|Fungal endophyte (green) growing into plant cells|
There are also examples of Aspergillus providing growth hormones when the plant is put under stress, helping the plant to grow when under drought conditions for example.
This information has recently been put to use by researchers trying to help banana farmers overcome Fusarium Wilt, a disease currently devastating banana plantations in The Phillipines. Fusarium is a fungus that causes rapid death of banana plants and renders the soil unable to support further growth for 10 years - extremely bad news if you are a small farmer.
Researchers have found that certain local strains of Aspergillus can be grown with plants to help prevent Fusarium Wilt - plants do much better in Fusarium-infected soils if they have been treated with Aspergillus. Aspergillus apparently grows around the roots causing a physical barrier and considering what we know about how this fungus works as an endophyte may well produce chemicals that help encourage growth and even produce chemicals toxic to Fusarium.
This technique along with several other techniques also being investigated should go a long way to reducing the threat from Fusarium Wilt for poor banana farmers.