Breeding tools to prevent production losses caused by Erwinia:
Reduced susceptibility/enhanced resistance to soft rot

Projecttitel: Breeding tools to prevent production losses caused by Erwinia: Reduced susceptibility/enhanced resistance to soft rot
Projectnummer: LWV19033
Missie: Sleuteltechnologieën
MMIP: ST2 - Biotechnologie en veredeling
Looptijd: 2020 – 2023
Projectleider:  Jack Vossen

Soft rot diseases are caused by a range of Pectobacteriaceae, mutually referred to as soft rot Pectobacteriaceae (SRP). Also in potato cultivation of these bacteria cause serious problems. Currently, cultivation and hygiene measures are the only means to deal with SRPs in potato. Still, in seed potato cultivation in the Netherlands SRP induced losses account for 22 M€ annually. 
Losses are due to downgrading and rejection of seed lots, soft rot during storage and costs to prevent SRP spread during harvest, storage and seed multiplication. 
The complexity of the SRP problem is caused by different Dickeya and Pectobacterium species and subspecies that can cause both latent and symptomatic infections. 
In addition, the SRP epidemiology is complex as the inoculum sources are diverse (seed tubers, flooding, aerosols, rain and insects) and the different plant organs show different susceptibility levels and symptoms (tuber soft rot, blackleg, slow wilt). 
Not surprisingly, breeding for resistance against SRPs has not been very successful, so far. 
For a successful breeding approach, all infection routes and stages should be taken into account. 

In this project we will, for the first time pursue a combined approach to reduce susceptibility and to enhance resistance to SRP in potato. 
To reduce susceptibility, we will genetically determine why some varieties in the current breeding germplasm are more susceptible than others and develop tools to select against super-susceptibility in breeding programs. 
Secondly, we will target susceptibility (S) genes to enhance resistance and deploy them in non-GM way. 
Thirdly, we will deploy recently discovered SRE resistances from a wild potato plant. 

The genes underlying the reduced susceptibility and enhanced resistance will be introgressed and combined in cultivated potatoes. 
To accomplish these three goals, dedicated high throughput bioassay for the different infection routes and stages will be deployed and further developed. 
This combined approach will generate plant material and unique insights in SRP pathogenicity, that can be applied directly in potato, and provides a model for SRP diseases in other crops. The total package of genetic improvement has never been applied before and will for the first time provide an outlook to potato varieties with SRP resistance. 
These varieties will be resilient to SRP infection and climate induced changes in pathogen population and will strongly contribute to robust novel agricultural systems like mixed and stripped cropping. Herewith, our research provides greater certainties and lower losses to seed potato growers, resellers, farmers and consumers. 
Reduced losses and efficiency inherently contribute to improved circularity, reduced energy input and CO2 emissions, thereby benefitting the entire society.