The WRKY proteins constitute a large family of transcription factors in plants containing highly conserved WRKYGQK sequences and zinc-finger-like motifs. To comprehensively study WRKY III genes in cotton, we analyzed the genome sequences of Gossypium hirsutum, G. raimondii and G. arboreum. According to the three genome sequences, 18 group III GhWRKY genes were identified in G. hirsutum, 12 both in G. raimondii and G. arboreum. Phylogenetic and motif analysis showed that proteins with high similarities could be clustered together and had the same motif components. The ratios of non-synonymous (Ka) to synonymous (Ks) of the GhWRKY to GrWRKY or GaWRKY were lower than 1, which indicated that group III WRKY genes in Gossypium species are under purifying selection. Expression analysis revealed that group III GhWRKY genes expressed during fiber development and leaf senescence, and most of them could be induced by salicylic acid (SA), jasmonic acid (JA), ethylene, abscisic acid (ABA), mannitol, and NaCl both in roots and cotyledons. Our study gives a briefly introduction on cotton group III WRKY genes and implicates their potential function in cotton fiber development, leaf senescence and abiotic stresses.

Nanog, Oct4 and Sox2 are important transcription factors that are expressed in embryonic stem (ES) cells or embryoniccarcinoma (EC) cells, but in most cases they are absent in somatic cells. These factors play a key role to maintain embryonic stemcell self-renew and pluripotency. Down-regulation of Nanog and Sox2 gene expression can change multiple gene expressionpatterns and signal transduction pathways, and will initiate ES cell differentiation. This study was designed to select theefficient small interfering RNA (siRNA) fragments that inhibit Nanog and Sox2 gene expression in mouse J1 ES cells and P19 ECcells. Among synthesized siRNAs we screened out the siRNA N301 for Nanog and siRNA S720 for Sox2, which not only downregulatedof Nanog and Sox2 gene expression, but also interfered embryoid bodies formation. Our study provided the definedsiRNA fragments that could be used to investigate the epigenetic function of Nanog and Sox2 genes.