Abstract
Plant leaf morphology has a great impact on plant drought resistance, ornamental research and leaf yield. In this study, we identified a new gene in Nicotiana plumbaginifolia, NpFBA1, that causes leaf curl. The results show that the NpFBA1 protein contains only one unique F-box associated (FBA) domain and does not have an F-box conserved domain. Phylogenetic analysis placed this gene and other Nicotiana FBA genes on a separate branch, and the NpFBA1 protein localized to the nucleus and cytoplasm. The expression of NpFBA1 was induced by black shank pathogen (Phytophthora parasitica var. nicotianae) infection and treatment with salicylic acid (SA) and methyl jasmonate (MeJA). NpFBA1-overexpressing transgenic lines showed leaf curling and aging during the rosette phase. During the bolting period, the leaves were curly and rounded, and the plants were dwarfed. In addition, NpFBA1-overexpressing lines were more susceptible to disease than wild-type (WT) plants. Further studies revealed that overexpression of NpFBA1 significantly downregulated the expression of auxin response factors such as NtARF3 and the lignin synthesis genes NtPAL, NtC4H, NtCAD2, and NtCCR1 in the leaves. In conclusion, NpFBA1 may play a key role in regulating leaf development and the response to pathogen infection.
Highlights
Introduction published maps and institutional affilThe ubiquitin-proteasome system (UPS) is the predominant proteolytic pathway within eukaryotes
N. plumbaginifolia material was used for gene cloning and spatiotemporal expression, N. tabacum was used for transgene tests, and N. benthamiana was used for transient expression
The alignment of NpFBA1 to the mRNA of the common tobacco FBA gene revealed that it has a base insertion at 651 bp, which results in a backward shift of stop codons and altered amino acid sequences, which may cause large functional differences
Summary
The ubiquitin-proteasome system (UPS) is the predominant proteolytic pathway within eukaryotes. Ubiquitin is activated by covalent ligation to ubiquitin activating enzyme (E1), transferred to ubiquitin conjugating enzyme (E2) and added to ubiquitin ligase (E3), and the ubiquitin labeled target protein is recognized and degraded by the. The UPS regulates key physiological processes in plants, such as growth and development, hormone signaling, self-incompatibility, and resistance to pathogen invasion [2]. The selection of targeted substrates is often determined by the secondary domain of the F-box protein (FBP) [4]. The F-boxassociated (FBA) domain often appears as the C-terminal secondary domain of the F-box protein. Secondary domains of the F-box include leucine zipper (LRR), WD iations
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