The plant hormone abscisic acid (ABA) plays a crucial role throughout the plant life cycle and in adaptive responses to environmental stresses. The pyrabactin resistance 1-like (PYR/PYL/RCAR) proteins act as key regulators in the ABA signal transduction pathway by functioning as direct receptors for ABA. Although PYL genes have been identified in a variety of plant species, their evolutionary and structural characteristics in tomatoes (Solanum lycopersicum) remain elusive. To address this gap, we identified nine SlPYL genes, which were classified into three subfamilies: I (two genes), II (three genes), and III (four genes), and their encoded proteins were predicted to be primarily localized in the cytosol and chloroplast. Structural analysis revealed diverse exon–intron organizations along with five conserved motifs. All identified SlPYLs contained the START domain (PF10604), validating their identity as actual PYL proteins. Prediction of cis-acting regulatory elements in SlPYL’s promoter regions was found to be associated with light responsiveness, hormone signaling, stress responses, and plant growth and development. Prediction of post-translational modification sites indicated that SlPYLs are predominantly phosphorylated and acetylated at serine and lysine residues, respectively. Tertiary structure modeling demonstrated conserved three-dimensional architectures among SlPYL proteins, supporting their functional conservation. Expression profiling revealed that specific SlPYL genes exhibit distinct expression patterns across different tissues (root, leaf, and bud) following ABA treatment, indicating functional diversification. Considering the well-established negative correlation between ABA accumulation and bud outgrowth, the ABA-induced differential expression (3~5-fold) of some SlPYL genes (SlPYL3, SlPYL4, SlPYL7, and SlPYL8), particularly in bud tissues after 24 hpt, suggests a potential role in ABA-mediated suppression of bud outgrowth. However, these functional inferences are primarily based on genome-wide computational analyses and expression profiling and therefore require further experimental validation.

Turnip mosaic virus (TuMV), an important member of the Potyvirus genus, exhibits broad host adaptability with increased prevalence under moderate drought and elevated temperature conditions. While our previous research identified eukaryotic translation initiation factor 2Bβ (eIF2Bβ) as a critical resistance determinant against TuMV in mustard (Brassica juncea), the mechanistic interplay between environmental factors and viral pathogenesis remains poorly understood. Here, we demonstrated that drought facilitates TuMV infection in an abscisic acid (ABA)–dependent manner in B. juncea. Integrated coexpression analysis revealed the functional relevance between ABA signaling and eukaryotic translation initiation pathways. We showed that ABA-responsive element–binding factor 4 (ABF4) directly binds to the eIF2Bβ promoter and activates its expression and that ABF4 overexpression significantly enhances TuMV accumulation in wild-type plants. Notably, eIF2Bβ knockout lines exhibited significantly reduced viral accumulation even when ABF4 was overexpressed, establishing that functional eIF2Bβ is required to mediate ABF4-dependent viral infection. These findings elucidate a new ABA–eIF2Bβ regulatory module that links drought responses with plant–virus interactions, providing mechanistic insights into the role of environmental factors in modulating pathogen susceptibility.