不同采收贮藏条件下鸭梨果实LOX基因表达及其与果心褐变的关系

以河北鸭梨为试材,通过测定鸭梨果实呼吸强度、乙烯释放量、果心褐变指数等生理指标变化及不同部位脂氧合酶(lipoxygenase,LOX)基因表达特性和LOX活性变化,研究了两种降温条件下不同采收成熟度鸭梨LOX基因表达及其与鸭梨果心褐变的关系。结果表明:不同贮藏期果心LOX活性及果心褐变指数顺序均为晚采果早采果中采果,急速降温果缓慢降温果;贮藏期间,鸭梨果心LOX基因表达量呈现先缓慢上升后下降,贮藏末期又上升的变化趋势;急速降温鸭梨LOX基因表达量大于缓慢降温果,中采果LOX基因表达量小于早采及晚采果。中采结合缓慢降温抑制了鸭梨果肉及果心部位LOX基因表达,进而减少了果心褐变的发生;LOX基因的表达与LOX活性及鸭梨褐变指数变化趋势一致,说明该基因与鸭梨褐变关系密切。

LOX Gene Expression and Its Relationship with Core Browning of Yali Pear under Different Harvest and Storage Conditions

Hebei-grown Yali pears (Pyrus bretschneideri Rehd cv. Yali) of different maturities were stored at (0 ± 1) ℃
directly or after pre-cooling at gradually decreasing temperature. Changes in respiration intensity, ethylene production and
core browning index and lipoxygenase (LOX) activity and LOX gene expression pattern during storage were determined and
the relationship of LOX gene expression with core browning was studied as well. The results showed that during storage,
the decreasing order of LOX activity and core-browning index was as follows: late-harvested fruit > early-harvested fruit >
middle-harvested fruit, as well as rapid-cooling fruit > slow-cooling fruit. The expression level of LOX gene in core tissues
initially increased slowly, then declined, and increased again until the end of storage. The expression level of LOX gene in
rapid-cooling fruits was higher than in slow-cooling fruits, and the expression level of LOX gene in middle maturity fruits
was lower than in fruits of early and late maturities. Middle-maturity harvest combined with slow pre-cooling inhibited the
LOX gene expression of flesh and core tissues, thereby suppressing core browning of Yali pears. LOX activity and the gene
expression level of LOX were coordinated with core browning index, suggesting that the expression level of this gene was
correlated closely with core browning of Yali pears.