【作者】 薛炳烨；

【导师】 束怀瑞；

【作者基本信息】 山东农业大学 ， 果树学， 2002， 博士

【摘要】 一．本研究以肥城桃(Prunus persica[L.]Batsch)中的两个成熟软化特性不同的品系为试材，这两个品系一个是典型的红里桃，即与果核相连的果肉呈红色，成熟后期变软快，采后不耐藏；另一个是典型的白里桃，即与果核相连的果肉无颜色，成熟后期变软慢，采后较耐藏。于2000和2001两年度对上述两品系果实生长发育和贮藏过程中的生理生化变化进行了研究，结果如下： 1．肥城桃果实重量的增长具有双‘S’曲线特性。其重量的60％以上是在商业采收期前一个月即7月31日至8月30日间获得的。蔗糖、果糖和葡萄糖是肥城桃果实中的主要糖类，也含有相当量的山梨糖醇。桃果实发育过程中蔗糖含量不断增加，蛋白质含量不断下降，成熟后期蛋白质增加。果实果肉含水量在80-88％之间。7月4日肥城桃结束硬核期，开始进入第Ⅲ阶段快速生长期。发育过程中果实硬度不断下降，成熟后期红里桃果实硬度下降明显地大于白里桃果实。果实开始快速生长后硬度下降最快。4℃下贮藏过程中，果实硬度不断下降，但在贮藏一周时，果肉硬度稍有增加。 2．果实生长过程中细胞壁含量及成分不断变化。随着果实发育成熟，细胞壁占果实果肉重量的百分比在不断下降。可溶性果胶从8月1日至8月16日明显增加，这时果肉硬度下降最快。红里桃离子结合果胶不断下降，但白里桃的保持不变。果胶变化与果实硬度下降密不可分。细胞壁中纤维素含量的减少，也是造成果实软化的因素之一。乙烯利、脱落酸和赤霉素有促进果实细胞壁降解的作用，6-BA和萘乙酸有抑制细胞壁成分降解的作用，但不同的生长调节剂对不同的细胞壁成分作用不同。 3．肥城桃果实贮藏期间的呼吸由三个途径组成，TCA途径是主要途径，HMP途径随贮藏期延长而减弱。8月30日采收并在4℃下贮藏的肥城桃果实，两周后出现呼吸高峰。呼吸高峰期与果实冷害或絮败的发生期相吻合。 4．肥城桃果实成熟软化与细胞壁水解酶活性有关，红里桃的成熟软化与纤维素酶活性升高有关，而白里桃在发育成熟后期纤维素酶活性不升高。白里桃和红里桃纤维素酶活性变化的不同，说明了纤维素酶在肥城桃果实软化中的重要作用。红里桃后期硬度下降快，是因为纤维素酶一直起作用。而白里桃硬度下降慢，是因为纤维素酶活性降低了。 外用植物生长调节剂对果胶酶活性影响很小。肥城桃果实中没有检测到内切PG活性，成熟后期外切PG活性上升，低温对PG活性影响很大。PG与发育成熟后期果实软化有关。 5．肥城桃果实中α-半乳糖苷酶活性很高，而且是一种与壁结合的酶，与果实硬度下降密切相关；采收后的果实中检测到较高的β-半乳糖苷酶活性，它与采后果实软化有关。 薛炳烨：肥城桃和草毒果实发育成熟软化生理机理的研究 肥城桃在发育过程中没有检测到葡萄糖昔酶和甘露糖昔酶活性，但果实采收后有葡萄糖昔酶活性。 6．过氧化物酶与硬核期桃果实的生理变化有关。因为硬核期的肥城桃果实中有很高的过氧化物酶活性，硬核期结束后，过氧化物酶活性下降。二．2000年至2002年对大田和温室栽培的具有不同成熟软化特性的7个草毒（Farlti Xb；1。assa Duch．）品种发育成熟过程中生理生化变化进行了研究，主要结果如下： 1．所有测定的草萄品种的纤维素酶活性都随着发育成熟而升高。几乎所有品种各个时期采收的草萄在4℃下放置48小时后纤维素酶活性都明显升高。蔡乙酸对草萄果实中纤维素酶活性的调控因品种和发育时期而不同。纤维素酶活性与草萤果实的耐贮运性密切相关，且呈负相关。 2．草荡果实发育成熟过程中，果胶酶活性不断增加。在4℃下存放48小时后，果胶酶活性普遍下降，茶乙酸对果胶酶活性无影响。草荡果实中没有检测到内切PG活性，外切PG与成熟软化无关，PG不受素乙酸的影响。 3．p．半乳糖昔酶活性变化与草萤果实的成熟密切相关，Q－半乳糖昔酶也与成熟有关，但不如p．半乳糖昔酶关系密切。 4．早美光中的p－葡萄糖昔酶随果实成熟不断提高，与果实成熟关系密切。葡萄糖苦酶是与丰香草毒果实早期发育相关的一种酶。红丰草萄果实中的葡萄糖昔酶活性与成熟没有关系。 5．a－甘露糖昔酶与草萄果实软化有关，而且其与细胞壁离子结合部分的酶活性较高。在草萄果实上未检测到p－甘露糖昔酶活性。 6．草墓果实内的蛋白质含量随着成熟而下降，成熟后期下降很快。果实中蔗糖含量较低。葡萄糖在白熟期最高，红熟期下降，过熟时又急剧上升。果糖和葡萄糖具有相同的变化趋势。草萄中有较高的甘露糖醇，但山梨糖醇很低。 7．草萄果实发育成熟过程中细胞壁变化与成熟软化密切相关。可溶性果胶不断增加，离子结合果胶和纤维素减少，共价果胶不变，半纤维素在红熟期前不断增加，过熟期下降。白熟期前细胞壁含量快速下降，白熟期到红熟期保持不变，过熟期又下降。 8．运用RT－PCR技术从红熟期丰香草萄果实总RNA中克隆到纤维素酶基因753hp的CDNA片段，通过同源性分析认为得到的CDNA片段是与草蒋果实成熟软化密切相关的纤维素酶基因的。DNA克隆。更多还原

