# Characterization of the PHO1 Gene Family in Vigna radiata L. and Its Expression Analysis Under Phosphate-Deficient Stress

## TL;DR

This study identifies and analyzes the PHO1 gene family in mung beans to understand how they respond to low phosphorus stress, which could help in developing better mung bean varieties.

## Contribution

The study provides the first genome-wide characterization of the PHO1 gene family in mung beans and identifies key genes responding to phosphorus-deficient stress.

## Key findings

- Mung bean PHO1 genes were grouped into three phylogenetic groups and show closer relationships with legume PHO1 genes.
- Six collinear gene pairs with soybean suggest purifying selection in mung bean PHO1 genes.
- Expression of specific VrPHO1 genes was significantly induced by prolonged phosphorus-deficient stress in roots.

## Abstract

Background: Phosphorus is an essential nutrient for plant growth and development, playing a multifaceted and vital role in plants. Phosphate Transporter 1 (PHO1) is a class of important functional genes involved in plant phosphorus uptake and transport. We identify PHOSPHATE 1 (PHO1) members in mung beans and investigate their response to low phosphorus stress, thereby aiding in the development of stress-tolerant, high-yielding mung bean varieties. Methods: A bioinformatic analysis was performed, which led to the identification of the PHO1 homologue sequence in mung beans. This analysis also elucidated its gene and protein structural characteristics alongside its phylogenetic relationships. qRT-PCR was used to analyze the expression patterns of genes in roots and leaves in response to conditions of prolonged low-phosphorus and phosphorus-deprivation stress. Results: Total PHO1 homologues were identified in mung beans, which can be grouped into 3 groups (Group I-III). Phylogenetic analysis indicates that VrPHO1s shares closer evolutionary relationships with PHO1 in legumes, and exhibits 6 collinear gene pairs with Glycine max (soybean), all with Ka/Ks ratios below 1, suggesting they have undergone purifying selection. The gene promoter region contains multiple cis-acting elements capable of participating in plant growth and development, stress responses, and plant hormone responses. Expression analysis revealed that more VrPHO1 genes responded to phosphorus stress in roots than in leaves; of these, the expression of VrPHO1; H2, VrPHO1; H3, and VrPHO1; H5 genes was significantly induced by continuous phosphorus-deficient stress. Conclusions: This study provides a comprehensive genome-wide identification of the PHO1 family in mung bean and provides valuable candidate gene resources for the future study of their biological functions and regulatory roles in phosphate-deficient stress.