Isolation and characterization of two knotted-like homeobox genes from tomato.

Homeobox genes are known to play a role in developmental regulation. The knotted-like homeobox (knox) genes fall into two classes. The class I knox genes like knl, stml, and knatl are involved in maintaining meristem identity in cells. The function of class II knox genes is at yet undetermined. We have characterized two knox genes from tomato. LeT6 and LeT12 map to distinct chromosome locations that are different from the location for a recently cloned knox gene from tomato, tknl, confirming that plant homeobox genes are not clustered on chromosomes. These genes have a distinct expression pattern. Unlike other class I knl-like genes, LeT6 is expressed in developing lateral organs and developing ovaries in flowers. LeT12 is more ubiquitously expressed in the mature plant. RNA in situ localization data suggest that both these genes may have a role to play in formative events in ovule and embryo morphogenesis.