# Genome-Wide Identification of the LsaPHR1 Gene Family and Preliminary Functional Validation of LsaPHR1.1 in Phosphorus Tolerance in Lactuca sativa

## TL;DR

This study identifies and validates a gene family in lettuce that helps plants cope with phosphorus stress, offering a strategy to improve crop resilience.

## Contribution

The study identifies the LsaPHR1 gene family in lettuce and functionally validates LsaPHR1.1 in phosphorus tolerance using CRISPR/Cas9.

## Key findings

- LsaPHR1 genes in lettuce respond to phosphorus stress, hormones, and darkness.
- LsaPHR1.1 knockout mutants showed improved nitrate, ammonium, and antioxidant levels under phosphorus stress.
- The findings suggest a potential strategy to enhance phosphorus stress tolerance in lettuce.

## Abstract

Phosphorus (P) is a limiting nutrient for plant growth and productivity. Improving P use efficiency is important for crop production. In Lactuca sativa (lettuce), five phosphate starvation response 1 (PHR1) genes were identified and characterized through a bioinformatics approach. The expression patterns of LsaPHR1s were examined using qRT-PCR under various treatments, including devoid phosphorus (DP), low phosphorus (LP), high phosphorus (HP), darkness, ABA, IAA, and MeJA. The results indicate that LsaPHR1s in lettuce responded to phosphorus stress, hormones, and darkness. Furthermore, we engineered LsaPHR1.1 knock-out mutants via CRISPR/Cas9-mediated genome editing. Then, the mutants were subjected to phosphorus stress (DP, LP, and HP). In contrast to WT, the mutants improved nitrate and ammonium contents, increased antioxidant enzyme activity, and elevated antioxidant and chlorophyll contents. Our results offer a potential strategy for improving phosphorus stress tolerance in lettuce, which holds great significance for maintaining yield and quality.