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Expession Analyses of Organic Acid and Ethylene Related Genes in Postharvest Ponkan (Citrus Reticulata Blanco) Fruits

Author: LiWenYun
Tutor: ChengYunJiang
School: Huazhong Agricultural University
Course: Pomology
Keywords: Citrus Storage Gene Expression Sugar metabolism Organic acids Ethylene
CLC: S666.9
Type: Master's thesis
Year: 2009
Downloads: 96
Quote: 2
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Abstract


Ponkan mandarin (Citrus reticulata Blanco) is one of China's major wide leather citrus fruits of Ponkan mining often need to go through cooked, while the long-term storage Ponkan prone floating leather grain oriented and other physiological diseases, therefore Ponkan storage research is our citrus industry the urgent need to address one of the key technologies. In this study, two consecutive years (2006-2007 and 2007-2008) the Ponkan ripe fruit, fruit ripening and placed in cold storage (4 ℃) and room temperature (20 ° C) Storage. Ponkan fruit during Postharvest Storage soluble sugar and organic acid content measured using gas chromatography (Gas Chromatography, GC), using real-time quantitative PCR (Real-time PCR) technology to analyze the metabolic pathways of organic acid and ethylene-related gene expression changes. The purpose of this study is to clarify the relationship between the soluble sugar and organic acid content changes and related changes in gene expression, as well as different storage conditions on soluble sugar and organic acid content and changes in gene expression, in order to Citrus Preservation techniques laid theoretical basis. The main results are as follows: 1, measured using gas chromatography technology content of citric acid in the peel and flesh of Ponkan. Two years of repeated experiments show Ponkan fruit during storage at low temperature (4 ℃) citric acid content in the flesh there is a greater difference :2006-2007 Ponkan 4 ° C during storage in the citric acid content gradually increased, while the 2007-2008 citric acid The content was fluctuated downward trend. This may be due to the citric acid content by postharvest fruit before harvest maturity and growth conditions. 2, a two-year low temperature (4 ℃) during storage sucrose, fructose, glucose content trend is more consistent: the three soluble sugar content showed a trend first and then decreased in the flesh; fructose and glucose content has been declining in the peel, the peel sucrose content increased first and then decreased. 3, both soluble sugar and organic acid content or the level of gene expression changes in the peel than the pulp significantly. The reason may peel direct contact with the outside world, sufficient supply of oxygen, and the reaction to bad storage environment faster than flesh. 4 Real-time PCR technology to analyze the gene expression of key enzymes in organic acid metabolic pathways in the skin and flesh of Ponkan. Related genes in the citric acid metabolic pathway analysis include: citrate synthase gene (CitrateSynthase CS), isocitrate dehydrogenase gene (Isocitrate Dehydrogenase IDH), isocitrate lyase gene (the Isocitrate Lyase ICL), Ukraine the head acid enzyme gene (Aconitate Hydratase, Acon), malate dehydrogenase gene (Malate Dehydrogenase, MDH), etc.. The expression of these genes to different degrees by the influence of the post-harvest storage conditions. 5, by comparing the room temperature (20 ℃) ??and low temperature (4 ℃) storage conditions ethylene metabolism related gene expression levels: the Ponkan Fruit Storage 30d, in addition to ethylene receptor 2 (Ethylene Receptor 2, ETR2) gene, ethylene by gene body 1 (Ethylene Receptor 1, ETR1), ACC synthase (ACC Synthase, ACS) and ACC oxidase (ACC Oxidase, ACO) gene, ethylene-insensitive transcriptional regulator gene (Ethylene insensitive 3, Ein3 f-box) a gene expression were elevated at room temperature and low temperature conditions, and low temperature storage is higher than the amount of storage at room temperature expression; especially ACS gene expression levels nearly 70 times higher. Speculated the five ethylene metabolic pathways related gene expression may be induced by low temperature, but also indirectly description of ethylene may be involved in the physiological and metabolic processes of the the Ponkan low temperature during storage. 6, variable temperature during storage, the Ponkan pulp organic acid and ethylene metabolism pathway key enzyme gene expression analysis showed that: compared to only 20 ° C or 4 ℃ storage conditions, variable temperature during storage except for 2 - ketoglutarate dependent dioxygenase (2-Oxoglutarate-dependent Dioxygenase ,2-ODD) and ACC oxidase (ACO) gene only in the late storage expression level was increased, isocitrate dehydrogenase gene (IDH), isocitrate lyase (ICL) genes, ACC synthase (ACS) gene expression in the variable temperature during storage volume at a low level, suggesting that the variable temperature storage fruit metabolism slowing, it is possible to extend the storage life of fruit and shelf. This will further improve the the Citrus Preservation techniques have important reference value. The study suggests that, the Ponkan fruits postharvest storage process, a series of physiological and biochemical changes (such as: soluble sugars, organic acids content and endogenous ethylene levels), thus affecting the flavor and quality of the fruit. The postharvest storage process, the storage temperature, humidity and gas conditions, and other factors will affect the quality of. Therefore, the control of citrus postharvest storage environment is one of the key technologies that delay senescence and prolong shelf life.

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