漆酶LAC表达与鸭梨果心褐变的关系

【目的】探究在不同成熟度和降温贮藏方式下,LAC表达模式与鸭梨果心褐变的关系,为进一步解析鸭梨果心褐变机制提供理论依据。【方法】以鸭梨作为材料,通过对不同成熟度（早采、中采和晚采）的鸭梨进行急速降温（急降）和缓慢降温（缓降）处理,观察贮藏期间鸭梨果心褐变情况,测定漆酶（Laccase,LAC）活性及其基因LAC的相对表达量,研究LAC在鸭梨果心褐变过程中的参与作用。【结果】冷藏60 d时,晚采鸭梨出现褐变,晚采缓降处理的鸭梨果心褐变指数为0.32,是同期急速降温处理的2.56倍;在贮藏90 d时,中采缓降处理的褐变指数是0.24,中采急降处理的褐变指数仅为0.01。各个处理组在贮藏期间LAC活性多数表现为先逐渐升高后下降的趋势,晚采的果实在贮藏60 d时出现活性高峰,褐变发生;早采和中采鸭梨LAC活性高峰均在90 d时出现,褐变程度低于晚采鸭梨。在贮藏期间,缓慢降温处理的LAC活性高于急速降温处理。鸭梨LAC14和LAC7表达量呈先上升后下降的趋势,LAC6表现为先下降后上升再降低的变化趋势;中采、晚采鸭梨在贮藏60 d时,LAC14和LAC7表达量最高。【结论】与缓慢降温相比,急速降温处理减少了鸭梨果心褐变的发生。在整个贮藏期间,LAC活性呈先上升后下降然后又上升的趋势,其峰值时的活性高低次序为：晚采>中采>早采,这与果心褐变趋势一致;LAC在鸭梨果心褐变过程中上调表达。相比缓慢降温处理,急速降温处理具有较低的LAC7、LAC14和LAC6表达量。急速降温结合适时采收能够抑制LAC的上调表达,减少鸭梨果心褐变发生。

Relationship Between LAC Gene Expression and Core Browning of Yali Pear

【Objective】 The aim of this study was to explore the relationship between LAC gene expression patterns and core browning of Yali pear under different maturity and cooling storage methods, so as to provide a theoretical basis for further analysis of the mechanism of Yali core browning. 【Method】 Using Yali pear as the material, the Yali pears of different maturity levels (early harvesting, middle harvesting and late harvesting) were treated with rapid cooling and slow cooling to observe the core of the pear during storage. For browning situation, the activity of LAC and the relative expression of LAC gene were determined, and the role of LAC gene in the browning process of Yali pear core was studied. 【Result】 When the Yali pear samples were refrigerated for 60 days, the late-harvested pears browned, and the browning index of late-harvested pears gradually decreased was 0.32, which was 2.56 times the rapid temperature drop during the same period; after 90 days of storage, the middle-harvested browning index decreased slowly, and the index was 0.24, and the browning index of the medium mining was only 0.01. During the storage period, the LAC activity of each treatment group increased gradually and then decreased. The late harvested fruits showed a peak activity and browning occurred after 60 days of storage. The peak of LAC activity of early harvesting and middle harvesting Yali pears appeared in 90 days, and the degree of browning was lower than that of late harvesting Yali. During the storage period, the activity of slow cooling LAC was higher than that of rapid cooling. The LAC14 and LAC7 gene expressions of Yali pears increased first and then decreased. LAC6 realized a change trend of first decline, then increased and then decreased; the expression of LAC14 and LAC7 genes reached the highest when the middle and late harvested pears were stored for 60 days. 【Conclusion】 Compared with slow cooling, rapid cooling treatment reduced the browning of Yali fruit core. During the whole storage period, the activity of LAC showed a trend of rising first, then falling, and then rising again, and the order of activity at its peak was: late harvesting>medium harvesting>early harvesting, which was consistent with the browning trend of the core. LAC was in the Yali fruit Up-regulated expression during heart browning. The rapid cooling was slower than the slow cooling, and the expression of LAC7, LAC14 and LAC6 genes was lower. A timely harvesting with the rapid cooling could inhibit the up-regulated expression of LAC and reduce the browning of Yali pear core.