Arabinogalactan protein gene family from Centaurium erythraea Rafn

Abstract

Arabinogalactan proteins (AGPs) are heavily glycosylated cell walls proteins involved in plant defense and cell-cell interactions. AGPs are also novel and promising markers for in vitro morphogenetic processes such as somatic embryogenesis. We have isolated and sequenced an AGP gene family from common centaury (Centaurium erythraea Rafn.), a pharmacologically valuable and endangered species with unusually versatile in vitro morphogenetic pathways and vigorous regenerative potential. Starting from sequenced and de novo assembled C. erythraea transcriptome, five potential AGP sequences were found by BLAST-ing local leaf and root databases using known plant AGP sequences as queries. The five isolated sequences were resequenced, labeled as CeAGP1 through CeAGP5, annotated and uploaded to the GenBank (accessions KC733S82 through KC733886). Searching GenBank protein database using translated centaury sequences as queries revealed that CeAGP1, 2 and 4 are fasciclin-like proteins with the FAS1 domains, belonging to the Fasciclin superfamily. CeAGP3 and CeAGP5 also have homology with other plant AGPs, but have no known conserved domains. While CeAGP2, 3 and 5 appear to be complete coding sequences with 461, 64 and 202 amino acids respectively, CeAGP1 and 4 are partial sequences with more than 225 and 335 amino acids respectively. The sequenced transcripts differ in the degree of homology with other known plant AGPs. The alignments of novel putative AGPs with published plant AGPs, as well as recognized protein domains are presented. Expression of all 5 genes was confirmed in both leaves and roots by RT-PCR. The sequenced centaury AGPs will be evaluated as potential molecular markers for early developmental stages of somatic embryogenesis in centaury.