ИСТИНА

The traditional functions of fibrillarin are methylation and processing of pre-rRNA. Fibrillarin also participates in virus-host interactions in both animals and plants. To assess whether fibrillarin is involved in other responses to biotic and abiotic stress, we generated potato plants (Solanum tuberosum cv. Chicago), which either transgenically overproduced fibrillarin or possessed markedly decreased levels of fibrillarin activity caused by virus (tobacco rattle virus, TRV) induced gene silencing (VIGS/RNAi). Heat stress (28℃) has been shown to cause serious injuries such as leaf curling and senescence. Under such a heat-stress condition, potato virus Y accumulates to markedly increased levels compared with normal temperature (22℃) and significantly aggravates these symptoms. The knockdown of fibrillarin achieved by TRV-mediated VIGS notably attenuates these symptoms and suppresses the virus infection. In contrast, overproduction of fibrillarin in the overexpressing potato transgenic lines significantly accelerates all of these processes, suggesting involvement of fibrillarin in the responses of potato plants to heat stress combined or uncombined with potato virus Y infection. Thus, fibrillarin may possess a completely new non-canonical function in specific signaling pathways. The possible molecular basis of fibrillarin effect and practical implications for control of virus infections will be discussed.