【Abstract】 1. The experiments were carried out for two years with two cultivars of ’Feicheng’ peach (Prunus persica[L.] Batsch) , which have different softening characteristics during maturation and postharvest storage. Of the two cultivars, one was ’Hongli’ with red flesh clinged to the pit which softened faster after harvest; the other was ’Baili’ with white flesh clinged to the pit which softened slower than ’Hongli" after harvest and could be stored longer. The main results were as follow.1) The fruit weight growth curve of Feicheng peach exhibited the characteristic of double sigmoidal growth pattern. Sixty percent of total weight gained within one month prior to commercial harvest. Water content in flesh ranged from 80-88%. The main sugars were sucrose, glucose and frucose. Sorbitol also existed in considerable amount. The protein content decreased during fruit development, but increased in the last stage before harvest. With the ending of pit hardening around July 4, the fruit enlarged rapidly until the fruit was firm ripe. The firmness decreased gradually till harvest and the firmness of ’Hongli’ peach decreased much more than ’Baili’ did. During the phase of rapid expanding the firmness of fruits decreased dramatically. Fruit firmness decreased gradually during storage under 4癈, but the firmness increased a little bit after one week of storage.2) The proportion and components of cell wall in fruit changed during fruit development and storage. In the process of fruit ripening, the proportion of cell wall to fruit weight decreased. Soluble pectins increased remarkably from August 1 to Augustl6, leading to fruit firmness decrease. The ionically bound pectin remained stable in ’Baili’ peach, but it decreased in ’Hongli’ peach. Changes of pectins directly related to fruit firmness. Decreasing of cellulose content in cell wall also played an important role in the reduction of firmness. Of the PGRs (plant growth regulators) used, ethephon, ABA and GA3 stimulated the degradation of cell wall, and 6-BA and NAA inhibited this process.3) The respiration of peach comprises three pathways of TCA, BMP and HMP. TCA was the primary one and HMP reduced gradually to a very low level during storage. Fruit respiration climacteric occurred after two weeks of storage with fruits harvested at August 30. This peak of respiration coincided with the occurrence of chilly injury or wooliness.4) Both PME and EGases played important role in peach fruit softening. The results from the two cultivars implicated that EGases were essential in initiation of fruit softening. The PGRs have little effect on PME. ABA stimulated the activity of EGases. However theincrement of EGases was not related to fruit softening. Endo-PG had not been detected in ’Feicheng’ peach. Exo-PG took part in the process of later stage of ripening.5) Activities of a -galactosidase were very high in ’Feicheng’ peach and a - galactosi-dase was a kind of enzymes which ionically bound with cell wall. It was correlated with the decreasing of fruit firmness. P -galactosidase existed in the harvested fruits and was related to the softening of fruits during storage at low temperature. For glucosidases the situation were similar to P -galactosidase. No activity of mannosidase has been detected in ’Feicheng’ peach. The peroxidases was related to pit hardening in ’Feicheng’ peach which showed a high activity during pit hardening and then decreased.2. The results from several varieties of strawberry (FragariaX ananassa Duch) grown in field or greenhouse were as follow.1) The activities of EGases increased as the strawberry fruits developed from stage of small green to stage of overripe. After two day’s storage at 4℃, the activities of EGases increased remarkably in all 7 varieties. The action patterns of NAA on EGases activities were different with fruits from various developmental stages. EGases activities were negatively correlated to the storability of strawberry fruits.2) The activities of PME increased during the development of st更多还原