Cassava (Manihot esculenta Krantz) genome harbors KNOX genes differentially expressed during storage root development

In plants, homeodomain proteins play a critical role in regulating various aspects of plant growth and development. KNOX proteins are members of the homeodomain protein family. The KNOX transcription factors have been reported from Arabidopsis, rice, and other higher plants. The recent publication of the draft genome sequence of cassava (Manihot esculenta Krantz) has allowed a genome-wide search for M. esculenta KNOX (MeKNOX) transcription factors and the comparison of these positively identified proteins with their homologs in model plants. In the present study, we identified 12 MeKNOX genes in the cassava genome and grouped them into two distinct subfamilies based on their domain composition and phylogenetic analysis. Furthermore, semi-quantitative reverse transcription polymerase chain reaction analysis was performed to elucidate the expression profiles of these genes in different tissues and during various stages of root development. The analysis of MeKNOX expression profiles of indicated that 12 MeKNOX genes display differential expressions either in their transcript abundance or expression patterns.