# The FBXL Gene Family in Tobacco (Nicotiana tabacum L.): Identification and Expression Response to TMV and Abiotic Stresses

## TL;DR

This study identifies and analyzes the FBXL gene family in tobacco, revealing their roles in stress responses and potential for improving stress resistance.

## Contribution

The first genome-wide analysis of the FBXL gene family in tobacco, identifying 47 genes and their roles in stress and antiviral defense.

## Key findings

- 47 NtaFBXL genes were identified and classified into five clades, with Clade III showing notable expansion.
- Six NtaFBXL genes negatively correlated with TMV accumulation, suggesting antiviral roles.
- Drought and TMV stress disrupted redox homeostasis, linked to specific NtaFBXL gene expression and antioxidant enzyme activity.

## Abstract

F-box-LRR (FBXL) proteins are crucial components of the SCF ubiquitin ligase complex, regulating diverse processes such as development and stress responses in plants. However, the FBXL family in tobacco (Nicotiana tabacum L.) remains poorly characterized. This study performed the first genome-wide analysis of the FBXL gene family in tobacco and identified 47 NtaFBXL genes. Phylogenetic analysis classified them into five clades, among which Clade III exhibited notable expansion. Promoter analysis revealed abundant stress- and hormone-related cis-elements. Expression profiling demonstrated tissue-specific patterns and strong responses to drought, ABA, IAA, and TMV infection. Importantly, six genes exhibited a significant negative correlation with TMV accumulation, suggesting their potential roles in antiviral defense. Moreover, both drought and TMV stress triggered a disturbance of redox homeostasis, a dynamic process that was closely associated with the expression of specific NtaFBXL genes, characterized by upregulated antioxidant enzymes (SOD, POD, CAT) and accumulated oxidative markers (H2O2, MDA). Collectively, this study provided a foundational resource for understanding the function of NtaFBXLs and identified key candidate genes for the genetic improvement of stress resistance in tobacco.