GhFAD2-3 is Required for Anther Development in Gossypium hirsutum
Abstract Background In higher plants, FAD2 gene encodes the microsomal oleate Δ12-desaturase, one of the key enzymes essential for biosynthesis of polyunsaturated lipids that serve many important functions in plant development and stress responses. FAD2 catalyzes the first step, towards biosynthesis of polyunsaturated fatty acids (PUFAs) found in cell membrane and wall, and it is thus of great importance to investigate the regulatory role of FAD2 in anther development. Results We reported the molecular characterization of the cotton (Gossypium hirsutum) GhFAD2 gene family and the essential role of GhFAD2-3 in cotton anther development. G. hirsutum contains four pairs of homoeologous FAD2 genes (GhFAD2-1 to GhFAD2-4). GhFAD2-3 is ubiquitously and relatively highly expressed in all tissues analyzed, particularly in anthers. Specific inhibition of GhFAD2-3 using the RNA interference approach resulted in male sterility due to impaired anther development at the stages from meiosis to maturation. The cellular phenotypic abnormality observed at the meiosis stage of the GhFAD2-3 silenced plant (fad2-3) coincides with the significant reduction of C18:2 in anthers at the same stage. Compared with that of wild type (WT), the content of C18:1 was 41.48%, accordingly increasing by 5 fold in fad2-3 anther at pollen maturation stage. Moreover, the ration of monounsaturated and polyunsaturated fatty acid reached to 5.43 in fad2-3 anther, far beyond WT that of which was only 0.39. Based on compositional analysis of anthers cuticle and transcriptome data, we demonstrated it was unfavorable to the development of anther by regulating GhFAD2-3 expression level to increase the oleic acid content. Conclusions Our work demonstrated the importance of C18:2 and/or C18:3 in development of pollen exine and anther cuticle in cotton, and provided clue for further investigation of the physiological significance of the fatty acid composition in plant growth and development.