Generation and Analysis of ESTs for Differential Gene Expression to Anthracnose in Yam (Diascorea alata L)

Molecular markers are ideal to investigate genetic effects on the resistance/susceptibility to disease. Simple Sequence Repeats (SSRs), repetitions of nucleotide motifs of 1-5 bases, are currently the markers of choice due to their abundant distribution in the genomes, and suitability for high-throughput analysis.  Yam, (Dioscorea alata L), the main food source for over 100 million people in humid and sub-humid tropics, is vulnerable to anthracnose (Colletotrichum gloeosporioides) disease.  This is one of the major limiting factors in the production of yam worldwide. A collaborative project between the International Institute of Tropical Agriculture (IITA) in Ibadan, Nigeria, Africa and Virginia State University, Petersburg, Virginia, USA was developed for genetic improvement and germplasm characterization of yams using molecular tools.  Very limited sequence information is available from public genome databases. Total RNA was isolated from young leaves of resistant and susceptible genotypes and cDNA libraries corresponding to these two lines were constructed using Clontech's Creator SMART cDNA library construction kit.  The libraries from the resistant and susceptible genotypes now have a total of 85,000 and 80,000 cDNA clones, respectively.  These cDNA clones are currently being sequenced and nearly 80,000 EST sequences generated from this project are presented.