Scientists from the University of Missouri-Columbia in the Unites States have found a way to construct, engineer and attach useful genes to minichromosomes in maize.  Minichromosomes are very small versions of chromosomes, which function just like a regular chromosome, but have the ability to have new genes stacked into them.
This innovation could open new possibilities for the development of crops with multiple resistance to a wide spectrum of pathogens and pests, for the production of medically useful plant metabolites, and for the development of “third generation biofuel crops”. Third generation biofuel crops are those whose properties have been modified to meet a specific bioenergy conversion process. Details of the innovation are published in the Proceedings of the National Academy of Sciences of the United States of America (URL above)..