The conserved splicing factor SUA controls alternative splicing of the developmental regulator ABI3 in Arabidopsis.

Matteo Sugliani,Maarten Koornneef,Vittoria Brambilla,Emile J M Clerkx,Wim J J Soppe

doi:10.1105/tpc.110.074674

Abstract

ABSCISIC ACID INSENSITIVE3 (ABI3) is a major regulator of seed maturation in Arabidopsis thaliana. We detected two ABI3 transcripts, ABI3-alpha and ABI3-beta, which encode full-length and truncated proteins, respectively. Alternative splicing of ABI3 is developmentally regulated, and the ABI3-beta transcript accumulates at the end of seed maturation. The two ABI3 transcripts differ by the presence of a cryptic intron in ABI3-alpha, which is spliced out in ABI3-beta. The suppressor of abi3-5 (sua) mutant consistently restores wild-type seed features in the frameshift mutant abi3-5 but does not suppress other abi3 mutant alleles. SUA is a conserved splicing factor, homologous to the human protein RBM5, and reduces splicing of the cryptic ABI3 intron, leading to a decrease in ABI3-beta transcript. In the abi3-5 mutant, ABI3-beta codes for a functional ABI3 protein due to frameshift restoration.

Highlights

Seeds are essential for the spread and survival of most plant species and constitute a major food source
abscisic acid (ABA) signaling at this stage is concomitant with the expression of four major regulatory genes of seed maturation with partially redundant functions: LEAFY COTYLEDON1 (LEC1), LEC2, FUSCA3 (FUS3), and ABSCISIC ACID INSENSITIVE3 (ABI3) (Kroj et al, 2003; To et al, 2006)
A strong suppressor mutant of abi3-5 was identified in the M2 generation and named suppressor of abi3-5

Summary

Introduction

Seeds are essential for the spread and survival of most plant species and constitute a major food source. In Arabidopsis thaliana, the phytohormone abscisic acid (ABA) controls seed maturation and dormancy by preventing germination and reserve mobilization. ABA signaling at this stage is concomitant with the expression of four major regulatory genes of seed maturation with partially redundant functions: LEAFY COTYLEDON1 (LEC1), LEC2, FUSCA3 (FUS3), and ABSCISIC ACID INSENSITIVE3 (ABI3) (Kroj et al, 2003; To et al, 2006). B2 and B3 are two basic DNA binding domains responsible for the ABA-dependent activation of seed maturation genes (Suzuki et al, 1997; Ezcurra et al, 2000; Nag et al, 2005)

Methods

Results

Conclusion