*Article* **Identification and Expression Profiling of Protein Phosphatases (***PP2C)* **Gene Family in** *Gossypium hirsutum* **L.**

**Hamna Shazadee 1,†, Nadeem Khan 2,†, Jingjing Wang <sup>1</sup> , Chencan Wang <sup>1</sup> , Jianguo Zeng <sup>1</sup> , Zhongyi Huang <sup>1</sup> and Xinyu Wang 1,\***


Received: 28 February 2019; Accepted: 18 March 2019; Published: 20 March 2019

**Abstract:** The protein phosphatase (*PP2C*) gene family, known to participate in cellular processes, is one of the momentous and conserved plant-specific gene families that regulate signal transduction in eukaryotic organisms. Recently, PP2Cs were identified in *Arabidopsis* and various other crop species, but analysis of PP2C in cotton is yet to be reported. In the current research, we found 87 (*Gossypium arboreum*), 147 (*Gossypium barbadense*), 181 (*Gossypium hirsutum*), and 99 (*Gossypium raimondii*) PP2C-encoding genes in total from the cotton genome. Herein, we provide a comprehensive analysis of the *PP2C* gene family in cotton, such as gene structure organization, gene duplications, expression profiling, chromosomal mapping, protein motif organization, and phylogenetic relationships of each species. Phylogenetic analysis further categorized *PP2C* genes into 12 subgroups based on conserved domain composition analysis. Moreover, we observed a strong signature of purifying selection among duplicated pairs (i.e., segmental and dispersed) of *Gossypium hirsutum*. We also observed the tissue-specific response of *GhPP2C* genes in organ and fiber development by comparing the RNA-sequence (RNA-seq) data reported on different organs. The qRT-PCR validation of 30 *GhPP2C* genes suggested their critical role in cotton by exposure to heat, cold, drought, and salt stress treatments. Hence, our findings provide an overview of the *PP2C* gene family in cotton based on various bioinformatic tools that demonstrated their critical role in organ and fiber development, and abiotic stress tolerance, thereby contributing to the genetic improvement of cotton for the resistant cultivar.

**Keywords:** protein phosphatase (PP2C); cotton; syntenic relationships; expression patterns; evolutionary analysis
