哈密瓜不同品种采后冷害表现特点及控制研究

发布时间：2018-02-22 05:30

  本文关键词： 哈密瓜 冷害 耐冷性 CBF 低温预贮 一氧化氮　出处：《西北农林科技大学》2017年博士论文　论文类型：学位论文

【摘要】：哈密瓜(Cucumis melo L.)肉质松脆,风味浓郁,营养丰富,深受国内外消费者的喜爱,是新疆重要的园艺特产之一。由于其采收季节温度高,采后常温贮藏极易变质腐烂。低温冷藏虽能延缓哈密瓜果实衰老,但其对低温敏感,不适宜的低温易导致冷害发生,严重降低了果实的品质,影响其商品附加值,限制了低温冷藏及冷链物流技术在哈密瓜采后保鲜领域的应用与推广。因此,研究哈密瓜果实采后冷害表现特点及控制方法,已成为哈密瓜产后产业亟待解决的关键技术问题。本文以当地代表性品种早熟‘西周密25号’、中熟‘新密3号’及晚熟‘新密11号’为试材,研究3±0.5℃贮藏条件下不同品种哈密瓜果实采后冷害表现特点、耐冷性差异及转录因子CBF(C-repeatbinding factor)的表达特性,探讨低温预贮(low temperature conditioning LTC)和一氧化氮(Nitric oxide NO)对哈密瓜果实采后冷害的控制作用及其内部机制,以期为哈密瓜果实采后耐冷性评价体系的建立奠定基础,为生产中冷害的识别及控制提供理论和技术依据。主要研究结果如下:1.不同品种哈密瓜果实采后冷害表现特点及采后耐冷性不同。‘西周密25号’贮藏21d出现冷害,主要表现为:表皮褐变、凹陷及失水皱缩等症状;‘新密3号’贮藏7d出现冷害,主要表现为:表皮褐变、变色及腐烂等症状;‘新密11号’贮藏42 d出现轻微冷害,主要表现为:表皮点状褐变等症状。不同品种哈密瓜果实采后冷害主要表现在果皮组织,果肉组织未表现冷害症状。冷藏期间,‘新密11号’果实冷害指数和冷害率显著低于‘西周密25号’和‘新密3号’,果实硬度、可滴定酸(TA)及维生素C含量(Vc)等品质指标显著高于后两者;贮藏49 d后,‘新密11号’果实冷害率仅为6.67%,好果率达到84.44%。表明,‘新密11号’果实采后耐冷性强于‘西周密25号’和‘新密3号’。2.不同品种哈密瓜果实采后冷害发生与果皮组织活性氧代谢、膜脂膜肪酸代谢及内源多胺代谢直接相关。相关性分析结果表明,果皮中亚油酸(C18:2)、亚麻酸(C18:3)、腐胺(Put)、精胺(Spm)以及超氧化物歧化酶(SOD)、过氧化物酶(POD)、抗坏血酸过氧化物酶(APX)活性等指标与哈密瓜果实采后耐冷性正相关;乙烯释放速率、过氧化氢(H_2O_2)、丙二醛(MDA)、超氧阴离子(O_2~(-·))、细胞膜透性、脂氧合酶(LOX)活性及棕榈酸(C16:0)含量等指标与哈密瓜果实采后耐冷性负相关。因此,建议将以上指标作为哈密瓜果实采后耐冷性评价的重要参考指标,同时也可将其作为哈密瓜采后果实冷害发生的预测性指标。3.从哈密瓜果实中分离并克隆获得转录因子Cm CBF1(Gen Bank登录号:KT737742)和Cm CBF3(Gen Bank登录号:KT737743),分别编码212个氨基酸和204个氨基酸。序列分析表明,Cm CBF1和Cm CBF3包含有一个高度保守的AP2/EREBP DNA结合结构域,并含有CBF在AP2/ERF两侧都含有高度保守的CBF信号序列及其它特征性结构域。系统进化树分析结果显示,Cm CBF1与Md CBF1亲缘关系较近,Cm CBF3与Cs CBF3亲缘关系较近。q RT-PCR分析结果显示,不同品种哈密瓜果实转录因子Cm CBF1和Cm CBF3均受低温诱导特异性表达,果皮及果肉中Cm CBF1和Cm CBF3分别在低温诱导6 h和12 h出现短时表达高峰,在贮藏14 d和21 d出现长时表达高峰,Cm CBF3对低温反应更强烈。‘新密11号’果皮及果肉中的Cm CBF1和Cm CBF3相对表达量显著高于‘西周密25号’和‘新密3号’。相关性分析结果表明,转录因子CBF1和Cm CBF3的表达与哈密瓜果实采后耐冷性正相关。4.研究了不同LTC(10℃预贮3 d、6 d及9 d转至3℃贮藏)对‘西周密25号’果实采后冷害指数、冷害率、失重率、好果率及品质指标的影响。结果发现,LTC(10℃预贮3 d后转至3℃贮藏)可显著抑制冷藏期间哈密瓜果实呼吸速率和乙烯释速率,提高果皮中SOD、POD、CAT及APX活性,减少O_2~(-·)生成速率和H_2O_2含量,降低相对电导率和MDA含量;同时诱导果皮Cm CBF1及Cm CBF3基因的表达,使果皮中脱落酸(ABA)、生长素(IAA)及赤霉素(GA)含量保持较高的水平,抑制了多酚氧化酶(PPO)和LOX活性,降低了果皮的水分蒸发,从而减轻‘西周密25号’果实冷藏期间表皮凹陷、褐变及皱缩失水等冷害症状,使其保持较高的果实硬度、可溶性固形物、维生素C含量,贮藏49 d后,失重率仅为6.85%,好果率达40.67%。5.研究了不同NO(0、20、60及100μL/L)处理对‘新密11号’果实采后冷害指数、冷害率、失重率、好果率及品质指标的影响。结果显示,60μL/L NO处理可缓解‘新密11号’果实采后冷害症状,并使其冷害发生推迟7 d,贮藏49 d后,冷害率比对照组低26.67%。NO处理通过促进‘新密11号’果皮中Put、Spm及亚精胺(Spd)含量的积累,进而抑制果实乙烯的合成,使乙烯峰出现的时间推迟7 d,从而缓解并推迟果实采后冷害的发生;同时显著提高冷藏期间果皮中SOD、POD、CAT及APX活性,促进游离脯氨酸、可溶性蛋白及可溶性糖等渗透调节物质的积累,维持较低的O_2~(-·)生成速率和H_2O_2含量,进而降低活性氧对细胞膜的损伤,维持膜结构稳定性及膜系统完整性,减轻哈密瓜果实在低温胁迫下的冷害症状。另外,NO通过诱导果皮中Cm CBF1及Cm CBF3的表达,提高了哈密瓜果实采后抗冷性,从而使其保持较好的货架期品质。
[Abstract]:Melon (Cucumis melo L.) flesh crisp, rich flavor, rich nutrition, by domestic and foreign consumers, is one of the important horticultural products in Xinjiang. Because of the high temperature seasons, postharvest storage at room temperature is extremely easy to decay. Low temperature can delay the aging of Hami melon fruit, but it is sensitive to the temperature, not suitable for the low temperature is easy to cause the occurrence of chilling injury, decrease the fruit quality and the effect of the additional value of the goods, limiting the cryogenic cold chain logistics technology and application in the field of fresh Hami melon. Therefore, research on melon postharvest chilling injury characteristics and control methods, has become a key technical problem to be solved after the melon industry. The local representative early-maturing "West careful No. 25 ',' Xinmi 3 'medium and late' Xinmi 11 'as test material, study of 3 - 0.5 DEG C storage under the condition of different varieties The characteristics of symptoms of chilling injury of Postharvest Hami melon, difference in cold tolerance and transcription factor CBF (C-repeatbinding factor) expression, explore the low temperature storage (low temperature conditioning LTC) and nitric