Identification and molecular evolution of the La and LARP genes in 16 plant species: A focus on the Gossypium hirsutum

La and La-related proteins (LARPs) are RNA-binding proteins regulating gene expression. Here, identification and molecular evolution of La and LARP gene family were performed in 16 plant species. Firstly, 188 La and LARP genes were identified. Based on phylogenetic tree and gene structure, they can be divided into three categories: La, LARP1 and LARP6. LARP1 can be further divided into LARP1-L and LARP1-S sub-categories. Compared with the LARP1-S, one additional DM15 domain was found in the C-terminal of LARP1-L. La and LARP genes are mainly distributed at both ends of chromosomes with a relatively consistent distribution position in A and D genomes of Gossypium hirsutum. Las and LARPs of G. hirsutum probably came from cruciferae, and gene recombination and chromosome structure variation occurred in G. hirsutum during evolution. The expression patterns and the distribution of cis-acting elements were also analyzed. The results showed that Las and LARPs respond to some abiotic stresses and hormone stimulation. The protein interaction network indicated that La and LARP proteins may be involved in meristem differentiation, hormone signal transduction, and post-translational modification. This study will provide a basis for the further functional and evolutional study of this gene family.