The role of arabinogalactan proteins (AGPs) in fruit ripening\u2014a review

Agata Leszczuk,Artur Zdunek,Konstantinos N Blazakis,Panagiotis Kalaitzis

doi:10.1038/s41438-020-00397-8

Abstract

Arabinogalactan proteins (AGPs) are proteoglycans challenging researchers for decades. However, despite the extremely interesting polydispersity of their structure and essential application potential, studies of AGPs in fruit are limited, and only a few groups deal with this scientific subject. Here, we summarise the results of pioneering studies on AGPs in fruit tissue with their structure, specific localization pattern, stress factors influencing their presence, and a focus on recent advances. We discuss the properties of AGPs, i.e., binding calcium ions, ability to aggregate, adhesive nature, and crosslinking with other cell wall components that may also be implicated in fruit metabolism. The aim of this review is an attempt to associate well-known features and properties of AGPs with their putative roles in fruit ripening. The putative physiological significance of AGPs might provide additional targets of regulation for fruit developmental programme. A comprehensive understanding of the AGP expression, structure, and untypical features may give new information for agronomic, horticulture, and renewable biomaterial applications.

Highlights

Fruits are one of the main horticultural products
In two different glycosylation forms isolated from Arabidopsis thaliana culture suspension containing pectin and arabinoxylan glycan domains, covalent binding of carbohydrates to the Arabinogalactan proteins (AGPs) was recognized. These results showed that AG, rhamnogalacturonan type I (RG-I), and arabinoxylan glycan domains were O-linked to the Hyp of AGPs
Conclusions the knowledge of the presence and functions of AGPs in fruit tissue is very limited, the available structural and genetic mutant data show that the occurrence of AGPs and in vitro properties may be related to their high importance for fruit metabolism and quality

Summary

Introduction

Fruits are one of the main horticultural products. They are eaten fresh or processed delivering pro-health and nutritional components. Most of the quality parameters of fruit and biotechnological usefulness of plants relate to mechanical characteristics[1]. From mechanical point of view, cells linked with middle lamella, turgor (water content), intercellular spaces and cell wall properties play the key role[2]. This macroscopic model of the plant tissue biomechanics is accepted, knowledge about processes at

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