# Genome-wide analysis of the glutathione S-transferase family in Vaccinium corymbosum and functional characterization of VcGSTU53 in response to abiotic stress

## TL;DR

This study identifies and characterizes the GST gene family in blueberries, focusing on VcGSTU53's role in helping plants cope with environmental stress.

## Contribution

The first genome-wide analysis of GSTs in blueberry and functional characterization of VcGSTU53 under abiotic stress.

## Key findings

- 190 VcGST genes were identified and classified into 14 subclasses, with no iota class GST found.
- VcGSTU53 enhances bacterial tolerance to aluminum, drought, and cadmium stresses when heterologously expressed.
- Approximately 46.32% of VcGST proteins are predicted to localize in the cytoplasm.

## Abstract

As a high-value small fruit crop worldwide, blueberry is prized for its health-promoting properties. Glutathione S-transferases (GSTs) are a large and complex family of enzymes that play vital roles in flavonoid metabolism, plant growth and development, and responses to abiotic stress. However, relatively little is known about the GST gene family in blueberry.

In this study, genome-wide identification and bioinformatics analysis of the blueberry GST gene family were conducted. The candidate gene VcGSTU53 was further analyzed for its response to abiotic stress using transcriptome profiling, subcellular localization, and heterologous expression assays.

A total of 190 VcGST genes were identified and classified into 14 subclasses: tau (U, 75), phi (F, 28), EF1G (17), lambda (L, 10), MAPEG (10), zeta (Z, 8), GHR (8), Metaxin (M, 7), GST2N (6), DHAR (5), hemerythrin (H, 4), mPGES2 (4), TCHQD (4) and theta (T, 4); however, no iota (I) class GST was found. The lengths of the VcGST genes ranged from 366 bp to 4386 bp, encoding polypeptides of 121 to 1461 amino acids, with predicted molecular weights ranging from 13.86 kDa to 163.02 kDa, and theoretical isoelectric points ranging from 4.77 to 9.56. Approximately 46.32% of VcGST proteins were predicted to localize in the cytoplasm, with the remainder predicted to localize in the endomembrane system, chloroplasts, nucleus, mitochondria, extracellular space, and plasma membrane. Based on a comparative transcriptome profiling of 30 AlCl3-treated root samples from two cultivars, VcGSTU53 was screened as a key aluminum-stress-responsive gene. VcGSTU53 encodes a protein of 230 amino acids, is localized in the cytoplasm, and exhibits transferase activity. Heterologous expression of VcGSTU53 in Escherichia coli did not inhibit bacterial growth, but enhanced tolerance to aluminum stress. Notably, it also increased bacterial resistance to drought and cadmium stresses.

These findings contribute to a deeper understanding of the functions of the GST family in plants under abiotic stress, which is of great significance for the development of new stress-resistant blueberry varieties.