【作者】 赵晓芳；

【导师】 祝美云； 王贵禧；

【作者基本信息】 河南农业大学 ， 食品科学， 2008， 硕士

【摘要】 梨果实轮纹病是造成梨果实烂果的主要原因,由于轮纹病菌是在幼果期潜伏侵染,在果实成熟及贮运期间发病,控制和防范都有很大困难。控制轮纹病害的首要任务是要认识病原真菌对果实的致病性和果实对病原菌的抗病性。目前对梨轮纹病害的发病机理已基本明确,而果实对轮纹病菌的抗性机制并不十分清楚。为了深入探讨梨果实自身抵抗病原菌的能力,本文研究了鸭梨果实在生长发育期、贮藏期以及受轮纹病菌侵染后的有机酸类、酚类和酶类物质的变化,为阐述梨果实轮纹病的抗病机理提供理论依据,也为其它果实病害的研究提供可借鉴的研究方法。1.研究发现鸭梨果实在近成熟期的有机酸以苹果酸、柠檬酸、莽草酸为主,并且随成熟度增加各种有机酸和总酸含量呈下降趋势。在贮藏阶段前期,果实中主要有机酸积累增加,随贮藏期延长各类有机酸总体呈下降趋势。通过对比测量发现,受病菌侵染的腐烂果肉中苹果酸、柠檬酸含量均高于病健交界处,而奎宁酸和酒石酸含量却低于后者,并在腐烂果肉及腐烂果肉边缘检测到新的有机酸乳酸,腐烂果肉边缘亦检测到微量琥珀酸。2.在对感病鸭梨果实不同部位酚类物质种类和含量的HPLC分析结果显示,病斑部位和病健交界处果肉中没食子酸、绿原酸和咖啡酸含量显著高于健康果肉中含量,且腐烂部位的儿茶酚也显著高于健康果肉。鸭梨果实在幼果期与抗病性相关的酚类物质主要是绿原酸、没食子酸和单宁酸,而在果实膨大期三种物质含量明显下降,近成熟期儿茶酚、芦丁和香豆酸的积累增多,可能与果实在这个时期的抗病性相关。鸭梨果实在贮藏期绿原酸、没食子酸等与抗病相关的酚类物质含量随着生理机能的衰退而下降甚至消失。3.通过对抗性活性酶的研究发现,鸭梨果实在感染病菌,其果实中PPO活性72h内显著高于对照,说明PPO与鸭梨果实感染轮纹病早期抗病相关;PAL在120h内活性均显著高于对照果实,果实中的POD、几丁质酶和β-1,3-葡聚糖酶的活性均迅速提高至72h时达到活性高峰,这4种酶与鸭梨果实感病的全程抗病性密切相关;CAT和SOD在果实感病过程中活性也显著高于对照,对抑制病原菌的扩展起到抑制作用。鸭梨果实幼果期的主要抗性酶类为PPO、POD、CAT和PAL,鸭梨果实在膨大期的抗性酶类的总体活性处于最低值,鸭梨果实在近成熟期主要的抗性相关酶类是SOD、PAL、几丁质酶和β-1,3-葡聚糖酶。梨果实在贮藏期几种抗性酶的活性呈下降趋势或变幅很小,主要的抗性酶类是SOD和PPO,几丁质酶和β-1,3-葡聚糖酶活性在贮藏2个月时出现活性高峰,也能对病菌的生长起到抑制作用。4.离体条件下不同种类和浓度抗性物质对病原菌生长影响结果显示:50mg/100g以上苹果酸、150mg/100g以上柠檬酸、80mg/100g以上的乳酸、10mg/100g以上琥珀酸均能够抑制病原菌生长,5mg/100g以上奎宁酸和20mg/100g以上的富马酸能够促进病原菌生长。添加浓度高于10mg/100g的没食子酸、10mg/100g的绿原酸、5mg/100g的单宁酸、0.05mg/100g的香豆酸能对病原菌菌落生长有显著抑制作用;浓度低于1 mg/100g的芦丁能够抑制病原菌的生长。较高活力的PPO/POD、PAL和CHT/β-1,3-GLU能够明显抑制轮纹病菌的生长,此结果与受病菌侵染果实后酶活性变化相一致。综上所述,本文研究发现鸭梨果实在感染轮纹病菌后,果实内部有机酸类、酚类和酶类等抗性物质含量(活性)能够随病情发展而增加(提高),并且受病原菌诱导能够形成与抗轮纹病菌生长密切相关的新抗性成分。离体抗性有机酸类、酚类和酶类物质不同种类和含量(活性)对轮纹病菌的生长影响不同。鸭梨果实在生长期和贮藏期不同阶段抗性物质的种类和含量也呈阶段性变化。更多还原

