Geraniums (also known as Storkbills) are one of the world's most popular plants. The South African native plant has been cultivated since the 17th century, and through breeding hundreds of varieties, differing by timing of flowering, color, resistance to disease and consistent growth have been produced. Now, gardeners and industrial planters can add a few more tricks to the mix: longer life, and pollen-free plants. These traits were not available using traditional cultivation (where planters select certain plants they like and breed them). Intead, a little genetic manipulation was required.
A group of Spanish researchers found that a single gene extended the 6-day life span of a normal geranium to at least 22 days before signs of aging appear. In another experiment, introducing a gene that stunted the growth of pollen-making mechanisms rendered the plant sterile. Not only could the plant not reproduce, it could not spread pollen to other plants (including, importantly, traditionally cultivated plants which might not react well to the genetically engineered variety). The new study appears in the August 31 issue of BMC Plant Biology.
To stave off aging, the group used a gene that produced an enzyme called isopentenyl phosphotransferase, or ipt. This enzyme increases the levels of plant hormone in the geranium, which delay the aging process. The enzyme also resulted in plants with smaller leaves, more branches and flowers with more intense colors. Then, to make the plant pollen-free, the group used a gene called barnase, which halted the development of the plant's pollen-making reproductive organs. This process eliminated pollen production, which would benefit those who are allergic to the plant. This trait is also an advantage for growers who are concerned about introducing a genetically modified trait to traditionally cultivated plants. "This would be especially useful to produce environmentally friendly transgenic plants carrying new traits by preventing gene flow," the researchers wrote.
To modify the genes of this old garden mainstay, the researchers used what is now an old genetic engineering warhorse: the bacteria causing crown gall disease. Known as Agrobacterium tumefaciens, the bacteria can inject itself into plant cells (that's how it causes crown gall disease). Carrying the gene, however, the bacterial injection results in a new generation of plants carrying the intended gene and displaying the new trait.