Low-abundance plant protein enrichment with peptide libraries to enlarge proteome coverage and related applications

[Display omitted] •The reduction of protein dynamic range is a way to detect low-abundance plant proteins.•The enrichment of very dilute proteins in plant extract extends the knowledge for plant proteomes.•Novel allergen discoveries and protein markers contingent upon abiotic and biotic stresses are detectable.•Plant protein expression is altered upon given environmental changes. In plant tissues proteins are present in low amounts but in a very large number. To this peculiar situation many complex foreign components render protein extraction and purification very difficult. In the last several years interesting technologies have been described to improve the technical situation to the point that some methodologies allow reaching very low-abundance proteins and minor allergens. Among enrichment methods the one documented in this report is based on combinatorial peptide ligand libraries (CPLLs) that emerged in the last decade by contributing to largely improve the knowledge in plant proteomics. It is the aim of this review to describe how this technology allows detecting low-abundance proteins from various plant tissues and to report the dynamics of the proteome components in response to environmental changes and biotic attacks. Typical documented examples with the description of their scientific interest are reported. The described technical approach and selected applications are considered as one of the most advanced approaches for plant proteomics investigations with possibilities not only to enlarge the knowledge of plant proteomes but also to discover novel allergens as well as plant biomarkers subsequent to stressful situations.