| Syntrichia ruralis (Hedw.) F. Weber & D. Mohr ( Tortula ruralis) is a useful model system for the study of gene control in response to severe water deficit-stress. Two truncated cDNAs (designated Elipa and Elipb) were isolated with significant similarity to the early light-inducible proteins (ELIPs). ELIPs are nuclear encoded, chloroplast thylakoid membrane-associated proteins and were first discovered during early greening of etiolated plants. ELIPs respond to a variety of stress factors, including high light and desiccation, and are postulated to protect the chloroplast from photooxidative damage. Full-length cDNAs of Elipa and Elipb were obtained by 5′ RACE and RLM-RACE respectively. Elipa is 1006 bp in length, encoding a predicted peptide with 212 amino acids (23.3 kDa, pI 5.57). Elipb is 997 bp in length, encoding a predicted peptide with 224 amino acids (24.4 kDa, pI 9.27). ELIPa and ELIPb are most similar to each other, but ELIPa has more similarity to ELIPs from other species. ELIPa contains three transmembrane helices and two potential destruction-liable PEST sequences while ELIPb lacks these motifs entirely. RNA blot hybridization was used to analyze Elipa and Elipb mRNA abundance in response to a variety of stresses. Elipa is a more abundant message than Elipb. Elipa was detectable in all treatments including control and dark treatment. Elipa mRNA was increased in abundance by slow desiccation, rapid dry/rehydration, rehydration in high light, low temperature, high salt, ABA, jasmonic acid and UV-C. Elipb RNA was only detectable in S. ruralis gametophyte subjected to rehydration in high light and ABA treatment.;In addition, a truncated cDNA was isolated with significant similarity to the large-subunit ribosomal protein L15 (RPL15). The full-length cDNA of Rpl15 was obtained using 5′RACE. Rpl15 encodes a predicted peptide with 203 amino acids (24.1 kDa, pI 11.1). RNA blot hybridization demonstrated that Rpl15 mRNA abundance does not change in S. ruralis during a desiccation-rehydration cycle and that Rpl15 transcripts are maintained in desiccated gametophytes as conserved mRNAs. |
