Physiological and Molecular Osmotic Stress Responses in Three Durum Wheat (Triticum Turgidum ssp Durum) Genotypes

Salma Jallouli,Sawsen Ayadi,Youssef Trifa,Giorgia Santini,Simone Landi,Fatma Ezzahra Ben Azaiez,Inés Zouari,Giorgia Capasso,Zoubeir Chamekh,Sergio Esposito

doi:10.3390/agronomy9090550

Abstract

This study aims to investigate the activities and expression of enzymes of primary metabolism and relate these data with the growth performance of three different durum wheat genotypes (Maali; YT13; and ON66) under osmotic stress. Growth traits—including plant height, dry weight (DW) and relative water content (RWC)—were measured to classify genotypes depending on their tolerance to stress. Several enzymes were investigated: Ascorbate peroxidase (APX), Glutamine Synthetase (GS), Glutamine dehydrogenase (GDH), Glutamate synthase (GOGAT), Glucose 6-phosphate dehydrogenase (G6PDH), and Phosphoenolpyruvate Carboxylase (PEPC). The expression of the cytosolic and plastidic glutamine synthetase (TaGS1 and TaGS2), high affinity nitrate transporters (TaNRT2.3) and Glutamate dehydrogenase (TaGDH) were also detected by qRT-PCR. The results indicated different growth performances among genotypes, indicating Maali and YT13 as tolerant genotypes and ON66 as a drought-susceptible variety. Data showed a decrease in PEPC and increase in APX activities under osmotic stress; a slight decrease in GS activity was observed, together with an increase in G6PDH in all genotypes; GS and NRT2 expressions changed in a similar pattern in the different genotypes. Interestingly, Maali and YT13 showed higher transcript abundance for GDH under stress compared to ON66, suggesting the implication of GDH in protective phenomena upon osmotic stress.

Highlights

Drought is considered as the most limiting environmental factor affecting plant growth and productivity; this is true considering the consequences of global warming and climate change
The Glutamine dehydrogenase (GDH) gene did not show the same expression under stress: in Maali and YT13, the GDH expression showed an increase by 121% and 340% respectively, whereas ON66 showed a strong decrease in GDH expression under osmotic stress (Figure 5D)
The GDH expression showed an increase by 121% and 340% respectively, whereas ON66 showed a strong decrease in GDH expression under osmotic stress (Figure 5D)

Summary

Introduction

Drought is considered as the most limiting environmental factor affecting plant growth and productivity; this is true considering the consequences of global warming and climate change. Breeding for drought tolerance is a main objective for plant and cereal breeders. The comprehension of drought tolerance mechanisms in durum wheat, and its ability to cope with abiotic stresses, is of wide interest for researchers. Distinct behaviors were observed in susceptible and tolerant genotypes resulting in changes in biomass production, plant height, and greenness [3,6]; these variations are consequences of many visible responses, such as osmolytes syntheses, enzymatic activities, antioxidant machinery, and specific gene expression [3,7,8,9]

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Conclusion