MOSS (PHYSCOMITRELLA PATENS) EXPRESSED SEQUENCE TAGS INCLUDE SEVERAL SEQUENCES WHICH ARE NOVEL FOR PLANTS

The moss Physcomitrella patens (Hedw.) B.S.G. is the first land plant in which gene disruption by homologous recombination is directly acces sible. In order to obtain cloned sequences which may be used in such a n approach, complementary DNAs (cDNAs) have been isolated by subtracti ve hybridisation of representative cDNA libraries from cytokinin-treat ed tissue. Sequencing of these clones from both ends yielded over 35 k b of non-redundant sequence information, of which 20 kb results from c lones which appear to be novel to plants. Database comparisons have re vealed that 39 of the expressed sequence tags (ESTs) generated show si gnificant homology to identified sequences. Analysis of these ESTs sho ws a high degree of conservation between Physcomitrella and seed plant sequences, and codon usage is found to be very similar to that in dic otyledonous species. Furthermore, 43 sequences showing no significant homology to sequences in the databases represent previously unidentifi ed expressed genes.