设施油桃果实发育过程中有机酸代谢的研究

Organic acid metabolism in nectarine fruit development under protected cultivation

以设施栽培"超红珠"油桃为试材,测定了果实发育过程有机酸含量及相关代谢酶——柠檬酸合酶(CS)、苹果酸酶(ME)、苹果酸脱氢酶(MDH)的活性,并对果实中有机酸积累及酶活性的关系进行了分析。研究结果表明:随油桃果实发育,其有机酸含量呈先升高后降低趋势,于盛花后49d达到最高值;苹果酸含量与总有机酸含量变化趋势相似;柠檬酸含量呈逐渐升高趋势,至果实成熟有所降低;果实成熟期苹果酸与柠檬酸含量相近。有机酸相关代谢酶CS活性变化与柠檬酸含量相关性不大;果实发育后期ME活性逐渐升高,促进了苹果酸的降解和转化;MDH活性变化与苹果酸含量显著相关。因此抑制果实发育前期MDH的活性、促进果实发育后期ME的活性可以降低果实酸含量,提高糖酸比。

Changes in organic acid contents and their relationship with relevant enzyme activities in nectarine fruits “Chaohongzhu” were studied. Results show that nectarine fruit total acid content hits a peak 49 days after full blossom and then gradually declines during later fruit development stages. Malic acid has similar change pattern as total acids, but citric acid gradually increases in content during fruit development with little reduction in the ripening stage of the fruit. Analysis on the activities of organic acids in relation to relevant enzymes shows no relation between citrate synthase activity （CS） and citric acid content. Increase in the activity of malic enzyme （ME） in the late period of nectarine fruit development accelerates degradation of malic acid in fruits. There is a significant correlation between malate dehydrogenase（MDH） activity and fruit malic acid content. This shows that nectarine fruit organic acid content can be reduced by MDH activity inhibition and enhancement of ME activity. This can equally increase the sugar to acid ratio of nectarine fruits.