Exploring the potential of engineering polygalacturonase‐inhibiting protein as an ecological, friendly, and nontoxic pest control agent

Abstract

In plants, polygalacturonase-inhibiting proteins (PGIPs) play critical roles for resistance to fungal disease by inhibiting the pectin-depolymerizing activity of endopolygalacturonases (PGs), one type of enzyme secreted by pathogens that compromises plant cell walls and leaves the plant susceptible to disease. Here, the interactions between PGIPs from Phaseolus vulgaris (PvPGIP1 and PvPGIP2) and PGs from Aspergillus niger (AnPG2), Botrytis cinerea (BcPG1 and BcPG2), and Fusarium moniliforme (FmPG3) were reconstituted through a yeast two hybrid (Y2H) system to investigate the inhibition efficiency of various PvPGIP1 and 2 truncations and mutants. We found that tPvPGIP2_5-8, which contains LRR5 to LRR8 and is only one-third the size of the full length peptide, exhibits the same level of interactions with AnPG and BcPGs as the full length PvPGIP2 via Y2H. The inhibitory activities of tPvPGIP2_5-8 on the growth of A. niger and B. cinerea were then examined and confirmed on pectin agar. On pectin assays, application of both full length PvPGIP2 and tPvPGIP2_5-8 clearly slows down the growth of A. niger and B. cinerea. Investigation on the sequence-function relationships of PGIP utilizing a combination of site directed mutagenesis and a variety of peptide truncations suggests that LRR5 could have the most essential structural feature for the inhibitory activities, and may be a possible target for the future engineering of PGIP with enhanced activity. This study highlights the potential of plant-derived PGIPs as a candidate for future in planta evaluation as a pest control agent.

Glycine maxpolygalacturonase inhibiting protein 11 (GmPGIP11) functions in the root to suppressHeterodera glycinesparasitism

“…The much shorter length of these proteins indicated they could be the result of genetic truncations. However, genetically truncated PGIP s encoding proteins that are even one-third the size of the full length polypeptide can have the same activity against some pathogen PGs (Chiu et al 2021). Thus, the shorter GmPGIP s were included in subsequent bioinformatics analyses.…”

The potential of plant proteins as antifungal agents for agricultural applications

“…Similarly, expression of PGIP3 from soybeans ( Glycine max ) in tobacco has been shown to inhibit the growth of pathogenic Sclerotinia sclerotiorum, Fusarium moniliforme, B. aclada, A. niger, Collectotrichum acutatum, and F. graminearum [ 141 , 142 ]; and expressing PGIP2 from lima beans ( Phaseolus lunatus ) in tobacco also delayed growth of Collectrichum lupini , B. cinerea , F. moniliforme , and A. niger [ 143 ]. Recently, it is also found that truncated PvPGIP2 with only the optimal docking area retains similar level of inhibitory activities towards PGs from A. niger and B. cinerea to the full-length PvPGIP2 [ 144 ]. Yeast strains secreting full-length or truncated PvPGIP2 with the Ost 1 signal peptide were also able to reduce fungal growth and delay sporulation by 1–2 days [ 144 ].…”

“…Recently, it is also found that truncated PvPGIP2 with only the optimal docking area retains similar level of inhibitory activities towards PGs from A. niger and B. cinerea to the full-length PvPGIP2 [ 144 ]. Yeast strains secreting full-length or truncated PvPGIP2 with the Ost 1 signal peptide were also able to reduce fungal growth and delay sporulation by 1–2 days [ 144 ]. Although the function of PGIPs when applied exogenously on plants has not been reported, this group of proteins is still considered as a promising candidate to be developed into an eco-friendly fungal control agent.…”

Recent Advances in Understanding the Function of the PGIP Gene and the Research of Its Proteins for the Disease Resistance of Plants

“…The seven OsPGIPs are all hydrophobic proteins, with good fat solubility, transmembrane structure, extracellular localization, and multiple N-glycosylation sites, making these proteins insoluble when expressed in E. coli [26]. The exposed LRR motif is critical for the affinity and specificity of PGIP [25][26][27][28].…”

“…The PGIP anti-disease effect has been confirmed in a series of in vivo experiments. PGIP-mediated fungi resistance has been shown in various important cash crops, such as grapes [57,58], papaya [59], potatoes [51], alfalfa [15], cotton [60], green beans [6,28,61], tomatoes [62], peas [63], mandarin orange [64], tobacco [65], and Arabidopsis [66]. PGIP expression does not affect plant phenotype or inhibit plant growth in sugar beet [67] or tobacco [67].…”