Unveiling the Enigmatic Structure of TdCMO Transcripts in Durum Wheat

Loredana Ciarmiello,Antimo Di Maro,Ioannis Kafantaris,Antonio Mirto,Federica Iannuzzi,Petronia Carillo,Maria Annunziata,Pasqualina Woodrow,Amodio Fuggi

doi:10.3390/agronomy8110270

Abstract

Durum wheat is one of the oldest and most important edible cereal crops and its cultivation has considerable economic importance in many countries. However, adverse conditions, such as high irradiance and increasing salinity of soils, could lead to a decrease in productivity over the next few decades. Durum wheat plants under salinityare able toaccumulate glycine betaine to osmotically balance the cytosol and reduce oxidative stress, especially in young tissues. However, the synthesis of this fundamental osmolyte is inhibited by high light in T. durum even under salinity. Choline monooxygenase is the first enzyme involved in the glycine betaine biosynthetic pathway. Thus, to explain the glycine betaine inhibition, we analyzed the effect of both salinity and high light on the putative TdCMO gene expression. Thirty-eight TdCMO different transcripts were isolated in the young leaves of durum wheat grown in different stress conditions. All translated amino acid sequences, except for the TdCMO1a6 clone, showed a frame shift caused by insertions or deletions. The presence of different transcripts could depend on the presence of duplicated genes, different allelic forms, and alternative splicing events. TdCMO1a6 computational modeling of the 3D structure showed that in durum wheat, a putative CMO-like enzyme with a different Rieske type motif, is present and could be responsible for the glycine betaine synthesis.

Highlights

Plants frequently undergo environmental stresses that are harmful factors that decrease crop growth and productivity [1]
To shed lighton the mechanisms underlying the specific inhibition of glycine betaine (GB) synthesis under high light, we investigated the effects of salinity both in low and high light conditions on the expression of choline monooxygenase (CMO), the first of the two key enzymes involved in its synthesis
Total RNA was isolated from young leaves of durum wheat grown in different conditions: control (LLC; 0 mM NaCl, 350 μmol m−2 s−1 PAR), high salinity (LLS; 100 mM NaCl, 350 μmol m−2 s−1 PAR), high light (HLC; 0 mM NaCl, 900 μmol m−2 s−1 PAR), and high light and salinity (HLS; 100 mM NaCl, 900 μmol m−2 s−1 PAR)

Summary

Introduction

Plants frequently undergo environmental stresses that are harmful factors that decrease crop growth and productivity [1]. Due to climate change and land and water quality pauperization, salt stress together with drought, will become a hot topic of crop studies [3]. Agronomy 2018, 8, 270 into the vacuole, and the synthesis and accumulation of compatible solutes [7]. These latter are small molecules, water soluble, and uniformly neutral with respect to the perturbation of cellular functions, even when present at high concentrations [8,9]. Among the best known compatible solutes, glycine betaine (GB) has been reported to increase greatly under salt and drought stresses [8], and constitutes one of the major metabolites found in durum wheat under salinity, as in other

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Conclusion