# Genome-Wide Identification and Abiotic Stress Response Analysis of the Isopentenyl Transferase (IPT) Gene Family in Soybean (Glycine max L.)

## TL;DR

This study identifies and analyzes soybean IPT genes, revealing their roles in abiotic stress response and providing insights for soybean breeding.

## Contribution

The study provides genome-wide identification and functional analysis of the soybean IPT gene family, including stress response and haplotype associations.

## Key findings

- 15 GmIPT genes were identified and characterized in soybean, distributed across 12 chromosomes.
- GmIPT7, GmIPT10, and GmIPT15 show differential responses to drought, salt, and low-temperature stress.
- A putative elite haplotype of GmIPT15 is associated with cold tolerance based on germination index.

## Abstract

Isopentenyltransferase (IPT) is the rate-limiting enzyme in cytokinin biosynthesis and plays a critical role in plant acclimation to abiotic stress. To explore soybean IPT genes, we performed genome-wide identification, bioinformatics analysis, and molecular experimental validation to systematically characterize the features and functions of the soybean IPT (GmIPT) gene family. We identified 15 GmIPT genes in the soybean genome, which are unevenly distributed across 12 chromosomes; their evolutionary expansion is primarily driven by whole-genome duplication events. Phylogenetic analysis of soybean IPT proteins with those from Arabidopsis, rice and maize clustered them into four groups, exhibiting lineage-specific functional specialization. GmIPT genes exhibit significant variations in conserved motifs, gene structure, and cis-acting elements; their promoter regions are enriched in light-responsive, abiotic stress-responsive, and hormone-responsive elements, indicating their involvement in complex transcriptional regulatory networks. Tissue expression profiling revealed that GmIPT7 and GmIPT10 are highly expressed in various tissues, whereas GmIPT14 shows specific expression in flowers and the shoot apical meristem. Transcriptomic analysis and qRT-PCR validation demonstrated that GmIPT7, GmIPT10 and GmIPT15 respond differentially to drought, salt and low-temperature stress, with GmIPT15 exhibiting a transient upregulation at 3 h (p < 0.01) followed by a gradual decline to levels close to the pre-treatment control at 6–12 h under low-temperature stress. We further performed haplotype analysis of GmIPT15 and identified a putative elite haplotype (hap1) associated with cold tolerance based on low-temperature germination index assessment. This study provides useful insights for the future functional characterization of plant IPT genes and offers potential genetic resources and molecular markers that may support molecular-assisted breeding for soybean abiotic stress tolerance.