Comprehensive analysis of fatty acid hydroxylase genes reveals GhFAHS11 affecting cotton anther fertility

The cuticular wax of terrestrial plants' outer epidermis is indispensable in plant reproductive development and response to external environmental stress. Alkanes are the main component of cuticle wax and fatty acid hydroxylases play a key role in alkane biosynthesis; however, their function in cotton remains elusive. Here, 53, 55, 28 and 28 candidate fatty acid hydroxylase superfamily (FAHS) genes in four cultivated cotton species were identified. The FAHSs share relatively conserved gene tructure and motifs. We conducted a systematic structural, expression and functional regulatory analysis of the FAHS genes in cotton. Transcriptome analysis indicated that GhFAHS11 is highly expressed specifically in reproductive organs, especially stamens. Sequence analysis revealed that Gh FAHS11 and At CER1 share conserved histidine-rich domains, LEGW motif and seven transmembrane domains. Yeast two-hybrid analyses showed that Gh FAHS11, Gh FAR3 and Gh CER2 are all subcellularly localized to the endoplasmic reticulum (ER) and interacted with each other. Moreover, GhFAHS11 is co-expressed with CER3 and CYTB5, involved in cuticular wax biosynthesis. When GhFAHS11 transcription was reduced in cotton, anther dehiscence was blocked, pollen grains were depressed, and pollen activity was reduced. These findings indicate that GhFAHS11 affects the biosynthesis of cotton anther cuticular wax, which regulates the development of anther and pollen, ultimately affecting male fertility. This study provides a reference for the biosynthesis of cotton cuticle wax and its effects on reproductive development and environmental stress responses. • We identified 53, 55, 28 and 28 candidate FAHS s in four cultivated cotton species. • The gene structure of GhFAHSs and motifs are relatively conserved. • GhFAHS s are the key enzymes for alkane biosynthesis. • GhFAHS s play important roles in the cotton life cycle. • GhFAHS11 interacts with FAR3 and CER2 in the ER to affect male fertility of cotton.