荞麦根系分泌液对甘蓝根肿病的抑制效果及其抑病机理研究

发布时间：2018-06-12 00:39

本文选题：甘蓝 + 根肿病　；参考：《西南大学》2017年硕士论文

【摘要】：结球甘蓝(Brassica oleracea L.var.capitata L.)简称甘蓝,十字花科芸薹属作物,是我国主要的蔬菜作物之一。根肿病是由芸薹根肿菌(Plasmodiophora brassicae Woron.)侵染引起的一种世界性的土传病害,主要危害十字花科作物。近年来,甘蓝根肿病呈现迅速蔓延趋势,给甘蓝的安全生产造成严重威胁。荞麦(Fagopyrum esculentum Moench.)是蓼科(Polygonaceae)荞麦属(Fagopyrum Mill.)的双子叶禾谷类作物,前期对重庆市涪陵区大木乡根肿病发病区调研以及田间试验表明,荞麦与甘蓝轮作对根肿病的防控具有良好的效果,但是具体的抑病机理尚不了解。本研究通过室内人工接种根肿菌,采用荞麦根系分泌液灌根法,分析荞麦对甘蓝根肿病的抑制效果,并通过甘蓝根际土壤理化性质、土壤酶类、甘蓝根肿病发生相关基因和根系生长发育相关基因表达的变化,来揭示荞麦抑制根肿病的作用机理,为今后甘蓝根肿病防控提供新思路和新方法。研究结果如下:1、荞麦根系分泌液对甘蓝根肿病发生的影响本研究显示,荞麦根系分泌液灌溉处理接种根肿病的甘蓝,其甘蓝根肿病发病率(80%)和病情指数(40.83)显著低于用营养液灌溉处理的甘蓝根肿病发病率(100%)和病情指数(62.12),能诱导苗期甘蓝对根肿病产生抗性,诱抗指数为34.27%。这说明荞麦根系分泌物能一定程度上减缓甘蓝根肿病的发生。同时,灌溉荞麦根系分泌液能提高甘蓝单株鲜重、根长及须根重,这说明荞麦根系分泌液对甘蓝植株的生长有一定促进效果。2、荞麦根系分泌液对土壤理化性质和土壤酶类的影响本研究发现,接种根肿病的甘蓝灌溉荞麦根系分泌液处理与灌溉营养液处理相比,甘蓝根际土壤碱解氮含量降低、土壤有效硼含量增加、土壤酸性磷酸酶活性增加、土壤蔗糖酶活性增加、土壤脲酶活性增加。甘蓝根肿病病情指数与根际土壤酸性磷酸酶活性和土壤全磷含量呈显著负相关,与土壤过氧化氢酶活性呈极显著正相关。3、荞麦根系分泌液对甘蓝根部基因表达的影响本研究发现,接种根肿病的甘蓝被灌溉荞麦根系分泌液后,与甘蓝根肿病发生相关PR1、PR3、PR4、PR5、LOX2、PDF1.2基因表达提前,且表达量显著高于灌溉营养液处理。而且,灌溉荞麦根系分泌液的甘蓝植株接种根肿菌后,与根系生长发育相关的基因NIT2和CDKA;1在根肿病发病早期表达量显著高于营养液处理,发病后期表达量低于营养液处理。这说明荞麦可能通过SA/JA途径来防御甘蓝根肿病,其通过促进病程相关基因提前表达,促进早期根系生长发育相关基因的表达,促进甘蓝生长发育提高植株健壮度增加抗病性,降低根肿病发病后期生长相关基因表达,延缓肿根的形成。综上所述,荞麦根系分泌液灌溉处理能够抑制根肿病的发生,主要是通过降低土壤碱解氮含量,增加土壤有效硼含量促进甘蓝根系发育,提高土壤酸性磷酸酶、脲酶和蔗糖酶的活性增加土壤肥力促进植株生长等方面达到减缓根肿病发生;同时,荞麦根系分泌液灌溉处理能通过诱导植物SA、JA途径相关基因的提前表达,增加各基因mRNA积累量,诱导植株系统抗病反应,提高植株抗病性;甘蓝根肿病发病早期促进甘蓝植株生长发育,提高抗病能力,降低发病后期生长素和细胞分裂素含量,延缓肿根的形成。
[Abstract]:Brassica oleracea L.var.capitata L. (Brassica L.var.capitata L.) is one of the main vegetable crops in China. The root swelling is a worldwide soil borne disease caused by the infection of Brassica (Plasmodiophora brassicae Woron.), and it is mainly harmful to the cruciferous crops. In recent years, the disease of cabbage root is presented. The rapid spread trend is a serious threat to the safe production of cabbage. Buckwheat (Fagopyrum esculentum Moench.) is a dicotyledonous cereal crop of Polygonaceae (Polygonaceae) buckwheat (Fagopyrum Mill.). In the earlier period, the investigation on the root of root swelling in Da Mu Xiang, Fuling District, Chongqing and field test showed that the buckwheat and Brassica oleracea rotations were resistant to root swelling. Control has good effect, but the specific mechanism of disease suppression is not yet understood. In this study, the inhibitory effect of buckwheat on the root swelling of cabbage was analyzed by artificial inoculation of rhizomatosis in indoor and root secretion of buckwheat root secretion, and the related genes and root growth of the soil enzymes, cabbage root swelling and the growth and development of the rhizomatosis in the rhizosphere of Brassica kale were analyzed. The changes of related gene expression to reveal the mechanism of buckwheat to inhibit root swelling and provide new ideas and new methods for the prevention and control of cabbage root swelling in the future. The results are as follows: 1, the effect of buckwheat root secretion on the occurrence of cabbage root swelling showed that the root secretion of Buckwheat root secretion was irrigated with Brassica kale and its root swelling disease. The incidence (80%) and the disease index (40.83) were significantly lower than the incidence of Brassica rhizomatosis (100%) and disease index (62.12) treated with nutrient solution irrigation. It could induce the resistance of cabbage to root swelling, and the inducement index was 34.27%.. The root exudates of buckwheat could slow down the occurrence