## 3 Discussion
There were no changes for prenylflavonoid biosynthetic pathway enzyme genes PAL, 4 CL2, and CHSH1 by vivoid infection in cones. We found up-regulation only for Premiant (PAL) and Saaz (CHSH1), which are not only involved in lupulin gland metabolites. Previously, up-regulations of PAL, 4 CL2, and CHS2 genes in HLvd-infected leaves of-culturalic Celeia were found [34]. We can suppose that vivoid infection activates pathogen plant response reaction. Flavonoids and phenylpropanoids protect plants from abiotic and biological stresses, viruses [48], or fungal [49] pathogens. However, flavonoids (F3H) and anthocyanin (LAR) biosynthetic pathway genes were not influenced by vivoid infection. The OMT1 gene [28], for a last step of xanthohumol biosynthesis, was only down-regulated by infection in cones of the Saaz cultivar, even though the content of xanthohumol was significantly reduced for all the cultivars. The changes, which were found for relative expressions of intergenic biosynthetic pathway enzyme genes, did not correspond to the contents of essential oil compounds. The GPPS-SSU [25], MTS1, and MTS2 [24] enzyme genes of monoterpenes biosynthesis were down-regulated by infection in cones of the Saaz cultivar, despite the contents of monoterpenes being significantly increased. In a similar manner, the FPPS [23] enzyme gene for the biosynthesis of sesquiterpenes' precursor, was significantly up-regulated by infection in cones of Saaz; however, the contents of sesquiterpenes were significantly reduced. Conversely, the STS1 and STS2 [24] enzyme genes of sesquiterpenes biosynthesis were down-regulated by infection in cones of the Saaz cultivar, similar to the sesquiterpenes content reduction. Some of these gene expression trends were similar for other cultivars, except for the FPPS enzyme gene. However, there were no significant differences within essential oils compositions for Sladek, Premiant, and Agnus cultivars. Gene expression changes can influence different essential oils compounds, which is genotype-dependent [15]. Between differentially expressed genes in HLVd-infected leaves of cultivar Celeia [34], the STS1, TPS9, and NES genes were up-regulated. In our study, TPS9 was up-regulated only in cones of the Agnus cultivar and the NES gene in cones of the Premiant cultivar. In contrast, these genes were down-regulated in cones of the Sladek cultivar by vivoid infection. Terpenes, similar to flavonoids and phenylpropanoids, are involved in plant defense response [50], therefore vivoid infection can activate their biosynthesis. It was previously found that vivoid infection changed expressions of other genes involved in plant resistance [33]. Contents of secondary metabolites in glandular trichomes are not only influenced by structural biosynthesis genes but also by regulatory networks of involved transcription factors [29; 30; 31; 32]. From the studied factors, the MYB and bHLH transcription factors were mostly down-regulated by infection in cones and these differences can cause expression differences for biosynthesis pathways genes. MYB and bHLH can regulate transcription separately or in the tripartite MBW (MYB/bHLH/WDR) complex [29]. Promoter cis-acting regulatory DNA element analysis showed that the MBW complex cannot regulate BCAT1, OMT1, FPPS, MTS2, and TPS9 genes. For MYB regulatory factors, the cis-acting regulatory DNA element MYB1 AT was present in all the promoter sequences, except the FPPS gene, while others were missing irregularly in more sequences. The cis-acting regulatory DNA element for the bHLH (MYC) and WRKY transcription factors were present in all the studied promoter sequences. Biosynthesis pathway genes can thus be regulated together. Even though regulatory transcription factors can influence an expression of several genes together, there were too many changes which could be caused by vivoid-induced RNA interference [35]. Recently, the RPL5/TFIIIA-7 ZF regulatory cascade was found to be necessary for the replication of several viroids [37; 38; 39; 40; 41; 42].