Genome-wide identification and expression of SAUR gene family in peanut (Arachis hypogaea L.) and functional identification of AhSAUR3 in drought tolerance.

Background: Small auxin-upregulated RNAs (SAURs) gene family plays important roles in plant growth, development, and stress responses. However, the function of few SAUR genes is known in the peanut (Arachis hypogaea L.), one of the world's major food legume crops. This study aimed to perform a comprehensive identification of the SAUR gene family from the peanut genome.

Results: The genome-wide analysis revealed that a total of 162 SAUR genes were identified in the peanut genome. The phylogenetic analysis indicated that the SAUR proteins were classified into eight subfamilies. The SAUR gene family experienced a remarkable expansion after tetraploidization, which contributed to the tandem duplication events first occurring in subgenome A and then segmental duplication events occurring between A and B subgenomes. The expression profiles based on transcriptomic data showed that SAUR genes were dominantly expressed in the leaves, pistils, perianth, and peg tips, and were widely involved in tolerance against abiotic stresses. A total of 18 AhSAUR genes selected from different subfamilies randomly presented 4 major expression patterns according to their expression characteristics in response to indole-3-acetic acid. The members from the same subfamily showed a similar expression pattern. Furthermore, the functional analysis revealed that AhSAUR3 played a negative role in response to drought tolerance.

Conclusions: This study provided insights into the evolution and function of the SAUR gene family and may serve as a resource for further functional research on AhSAUR genes.