Ce. Deutch et I. Winicov, POSTTRANSCRIPTIONAL REGULATION OF A SALT-INDUCIBLE ALFALFA GENE ENCODING A PUTATIVE CHIMERIC PROLINE-RICH CELL-WALL PROTEIN, Plant molecular biology, 27(2), 1995, pp. 411-418
A cDNA previously shown to identify a salt-inducible root-specific tra
nscript in Medicago saliva was used to screen an alfalfa library for t
he corresponding genomic sequence. One positive clone was recovered. T
he nucleotide sequence of a subclone contained a 329 bp 5' region upst
ream of the first ATG codon, a 1143 bp coding segment, and a 447 bp 3'
-untranslated region interrupted by a single 475 bp intron. Translatio
n of the coding segment, which was designated MsPRP2, suggested it enc
odes a chimeric 40569 Da cell wall protein with an amino-terminal sign
al sequence, a repetitive proline-rich sequence, and a cysteine-rich c
arboxyl-terminal sequence homologous to nonspecific lipid transfer pro
teins. The 3'-untranslated region of MsPRP2 contained a sequence simil
ar to one found to destabilize mRNAs transcribed from the elicitor-reg
ulated proline-rich protein gene PvPRP1. Transcription run-on experime
nts using nuclei from salt-sensitive and salt-tolerant alfalfa callus
suggested that the accumulation of MsPRP2 transcripts in salt-tolerant
alfalfa cells grown in the presence of salt is due primarly to increa
sed mRNA stability. The MsPRP2 gene thus may be a useful model for stu
dying post-transcriptional salt-regulated expression of cell wall prot
eins.