2 RELATED, LOW-TEMPERATURE-INDUCED GENES FROM BRASSICA-NAPUS ARE HOMOLOGOUS TO THE HUMAN TUMOR BBC1 (BREAST BASIC CONSERVED) GENE

In order to identify genes involved in cold acclimation, we have const ructed a cDNA library from Brassica napus (cv. Samourai) cold-acclimat ed etiolated seedlings. By differential screening, a cDNA clone named pBnC24 (Brassica napus Cold), corresponding to a new cold-inducible pl ant gene, was isolated. Northern blot hybridizations using total RNA f rom acclimated and unacclimated seedlings confirmed that BnC24 represe nts a cold-regulated gene. In contrast with a number of cold-inducible plant genes, BnC24 does not seem to be responsive to abscisic acid (A BA). In addition, further screening of the 'cold-acclimated' cDNA libr ary using pBnC24 cDNA as a probe, allowed the isolation of a second ty pe of homologous cDNA. Sequence analysis showed that the two BnC24 gen es encode basic 24 kDa proteins, which are highly hydrophilic and rich in alanine, lysine and arginine. The nucleotide and deduced amino aci d sequences of these clones do not show any homology with other previo usly described cold-induced plants genes. However they have strong hom ology with a recently discovered human tumour gene, bbc1 (breast basic conserved), which seems to be highly conserved in eukaryotes.