Plants need mineral elements from the soil to ensure their proper development. Phosphorus and nitrogen are two of the most important ones. To assure an appropriate supply of those two elements, petunia and maize enter symbiosis with mycorrhizal fungi. For this symbiosis to occur, the fungus must recognise the plant host and receive a molecular permit before entry. Approximately 80% of all plant species, many of great agricultural importance, depend on this association.

This mutual recognition relies on the exchange of chemical signals, which in turn are controlled by genes. Some of the genes controlling absorption of phosphorous from the soil have already been identified but many genes involved in triggering mycorrhizal symbiosis remain to be discovered. Their knowledge will assist in the smart breeding of plants with enhanced phosphorus and nitrogen absorption.