Expressed sequence tags (ESTs) from desiccated Tortula ruralis identify a large number of novel plant genes

The desiccation-tolerant moss Tortula ruralis [Hedw.] Gaerten., Meyer & Sch erb. has both a constitutive protection system and an active rehydration in duced recovery mechanism apparently unique to bryophytes. Immediately follo wing rehydration, desiccated T. ruralis gametophytes produce a set of polyp eptides whose synthesis is unique to the rehydrated state. We report the co nstruction of a cDNA expression library from the polysomal mRNA of desiccat ed gametophytes and the single-pass sequencing of randomly selected clones. 152 expressed sequence tags (ESTs) were generated representing more than 6 0,000 bp of non-redundant DNA sequence. 44 ESTs (29%) demonstrated signific ant homology to previously identified nucleotide and/or polypeptide sequenc es, such as ribosomal proteins, desiccation-related peptides, early light-i nducible proteins and a V-type ATPase, Analysis of a subset of these homolo gous ESTs reveals that codon preference in T, ruralis is similar to that of vascular plants, particularly the Magnoliopsida. 108 ESTs (71%) demonstrat ed no significant homology to deposited sequences and represent a large num ber of novel plant genes. Analysis of these ESTs will define the range of g enes involved in cellular repair and recovery and may provide greater insig ht to the complex phenotype of vegetative desiccation-tolerance.