一步揭示了大麥耐低氮能力的基因型差異,并顯示改善一些生理特性(如氮代謝有關(guān)酶)對于提高氮肥利用效率可能具有實質(zhì)性的作用。以4個耐低氮不同的大麥基因型(栽培大麥和野生大麥各2個基因型)為材料,利用水培試驗研究了氮吸收相關(guān)基因(NRT2.1)和氮同化相關(guān)基因(GS1和GS2)在不同氮水平下的表達(dá)模式。與正常供氮(2 mM N)相比,低N (0.1mM N)脅迫下,所有供試基因型的單株分蘗、可溶性蛋白質(zhì)含量、葉綠素及氮濃度等均明顯降低,但降低程度基因型之間差異顯著,氮高效基因型(ZD9和XZ149)明顯要小于氮低效基因型(HXRL和XZ56)。在低氮脅迫下,兩個氮高效基因型的葉片與根中硝酸鹽轉(zhuǎn)運(yùn)蛋白基因NRT2.1的表達(dá)水平在測定的各個時間點均表現(xiàn)提高,而谷氨酰胺合成酶基因GS1和GS2的表達(dá)在正常供氮水平下較高�？偨Y(jié)以上結(jié)果可看,與低NUE基因型(HXRL和XZ56)相比,高NUE基因型(ZD9和XZ149)在低氮脅迫下表現(xiàn)較好,因此需要相對較少的氮肥供應(yīng)。
[Abstract]:Nitrogen (N) plays an important role in plant growth and development because it is a major component of DNA, RNA proteins and other macromolecular compounds, including enzymes, chlorophyll, ATP, auxin and cytokinins. Hordeum vulgare is the fourth most widely grown food crop in the world and is widely used in beer, feed production and human beings. Nitrogen uptake, transport and accumulation, and genetic differences in nitrogen use efficiency (NUE) have been extensively studied, but the mechanism of genotypic differences in barley has not been fully revealed and clarified. Physiological, biochemical and molecular differences in response of wild and cultivated barley to low nitrogen stress were studied. The expression levels of genes related to nitrogen uptake and metabolism in different low nitrogen tolerant barley genotypes under low nitrogen stress were studied. In this study, four barley genotypes (two Tibetan wild barley and two cultivated barley) with different nitrogen use efficiency (NUE) were identified in the laboratory. Normal nitrogen supply and low nitrogen treatment were set up to study their effects on low nitrogen stress. Growth and Physiological Responses. Genotypes ZD9 and XZ149 had higher NUE, showing less decrease in shoot dry weight and photosynthetic parameters under low nitrogen stress, higher activities of antioxidant enzymes, higher tissue N concentration and higher accumulation. The results showed that there was a difference between low nitrogen tolerant barley genotypes. It is obvious that the wild barley germplasm has unique genotypes with low nitrogen tolerance, which can provide useful genetic resources and related genes for improving NUE of cultivated barley. The leaf area, chlorophyll content and the maximum photochemical efficiency of photosystem II of high NUE genotype ZD9 (cultivated variety) and XZ149 (wild genotype) plants at low nitrogen level had relatively little change compared with the control. The concentrations of nutrient elements (including P, K, Ca, Fe, Cu and Mn) in plant tissues were significantly higher than those at low N levels, and the decreases of these elements in N-efficient genotypes ZD9 and XZ149 were relatively small at low N levels. The activities of metabolic enzymes, such as nitrate reductase (NR), glutamine synthase (GS), nitrite reductase (NIR), glutamate synthase (GOGAT) and glutamate dehydrogenase (GDH), were higher at high nitrogen levels. The degree of inhibition of these enzymes by low nitrogen stress was significantly different between genotypes, and the degree of inhibition of the two nitrogen-efficient genotypes was similar. This study further revealed the genotype differences of barley tolerance to low nitrogen and suggested that improving some physiological characteristics (e.g. enzymes involved in nitrogen metabolism) might play a substantial role in improving nitrogen use efficiency. The expression patterns of nitrogen uptake-related genes (NRT2.1) and nitrogen assimilation-related genes (GS 1 and GS2) at different nitrogen levels were studied. Compared with the normal nitrogen supply (2 mM N), the tillering, soluble protein content, chlorophyll and nitrogen concentration of all genotypes decreased significantly under low N (0.1 mM N) stress, but the degree of genotype reduction was observed. Nitrogen efficient genotypes (ZD9 and XZ149) were significantly lower than nitrogen inefficient genotypes (HXRL and XZ56). Under low nitrogen stress, the expression level of nitrate transporter gene NRT2.1 in leaves and roots of the two nitrogen efficient genotypes increased at all time points, while the expression of glutamine synthase gene GS1 and GS2 increased. The results showed that the high NUE genotypes (ZD9 and XZ149) performed better under low nitrogen stress than the low NUE genotypes (HXRL and XZ56), so a relatively low nitrogen supply was needed.
