Effects Of Cooling Method And Harvesting Maturity On Core Browning And Related Genes In Yali Pear

Yali(Pyrus bretschneideri Rehd cv.Yali)has the advantages of rich nutrition,tenderness and juicyness,However,the core browning of the Yali pear seriously restricts the development of the pear industry.Therefore,in this experiment,different harvesting maturity pears were used as materials to study the effects of different cooling methods on the quality,related enzyme activities and genes expression of Yali pear.By analyzing the relationship between genes expression,enzyme activities and browning,the roles of POD,LAC and LOX genes in the core browning of pear were studied.The main conclusions are as follows:1.Compared to slowly cooling,rapidly cooling treatment maintained a high rate of marketable fruit,maintained the higher hardness of the pear fruit,inhibited the respiration and ethylene release of the fruit,inhibited the core browning of pear.while the slowly cooling accelerates the browning of the pear.The early-harvest fruit can be titrated with high acid content,and Late-harvest pear fruit browning is serious.The middle-harvest delays the appearance of the respiration and ethylene peak,Inhibition of browning and decreases the hardness,and Maintains moderate soluble solids and titratable acid contents.Therefore,the combination of middle-harvest pear and rapidly cooling can inhibit the core browning and maintain the high quality of the fruit.2.Rapidly cooling can Maintain high POD activity and lower LAC and LOX activity,reduce browning degree,maintain fruit quality.POD activity was negatively correlated with core browning index and fruit browning index,LOX,LAC and browning index were positively correlated.Early-harvest and middle-harvest pears maintained higher POD activity,inhibited the increase of LAC and LOX activities,and early-harvest had the lowest browning index.Appropriate early-harvest can delay the browning of pears during storage,while late-harvest pears promoted the increase of LAC and LOX activities,accelerated the decline of POD activity,and the browning is the most serious.3.The genes related to core browning of pear POD,LAC6,LAC7,LAC14,LOX5 and LOX31 were selected from the core of Yali pear by RNA-seq.Rapidly cooling inhibited the down-regulation of POD gene,inhibited the up-regulation of LAC7,LAC14 and LAC6 genes,promoted the down-regulation ofLOX5,inhibited the up-regulation of LOX31,maintained the high expression of POD gene,and made POD activity higher.Level.The rapid down-regulation of LAC6,LAC7,LAC14 and LOX31 genes was up-regulated,and the down-regulation of POD and LOX5 genes inhibited the browning of pear fruit.The slow cooling was reversed.LOX31 and LAC14 were sensitive to maturity,and the expression of gene expression was the lowest in the late harvest,indicating that high maturity can induce the expression of LOX31 and LAC14.The slowly cooling stimulated the down-regulation of POD gene in the pear fruit,promoted the up-regulation of LAC7,LAC14 and LAC6 genes and up-regulated the expression of LOX31,inhibited the down-regulation of LOX5,decreased POD activity,and increased the activities of LAC and LOX,Promotes respiration,ethylene release,and accelerates the decline of fruit quality,resulting in core browned of pear;and it increases as maturity increases.The expression levels of LOX31 and LAC14 genes increased with the maturity of Yali pear,and the browning was gradually serious.