Role of SIW14 in Plant Genetics and Physiology

Abstract

When soil inorganic phosphate (Pi) availability is low, plants upregulate Pi starvation response (PSR) genes to maintain Pi-homeostasis. Recent evidence shows that inositol pyrophosphates (PP-InsPs), energy-rich molecules that have seven and eight Pi groups (InsP7 and InsP8), aid in PSR gene regulation. InsP8 levels are controlled by conserved enzymes that add or remove Pi group from its precursors. In yeast, Siw14 is one of the conserved phosphatases that removes Pi from PP-InsPs. Yeast Siw14 loss-of-function mutants (siw14Δ) have higher PP-InsPs compared to Wild-Type (WT) yeast. While plants also have SIW14 and it is suggested to bind and hydrolyze PP-InsPs, its role in planta remains elusive. To explore the role of SIW14 in planta, we studied the genetic impacts of SIW14 in Arabidopsis thaliana in two disparate environments. Additionally, we investigated if there are genes that overlap between the yeast environment-stress-response (ESR) system and the plant PSR. As PP-InsPs act as signaling molecules in both yeast and plants, we determined whether yeast ESR response is conserved in Arabidopsis by comparing transcriptomic data. We queried individual genes from three independent studies with transcriptomic data from yeast and Arabidopsis mutants with altered PP-InsPs. While further study is required, Arabidopsis does not appear to have a conserved ESR response compared to yeast. Based on our observations and previous studies, SIW14 has a role in altering the level of PP-InsPs in Arabidopsis which are suggested to impact the plant PSR.