Drought responsiveness in six wheat genotypes: identification of stress resistance indicators

Asma Guizani; Hend Askri; Maria Laura Amenta; Roberto Defez; Elyes Babay; Carmen Bianco; Nicoletta Rapaná; Mariella Finetti-Sialer; Fatma Gharbi

doi:10.3389/fpls.2023.1232583

Drought responsiveness in six wheat genotypes: identification of stress resistance indicators

Front Plant Sci. 2023 Sep 13:14:1232583. doi: 10.3389/fpls.2023.1232583. eCollection 2023.

Authors

Asma Guizani¹, Hend Askri², Maria Laura Amenta³, Roberto Defez³, Elyes Babay^{4

5}, Carmen Bianco³, Nicoletta Rapaná⁶, Mariella Finetti-Sialer⁶, Fatma Gharbi¹

Affiliations

¹ Laboratory of Mycology, Pathologies and Biomarkers LR16ES05, Faculty of Sciences of Tunis, University of Tunis El Manar, Tunis, Tunisia.
² Laboratory of Valorization of Non-Conventional Water (LR16INRGREF02), National Institute of Rural Engineering, Water and Forestry, Carthage University, Tunis, Tunisia.
³ Institute of Biosciences and BioResources, National Research Council, Naples, Italy.
⁴ Laboratory of Cereals and Food Legumes, National Gene Bank of Tunisia (BNG), Tunis, Tunisia.
⁵ Agricultural Applied Biotechnology Laboratory (LR16INRAT06), Institut National de la Recherche Agronomique de Tunisie (INRAT), University of Carthage, Tunis, Tunisia.
⁶ Institute of Biosciences and BioResources, National Research Council, Bari, Italy.

Abstract

Introduction: Wheat (Triticum aestivum L.) is among the world's most important staple food crops. In the current climate change scenario, a better understanding of wheat response mechanisms to water stress could help to enhance its productivity in arid ecosystems.

Methods: In this study, water relations, gas exchange, membrane integrity, agronomic traits and molecular analysis were evaluated in six wheat genotypes (D117, Syndiouk, Tunisian durum7 (Td7), Utique, Mahmoudi AG3 and BT) subjected to drought-stress.

Results and discussion: For all the studied genotypes, drought stress altered leaf area, chlorophyll content, stomatal density, photosynthetic rate and water-use efficiency, while the relative water content at turgor loss point (RWC0) remained stable. Changes in osmotic potential at turgor loss point (Ψπ⁰), bulk modulus of elasticity (Ɛmax) and stomatal regulation, differed greatly among the studied genotypes. For the drought-sensitive genotypes AG3 and BT, no significant changes were observed in Ψπ⁰, whereas the stomatal conductance (gs) and transpiration rate (E) decreased under stress conditions. These two varieties avoided turgor loss during drought treatment through an accurate stomatal control, resulting in a significant reduction in yield components. On the contrary, for Syndiouk, D117, Td7 and Utique genotypes, a solute accumulation and an increase in cell wall rigidity were the main mechanisms developed during drought stress. These mechanisms were efficient in enhancing soil water uptake, limiting leaf water loss and protecting cells membranes against leakage induced by oxidative damages. Furthermore, leaf soluble sugars accumulation was the major component of osmotic adjustment in drought-stressed wheat plants. The transcriptional analysis of genes involved in the final step of the ABA biosynthesis (AAO) and in the synthesis of an aquaporin (PIP2:1) revealed distinct responses to drought stress among the selected genotypes. In the resistant genotypes, PIP2:1 was significantly upregulated whereas in the sensitive ones, its expression showed only a slight induction. Conversely, the sensitive genotypes exhibited higher levels of AAO gene expression compared to the resistant genotypes. Our results suggest that drought tolerance in wheat is regulated by the interaction between the dynamics of leaf water status and stomatal behavior. Based on our findings, Syndiouk, D117, Utique and Td7, could be used in breeding programs for developing high-yielding and drought-tolerant wheat varieties.

Keywords: cell wall integrity; drought; osmotic adjustment; stomatal regulation; transcriptional analysis; water relations; wheat.

Grants and funding

The authors declare financial support was received for the research, authorship, and/or publication of this article. This work was supported by the grant “MICRO4Legumes” (Il microbioma vegetale simbionte come strumento per il miglioramento delle leguminose foraggere), D.M.n.89267 (Italian Ministry of Agriculture). This work was also partially supported by the grants “E-Crops” (Tecnologie per l’Agricoltura Digitale Sostenibile), ARS01_01136 (MIUR), and “ALIFUN” (Sviluppo di ALImenti FUNzionali per l’innovazione dei prodotti alimentari di tradizione italiana), PON ARS01_00783 (MIUR).