A FAMILY OF NOVEL MYB-RELATED GENES FROM THE RESURRECTION PLANT CRATEROSTIGMA-PLANTAGINEUM ARE SPECIFICALLY EXPRESSED IN CALLUS AND ROOTS IN RESPONSE TO ABA OR DESICCATION

A cDNA and two genomic clones comprising highly similar genes that enc ode a protein with a Myb-related DNA-binding domain were isolated from the resurrection plant Craterostigma plantagineum. The structure of c pm5 and cpm10 (Craterostigma plantagineum myb) genes consists of three putative exons encoding a protein of 36.6 kDa. The cDNA of cpm7 encod es a closely related protein of 36.8 kDa. The canonical Myb domain pre sent in transcriptional activators of yeast, animals and plants was lo calized in the amino terminus of deduced Cpm5, Cpm7 and Cpm10 proteins and corresponds to the two Myb repeats found in plants. The Myb domai n of Cpm deduced proteins and a short stretch of amino acids adjacent to this region are closely related to a myb gene from Arabidopsis thal iana which is expressed in response to osmotic stress and ABA. The res t of the deduced protein has no similarity to other reported sequences . The myb-related genes in the Craterostigma genome comprise a small g ene family of 6-8 members as estimated by hybridization with a bona fi de Myb domain probe. Northern blot experiments showed specific express ion of cpm10 in undifferentiated callus tissue up-modulated by ABA and expression of cpm7 mRNA in roots up-regulated by dehydration.