A differentially expressed proteomic analysis in placental tissues in relation to pungency during the pepper fruit development

Abstract

Using proteomic analysis including 2-DE, image analysis, and protein identification with LC-MS/MS, an investigation aimed at a better understanding of the differentially expressed proteins and/or gene products was carried out with total cell extracts from placental tissues in nonpungent (Capsicum annuum cv. Saeng-Ryeog #213) and pungent peppers (C. annuum cv. Saeng-Ryeog #211). Mobilization of the most abundant proteins, which were on the gels of pH ranges of 4-7, 4.5-5.5, 5.5-6.7, and 6-9, and showed very similar profiles in the two tissues, revealing approximately 2600 protein spots consisting of 1200 on pH 4-7, 600 on 4.5-5.5, 550 on 5.5-6.7, 250 on 6-9. Of these, 37 protein spots, which appeared in only pungent tissues but not in nonpungent tissues or markedly increased in their staining intensities on the gels from pungent tissue, were selected, excised, in-gel trypsin digested, and analyzed by LC-ESI-MS/MS. Peptide MS/MS data were searched against publicly available protein and EST databases, and 22 proteins were identified. Based on this result, we tested and compared the differential expression during fruit development on the 2-DE gels with total cell extracts from placental tissues of pungent and nonpungent peppers at an interval of 10 days from 10 to 40 days after flowering. In addition, this differential protein expression was further confirmed for some subsets of candidates by Northern-blot analysis with RNA samples from placental tissues harvested from each pepper fruit at the same sampling intervals. In this study, the physiological implications, revealed from the experimental data in the levels of proteome and transcripts, are discussed in the context of a complex biosynthesis network of capsaicinoids in pepper cells responsive to pungency.

A Dynamic Interface for Capsaicinoid Systems Biology

“…Future iterations of this model can include genes that were not predicted to be part of the metabolic pathways by the inclusion of genes that are up-regulated during capsaicinoid biosynthesis. Previously, the spatial and temporal expression pattern of capsaicinoids has been used to identify new candidate genes for this pathway, including regulatory factors (Curry et al, 1999;Kim et al, 2001;Aluru et al, 2003;Blum et al, 2003;Lee et al, 2006). A microarray approach in Solanum has already generated many candidates that are up-regulated in trichomes (Slocombe et al, 2008).…”

“…While progress has been made in the identification and analysis of genes and proteins found in the historical conceptualization of capsaicinoid biosynthesis (Curry et al, 1999;Kim et al, 2001;Aluru et al, 2003;Lee et al, 2006), the overall capsaicinoid metabolic scheme has not been updated in light of revisions of related pathways in other organisms or considered in terms of its cellular context (Fig. 2).…”

Array Platform for Food Safety and Quality

“…Differentially expressed proteomic analysis in placental tissues from nonpungent and pungent peppers during fruit development revealed protein markers related to pungency (Lee et al 2006). These proteins are involved in a complex biosynthesis network of capsaicinoids in pepper cells.…”

Proteomics for the Food Industry: Opportunities and Challenges

“…Such studies allowed the identification of markers for specific horticultural quality aspects (Lee et al, 2006), for detecting optimum harvest maturity (Abdi et al, 2002) and for the detection of variations among genotypes (Rocco et al, 2006).…”