Balancing Growth and Defense: The Role of SIP68 in Tobacco Stress Responses
Abstract
UDP-glucosyltransferases (UGTs) are essential enzymes in plant metabolism that regulate growth, development, and stress responses through glucosylation of diverse substrates. SIP68, a UDP-glucosyltransferase identified as an interactor of salicylic acid-binding protein 2 (SABP2), has been implicated in salicylic acid (SA)-mediated defense signaling. Here, we investigated the broader role of SIP68 in plant development and stress responses. In-silico analyses generated testable hypotheses regarding its biological function/pathway involvement and guided subsequent wet-lab experiments, stress treatment, and targeted physiological and biochemical assays. It suggests a potential role for SIP68 in cytokinin-mediated metabolic pathways, implicating it in the regulation of plant growth and cell proliferation. To experimentally validate SIP68 function, SIP68-silenced transgenic tobacco plants were compared with wild-type controls under salinity and osmotic stress conditions. SIP68-silencing resulted in significant alterations in root and shoot growth, leaf width, and overall biomass accumulation, highlighting its importance in plant development. Physiological and biochemical analyses revealed increased chlorophyll content and altered antioxidant responses in SIP68-silenced plants. Catalase and peroxidase activity assays indicated changes in redox homeostasis, particularly under stress conditions. Furthermore, SIP68 contributes to plant defense against biotic stress. Infection assays using Tobacco mosaic virus (TMV) and bacterial pathogens demonstrated differential immune responses between wild-type and SIP68-silenced plants, consistent with its involvement in SA-mediated defense signaling. Earlier in vitro substrate-binding assays showed interaction with multiple flavanols, although identification of specific in-planta substrates remains unresolved. Collectively, these findings establish SIP68 as a multifunctional UGT integrating plant growth, oxidative stress regulation, and immune responses.
Start Time
15-4-2026 10:00 AM
End Time
15-4-2026 11:00 AM
Room Number
311
Presentation Type
Oral Presentation
Presentation Subtype
Grad/Comp Orals
Presentation Category
Science, Technology, and Engineering
Student Type
Graduate
Faculty Mentor
Dhirendra Kumar
Balancing Growth and Defense: The Role of SIP68 in Tobacco Stress Responses
311
UDP-glucosyltransferases (UGTs) are essential enzymes in plant metabolism that regulate growth, development, and stress responses through glucosylation of diverse substrates. SIP68, a UDP-glucosyltransferase identified as an interactor of salicylic acid-binding protein 2 (SABP2), has been implicated in salicylic acid (SA)-mediated defense signaling. Here, we investigated the broader role of SIP68 in plant development and stress responses. In-silico analyses generated testable hypotheses regarding its biological function/pathway involvement and guided subsequent wet-lab experiments, stress treatment, and targeted physiological and biochemical assays. It suggests a potential role for SIP68 in cytokinin-mediated metabolic pathways, implicating it in the regulation of plant growth and cell proliferation. To experimentally validate SIP68 function, SIP68-silenced transgenic tobacco plants were compared with wild-type controls under salinity and osmotic stress conditions. SIP68-silencing resulted in significant alterations in root and shoot growth, leaf width, and overall biomass accumulation, highlighting its importance in plant development. Physiological and biochemical analyses revealed increased chlorophyll content and altered antioxidant responses in SIP68-silenced plants. Catalase and peroxidase activity assays indicated changes in redox homeostasis, particularly under stress conditions. Furthermore, SIP68 contributes to plant defense against biotic stress. Infection assays using Tobacco mosaic virus (TMV) and bacterial pathogens demonstrated differential immune responses between wild-type and SIP68-silenced plants, consistent with its involvement in SA-mediated defense signaling. Earlier in vitro substrate-binding assays showed interaction with multiple flavanols, although identification of specific in-planta substrates remains unresolved. Collectively, these findings establish SIP68 as a multifunctional UGT integrating plant growth, oxidative stress regulation, and immune responses.
