Research Projects

Crop improvement is essentially the balancing aspect between food security and the emergent global population. Rice is a major cereal crop, consumed worldwide and maximizing its yield potential to meet the expanding global population is of paramount concern. Nutrient such as nitrogen (N) is one of the key determinant controlling rice plant growth and its architectural plasticity by modulating the growth hormones such as auxin, cytokinin, and brassinosteroids. However, achieving optimal productivity is challenging due to the complex and interconnected relationships between internal factors, such as growth hormones, and environmental factors like nutrients. Brassinosteroids (BRs) are polyhydroxysteroid growth hormones, governing essential plant responses under optimal and stress conditions. In rice, BR mediates several agronomic traits such as height of plant, leaf angle and erectness, seed germination, flowering time, grain size, grain filling, grain number, and tillering (Xiong et al., 2022). Furthermore, manipulating BR-biosynthetic and signaling genes leads to severe dwarfism, reduced development, and limits grain yield (He et al., 2024). In rice, OsBZR1 is the principal regulator of the BR-signaling pathway, which is phosphorylates and suppressed by OsGSK2 through 14-3-3-mediated cytoplasmic retention. It is well established that BR signaling regulates N-responsive growth in plants including tomato, Arabidopsis and maize (Devi et al., 2022, Xing et al., 2023). However, the mechanisms of BR regulated N uptake and homeostasis and genes modulating BR-signaling response under low N condition are still lacking. In rice, several U-box E3 ligases have been validated for their role in plant growth (Ban Z & Estelle M., 2021). These proteins lead to ubiquitination and degradation of proteins involved in abiotic and biotic stress responses including plant defense mechanism, and reproductive organ development (Kaur et al., 2023, Yoo et al., 2020, Kim et al., 2024). A recent study has reported OsPUB24 negatively regulates BR-signaling by degrading OsBZR1 through 26S proteasome-dependent degradation. Additionally, OsGSK2 which directly inhibits the activity of OsBZR1, phosphorylates OsPUB24 and enhances its cellular integrity (Min et al., 2019). However, so far, the function of OsPUB24 in governing the plant growth and nutrient homeostasis is completely unknown. Therefore, in this research plan, we aim to understand OsPUB24-dependent BR signaling responses under deficient N conditions in rice (MTU1010). This proposal deciphers the mechanisms (physiological and molecular) of OsPUB24 in governing N homeostasis by using CRISPR/Cas9 edited knockout lines of OsPUB24. Further, identification of interacting partners, potentially regulating N deficiency dependent plant growth and N homeostasis will be pivotal for developing rice lines with improved N exploitation and assimilation.