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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Molecular Plant Pathology Laboratory » Research » Publications at this Location » Publication #327433
Title: Regulatory elements and structural features of Beta vulgaris polygalacturonase-inhibiting protein gene for fungal and pest control

Author
item Smigocki, Anna
item MONGEON, JULIE - University Of Maryland
item BRAZA, REZIA - Oak Ridge Institute For Science And Education (ORISE)
item Li, Haiyan

Submitted to: Annual Beet Sugar Development Foundation Research Report
Publication Type: Research Technical Update
Publication Acceptance Date: 3/31/2016
Publication Date: 5/13/2016
Citation: Smigocki, A.C., Mongeon, J., Braza, R., Li, H. 2016. Regulatory elements and structural features of Beta vulgaris polygalacturonase-inhibiting protein gene for fungal and pest control. Annual Beet Sugar Development Foundation Research Report. http://www.bsdf-assbt.org/assbt/assbt.htm.

Interpretive Summary: Plants are under constant threat of invasion by viruses, bacteria, fungi, nematodes and insects. As a consequence, plants have evolved a number of strategies for self-protection. One strategy involves the production of inhibitory compounds, among them polygalacturonase-inhibiting proteins (PGIPs). PGIPs are produced in plants to inhibit polygalacturonases, the enzymes released by pathogens and insect pests to break down cell walls during attack. To better understand how plants protect themselves from disease and insect pests, we isolated five sugar beet PGIP components. The sugar beet PGIPs shared the typical structure of other plant PGIPs but contained a longer stretch of repeating amino acids that was responsible for disease response. We demonstrated that the sugar beet PGIP components were involved in insect feeding and inhibited several disease causing fungal enzymes. The regulatory switch that activates the expression of the PGIP trait (gene) was isolated and shown to be highly targeted to the roots. Root and leaf production was shown to be enhanced to higher levels by insect damage and mechanical wounding. This information will be used by scientists to develop improved crops capable of resisting pests and diseases thus improving the safety of consumable foods by reducing the usage of pesticides

Technical Abstract: Polygalacturonase-inhibiting proteins (PGIPs) are involved in plant defense. PGIPs are cell wall leucine-rich repeat (LRR) proteins that are known to inhibit pathogen and pest polygalacturonases (PGs) during the infection process. Several sugar beet (Beta vulgaris L.) PGIP genes (BvPGIP) were cloned from breeding lines F1016, F1010 and FC607. BvPGIP clones shared closest similarity with five PGIP-like sequences found in the sugar beet reference genome (RefBeet 1.2.1). The sugar beet PGIP peptides were longer and encoded an additional LRR region as compared to the structure of defense PGIPs in other species. BvPGIP gene expression was highest in the roots and increased in leaves and roots in response to insect feeding and mechanical wounding. GUS gene expression driven by the BvPGIP promoter was observed predominantly in seedling roots and leaves of transformed N. benthamiana plants. BvPGIP protein extracts prepared from sugar beet tissues inhibited PG fungal proteins from Rhizoctonia solani, Fusarium oxysporum f. sp. gladioli and F. oxysporum f. sp. betae. These findings demonstrated a unique structure for the cloned sugar beet genes, their probable role in defense responses and root and leaf driven expression that can be used to design a strategy for improving disease resistance in plants.