Genome-Wide Identification and Transcript Analysis Reveal Potential Roles of Oligopeptide Transporter Genes in Iron Deficiency Induced Cadmium Accumulation in Peanut

Abstract

The oligopeptide transporter (OPT) family is a group of proton-coupled symporters that play diverse roles, including metal homeostasis. However, little is known about this family of peanuts. To reveal the potential roles of <i>AhOPT</i> genes in Fe/Cd interactions, peanut <i>AhOPT</i> genes were genome-widely identified, and the relationships between gene expression and Cd accumulation were detected in two contrasting peanut cultivars (Fenghua 1 and Silihong) under Fe-sufficient or Fe-deficient conditions. A total of 40 <i>AhOPT</i> genes were identified in peanuts, which were divided into two subfamilies (PT and YS). Most <i>AhOPT</i> genes underwent gene duplication events predominated by whole-genome duplication. Clustered members generally have similar protein structures. However, gene structural divergences occurred in most of the duplicated genes. Transcription analysis revealed that <i>AhOPT3.2</i>/<i>3.4</i> and <i>AhYSL3.1</i>/<i>3.2</i> might be responsible for Fe deficiency tolerance, while <i>AhOPT3.1</i>/<i>3.4, AhOPT7.1</i>/<i>7.2</i>, and <i>AhYSL1.1</i> be involved in Fe/Cd interactions. These genes might be regulated by transcription factors, including <i>ATHB-12, ATHB-6, DIVARICATA, MYB30, NAC02, DOF3.4, IDD7</i>, and <i>LUX</i>. Reduced expressions of <i>AhYSL3.1</i>/<i>3.2</i> and higher expressions of <i>AhOPT3.4</i> might contribute to higher Fe-deficiency tolerance in Silihong. Higher expression of <i>AhOPT7.3</i> and <i>AhOPT6.1</i> might be responsible for low Cd accumulation in Fenghua 1. Our results confirmed that <i>AhOPT3</i>/<i>6</i>/<i>7</i> and <i>AhYSL1</i>/<i>3</i> might be involved in the transport of Fe and/or Cd in peanuts and provided new clues to understanding potential mechanisms of Fe/Cd interactions.