Inducing effect of PGRs on small regulatory si/miRNA in resistance to sugar beet cyst nematode.

Sugar beet cyst nematode Heterodera schachtii Schmidt is an economically important plant parasite of sugar beet in Ukraine. The pest control options are limited. Sugar beet cyst nematode resistant varieties are not available on the market. Carbamate and organophosphate pesticides have been banned due to the high toxicity. The problem is aggravated by continuously increasing of oilseed rape (which is suitable host for H. schachtii) growing area due to biofuel demands. Several studies' results indicate that PGRs have role in management of plant parasitic nematodes but for sugar beet it is not studied well. We had an objective- studying of the role of four compositional PGRs created based of avermectin in suppression of sugar beet cyst nematode population on sugar beet and oilseed rape caused by enhancing of endogenous si/miRNA complementary to H. schachtii mRNA. Laboratory study was conducted in 2011 with using method DOT-blot hybridization si/miRNA with mRNA and by testing inhibitory activity in cell free system protein biosynthesis. That was shown that application of the PGRs enhances sugar beet and oilseeds rape plant immune-protective properties and resistance against plant-parasitic nematode Heterodera schochtii through enhancement of synthesis of small regulatory si/miRNA related (complementary) to an mRNA structure of the parasitic organisms. As a result, translation of mRNA of the nematode is blocked and causes the mortality of plant parasite juveniles.

Challenges to grow oilseed rape Brassica napus in sugar beet rotations.

The study was carried out in 1989-1991 and repeated in 2003-2006 to compare life cycle and dynamics of Heterodera schachtii Schm. on sugar beet, oilseed rape, fodder radish and to work out recommendations on how to decrease the risk of yield reduction while it grows in sugar-beet rotations. Research was carried out in plot experiment in natural conditions. Nematode community on rape, fodder radish and sugar beet was analyzed. Data of nematode community showed that composition of nematode species was very similar. Heterodera shachtii were dominated species with rape and sugar beet. All tested Brassica crops are susceptible to H. schachtii. However there is significant difference in population dynamics. The highest total number of brown cysts, eggs and juveniles of all ages was observed in winter rape. H.schachtii developed two generations on sugar beet and one generation on mustard. The voluntary seed germination after harvest contributes to increasing H. schachtii population. Therefore it is necessary to destroy oilseed rape voluntary chemically or physically. This operation should be done in about 2-4 weeks. The exact time can be calculated using the temperature- based model. Growing regular fodder radish and mustard as the trap crops can significantly reduce population of H. schachtii. The time of sowing is not earlier than August 20th. While estimating the time of destruction of trap crops it should be taken into consideration that H. schachtii can complete life cycle without foliage.