Barley has adapted to grow in acidic soils containing Aluminium - toxic to plant growth - by the modification of a certain gene, reports a study in Nature Communications this week. This adaptation is only found in the Aluminium-tolerant barley crop from Japan, Korea and China, which shows how it has evolved over the past 3,000 years to grow in the acidic soils common in East Asia. Aluminium toxicity is a major factor limiting crop growth in acidic soils, which make up 30-40% of the arable soil in the world. Plants like barley are able to secrete negatively charged ions, such as citrate, into the soil, which prevents Aluminium from binding to root cells. Jian Feng Ma and colleagues found that the Aluminium-tolerance in cultivated barley occurs through an insertion of a 1-kb sequence in the Aluminium-tolerant gene, HvAACT1. This altered gene acts by secreting citrate to the soil allowing the plant roots to take up essential metals like iron, but detoxifies the aluminium that is also present.