Expressed sequence tags and mRNA expression levels of tagged cDNAs from watermelon anthers and developing seeds

To understand the molecular events that occur during reproductive organ development and to provide genetic resources for molecular breeding, we generated 328 expressed sequence tags (ESTs) from randomly selected clones of four watermelon cDNA libraries. These libraries were prepared from young and mature anthers, as well as the seed coat and inner seed tissues. EST clones found in the young anthers and inner seed tissues showed similarity with genes related to development and signal transduction. We could deduce that, especially in the developing inner seed tissues, important morphological processes were associated exclusively with seed and embryo development In addition, seed metabolism was tailored toward the accumulation of economically valuable storage compounds such as lipids. In the seed coat, EST clones showed similarity with genes that influence the transport or conversion of nutrients such as porin, sucrose synthase, L-asparaginase, and arginine decarboxylase. We also selected two cDNA clones from each of the four classes of ESTs for studying expression levels and patterns in the various organs. Among those eight clones, three (An88, Is124, and Sc68) were expressed preferentially in their particular organ.