【作者】 杨勇；

【导师】 俞明亮；

【作者基本信息】 南京农业大学 ， 果树学， 2015， 硕士

【摘要】 一般而言,桃属呼吸跃变型果实,果实成熟过程中伴随着强烈的呼吸作用和乙烯跃变。鲜食桃属于时鲜水果,常温下货架期仅为2-5 d,耐贮运性能差,生产中主要通过不同成熟期品种的搭配调节市场供应。桃果肉的质地分为软溶质、硬溶质、不溶质、绵四种类型,近年来,日本科学家提出了一种新的桃果实肉质类型-Stonyhard。为了比较不同肉质类型的贮藏特性,了解它们乙烯生物合成及信号转导途径的相关信息,本研究通过气相色谱研究了软溶质、硬溶质、不溶质和Stonyhard桃品种的采后乙烯释放规律,结合硬度、可溶性固形物、可溶性糖和有机酸的变化,以及乙烯合成途径与软化相关基因的表达情况,主要结果如下:1、以8成熟软溶质品种’银花露’、硬溶质品种’湖景蜜露’、不溶质品种’金童6号’、Stonyhard品种’有名白桃’和’霞脆,果实为试验材料,通过GC气相色谱测定并比较采后贮藏过程中的乙烯释放规律。结果表明:采后贮藏过程中,’银花露’、’湖景蜜露’、’金童6号’桃果实乙烯释放均呈先升后降的趋势,并有显著的乙烯峰出现,果实硬度随贮藏时间推移而下降,’银花露,和’湖景蜜露,果实在贮藏末期硬度均低于1.0 kg/cm2。’有名白桃’和’霞脆’采后成熟过程中释放极少量乙烯,用外源乙烯处理后,’霞脆’果实硬度未出现快速下降现象,贮藏末期果实硬度仍可达到3.5 kg/cm2以上水平。研究认为’霞脆’桃肉质为Stonyhard类型,推测其基因型为hdhdmm。2、为比较不同肉质和成熟度的桃品种常温条件下的贮藏特性,以软溶质型桃’霞晖1号’、硬溶质型桃’霞晖6号’、不溶质型桃’金晖’为试材,研究7、8成熟度下果实常温贮藏过程中果实硬度、乙烯释放量、可溶性固形物、可溶性糖和有机酸含量的变化。结果表明,货架期间,所有处理桃果实均有正常乙烯释放峰值出现,不溶质桃果实具有最长的果实货架生理周期,但可溶性固形物和可溶性糖含量较软溶质和硬溶质品种低,风味不足,’霞晖6号’ 8成熟果实在贮藏过程中,能保持较高的可溶性固形物和可溶性糖含量,风味渐佳。硬溶质肉质类型桃在货架期间贮藏效果较好,8成熟是其适宜的采收成熟度。3、以8成熟Stonyhard桃’霞脆’和’有名白桃’、软溶质桃’银花露’、硬溶质桃’湖景蜜露’、不溶质桃’金童6号’为试材,研究了 25 °C和4 °C贮藏条件对果实软化及乙烯生物合成途径调控的影响。结果显示:两种贮藏温度下,’有名白桃’和’霞脆’果实释放极少量乙烯;25 °C常温条件下,Stonyhard桃果实硬度保持较高水平,但4 °C低温诱导了’有名白桃’果实软化。实时荧光定量PCR表明,软溶质、硬溶质和不溶质桃的PpACS1基因均具有高表达丰度,而’霞脆’和’有名白桃’表达水平则极低;两种贮藏温度下,5个桃品种果实在整个贮藏期间均未检测到PpACS2和PpACS3基因的表达。此外,低温诱导了PpACO 基因在’霞脆’和’有名白桃’上的表达,’有名白桃’果实endo-PG基因受低温刺激表达也上调。说明不同肉质类型桃贮藏期间果实软化与乙烯的生物合成关系密切,不同温度下,通过调节相关基因的表达水平进而调控果实软化。4、以8成熟软溶质桃’银花露’、硬溶质桃’湖景蜜露’、不溶质桃’金童6号’、Stonyhard桃’有名白桃’和’霞脆’为试材,研究了 25°C和4°C贮藏条件对采后果实乙烯信号转导途径调控的影响。结果显示:常温条件下,软溶质、硬溶质和不溶质品种桃果实的PpERS1基因的转录表达水平呈先升后降的趋势,且与乙烯生物合成水平变化保持一致。PpCTR1和PpEIN2基因的表达丰度在果实贮藏初期短暂增加,随后下降,并在贮藏末期再次上调。Stonyhard品种’霞脆,桃果实的PpCTR1和PpEIN2基因的表达丰度呈先降后升趋势,’有名白桃’则维持在较稳定水平。低温诱导了PpCTR1和PpEIN2基因在5个桃品种果实上的表达。表明软溶质、硬溶质和不溶质桃果实的PpERS1基因的转录表达水平与乙烯的生物合成关系密切,PpCTR1和PpEIV2基因可能参与调控果实的衰老进程调控。更多还原

