Characterization of the Transcription Factor and Transcriptionally Active Protein Gene Families in Cowpea (Vigna unguiculata L.)

Cowpea, Vigna unguiculata (L.) Walp., is an important food and forage legume in the semi-arid tropics. Among the greatest constraints of crop yield in cowpea are root-parasitic angiosperms such as Striga gesnerioides, which drain the cowpea plant of much needed nutrients. Thus, improved resistance to parasitic weeds, among other stresses, is among the most important goals of cowpea breeding programs. Plant response to such biotic and abiotic stresses involves complex regulatory networks; transcription factors (TFs) play a central role in these networks. Here, I have identified and classified the TF repertoire of cowpea, and demonstrated that some TF families have members whose expression changes when cowpea shows resistance to Striga parasitism, thereby demonstrating that these TFs have a role in cowpea resistance against parasitism. Moreover, I have demonstrated that these same TF families can have members whose expression is changed when cowpea shows susceptibility. In addition, to identify the role of sugar transporters in host-parasite interactions, I identified and classified sugar transporters in the genomes of three parasitic angiosperms and determined that in general, sugar transporter expression increases throughout the life cycles of parasitic weeds. Further, I discuss a possible ramification of the characterization of cowpea TFs, namely the possibility that cowpea and Striga gesnerioides are competing for sugars and that cowpea TFs may be involved with this competition.