降温方式对中采鸭梨果心ACO基因表达和褐变的影响

Effect of cooling methods on ACO gene expression and core browning of Yali pear

以河北鸭梨为研究对象,通过缓慢降温和急速降温处理,测定了贮藏过程中果实硬度、果实和内源乙烯释放量、果实呼吸强度以及内源二氧化碳浓度等生理指标变化,果心部位ACO(ACC氧化酶,1-aminocyclopropane-1-carboxylate oxidase)活性和ACO基因表达量的变化,同时观察果心褐变情况,以研究缓慢降温和急速降温对鸭梨成熟衰老的影响及其与果心褐变的关系。结果表明:与急速降温相比,缓慢降温显著推迟了鸭梨冷藏期间果实乙烯代谢高峰的出现,贮藏各阶段果心部位ACO表达量、内源乙烯浓度显著低于急速降温鸭梨;缓慢降温很好地保持了鸭梨果肉硬度、降低了贮藏期间果实内源CO_2浓度、推迟了呼吸强度高峰的出现。整体而言,缓慢降温通过抑制果实乙烯代谢、降低呼吸强度、保持果肉硬度达到延缓机体成熟衰老的作用,进而显著减少了鸭梨果心褐变。

To study the effect of two cooling conditions on ripening and senescence and the relationship between ripening and senescence and core browning, Yali fruits harvested from Hebei province were pre-cooled rapidly and slowly during storage, the browning situation of different treatment were counted, and changes in physiological indexes of ethylene production, respiration intensity, core browning index and firmness and biochemical indexes of ACO activity and gene expression were determined. The results showed that, compared with rapid cooling, slow cooling significantly postponed the occurrence of peak ethylene metabolism in Yali during cold storage. The ACO expression and endogenous ethylene concentration in the fruit and heart of each stage of storage were significantly lower than that of rapid cooling of Yali pear; the slow cooling was well maintained. the hardness of pear pulp, reduced the endogenous CO2 concentration during storage and delayed the peak of respiratory intensity. Overall, slow cooling had delayed the ripening and senescence of Yali by inhibiting ethylene metabolism, reducing respiratory intensity, maintaining flesh firmness, and further significantly reduced the core browning.