THE MADS-BOX GENE CUS1 IS EXPRESSED DURING CUCUMBER SOMATIC EMBRYOGENESIS

We report the isolation and characterisation of cDNA and genomic clone s of a MADS-box gene which is expressed in cucumber fruit and somatic embryos. The cDNA clone was isolated using a heterologous probe, MADS- box cDNA fragments from Antirrhinum majus. The CUS1 cDNA clone was seq uenced and the deduced amino acid sequence is highly similar to the pr oducts of the the PLENA gene from Antirrhinum majus, of the FBP6 gene from Petunia hybrida and of the AGL1 and AGL5 genes from Arabidopsis t haliana. The presence of single copy of CUS1 and a family of related g enes in the cucumber genome was demonstrated by Southern blots. The 10 50 bases long CUS1 transcript was only detected in embryogenic callus, in fruit and weakly in female flowers, and was absent in non-embryoge nic callus and other organs of the seedling and mature plant. More spe cifically the CUS1 transcript was detected only in the outer cell laye rs of the radicular part of the heart stage somatic embryo, in transmi tting tissue of female flowers and in tissues surrounding the ovules. The structure of the CUS1 gene was determined. (C) 1997 Elsevier Scien ce Ireland Ltd.