Chloroplasts participate in plant-pathogen interactions by affecting reactive oxygen species (ROS) homeostasis, photosystem II (PSII) functionality, and spectral signature modulation. Focusing on light-harvesting complex II (LHCII) components, we characterized the role of CaLhcb1-like in pepper (Capsicum annuum) resistance to Ralstonia solanacearum. Comparative transcriptomic analysis of susceptible (HS03) and resistant (HR01) cultivars revealed genotype-specific expression patterns of CaLhcb1-like. Subcellular localization confirmed that CaLhcb1-like is chloroplast-targeted. Virus-induced gene silencing (VIGS) showed that CaLhcb1-like knockdown enhanced bacterial wilt resistance. This was accompanied by attenuated multispectral reflectance changes at 400-690 nm, altered PSII parameters (effective quantum yield, Fq'/Fm', and relative electron transport rate, ETR), biphasic ROS dynamics with an early burst before 2 hpi followed by a decline at 6 hpi, and upregulation of genes in plant-pathogen interaction and phenylpropanoid biosynthesis pathways. Biochemical assays further validated increased peroxidase activity and lignin accumulation in silenced lines. These findings demonstrate that CaLhcb1-like negatively regulates defense responses through ROS homeostasis and lignin accumulation, providing molecular links between multispectral variation and disease progression.

Auxin/indole acetic acid (Aux/IAA) proteins repress the expression of auxin-responsive genes to mediate environmental abiotic stresses. Distinct auxinic herbicides are differentially involved in the auxin signaling pathway, affecting the functional role of specific Aux/IAA members. However, the role of Aux/IAA in modulating the sensitivity of eggplant (Solanum melongena L.) to the auxinic herbicide picloram remains largely unexplored. This study aims to identify putative Aux/IAA gene family members in eggplant and to characterized their functional roles in response to auxinic herbicide picloram (HRAC, group 4), offering potential molecular targets for the development of herbicide-resistant eggplant. We conducted the genome-wide identification of Aux/IAA gene family members in eggplant and analyzed their expression profiles in response to picloram. We systematically characterized the functional role of SmIAA15 in response to the herbicide picloram and uncovered the molecular mechanisms underlying SmIAA15-mediated sensitivity of eggplant to picloram using a combination of molecular and biochemical approaches. We identified twenty-three putative Aux/IAA gene family members in eggplant. Under picloram treatment, SmIAA15 was significantly induced and localized to the nucleus. Overexpression of SmIAA15 in tobacco notably decreased resistance against picloram, while virus-induced gene silencing of SmIAA15 in eggplant enhanced resistance to picloram. KEGG analysis of transcriptome data from SmIAA15-silenced lines revealed that the enhanced resistance to picloram was associated with the glutathione metabolism pathway, as evidenced by increased glutathione S-transferases (GST) enzyme activity and upregulation of GST-related genes in SmIAA15-silenced lines. Consistently, stable transgenic tomato lines overexpressing SmIAA15 displayed a picloram-induced phenotype with outwardly curved leaves, and decreased GST activity compared to the non-transgenic controls. Collectively, our findings demonstrate that SmIAA15 acts as a negative regulator in response to picloram by regulating the glutathione S-transferase enzyme activity, potentially contributing to the molecular breeding of picloram-resistant eggplant.

Verticillium wilt, caused primarily by Verticillium dahliae and, in some hosts, V. albo-atrum, causes substantial yield losses in solanaceous crops. The disease is characterized by colonization of the vascular system, which can impair water transport and plant growth. Effective resistance therefore requires restricting vascular colonization while preserving vascular function and plant performance. Although considerable progress has been made in identifying resistance genes and defense responses, the molecular and physiological basis of Verticillium wilt resistance varies widely, and remains incompletely understood across solanaceous crops. Here, we summarize current knowledge of Verticillium wilt resistance in tomato, eggplant, potato, and pepper, focusing on vascular defense, immune signaling, lignification, and major resistance genes, loci, and quantitative genetic factors. We also discuss grafting-mediated resistance, highlighting resistant rootstocks and genetic resources, physiological and rhizosphere mechanisms of rootstock-mediated protection, and the potential roles of mobile signals in rootstock–scion communication. Furthermore, we examine the potential role of lignin remodeling as an interface between vascular defense and plant performance, while distinguishing disease-associated growth losses from potential defense-associated costs. We propose an integrative framework for evaluating resistance through pathogen restriction, vascular function, and agronomic performance, emphasizing that the relationships among these processes require further experimental validation. Finally, we outline future research priorities, including the identification and functional validation of resistance genes, quantitative assessment of vascular defense and its potential growth costs, and investigation of the causal contributions of grafting-associated signals and rhizosphere microbiomes. This review provides a framework for understanding Verticillium wilt resistance across solanaceous crops and highlights research priorities for developing durable resistance while maintaining crop productivity and quality.