**1. Introduction**

Global warming has resulted in significant decreases in crop production over the last few decades [1]. Plants are exposed to numerous environmental stresses that disrupt biochemical and physiological processes [2]. Temperature, heat, drought, and salt stress directly reduce the quality and total yield [3,4]. To overcome annual yield losses in crops such as wheat, it is critical to identify and understand new sources of defense biomarkers. The TUBBY-like proteins are a family of bipartite transcription factors discovered in plants [5–7]. It was possible to trace the TUBBY-like gene family's phylogenetic history back to the earliest stages of eukaryotic evolution after discovering TUBBY-like genes in both single-celled and multicellular eukaryotes [7]. TUBBY-like proteins are distinguished

**Citation:** Altaf, A.; Zada, A.; Hussain, S.; Gull, S.; Ding, Y.; Tao, R.; Zhu, M.; Zhu, X. Genome-Wide Identification, Characterization, and Expression Analysis of TUBBY Gene Family in Wheat (*Triticum aestivum* L.) under Biotic and Abiotic Stresses. *Agronomy* **2022**, *12*, 1121. https://doi.org/ 10.3390/agronomy12051121

Academic Editor: Dilip R. Pathee

Received: 23 March 2022 Accepted: 2 May 2022 Published: 6 May 2022

**Publisher's Note:** MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

**Copyright:** © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

from other proteins by the presence of the conserved C-terminal tubby domain, which is composed of 12 antiparallels closed β-barrel strands with a central hydrophobic α–helix [5]. A conserved N-terminal F-box domain and the C terminal tubby domain are found in the *TLP* family of plants, which is much larger than the *TLP* family found in animals [8]. The function of *TLP* genes was studied in various plants such as *Arabidopsis thaliana, Oryza sativa, Populus deltoides* [9], *Malus domestica* [8], *Zea maize* [10], *Solanum lycopersicum* [11], and cotton [12]. In *A. thaliana,* 11 TUBBY family genes were identified, whereas in *Oryza sativa* 14, *Malus domestica* 15, *Zea maize* 10, *Solanum lycopersicum* 11, and cotton 105 *TLP* genes were previously identified [8–12]. *TLP* shows different expression levels in tissues in plants in response to various environmental and hormonal stresses [7,8,13]. It was found that At*TLP*3 and At*TLP*9 play an essential role in abscisic acid and osmotic stress [13], whereas At*TLP*9 plays a significant role in salt and drought stress [13,14]. Many TUBBY family genes showed up-regulation in *Malus domestica* in response to abiotic stresses, suggesting a substantial role of *TLP* genes in abiotic stresses [8]. Previous observation showed that Ca*TLP*1 in *Cicer arietinum* plays a vital role in dehydration stress resistance, and its overexpression in tobacco offers salt and drought stress resistance [15]. Thus, *TLP*s seem to have a significant role in abiotic stress tolerance in plants. However, the function of *TLP*s and their mode of action in plants is an unexplored topic [11].

Wheat is an important crop providing sustenance to 35% of the world's population. However, unpredictable climatic conditions have stagnated wheat production in the past two to three decades. Biotic and abiotic stresses affect the growth of wheat crops and have decreased the plant's output and performance [16]. Wheat crops' evolutionary diversity allows them to adapt to different environmental conditions, although the molecular basis of this adaptation is unknown. Therefore, we were interested in the evolution of the wheat TUBBY family genes and their function in response to abiotic stress. This research aimed to understand wheat TUBBY family genes to improve wheat production, plant quality, and abiotic stress response.
