Functional Divergence of the Glutathione S-Transferase Supergene Family in Physcomitrella patens Reveals Complex Patterns of Large Gene Family Evolution in Land Plants    

Abstract

Plant glutathione S-transferases (GSTs) are multifunctional proteins encoded by a large gene family that play major roles in the detoxification of xenobiotics and oxidative stress metabolism. To date, studies on the GST gene family have focused mainly on vascular plants (particularly agricultural plants). In contrast, little information is available on the molecular characteristics of this large gene family in nonvascular plants. In addition, the evolutionary patterns of this family in land plants remain unclear. In this study, we identified 37 GST genes from the whole genome of the moss Physcomitrella patens, a nonvascular representative of early land plants. The 37 P. patens GSTs were divided into 10 classes, including two new classes (hemerythrin and iota). However, no tau GSTs were identified, which represent the largest class among vascular plants. P. patens GST gene family members showed extensive functional divergence in their gene structures, gene expression responses to abiotic stressors, enzymatic characteristics, and the subcellular locations of the encoded proteins. A joint phylogenetic analysis of GSTs from P. patens and other higher vascular plants showed that different class GSTs had distinct duplication patterns during the evolution of land plants. By examining multiple characteristics, this study revealed complex patterns of evolutionary divergence among the GST gene family in land plants.

Structural and Functional Evolution of Positively Selected Sites in Pine Glutathione S-Transferase Enzyme Family*

“…Our previous study showed the moss Physcomitrella patens did not contain any Tau GST, whereas the lycophyte Selaginella moellendorffii had 47 Tau GSTs (30). The GST gene families in Oryza sativa, Arabidopsis thaliana, and P. trichocarpa have been previously characterized (2,31,32), and they reportedly contain 52, 28, and 58 Tau members, respectively.…”

The still mysterious roles of cysteine-containing glutathione transferases in plants

“…Poplar and P. patens orthologs have a similar localization (Liu et al, 2013; Tang and Yang, 2013). The two other proteins from Arabidopsis are predicted to be cytosolic as they do not exhibit visible targeting sequences.…”

“…The poplar ortholog, PtGSTL1, is also present in plastids but a priori not in peroxisomes (Lallement et al, 2014) and the P. patens isoform is also plastidial (Liu et al, 2013). The two other GSTLs found in A. thaliana and P. trichocarpa should be cytosolic proteins, although a nuclear localization was observed when poplar proteins were fused to GFP (Lallement et al, 2014).…”

Cloning and expression of a tau class glutathione S-transferase (ZjGSTU1) from Chinese jujube in response to phytoplasma infection

“…There are 53, 59 and 81 GSTs in arabidopsis (Sappl et al 2009), rice (Soranzo et al 2004) and poplar (Lan et al 2009), respectively. Preceding reports show that in plants GSTs are divided into eight classes: tau, phi, theta, zeta, lambda, EF1Bc, dehydroascorbate reductase (DHAR), and tetrachlorohydroquinone dehalogenase (Liu et al 2013). Among these, tau and phi GSTs are the most abundant.…”