The Correlation Between Chlorophyll Products And Oleocellosis At Break Stage Of ’Zaohong’ Orange Fruits

Oleocellosis is a physiological disease in citrus.It is one of the most prominent diseases which widely happens in the citrus-growing areas including Jiangxi province and Chongqing city at the harvest period.It not only caused a great economical loss to the citrus growers,but also has bad effect on the sustainable development of Citrus industrialization.The mechanism of Oleocellosis pathogenesis has not yet been well documented and there are not effective approaches to prevent this disease.We investigated in several citrus-growing areas,such as Jiangxi,Hubei,Chongqing for consecutive years and found out that the incidence of it is highly associated with the degree of the fruit coloration.The more chlorophyll the rind has,the higher probability to get sick.We analyzed the dynamic changes as the chlorophyll degraded.The finding showed that the positive effect between chlorophyll content and morbidity of Oleocellosis.The above motioned provide a great insight of the mechanisms underlying the Oleocellosis formation and also have a great significance on developing a promising way of prevention method.The ‘Zaohong’ navel orange fruits during the coloring period were used for the experiment.As we found out that Oleocellosis largely occurred during the coloring period,we used the UPLC to detect the change of the content of the chlorophyll degradation products of different parts of the citrus peel.And we analyzed the difference between healthy peel and the diseased peel of the diseased fruits.We also used a variety of physiological and biochemical methods to explore the Oleocellosis pathogenesis.The main results of the study are as follows:1.The UPLC test results showed the content of pheophytin a and pheophorbide a in the disease peel is higher than that in the normal peel.The sample of 2014 showed that there is an increasing of pheophytin a and pheophorbide a in the disease peel.The content of pheophytin a and pheophorbide a had risen 1.551 μg/g,0.290 μg/g respectively.The sample of 2015 showed that there’s a rise in pheophytin a in the disease peel.The content of pheophytin a had risen 3.174 μg/g.2.Cell rupture rate was remarkably higher in the protoplasts which cultured in the solution with pheophytin a or pheophorbide when compared with the controlgroup.We respectively added pheophytin a or pheophorbide a in the culture medium containing protoplasts which were extracted from ‘Zaojin’ navel orange.The observation showed that the protoplasts treated with pheophytin a or pheophorbide lead to a higher cell rupture rate than that in control treatment,indicating the chlorophyll degradation products did have a deleterious effect to the protoplasts.3.Chlorophyll products did cause the Oleocellolsis phenomena.In the study,the pheophytin a or pheophorbide a were respectively dissolved in alcohol and applied on the surface of the peel of healthy fruits.After 6 d,the serious Oleocellosis symptoms were clear found on the peel as compared with the alcohol control.4.Relevant substances of antioxidant system detection of ‘Zaohong’ navel oranges’ peel during the coloring period revealed that there’s a decrease in the diseased peel.Taken together the datas of 2014 and 2015,we could find out that the contents of SOD,CAT and POD in the diseased peel were lower than that in the healthy peel.But the content of POD in the diseased peel of 2014 was higher than that in the healthy peel.We also found out that the contents of H₂O₂,T-AOC and ASN in the diseased peel were significantly lower than that in the healthy peel.5.Rubisco activity detection of ‘Zaohong’ navel oranges’ peel during the coloring period shows that there’s a rise in the diseased peel.According to the datas of2014 and 2015,the Rubisco activity in the diseased peel were significantly higher than that in the healthy peel.The Rubisco acticity of the sample of 2014 and 2015 had risen 76.1947 nmol/min/g and 170.2510 nmol/min/g respectively.