Distribution of <i>GhFH</i> genes.

<div> FORMIN proteins distinguished by FH2 domain, are conserved throughout evolution and widely distributed in eukaryotic organisms. These proteins interact with various signaling molecules and cytoskeletal proteins, playing crucial roles in both biotic and abiotic stress responses. However, the functions of FORMINs in cotton (<i>Gossypium hirsutum</i> L.) remain uncovered. In this study, 46 FORMIN genes in <i>G. hirsutum</i> (referred to as <i>GhFH</i>) were systematically identified. The gene structures, conserved domains, and motifs of these <i>GhFH</i> genes were thoroughly explored. Phylogenetic and structural analysis classified these 46 <i>GhFH</i> genes into five distinct groups. <i>In silico</i> subcellular localization, prediction suggested that <i>GhFH</i> genes are distributed across various cellular compartments, including the nucleus, extracellular space, cytoplasm, mitochondria, cytoskeleton, plasma membrane, endoplasmic reticulum, and chloroplasts. Evolutionary and functional diversification analyses, based on on-synonymous (<i>Ka</i>) and synonymous (<i>Ks</i>) ratios and gene duplication events, indicated that <i>GhFH</i> genes have evolved under purifying selection. The analysis of <i>cis</i>-acting elements suggested that <i>GhFH</i> genes may be involved in plant growth, hormone regulation, light response, and stress response. Results from transcriptional factors TFs and gene ontology analysis indicate that FORMIN proteins regulate cell wall structure and cytoskeleton dynamics by reacting to hormone signals associated with environmental stress. Additionally, 45 putative ghr-miRNAs were identified from 32 families targeting 33 <i>GhFH</i> genes. Expression analysis revealed that <i>GhFH1</i>, <i>GhFH10</i>, <i>GhFH20</i>, <i>GhFH24</i>, and <i>GhFH30</i> exhibited the highest levels of expression under red, blue, and white light conditions. Further, <i>GhFH9</i>, <i>GhFH20</i>, and <i>GhFH30</i> displayed higher expression levels under heat stress, while <i>GhFH20</i> and <i>GhFH30</i> showed increased expression under salt stress compared to controls. The result suggests that <i>GhFH20</i> and <i>GhFH30</i> genes could play significant roles in the development of <i>G. hirsutum</i> under heat and salt stresses. Overall these findings enhance our understanding of the biological functions of the cotton FORMIN family, offering prospects for developing stress-resistant cotton varieties through manipulation of <i>GhFH</i> gene expression. </div>