of Brassica root swelling to some extent. The secretory fluid could improve the fresh weight, root length and fibrous weight of cabbage, which indicated that the root secretion of buckwheat root secretion has a certain effect on the growth of cabbage plant.2. The effect of buckwheat root secretion on soil physical and chemical properties and soil enzymes found that the root secreting of root swelling disease was inoculated with buckwheat root secretion solution and irrigation nutrient solution. In comparison, the content of alkali hydrolysable nitrogen in the rhizosphere soil of cabbage was reduced, the content of available boron in soil increased, the activity of soil acid phosphatase increased, the activity of invertase in soil increased and the soil urease activity increased. The index of the disease index of cabbage root swelling was negatively correlated with the activity of acid phosphatase and the total phosphorus in soil, and the activity of soil catalase. A very significant positive correlation.3, the effect of buckwheat root secretion on the gene expression in the root of Brassica oleracea has been studied. It was found that after the root exudation of the buckwheat root was irrigated with root swelling, PR1, PR3, PR4, PR5, LOX2, PDF1.2 gene expression was related to the occurrence of cabbage root swelling, and the expression of the PDF1.2 gene was significantly higher than that of the irrigated nutrient solution. The gene NIT2 and CDKA associated with root growth and development after the inoculation of the secretory broth plants, the genes NIT2 and CDKA related to the growth and development of root system; the expression amount in the early stage of the disease was significantly higher than that of the nutrient solution, and the expression amount in the late onset was lower than that of the nutrient solution. This suggests that the buckwheat may defend the Gump root swelling through the SA/JA pathway, and it can promote the related genes by promoting the disease course. Forward expression, promoting the expression of the early root growth and development related genes, promoting the growth and development of the cabbage to increase the plant robustness and increasing the disease resistance, reducing the expression of the growth related genes in the late stage of the disease, and postponing the formation of the swelling root. In summary, the irrigation treatment of buckwheat root secretion can inhibit the occurrence of root swelling, mainly by reducing soil. The content of soil alkali hydrolysable nitrogen, increasing the content of available boron in soil promoted the development of root of cabbage, increased the activity of soil acid phosphatase, urease and invertase, increased soil fertility and promoted plant growth. At the same time, the irrigation treatment of buckwheat root secretion could pass the early expression of related genes of plant SA and JA pathway through the irrigation treatment of the root secretion of buckwheat. Increase the amount of mRNA accumulation of each gene, induce plant system resistance to disease and improve plant disease resistance; Brassica root swelling in the early stage promoted the growth and development of cabbage plant, increased the resistance to disease, reduced the content of auxin and cytokinin in the late stage of the disease, and delayed the formation of swollen root.
【学位授予单位】：西南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S436.35

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