Those days, when Europeans had cultivated potatoes for its unusual flowers, have passed long ago. Now people know that the bulb is the most important thing in potatoes. Plant breeders unite their efforts in order to make its bulb bigger and starchier. RAS Plant Physiology Institute scientists use genetic engineering to enhance potatoes. Bacterial gene, introduced to the plant, enlarges starch grains significantly.

Potato plant synthesizes sugars, which move to the bulb and transform there to starch. That's the way the plant accumulates and stores nutrients. Potato bulb is a kind of plant storage, which humans break without mercy.

The scientists used genes of Agrobacterium - these microorganisms live in soil and infest plants, causing nodulation and knob formation. One of these genes, rolB, appeared to accelerate bulb formation of transgenic plants. It's high time to find out how this gene influences starch synthesis and storage in the bulb.

The researchers have inserted bacterial gene into potato plants of "Desire" species. Non-transgenic plants or plants with other inserted genes were used as control. The experiments were performed on plant cuttings, which were grown on artificial medium in absolute darkness at 20 C. Plants were kept in severe conditions in order to eliminate all factors, influencing starch synthesis, except inserted gene. It's impossible to grow normal potatoes without light, but small bulbs, which appear on the cuttings, are enough for research. The experiment lasted six weeks, during which the scientists measured these micro-bulbs and starch grains inside them. Starch, dyed with iodine, is well visible in ordinary light microscope.

RolB gene enlarges bulb cell size comparing to control plants. Each of these cells hosts twice as starch grains as control cell does, and each grain is several-fold larger than control grain. Starch grains grow constantly under bacterial gene influence, while control ones stopped growing to the end of the forth week.

New technologies often give rise to looking back. For many years physiologists study effects of phytohormones on every process, occurring in plants. Now they know that Agrobacterium genes can act like hormones and are going to proceed with studies of phytohormone influence on starch synthesis. It probably allows making potatoes even more starchy.