A genome-wide analysis of pentatricopeptide repeat (PPR) protein-encoding genes in four Gossypium species with an emphasis on their expression in floral buds, ovules, and fibers in upland cotton

Cotton is the most important natural fiber used in textiles. Breeding for “three-lines”, i.e., cytoplasmic male sterility (CMS)-based sterile (A), maintainer (B), and restorer (R) line, is a promising approach to harness hybrid vigor in cotton. Pentatricopeptide repeat (PPR) protein-encoding genes play an important role in plant growth and development including restoration of CMS plants to male fertility. However, PPRs, especially those...