Genes that make lemons sour revealed

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Scientists have found out why some citrus fruits are sour and others are sweet. It’s all down to genes that encode parts of plant cells called ‘proton-pumping proteins’. 

In plant cells, vacuoles are normally more acidic than the surrounding cytoplasm. The difference in acidity is controlled by protein pumps that transport protons (hydrogen ions) across the membrane into the vacuoles. Juice vesicles of sour lemon varieties express two genes encoding for two proton-pumping proteins. Expression levels of these genes are much lower in varieties with sweeter fruit. 

Read the full story in Chemistry World.