【作者】 徐擎；

【导师】 胡景江；

【作者基本信息】 西北农林科技大学 ， 森林保护学， 2010， 硕士

【摘要】 落叶松-杨栅锈菌(Melampsora larici-populina Kleb.)又称青杨叶锈菌,是一种转主寄生真菌,分布于世界各地,对寄主植物的危害性极强,可侵害青杨派、黑杨派及其杂交种的20多种杨树,遍及世界杨树栽培区。在我国主要分布于东北、西北、华北及西南地区,危害严重。本研究以中林美荷杨树(Populus deltoides×P.nigra)苗和离体叶片为材料,以水杨酸和低聚壳聚糖(壳寡糖)为诱导物,通过两种诱导物各自单独诱导和二者交叉处理后测定相关的生理抗病指标以及病原菌接种试验,研究了诱导物诱导杨树对落叶松-杨栅锈菌抗病性的可能生理机制以及水杨酸在诱导系统抗病性中的作用。取得以下研究结果：1、以壳聚糖为原料,采用H2O2氧化降解的方法制备低聚壳聚糖,经测定用该方法制备的水溶性低聚壳聚糖分子量在10000-20000之间,平均值为1.82×104,比壳聚糖平均分子量(1×106-2×106)降低了两个数量级。2、水杨酸和低聚壳聚糖对杨树叶片PAL、几丁质酶、β-1,3-葡聚糖酶活性以及木质素和HRGP合成(含量)均有显著的诱导作用。其诱导效果与诱导物的浓度和诱导时间有关。在一定浓度范围内诱导效果随诱导物浓度增加而增强,低聚糖浓度为10mg/L、水杨酸浓度为100mg/L时诱导效果达到最强,此后随浓度增加诱导效果不再增强或有所降低。这些结果均表现出了诱导物(激发子)所应具有的基本特征,由此证明水杨酸和低聚壳聚糖是有效的诱导物,诱导处理能明显提高植物的抗病性。3、从诱导时间进程来看,随诱导时间变化相关的抗病生理指标表现出明显的消长过程。两种诱导物对不同抗病指标的诱导在诱导的滞后期和高峰期存在一定的差异。PAL活性峰值出现的比较早在36小时左右,几丁质酶、p-1,3-葡聚糖酶的活性峰值出现在48小时附近,而HRGP含量的最大值60小时左右才出现,木质素含量的最大值出现的最晚诱导后72小时才出现。说明诱导处理后首先诱导表达的是合成酚类物质和植保素的相关酶的基因,其次是抗病水解酶相关基因,最后是与富含羟脯蛋白和木质素合成相关基因。4、水杨酸和低聚壳聚糖交叉处理对相关抗病指标的诱导效果明显高于两种诱导物各自单独诱导的效果,这说明二者在诱导植物抗病性的反应中存在着特定的内在关系。一般认为激发子处理诱导植物的抗病性,特别是诱导系统抗病性是通过诱导产生水杨酸,再由水杨酸作为信号分子诱发植物的抗病反应。从二者交叉处理诱导效果(具有一定的增效作用)来看,二者不是简单的线性作用关系,可能存在着某些特定的内在关系,有待进一步研究。5、水杨酸、低聚壳聚糖诱导处理一定时间后,杨树离体叶片病原菌(杨栅锈菌)接种实验表明,诱导处理使孢子堆产生的潜育期比对照推迟2d,而且明显抑制了孢子堆的生长,低聚糖处理的叶盘孢子堆比对照减少30%,水杨酸处理的叶盘孢子堆比对照减少50%。6、杨树幼苗局部(一个叶片)用水杨酸处理,可引起整体植株中其他未处理叶片相关抗病生理指标的升高或增强,同时通过病原菌接种试验也证明,局部处理能诱导杨树幼苗整体对杨栅锈菌的抗性,病原菌接种试验表明未经诱导处理的叶片产孢量明显减少。该结果说明水杨酸在诱导系统抗病性中起着关键作用,是SAR的重要诱导因子。更多还原

【Abstract】 Melampsora larici-populina Kleb. also known as Populus cathayana rehd puccinia triticina,a heteroecious fungi which is widespread and destructive,could invade cathay poplar group,black poplar and more than 20 kinds of hybrid poplar, and is all over the word of poplar cultivation area. It is distributed mainly in northeast, northwest, southwest and north china, which caused serious damage.In this paper, Populus deltoides×P. nigra seedlings and detached leaves have been taken as the materials, besides Salicylic acid and Chitosan oligosaccharides as the inducers, in two separate induction and their cross-processed to determine correlative resistance physiological index and pathogen inoculation, the possible physiological mechanism of disease resistance and role of Salicylic acid in the induced systemic acquired have been studied. The results are as follows:1. Using chitosan as raw material, to prepare Chitosan oligosaccharides by adopting the method of H2O2 oxidative degradation, the molecular weight of Chitosan oligosaccharides in this method was between 1000 and 2000, average value was 1.82×104, which was lower two orders of magnitude than chitosan’average molecular weight (1×106-2×106)2. Salicylic acid and chitosan oligosaccharides could induce a significant increase in PAL, Lignin,β-1,3-glucanase,Chitinase and HRGP, The induction effect was related to inducer concentration and induction time. The induction effect of elicitor was increased with the elevation of the concentration In a certain concentration range, when the concentration of Chitosan oligosaccharides was 10mg/L and of Salicylic acid was 100mg/L the effect was optimum, then not increasing or decreasing above this concentration. All the results have exhibited that the inducer (elicitor) had basic characteristics,which proved that Salicylic acid and Chitosan oligosaccharides were effective inducer, plant disease resistance was obviously increased through induction treatment.3. According to induction time process, correlative resistance physiological index showed obviously ebb and flow process. Induction of two indicators to different resistance index in induced lag and the peak period was some differences.The peak value of PAL activity emerged as early as 36 hours or so, and ofβ-1,3-glucanase and Chitinase appeared in 48 hours, while the peak value of HRGP did not appear until 60 hours, Lignin maximum content occurs later than 72 hours. It showed that, induction had expressed relative enzymes’gene, which could firstly synthetise phenolics and phytoalexin secondly the resistance hydrolase,finally the HRGP and Lignin.4. The induction effect of cross-processed of SA and COS to relative resistance index was apparently higher than their individual induction.Proved that there was a certain internal relation between SA and COS in eliciting resistance of plant. Generally recognized that elicitor induced resistance of plant, especially systemic acquired resistance by inducible producing SA,then inducing resistant response as SA a signal molecule.According to the induction effect of cross-processed(had definite synergized action),both were not a simple linear relationship,maybe a certain internal relationship,this will be proved by further study.5. Treating with SA and COS some time later, pathogen(Melampsora larici-populina Kleb.)inoculation experiment of poplar detached leaves proved that, the latent period was significantly delayed compared with contrast test, The sporulation of leaf disc which treated with chitosan oligosaccharides reduced by 30% compared with the control, treated with Salicylic Acid reduced by 50%.6. Local treating poplar seedlings(one Leaf) by SA, may cause resistance physiological index of other untreated leaves of the whole plant increased or enhanced. Meanwhile pathogen inoculation experiment Showed, local treatment could induce poplar seedlings’ resistance to Melampsora larici-populina Kleb, pathogen inoculation experiment proved that porulation of untreated lesves notably reduced, the result showed that SA played a key role in systemic acquired resistance,was an important elicitor in SAR.更多还原