Viroids are small, non-coding, pathogenic RNAs with the ability to disturb plant developmental processes. This dysregulation redirects the morphogenesis of plant organs, significantly impairing their functionality. Citrus bark cracking viroid (CBCVd) causes detrimental developmental distortions in infected hops (Humulus lupulus) and causes significant economic losses. CBCVd can infect cells and tissues of the model plant tobacco (Nicotiana tabacum), provided it is delivered via transgenesis. The levels of CBCVd in tobacco were enhanced in plant hybrids expressing CBCVd cDNAs and either the tobacco or hop variant of TFIIIA-7ZF, a viroid-mediated splicing derivative of transcription factor IIIA, which is important for viroid replication by DNA-dependent RNA polymerase II. The TFIIIA-7ZF variants can change the tobacco morphogenesis if expressed in leaves and shoots. In addition to the splitting of shoots, the "pathomorphogenic" network in hybrid plants expressing CBCVd and HlTFIIIA-7ZF induced leaf fusions and malformations. Moreover, CBCVd can dramatically change another morphogenesis into teratomic and petal-like tissues if propagated above some limit in young transgenic tobacco microspores and anthers. By comparative RNA profiling of transgenic tobacco shoots bearing TFIIIA-7ZFs and CBCVd-transformed/infected anthers, we found a differential expression of many genes at p < 0.05. As the main common factor showing the differential up-regulation in shoot and anther tissues, a LITTLE ZIPPER 2-like transcription factor was found. We propose that this factor, which can interact as a competitive inhibitor of the also dysregulated homeobox-leucin zipper family protein (HD-ZIPIII) in apical meristem, is essential for a network responsible for some morphological changes and modifications of plant degradome within shoot meristem regulation and secondary xylem differentiation.

• Klíčová slova
• Nicotiana tabacum, plant transformation, regulation of plant morphogenesis, transcription factors, transcriptome profiling, viroid pathogenesis,
• MeSH
• Citrus * metabolismus   MeSH
• Humulus * genetika   MeSH
• kůra rostlin metabolismus   MeSH
• malá nekódující RNA * MeSH
• nemoci rostlin genetika   MeSH
• tabák genetika   metabolismus   MeSH
• transkripční faktor TFIIIA genetika   metabolismus   MeSH
• viroidy * metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• malá nekódující RNA * MeSH
• transkripční faktor TFIIIA MeSH

Viroids are small, non-coding, pathogenic RNAs with a significant ability of adaptation to several basic cellular processes in plants. TFIIIA-7ZF, a splicing variant of transcription factor IIIA, is involved in replication of nuclear-replicating viroids by DNA-dependent polymerase II. We overexpressed NbTFIIIA-7ZF from Nicotiana benthamiana in tobacco (Nicotiana tabacum) where it caused morphological and physiological deviations like plant stunting, splitting of leaf petioles, pistils or apexes, irregular branching of shoots, formation of double-blade leaves, deformation of main stems, and modification of glandular trichomes. Plant aging and senescence was dramatically delayed in transgenic lines. Factors potentially involved in viroid degradation and elimination in pollen were transiently depressed in transgenic leaves. This depressed "degradome" in young plants involved NtTudor S-like nuclease, dicers, argonoute 5, and pollen extracellular nuclease I showing expression in tobacco anthers and leaves. Analysis of the "degradome" in tobacco leaves transformed with either of two hop viroids confirmed modifications of the "degradome" and TFIIIA expression. Thus, the regulatory network connected to TFIIIA-7ZF could be involved in plant pathogenesis as well as in viroid adaptation to avoid its degradation. These results support the hypothesis on a significant impact of limited TFIIIA-7ZF on viroid elimination in pollen.

• Klíčová slova
• Nicotiana tabacum, nucleolytic enzymes, plant aging, plant morphology changes, plant transformation, transcription factors, viroid,
• MeSH
• malá nekódující RNA * MeSH
• pyl genetika   MeSH
• tabák genetika   MeSH
• transkripční faktor TFIIIA MeSH
• užívání tabáku MeSH
• viroidy * genetika   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• malá nekódující RNA * MeSH
• transkripční faktor TFIIIA MeSH