Patzak Josef, Henychová Alena, Krofta Karel, Svoboda Petr, Malířová Ivana
Hop Research Institute Co., Ltd., Kadaňská 2525, 438 01 Žatec, Czech Republic.
Plants (Basel). 2021 Oct 26;10(11):2297. doi: 10.3390/plants10112297.
Viroids are small infectious pathogens, composed of a short single-stranded circular RNA. Hop ( L.) plants are hosts to four viroids from the family . Hop latent viroid (HLVd) is spread worldwide in all hop-growing regions without any visible symptoms on infected hop plants. In this study, we evaluated the influence of HLVd infection on the content and the composition of secondary metabolites in maturated hop cones, together with gene expression analyses of involved biosynthesis and regulation genes for Saaz, Sládek, Premiant and Agnus cultivars. We confirmed that the contents of alpha bitter acids were significantly reduced in the range from 8.8% to 34% by viroid infection. New, we found that viroid infection significantly reduced the contents of xanthohumol in the range from 3.9% to 23.5%. In essential oils of Saaz cultivar, the contents of monoterpenes, terpene epoxides and terpene alcohols were increased, but the contents of sesquiterpenes and terpene ketones were decreased. Secondary metabolites changes were supported by gene expression analyses, except essential oils. Last-step biosynthesis enzyme genes, namely humulone synthase 1 (HS1) and 2 (HS2) for alpha bitter acids and O-methytransferase 1 (OMT1) for xanthohumol, were down-regulated by viroid infection. We found that the expression of ribosomal protein L5 (RPL5) RPL5 and the splicing of transcription factor IIIA-7ZF were affected by viroid infection and a disbalance in proteosynthesis can influence transcriptions of biosynthesis and regulatory genes involved in of secondary metabolites biosynthesis. We suppose that RPL5/TFIIIA-7ZF regulatory cascade can be involved in HLVd replication as for other viroids of the family .
类病毒是一种小型传染性病原体，由短的单链环状RNA组成。蛇麻草（L.）植物是该科四种类病毒的宿主。蛇麻草潜隐类病毒（HLVd）在全球所有蛇麻草种植区传播，感染的蛇麻草植株没有任何可见症状。在本研究中，我们评估了HLVd感染对成熟蛇麻草球果中次生代谢物含量和组成的影响，并对萨兹、斯拉德克、普雷米安特和阿格努斯品种中参与生物合成和调控的基因进行了表达分析。我们证实，类病毒感染使α-苦味酸的含量显著降低了8.8%至34%。此外，我们发现类病毒感染使黄腐酚的含量显著降低了3.9%至23.5%。在萨兹品种的精油中，单萜、萜烯环氧化物和萜烯醇的含量增加，但倍半萜和萜烯酮的含量降低。除了精油外，基因表达分析支持了次生代谢物的变化。类病毒感染下调了最后一步生物合成酶基因，即α-苦味酸的葎草酮合酶1（HS1）和2（HS2）以及黄腐酚的O-甲基转移酶1（OMT1）。我们发现核糖体蛋白L5（RPL5）的表达和转录因子IIIA-7ZF的剪接受类病毒感染影响，蛋白质合成的失衡可能影响参与次生代谢物生物合成的生物合成和调控基因的转录。我们推测，RPL5/TFIIIA-7ZF调控级联可能像该科其他类病毒一样参与HLVd的复制。