oxide (Nitric oxide NO) and the internal mechanism of melon postharvest chilling injury control, in order to lay the foundation for establishment of cold tolerance evaluation system for melon fruit after harvest, to provide theory and technology for identification and control in the production of cold basis. The main research results are as follows: the chilling characteristics and mining 1. different varieties of melon fruit after cold tolerance. "West careful 25 'storage 21d damage, mainly for skin browning, depression shrinkage and other symptoms;' Xinmi 3 'storage 7d damage, the main performance is: Browning and decay, discoloration and other symptoms;' Xinmi 11 'storage 42 d slight damage, the main table Now: skin browning symptoms. Like different fruit varieties of Hami melon chilling injury mainly in peel tissue, pulp tissue showed no chilling injury symptoms. During cold storage, 'Xinmi 11' fruit chilling injury index and chilling injury rate was significantly lower than that of the "west well No. 25 'and' Xinmi 3 ', fruit firmness, titratable acid (TA) and the content of vitamin C (Vc) and other quality indicators were significantly higher than that of the latter two; after 49 D storage,' Xinmi 11 'chilling injury rate was only 6.67%, good fruit rate of 84.44%. showed that the' Xinmi 11 'postharvest resistance to oxygen metabolism of chilling cold and strong in the" West No. 25 well' and 'Xinmi 3'.2. of different varieties of melon fruit and pericarp tissue activity, is directly related to the polyamine metabolism membrane fatty acid metabolism and endogenous. Correlation analysis results showed that the pericarp of linoleic acid (C18:2), linolenic acid (C18:3), putrescine (Put), spermine (Spm) and superoxide Dismutase (SOD), peroxidase (POD), ascorbate peroxidase (APX) activity index and melon postharvest cold tolerance positive correlation; ethylene release rate, hydrogen peroxide (H_2O_2), malondialdehyde (MDA), superoxide anion (O_2~ (-)), cell membrane permeability lipoxygenase (LOX) activity and palmitic acid (C16:0) content and the indices such as melon postharvest cold tolerance negative correlation. Therefore, suggestions will be an important reference index for the above indexes as melon postharvest cold tolerance evaluation, but also can be used as a predictive index of.3. occurrence of chilling injury in Hami melon. After isolated and cloned transcription factor Cm CBF1 from melon fruit (Gen Bank accession number: KT737742) and Cm CBF3 (Gen, Bank accession number: KT737743), respectively, encoding 212 and 204 amino acids. Sequence analysis showed that Cm CBF1 and Cm CBF3 contains a highly conserved AP2/EREBP DNA binding domain, and contains a CBF CBF signal contains highly conserved sequence and other characteristic domains on both sides of the AP2/ERF. Phylogenetic analysis showed that Cm CBF1 and Md CBF1 near Cm CBF3 and Cs related, CBF3 is closely related to.Q RT-PCR analysis showed that the different varieties of melon fruit transcription factor Cm CBF1 and Cm CBF3 were affected by the specific expression induced by low temperature, peel and pulp in Cm CBF1 and Cm CBF3 respectively in 6 h and 12 h low temperature induced short-term peak expression, the peak expression in 14 d and 21 d long time storage, Cm CBF3 on the low temperature reaction more intense. 'Xinmi 11' and peel Cm CBF1 and Cm in the flesh of the relative expression of CBF3 was significantly higher than that of the western "careful No. 25" and "Xinmi No. 3". The results of correlation analysis showed that the study of intolerance is positively related to.4. cold expression of transcription factor CBF1 and Cm CBF3 and melon fruit after harvest 鍚孡TC(10鈩冮�勮矗�

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