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ARTICLE

Dithiothreitol and PEG Induced Combined Stress May Affect the Expressions of ABA Aldehyde Oxidase, Sucrose Synthase and Proline Metabolic Genes in Maize Seedlings

Cansu Altuntaş¹, Rabiye Terzi^1,*

1 Karadeniz Technical University, Department of Biology, Faculty of Science, Trabzon, 61080, Turkey

* Corresponding Author: Rabiye Terzi. Email:

(This article belongs to the Special Issue: Crop Production under Abiotic Stress: Physiological and Molecular Interventions)

Phyton-International Journal of Experimental Botany 2020, 89(3), 487-495. https://doi.org/10.32604/phyton.2020.08919

Received 24 October 2019; Accepted 06 December 2019; Issue published 22 June 2020

Abstract

The endoplasmic reticulum (ER) is an organelle in the cell where proteins are created and folded. Folding is a very elaborate process that is often interrupted by various biotic and abiotic stresses, leading to the formation of unfolded and misfolded proteins called ER stress. Dithiothreitol (DTT)-induced unfolded protein response (UPR) in endoplasmic reticulum (ER) has been recently reported in plants. Also, previous studies demonstrated that treatment with polyethylene glycol (PEG₆₀₀₀) could stimulate water deficit in crops. However, further researches should be conducted to elucidate the molecular mechanism of ER stress response and the relationship between water deficiency and ER. In this study, we examined the expressions of sucrose synthase (SuS) gene, proline metabolic genes and abscisic aldehyde oxidase (AAO3) gene in maize seedlings that were subjected to DTT and PEG induced combined stresses by using quantitative real-time RT-PCR. Three weeks old detached maize seedlings were treated with or without DTT and PEG₆₀₀₀ for 12 h. The treatment with DTT increased about 2-fold the expression of gene encoding proline synthesis enzyme, pyrroline-5-carboxylate synthetase (P5CS) but no statistically affected the proline catabolism enzyme, proline dehydrogenase (ProDH) in comparison with un-treated seedlings. PEG treatment was also up-regulated P5CS while it was down-regulated ProDH. The relative expression levels of SuS and AAO3 genes statistically enhanced about 2.5 fold under the DTT-induced ER stress. Likewise, the expression levels of SuS and AAO3 genes were up-regulated in the detached seedlings exposed to PEG-induced water deficit. Conversely, the induced gene expressions were down-regulated under the combined stress, the DTT-induced ER stress and PEG-induced water deficit in comparison with the singular stress responses (DTT or PEG). The results indicated that the expressions of genes, related to the synthesis of some signal osmolyte compounds such as proline and sucrose can be suppressed when ER stress occurred under water deficiency in maize seedlings. The changes in the expressions of genes involved in osmolyte and ABA metabolism can be related to ER stress response as well as variations in water status.

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