【Abstract】 Pear ring rot caused by Botryosphaeria erengriana f.sp.piricola is a main disease for pear.Because pathogenic germs can infect the host pear latently at growth stage,and induce rot during the post-harvest period.In order to control this kind of disease,it is necessary to know the mechanisms,how the pathogen developing in pear fruit and cause the decay,and how the fruit resist the disease development.Up to now,the developing mechanisms of ring rot have been ascertained basically,but the defensive mechanisms of fruit against pathogen are not distinct.In order to discuss the defensive ability of pear fruit against pathogen,the change of the variety and content of resistant substance including organic acids,phenolics and enzymes in Ya’ pear fruit inoculated with Botryosphaeria berengriana f.sp.piricola and sound pear fruit in growth and storage periods were studied,which can provide theoretic basis for resistance of pear against ring rot and also can offer feasible way to control the post-harvest disease.1.The main organic acids including Malic acid,Citric acid and Shikimic acid were found in premature pear fruit,and the content of all the organic acids and total acid decreased with the ripeness course of fruit.In the prophase of storage,the content of main organic acids increased,then all downtrend along with the storing extend.The content of Malic acid and Citric acid in rotten pulp was higher than that of edge of healthy pulp,while Quinic acid and Tartaric acid were lower than the latter.The new organic acids - Lactic acid measured from rot section and the edge of health,and Succinic acid also found at the edge of health.2.The HPLC results of different section of pear fruit infected by ring rot disease showed that the content of Chlorogenic acid,Gallic acid and Caffeic acid were higher than that of sound fruit, also Catehin content of rot section was markedly increased.All suggested that the increase of phenolics is closed relate to the ring rot disease development.The main defense phenolics of pear fruit during growth were Chlorogenic acid,Gallic acid and Tannic acid.The three phenolics content declined sharply,and the content of Catehin,Rutin and Coumaric acid were piled up in premature fruit,which are related to the defense of phenolic.The content of Chlorogenic acid,Gallic acid in pear during storage were decreased and disappeared accompany with the physiological functions declined.3.The determination results of several enzymes activity show that the PPO activity of pear fruit in 72hs inoculated by Botryosphaeria erengriana were higher than sound fruit,which suggest PPO is related to forepart resistant of fruit against ring rot disease;Compared with sound fruit,PAL activities of pear in 120hs and the activities of POD,Chitinase andβ-1,3-glucanase of inoculated fruits of pear in 72hs were also markedly increased after inoculated.The four enzymes above were related to the whole time defense after it inoculated.Also the CAT and SOD activities of pear fruit were also increased after being inoculated by ring rot disease.The main defense enzymes with high activity at the young stage of pear fruit were PPO、POD、CAT and PAL.the whole activities of these enzyme at rapid growing stage decreased sharply,the main defense enzymes with high activity at premature stage of fruit were SOD、PAL、Chitinase andβ-1,3-glucanase.The activities of these enzymes all declined during storage.4.The influence of isolated resistant substance with different verity and content to the pathogen were studied,and the result showed that the concentration higher than 50 mg/100g Malic acid,150 mg/100g Citric acid,80 mg/100g Lactic acid and 10 mg/100g Succinic acid can inhibit the hypal growing,higher than 5mg/100g Quinic acid and 20mg/100g Fumaric acid can improve it growing.The pathogen conlony growth was inhibited by higher concentration of 10mg/100g gallic acid,1mg/100g chlorgenic acid,5mg/100g Tannic acid 0.05mg/100g coumaric acid and lower concentration of 1mg/100g Rutin in PSA culture medium.Higher activities of PPO/POD、PAL and CHT/β-1,3-GLU also restrain pathogen growing,which were consistent with the enzymes activities change in pear fruit inoculated by Botryosphaeria erengriana.To sum up,the thesis found that the content(activity)of resistant substance such as organic acids,phenolics and enzymes of pear fruit infected by ring rot disease were improved,and the new resistant component can be abduced by pathogeny fungus.Isolated organic acids,phenolics and enzymes with different verity and content could affect pathogen growing differently.Different verity and content defense substance in pear fruit during growth and storage changed in phase.更多还原