Expression Analysis Of The Citric Acid Accumulation-related Genes During Citrus Fruit Development

Citric acid is an important factor in determining flavor and quility of citrus fruits.Citric aid accumulation is a complex and precise metabolic process,which is co-regulated by synthesis,decomposition and utilization,and storage and transportation.Systematically analyzed the changes of citric acid accumulation-related genes expression during the fruit devolopment progress of different cultivars to determine the key genes lead to differences in citric acid accumulation is a great significance to improve the citrus fruit citric acid accumulation theory and the quality and flavor of fruit.we firstly compared the relationship between citric acid accumulation dynamics and citric acid accumulation-related gene expression during fruit development in satsuma mandarin and Zaoxiang pomelo to determine the possible key factors influencing the citric acid accumulation in citrus citrus fruit.Then,Newhall navel orange,Lemon and Acidless pomelo were used as materials to compare and analyze the relationship between the citric acid accumulation dynamics and the possible key factors genes expression.Based on the above two results,the key factors influencing the citric acid accumulation dynamic during the development of citrus fruits were preliminarily determined.The main results of the experiment are as follows:1.Different varietise of citrus fruits have different levels of citric acid accumulation during fruit development.Determining citric acid accumulation dynamics showed that during the sampling period,the citric acid accumulation of satsuma mandarin and Zaoxiang pomelo first increased and then decreased;the citric acid accumulation of Newhall navel orange gradually decreased;the citric acid accumulation of lemon gradually increased;continuously low accumulation of citric acid in Acidless pomelo.2.In the citrus fruit with conventional citric acid accumulation mode(like satsuma mandarin,Zaoxiang pomelo,Newhall navel orange),the citric acid accumulation was mainly related to the negative regulation of Mit-Aco and CsCit1 and the positive regulation of proton pump,but the accumulation of citric acid in the satsuma mandarin fruit was related to V-PPase and V-ATPase,while Zaoxiang pomelo and Newhall navel were related to CsPH8.3.In the citrus fruit with citric acid accumulation Continuously rising mode(such as high-acid lemon),citrate accumulation was associated with low activity of Mit-Aco,up-regulated expression of CsPH8,and low expression of CsCit1.4.In the citrus fruit with continuoued low citric acid accumulation mode(such as Wusuan pomelo),Citric acid accumulation was associated with high activity of Mit-Aco,low expression of CsPH8 and VHP3,and high expression of CsCit1.By comparing the citric acid accumulation-related genes expression analysis in citrus fruits with different citrate accumulation patterns found that the key factors determining the difference in different citric acid accumulation patterns in citrus fruits might be Mit-Aco,protein carrier(CsCit1)and proton pump(V-PPase,V-ATPase,and CsPH8),while the key proton pump that determines the difference between the conventional citric acid accumulation mode and the continuoued low citric acid accumulation mode is CsPH8.