Sorghum is a very important food, feed and industrial crop, because it contains significant amounts of starch, proteins, fats and sugars. Some one has never tasted it, but everyone has seen it: brooms are made of this plant. Sorghum grows in arid regions and gives heavy crops, where other plants are unable to grow. In Russia grain sorghum (durra) is cultivated in Niznee Povolzh'e, Northern Caucasus, in some regions of Central Black Earth Belt and Southern Urals.
 

The problem is that large fields are scattered with seeds of one species, i.e. with plants of similar genetics. Such plantings are more vulnerable for pests than natural populations. And the most hazardous pests for sorghum are aphids. Different countries grow sorghum species, resistant to local aphids species. However, Eriosoma americanum-resistant sorghum can't resist Russian aphid species. As for Russian sorghum, it is destroyed by European pests. That is why the scientists needed to know rather quickly what aphid species are various sorghum species resistant to and what genes are responsible for that. Only this information could help breeding new sorghum species resistant to local aphid species.
 

The scientist from All-Russian Vavilov Science and Research Institute of Plant Industry, E.E. Radchenko, decided to find solution for this problem. His experiments lasted for several years and resulted in discovery of seven new genes, responsible for aphid resistance.
 

The scientist has first tested 32 sorghum species from Russia, Hungary, USA, China and Syria for resistance to various aphid populations. Then he bred various sorghum species and observed the damage aphids caused on breeding offsprings (hybrids). For this purpose he planted these hybrids together with vulnerable sorghum species and introduced four aphids on each plant. Then he calculated the hybrid leaves damaged by aphids, by the time vulnerable plants were completely destroyed by the pests. Plants with less than 20% of leaves damaged were classified as "tolerant".
 

The results of several years of experiments showed how each sorghum species inherits aphid tolerance. Several genes appear to be involved in the process; moreover, they can vary depending on the species. The obtained data will help scientists to create sorghum species, resistant to certain aphid population. This work has great theoretical value - it extends our knowledge of genetic mechanisms of plant tolerance to pests.