【學(xué)位授予單位】：浙江大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2016
【分類號】：S512.3
，
本文編號：2221943
[Abstract]:Nitrogen (N) plays an important role in plant growth and development because it is a major component of DNA, RNA proteins and other macromolecular compounds, including enzymes, chlorophyll, ATP, auxin and cytokinins. Hordeum vulgare is the fourth most widely grown food crop in the world and is widely used in beer, feed production and human beings. Nitrogen uptake, transport and accumulation, and genetic differences in nitrogen use efficiency (NUE) have been extensively studied, but the mechanism of genotypic differences in barley has not been fully revealed and clarified. Physiological, biochemical and molecular differences in response of wild and cultivated barley to low nitrogen stress were studied. The expression levels of genes related to nitrogen uptake and metabolism in different low nitrogen tolerant barley genotypes under low nitrogen stress were studied. In this study, four barley genotypes (two Tibetan wild barley and two cultivated barley) with different nitrogen use efficiency (NUE) were identified in the laboratory. Normal nitrogen supply and low nitrogen treatment were set up to study their effects on low nitrogen stress. Growth and Physiological Responses. Genotypes ZD9 and XZ149 had higher NUE, showing less decrease in shoot dry weight and photosynthetic parameters under low nitrogen stress, higher activities of antioxidant enzymes, higher tissue N concentration and higher accumulation. The results showed that there was a difference between low nitrogen tolerant barley genotypes. It is obvious that the wild barley germplasm has unique genotypes with low nitrogen tolerance, which can provide useful genetic resources and related genes for improving NUE of cultivated barley. The leaf area, chlorophyll content and the maximum photochemical efficiency of photosystem II of high NUE genotype ZD9 (cultivated variety) and XZ149 (wild genotype) plants at low nitrogen level had relatively little change compared with the control. The concentrations of nutrient elements (including P, K, Ca, Fe, Cu and Mn) in plant tissues were significantly higher than those at low N levels, and the decreases of these elements in N-efficient genotypes ZD9 and XZ149 were relatively small at low N levels. The activities of metabolic enzymes, such as nitrate reductase (NR), glutamine synthase (GS), nitrite reductase (NIR), glutamate synthase (GOGAT) and glutamate dehydrogenase (GDH), were higher at high nitrogen levels. The degree of inhibition of these enzymes by low nitrogen stress was significantly different between genotypes, and the degree of inhibition of the two nitrogen-efficient genotypes was similar. This study further revealed the genotype differences of barley tolerance to low nitrogen and suggested that improving some physiological characteristics (e.g. enzymes involved in nitrogen metabolism) might play a substantial role in improving nitrogen use efficiency. The expression patterns of nitrogen uptake-related genes (NRT2.1) and nitrogen assimilation-related genes (GS 1 and GS2) at different nitrogen levels were studied. Compared with the normal nitrogen supply (2 mM N), the tillering, soluble protein content, chlorophyll and nitrogen concentration of all genotypes decreased significantly under low N (0.1 mM N) stress, but the degree of genotype reduction was observed. Nitrogen efficient genotypes (ZD9 and XZ149) were significantly lower than nitrogen inefficient genotypes (HXRL and XZ56). Under low nitrogen stress, the expression level of nitrate transporter gene NRT2.1 in leaves and roots of the two nitrogen efficient genotypes increased at all time points, while the expression of glutamine synthase gene GS1 and GS2 increased. The results showed that the high NUE genotypes (ZD9 and XZ149) performed better under low nitrogen stress than the low NUE genotypes (HXRL and XZ56), so a relatively low nitrogen supply was needed.
【學(xué)位授予單位】：浙江大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2016
【分類號】：S512.3
，
本文編號：2221943
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