Location: Molecular Plant Pathology Laboratory
Project Number: 8042-21220-233-06-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Sep 1, 2018
End Date: Aug 31, 2019
Objective 1: Confirm a differential response to sugar beet polygalacturonase inhibitor protein genes BvPGIP1 and BvPGIP2 using multiple isolates representing the genetic diversity in Rhizoctonia solani AG2-2 and AG4 (Michigan State U.). Objective 2: Characterize expression of BvPGIP1 and BvPGIP2 in beet under R. solani exposure (ARS, Beltsville and East Lansing). Objective 3: Examine variability of polygalacturonase (PG) in R. solani (ARS, East Lansing, MI).
Currently the effectiveness of BvPGIP1 and BvPGIP2 to limit disease progress has only been examined using a single isolate each of AG2-2 and AG4. Previous studies have demonstrated significant variability in virulence among isolates and we hypothesize that this is due in large part to differences in the polygalacturonase enzymes produced by the fungus. Testing a diverse set of R. solani AG2-2 and AG4 isolates will allow us to confirm their differential response to BvPGIP1 and BvPGIP2 and to determine their range of inhibition. Transgenic Nicotiana benthamiana plants overproducing the BvPGIP1 or BvPGIP2 gene will be screened in a growth chamber using a set of R. solani AG2-2 and AG4 isolates that represent the genetic diversity and range of virulence identified in previous studies. Examine BvPGIP1 and BvPGIP2 expression in elite sugar beet breeding lines under R. solani exposure and measure expression levels of BvPGIP genes. Response can vary depending on the growth stage that infection occurs and therefore we would examine expression levels when inoculating at several growth stages. Since many putative cell wall degrading enzymes have been identified in R. solani, including polygalacturonases (PGs), we will examine PG variability with the R. solani AG2-2 group. Coupled with a separate sequencing project of 18 - 20 R. solani isolates, this data will be used to examine PG genes in silico, and based on the data generated in Objective 1, virulence will be correlated to variations in fungal PG enzymes.