Research Projects

Inositol pyrophosphates (PP-InsPs) such as InsP7 and InsP8, have recently been identified as pivotal cellular signaling molecules that regulate a broad spectrum of physiological processes, including phosphate homeostasis and immune responses in land plants. Mutants deficient in PP-InsPs often display impaired growth phenotypes and developmental deects. For example, Arabidopsis thaliana ipk1 mutants, defective in the synthesis of InsP₆ as well as InsP₇, and InsP₈, exhibit compromised growth relative to their isogenic wild-type counterparts. Similarly, the InsP8-deficient vih1vih2 double mutant is seedling-lethal. While some of these developmental abnormalities have been associated with altered hormonal signaling pathways, the precise molecular mechanisms by which PP-InsPs regulate plant growth and development remain poorly understood. Notably, the majority of research on PP-InsP species has focused on the model eudicot Arabidopsis, leaving a significant knowledge gap regarding the presence and functional roles of PP-InsPs in non-vascular and non-seed plant species. Moreover, it remains unclear whether the regulatory functions of PP-InsPs in modulating cellular physiology are conserved across the land plant lineage. Furthermore, it remains to be elucidated whether PP-InsPs contributed to the evolutionary transition of plants to terrestrial environments by mediating environmental signal transduction for key biological processes. We aim to address these outstanding questions in our proposed research. Specifically, we will employ M. polymorpha and Arabidopsis thaliana as the model plant species to illuminate the conserved role of VIH-derived inositol pyrophosphate, InsP8 in regulating growth and development in land plants. The key experiments of the proposed objectives are: Objective 1: We will perform SAX-HPLC and capillary electrophoresis-mass spectrometry (CE-MS) to determine the contribution of MpVIH in InsP8 synthesis in planta. Objective 2: We aim to investigate the physiological consequences of plants with compromised MpVIH function. We will generate a series of transgenic lines to determine the contribution of catalytic activity of MpVIH in regulating thallus growth. We will also explore the cell division pattern of MpVIH-defective lines. Objective 3: Molecular basis of InsP8-controlled plant differentiation and development: To this end, we will perform unbiased MS-based screen to identify novel cellular targets of InsP8 responsible for plant development. Subsequently, we will illuminate the role of InsP8 in controlling its receptor function in plant development and other physiological processes using biochemical and genetic approaches. Objective 4: We will determine the conserved role of VIH-type proteins in regulating development in the flowering plant, Arabidopsis. The findings of this study might have profound impact on different domains of plant science: i) Insights into the role of inositol pyrophosphate messengers in land plant evolution: The proposed study is expected to identify cellular targets of PP-InsP messengers that are unique to land plants. Illuminating the role of InsP8 in regulating land plant-specific receptors will shed light on the deeply rooted evolutionary functions of InsP8 in plant development and other physiological processes, potentially revealing how these cellular messengers contributed to land plant evolution. ii) Creating new avenues for plants with optimized growth and yield: This study employs the non-vascular bryophyte and the eudicot to elucidate the conserved role of InsP₈ in regulating plant growth and development. Our findings may reveal genetic strategies to enhance crop yield and resilience to climate change. In summary, our proposed research aims to make pioneering discoveries that will not only deepen our understanding of fundamental biological processes but might create avenues for translational applications with the potential to benefit society on a broad scale.