Although structurally simple, viroids can trigger numerous changes in host plants and cause loss of yield in agronomically important crops. This study investigated changes in the endogenous status of phytohormones and antioxidant enzyme activity in Solanum tuberosum cv. Désirée in response to Potato spindle tuber viroid (PSTVd) infection. Phytohormone analysis showed that the content of endogenous jasmonic acid (JA) and its precursor cis-OPDA significantly increased in leaves, while the content of castasterone (CS) increased in both leaves and tubers of systemically infected plants compared to mock-inoculated control plants at 8 weeks post-inoculation. The indole-3-acetic acid content moderately increased only in tubers, while no differences in salicylic acid and abscisic acid content were observed between infected and control plants. Changes in endogenous phytohormone content were associated with upregulated expression of genes involved in the biosynthesis of JA and brassinosteroids, and the metabolism of auxins. Additionally, PSTVd infection provoked overproduction of hydrogen peroxide, which coincided with increased activity of guaiacol peroxidase in leaves and ascorbate peroxidase in potato tubers. The activity of catalase decreased in leaves, while superoxide dismutase activity remained steady regardless of the treatment and organ type. Total ascorbate and glutathione did not change significantly, although a shift towards oxidized forms was observed. Results suggest the existence of organ-specific differences in phytohormone and antioxidative responses in potato upon PSTVd infection. Possible effects of the observed changes on symptom development are discussed.

• Klíčová slova
• Ascorbate, Brassinosteroids, IAA, JA, PSTVd, Peroxidases,
• MeSH
• antioxidancia metabolismus   MeSH
• brassinosteroidy metabolismus   MeSH
• chlorofyl metabolismus   MeSH
• cholestanoly metabolismus   MeSH
• cyklopentany metabolismus   MeSH
• hlízy rostlin metabolismus   MeSH
• kyseliny indoloctové metabolismus   MeSH
• listy rostlin metabolismus   MeSH
• nemoci rostlin virologie   MeSH
• oxylipiny metabolismus   MeSH
• regulátory růstu rostlin metabolismus   MeSH
• Solanum tuberosum metabolismus   fyziologie   virologie   MeSH
• viroidy metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• antioxidancia MeSH
• brassinosteroidy MeSH
• castasterone MeSH Prohlížeč
• chlorofyl MeSH
• cholestanoly MeSH
• cyklopentany MeSH
• indoleacetic acid MeSH Prohlížeč
• jasmonic acid MeSH Prohlížeč
• kyseliny indoloctové MeSH
• oxylipiny MeSH
• regulátory růstu rostlin MeSH

Habituated embryogenic line of pumpkin contained more CKs and IAA, but less ABA than the non-habituated line. Pronounced hypomethylation correlated with the absence of 2,4-D, addition of 5-azaC, and the process of habituation. A comparative analysis between habituated and non-habituated embryogenic cultures of pumpkin (Cucurbita pepo L.) in relation to endogenous phytohormones, global DNA methylation, and developmental and regeneration capacities of the cultures was conducted. The analysis revealed more cytokinins (CKs) and indole-3-acetic acid (IAA), but less abscisic acid (ABA) in the habituated HEC line than in the non-habituated DEC line. Ribosides and ribotides were the most abundant CK forms in both HEC and DEC lines (75.9 and 57.6 %, respectively). HEC contained more free-base CKs (5.8 vs. 3.2 %), whereas DEC contained considerably more O-glycosides (39.1 vs. 18.3 %). Although prevalence of IAA was common for both lines, relative ratio of CKs and ABA differed between DEC and HEC lines. ABA was prevailing over CKs in DEC, while CKs prevailed over ABA in HEC line. Taking into account the importance of ABA for embryo maturation, the reduced endogenous ABA content in HEC line might be the reason for a 5-fold reduction in regeneration capacity compared to DEC. Both habituated and non-habituated embryogenic lines were highly methylated in the presence of 2,4-dichlorophenoxyacetic acid (2,4-D). Pronounced hypomethylation correlated with the absence of 2,4-D, addition of 5-azacytidine (5-azaC), but also with the process of habituation. The habituated line was resistant to the effect of hypomethylation drug 5-azaC and remained highly methylated even after the addition of 5-azaC. Also, 5-azaC did not change the developmental pattern in the habituated line, indicating the existence of separate mechanisms by which 2,4-D influences global DNA methylation in comparison to habituation-related global DNA methylation.

• Klíčová slova
• ABA, CKs, DNA methylation, Habituation, IAA, Somatic embryogenesis,
• MeSH
• azacytidin farmakologie   MeSH
• Cucurbita účinky léků   embryologie   genetika   MeSH
• cytokininy metabolismus   MeSH
• epigeneze genetická účinky léků   MeSH
• herbicidy farmakologie   MeSH
• inhibitory enzymů farmakologie   MeSH
• kyselina 2,4-dichlorfenoxyoctová farmakologie   MeSH
• kyselina abscisová metabolismus   MeSH
• kyseliny indoloctové metabolismus   MeSH
• metylace DNA účinky léků   MeSH
• regulátory růstu rostlin metabolismus   MeSH
• somatická embryogeneze rostlin MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• azacytidin MeSH
• cytokininy MeSH
• herbicidy MeSH
• indoleacetic acid MeSH Prohlížeč
• inhibitory enzymů MeSH
• kyselina 2,4-dichlorfenoxyoctová MeSH
• kyselina abscisová MeSH
• kyseliny indoloctové MeSH
• regulátory růstu rostlin MeSH