[SCAN] Alternative splicing of root membrane transporter controls plant tolerance to zinc toxicity

SCAN

Title: Alternative splicing of root membrane transporter controls plant tolerance to zinc toxicity

Speaker: Paula Duque

Affiliation: Plant Molecular Biology, IGC

Abstract:

Alternative splicing, which generates multiple mRNAs from the same gene, is a key posttranscriptional regulatory mechanism in higher eukaryotes whose functional relevance in plants remains poorly understood. The sequestration of metal ions inside the vacuole of root cells is one of the best-conserved strategies employed by plants to cope with heavy metal toxicity. We identified a vacuolar transporter in Arabidopsis, ZIF2, that confers tolerance to zinc (Zn) by promoting root immobilization of the metal. The ZIF2 gene is highly induced in roots under Zn toxicity, and an intron retention event in its 5’UTR generates two splice variants encoding the same functional transporter that mediates Zn efflux when heterologously expressed in yeast. Importantly, high Zn favors production of the longer transcript, which confers greater Zn tolerance to transgenic plants by promoting higher root Zn immobilization. We show that the retained intron in the ZIF2 5’UTR enhances translation in a Zn-responsive manner, markedly promoting ZIF2 protein expression under excess Zn. This translational regulation is dependent on a stable stem loop that is lost upon splicing of the 5’UTR intron. Thus, alternative splicing controls the levels of a Zn-responsive mRNA variant of the ZIF2 transporter to enhance plant tolerance to the metal ion.