【Abstract】 In general,peach belongs to climacteric fruits.Its ripening process was accompanied by a strong respiration and ethylene release.Fresh peaches are seasonal fruits,they have only 2 to 5 days’ shelf life under normal temperature with poor storage transportation performance.People usually adjust market supplies and demands with different maturities of peaches.The flesh texture are divided into four categories which are softmelting,hardmelting,non-melting and wooliness.In recent years,Japanese scientists proposed a new type of flesh texture in peaches,named Stonyhard.In order to compare the storage characteristics of different flesh texture of peaches,understand the relevant information of the ethylene biosynthesis and signal transduction pathways,this study investigated the changes of ethylene production,fruit firmness,soluble solid content,main sugar and organic acid of soft melting,hard melting,non-melting and Stonyhard peaches,conbined the expression of some genes in the ethylene biosynthetic,singnal transduction and soften pathways.The results showed as follows:1.In order to identify the flesh texture and genotype of ’Xiacui’,fruits of ’Yinhualu’,’Hujingmilu’,’Babygold 6’,’Yumyeong’ and ’Xiacui’(Prunuspersica)were harvested in 8 tenth maturity and then stored at 25 ℃.The ethylene production and flesh firmness were measured during storage.The results showed that fruit ethylene production of ’Yinhualu’,’Hujingmilu’ and ’Babygold 6’ appeared a rise then falling trend with significant peaks,the flesh firmness of them decreased with time going on,and were lower than 1.0 kg/cm2 with’Yinhualu’ and ’Hujingmilu’ by the end of storage.While only a little of ethylene production were detected after harvest with ’Yumyeong’ and ’Xiacui’,and the treatment of endogenous ethylene failed to induce a rapid loss of flesh firmness of the latter,it could retain more than 3.5 kg/cm2 in the last period of storage.All these proved that the flesh texture of ’Xiacui’ peach cultivar is Stonyhard,and its genotype could be hdhdmm.2.In order to compare the storage characteristics of different flesh texture and maturity of peach,three cultivars of ’Xiahui 1’ soft-melting peaches,’Xiahui 6’ hard-melting peaches and non-melting ’Jinhui’ peaches were used to analyze the changes of flesh firmness,ethylene production,soluble solid content,main sugar and organic acid of two harvest maturities,including 7 tenth and 8 tenth.The results showed that all fruits of three peach cultivars have normal ethylene release peaks.The non-melting cultivar peaches possessed the longest shelf-life,accompanied with lower soluble solid and main sugar content,compared to that of the soft-melting and hard-melting cultivars.However,’Xiahui 6’ fruits of 8 tenth maturity had higher amount of soluble solid and main sugar content,and had better flavor during storage.The hard-melting cultivar peaches had better effect during shelf-life storage,and fruits of 8 tenth maturity kept better shelf-qualities.3.To study temperature modulate peach ripening and ethylene biosynthetic pathways,different cultivars of ’Xiacui’ and ’Yumeyong’ with Stonyhard,’Yinhualu’ with soft-melting,’Hujingmilu’ with hard-melting,and ’Baby gold 6’ with non-melting in 8 tenth maturity were collected as test materials.The ethylene production and firmness analysis showed that only a little ethylene production were detected after harvest with fruits of’Yumeyong’ and ’Xiacui’,under either room temperature(25 ℃)or low temperature(4 ℃).The fruit firmness of Stonyhard cultivars retain at high level under room temperature with time going on,whereas low temperature induced ’Yumeyong’ fruit to soften.Real-time quantitative PCR results indicated that PpACS1 gene was highly expressed in soft-melting,hard-melting and non-melting cultivars,but extremely low in Stonyhard peaches.However,PpACS2 or PpACS3 could not be detected in all five cultivars.Moreover,cold treatment induced the expression level of PpACO1 gene in ’Xiacui’ and ’Yumeyong’ peaches,and significantly enhanced endo-PG expression in ’Yumeyong’ peaches.In conclusion,this study revealed that fruit softening of peaches with different flesh textures were closely related to ethylene biosynthesis during the storage period,which were controlled via regulating relevant gene expression levels under different temperatures.4.Taking the fruit of peach cultivar ’Yinhualu’ with soft-melting,’Hujingmilu’ with hard-melting,’Babygold 6’ with non-melting,’Xiacui’ and ’Yumeyong’ with Stonyhard in 8 tenth maturity as test materials to study different postharvest conditions modulate ethylene signal transduction pathways in peaches.The results showed that the expression of PpERS1 in soft-melting,hard-melting and non-melting peachs appeared a rise then falling trend 25℃,in association with changes in ethylene biosynthesis,the PpCTR1 and PpEIN2 mRNA increased with starting time of storage,then decresed but increased again by the end of the storage.These two gene’s expreesion trend in ’Xiacui’ decresed firstly and then up-regulated,but maintained at a stable level in ’Yumeyong’.Moreover,cold treatment induced the expression level of PpCTR1 and PpEIN2 gene in all fruits of five peach cultivars.In conclusion,the expression of PpERSl was closed related to ethylene biosynthesis,PpCTR1 and PpEIN2 may participate the regulation of senescence process.更多还原