Plant Antimicrobial Peptides: An Overview of SuperSAGE Transcriptional Profile and a Functional Review

Defensin, thionin and lipid transfer protein (LTP) gene families, which antimicrobial activity has an attractive use in protein engineering and transgenic production of agronomically important plants, have been here functionally reviewed. Also, a transcriptional overview of plant SuperSAGE libraries and analysis of 26 bp tags possibly annotated for those families are presented. Tags differentially expressed (p < 0.05) or constitutively transcribed were identified from leaves or roots from SuperSAGE libraries from important Brazilian plant crops [cowpea (Vigna unguiculata (L.) Walp.), soybean (Glycine max (L.) Merr.) and modern sugarcane hybrids (Saccharum spp.)] submitted to abiotic [salt (100 mM NaCl) or drought] or biotic stresses [fungus inoculation (Phakopsora pachyrhizi; Asiatic Soyben Rust phytopathogen)]. The diverse transcriptional patterns observed, probably related to the variable range of targets and functions involved, could be the first step to unravel the antimicrobial peptide world and the plant stress response relationship. Moreover, SuperSAGE opens the opportunity to find some SNPs or even rare transcripts that could be important on plant stress resistance mechanisms. Putative defensin or LTPs revealed by SuperSAGE following a specific plant treatment or physiological condition could be useful for future use in genetic improvement of plants.