野生大麦和栽培大麦氮利用效率差异的生理与分子机理
发布时间：2018-09-04 11:23
【摘要】：氮(N)在植物生长和发育中具有重要作用,因为它是DNA、RNA蛋白质以及其它大分子化合物,包括酶、叶绿素、ATP、生长素和细胞分裂素等主要成分。大麦(Hordeum vulgare)是全球广泛种植的第四大粮食作物,用途多样,主要用于啤酒、饲料生产及人类食用。氮的吸收、运输和积累以及氮素利用效率(NUE)遗传差异已经有大量研究,但有关大麦基因型差异的机制尚未完全揭示与明确。因此,为了发掘耐低氮或氮素高效利用作物资源与品种,必须深入研究低氮耐性的机制。本研究评价了野生大麦和栽培大麦对低氮胁迫响应的生理、生化和分子差异,并研究了不同耐低氮大麦基因型在低氮胁迫下与氮素吸收和代谢相关基因表达水平。取得的主要结果总结如下：培育与推广耐低氮或氮素高效利用作物品种是促进农业可持续发展的重要目标,其实现则依赖于优异种质资源的开发与利用。本研究以实验室前期鉴定到的4个氮肥利用效率(NUE)不同的大麦基因型(二个西藏野生大麦,两个栽培大麦)为材料,设置正常供氮和低氮处理,研究它们对低氮胁迫的生长与生理反应。基因型ZD9(栽培品种)和XZ149(野生基因型)具有较高的NUE,表现为地上部干重和各项光合参数在低氮胁迫下降低较少,同时具有较高的抗氧化酶活性、组织N浓度和较大的积累量。研究结果显示,低氮耐性大麦基因型之间差异明显,野生大麦种质中具有低氮耐性表现独特的基因型,可以为改良栽培大麦NUE提供有用的遗传资源及相关基因。在温室利用水培试验研究了不同施氮水平(0,0.2和2 mM)对低氮耐性不同的大麦基因型的超微结构、无机营养浓度和氮代谢相关酶的影响,供试大麦基因型4个,其中栽培品种和野生基因型各2个。高NUE基因型ZD9(栽培品种)和XZ149(野生基因型)在低氮水平下植株叶面积、叶绿素含量和光系统Ⅱ的最大光化学效率等参数,与对照相比变化相对较小；高N水平下,植物组织的营养元素(包括磷、钾、钙、铁、铜和锰)浓度明显高于低氮水平,且N高效基因型ZD9和XZ149在低氮水平下这些元素的下降相对较少。透射电子显微镜观察显示,低氮下叶绿体结构严重受损,但两个氮高效基因型相对影响较小。5种氮代谢相关的酶,即硝酸还原酶(NR)、谷氨酰胺合成酶(GS)、亚硝酸盐还原酶(NIR)、谷氨酸合酶(GOGAT)和谷氨酸脱氢酶(GDH)的活性都表现在高氮水平下较高,低氮胁迫抑制这些酶活性的程度基因型之间差异显著,两个氮高效基因型受抑制程度相对较轻。本研究进一步揭示了大麦耐低氮能力的基因型差异,并显示改善一些生理特性(如氮代谢有关酶)对于提高氮肥利用效率可能具有实质性的作用。以4个耐低氮不同的大麦基因型(栽培大麦和野生大麦各2个基因型)为材料,利用水培试验研究了氮吸收相关基因(NRT2.1)和氮同化相关基因(GS1和GS2)在不同氮水平下的表达模式。与正常供氮(2 mM N)相比,低N (0.1mM N)胁迫下,所有供试基因型的单株分蘖、可溶性蛋白质含量、叶绿素及氮浓度等均明显降低,但降低程度基因型之间差异显著,氮高效基因型(ZD9和XZ149)明显要小于氮低效基因型(HXRL和XZ56)。在低氮胁迫下,两个氮高效基因型的叶片与根中硝酸盐转运蛋白基因NRT2.1的表达水平在测定的各个时间点均表现提高,而谷氨酰胺合成酶基因GS1和GS2的表达在正常供氮水平下较高。总结以上结果可看,与低NUE基因型(HXRL和XZ56)相比,高NUE基因型(ZD9和XZ149)在低氮胁迫下表现较好,因此需要相对较少的氮肥供应。
[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.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S512.3
，
本文编号：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.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S512.3
，
本文编号：2221943
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