Genome-Wide Characterization and Functional Analysis of ABCG Subfamily Reveal Its Role in Cutin Formation in Cotton.

ATP-binding cassette transporter G (ABCG) has been shown to be engaged in export of broad-spectrum compounds with structural differences, but little is known concerning its role in cutin formation of cotton ( spp.). In this study, we conduct a genome-wide survey and detected 69, 71, 124 and 131 ABCG genes within , , and , separately. The above ABCGs could be divided into four groups (Ia, Ib, Ic, II). Some genes such as , whose homologous gene transports cuticular lipid in , was preferentially expressed in the development of fiber. A weighted gene co-expression network analysis (WGCNA) demonstrated that expression was significantly associated with the amount of 16-Hydroxypalmitate (a main component of cutin precursor) in cotton fibers. Further, silencing of by virus-induced gene silencing (VIGS) in cotton generated brightened and crinkled leaves as well as reduced thickness of cuticle and increased permeability. Chemical composition analysis showed the cutin content in -silenced leaves had decreased while the wax content had increased. Our results provide an insight for better understanding of the role of the ABCG family and revealed the essential role of GhABCGs in cotton cutin formation.