Towards the Identification of New Genes Involved in ABA-Dependent Abiotic Stresses Using Arabidopsis Suppressor Mutants of abh1 Hypersensitivity to ABA during Seed Germination

Agata Daszkowska-Golec,Edyta Chorazy,Iwona Szarejko,Miroslaw Maluszynski

doi:10.3390/ijms140713403

Agata Daszkowska-Golec, Edyta Chorazy + Show 2 more

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https://doi.org/10.3390/ijms140713403

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Abstract

Abscisic acid plays a pivotal role in the abiotic stress response in plants. Although great progress has been achieved explaining the complexity of the stress and ABA signaling cascade, there are still many questions to answer. Mutants are a valuable tool in the identification of new genes or new alleles of already known genes and in elucidating their role in signaling pathways. We applied a suppressor mutation approach in order to find new components of ABA and abiotic stress signaling in Arabidopsis. Using the abh1 (ABA hypersensitive 1) insertional mutant as a parental line for EMS mutagenesis, we selected several mutants with suppressed hypersensitivity to ABA during seed germination. Here, we present the response to ABA and a wide range of abiotic stresses during the seed germination and young seedling development of two suppressor mutants—soa2 (suppressor of abh1 hypersensitivity to ABA 2) and soa3 (suppressor of abh1 hypersensitivity to ABA 3). Generally, both mutants displayed a suppression of the hypersensitivity of abh1 to ABA, NaCl and mannitol during germination. Both mutants showed a higher level of tolerance than Columbia-0 (Col-0—the parental line of abh1) in high concentrations of glucose. Additionally, soa2 exhibited better root growth than Col-0 in the presence of high ABA concentrations. soa2 and soa3 were drought tolerant and both had about 50% fewer stomata per mm2 than the wild-type but the same number as their parental line—abh1. Taking into account that suppressor mutants had the same genetic background as their parental line—abh1, it was necessary to backcross abh1 with Landsberg erecta four times for the map-based cloning approach. Mapping populations, derived from the cross of abh1 in the Landsberg erecta background with each suppressor mutant, were created. Map based cloning in order to identify the suppressor genes is in progress.

Highlights

IntroductionThe Role of Abscisic Acid in the Seed Germination Process
When abscisic acid (ABA) was applied in a concentration of 15 μM at the seedling stage, soa2 exhibited only a 30% root growth reduction compared to the control conditions, whereas root growth in soa3 Col-0 and abh1 was reduced by 70%
On the basis of a detailed characterization of suppressor mutants, an attempt was undertaken to identify the suppressor mutations that led to ABA insensitivity during germination

Summary

Introduction

The Role of Abscisic Acid in the Seed Germination Process. Seed germination commences with water uptake, which is triphasic and lasts until the emergence of the radicle. A complicated network of changes in transcription and protein metabolism, together with changes in the endogenous content of phytohormones, such as abscisic acid (ABA), gibberellins (GAs), brassinosteroids (BRs), ethylene (ET), salicylic acid (SA) and auxins, regulate the process of seed germination in order to ensure the survival of future generations [1]. When a sudden abiotic stress occurs between the first exposure of seeds to water and the cotyledon greening, the seed germination process can be arrested [2,3,4]. In order to maintain or break the period of arrested germination and to complete the germination program, different metabolic pathways, including phytohormone biosynthesis and signaling, are involved.

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