Stiftelsen Oscar och Lili Lamms Minne
Du är här: Hem // 2017 
TitelBiological control strategies that target notorious plant pathogens
NoDO2017-0020
UniversitetKTH Royal Institute of Technology
InstitutionBiotechnology
HuvudsökandeChristina Divne
Beviljat belopp2 000 000
Sammanfattning
Motivation and relevance Fruit constitutes the second most important crops, second only to grains, and offers an invaluable source of nutrients. Pome fruit orchards (e.g., apple) are regularly plagued by fire blight, a devastating infection caused by the bacterium Erwinia amylovora. Furthermore, the bacterial pathogen Xanthomonas causes enormous damage to fruit crops in many countries. Traditionally, bacterial plant infections have been treated with antibiotics, but due to the increased bacterial resistance, it is necessary to find new treatments. Virulence and pathogenicity in these notorious bacteria depends to a large extent on the production of phytopathogenic exopolysaccharides, amylovoran and xanthan gum, receptively. The phytoexopolysaccharides allow the pathogen to move in planta, and gradually block the xylem vessels physically, and eventually kill the tree. As a contribution to the larger effort to find new and sustainable ways to protect future fruit resources, we suggest two molecular combat strategies that do not depend on traditional antibiotics. The proposal concerns salary for a new PhD student for four years. Aim and preliminary results – strategy 1 We will start by characterizing biochemically, structurally and functionally the key enzymes AmsG and GumD that catalyze the production of the crucial glycolipid intermediates required for all subsequent biosynthesis of the phytoexopolysaccharides amylovoran and xanthan gum, respectively. Experimental structure-mechanistic data will allow us to evaluate chemical compounds in silico for their potential usefulness as enzyme inhibitors, which will lay the basis for later experimental screening of potential inhibitors that selectively block amylovoran and xanthan production. We recently characterized structurally and functionally a membrane enzyme that catalyzes biosynthesis of a similar glycolipid intermediate as do AmsG and GumD. A manuscript reporting on these results was recently accepted for publication in Nature Communications. Project feasibility is rated as high. Aim and preliminary results – strategy 2 Here, we intend to study enzymes that synthesize flavonoids that increase plant tolerance to bacterial infection. Our partner in Vienna noted that increased production of the flavonoid 3-hydroxyphloretin (3HPL) increases apple’s tolerance against fire blight. However, the production is low, and by understanding in more detail the molecular mechanisms that influence the plant’s ability to produce 3HPL, we can lay the basis for future genome editing to boost the plant’s own production of 3HPL and tolerance. To date, we have cloned several constructs of the ch3h gene from Dhalia variabilis. Both constructs show expression in E. coli, and can be purified. In addition, our collaboration partner has preliminary biochemical results for active flavonoid-producing enzymes produced in Saccharomyces cerevisiae. Project feasibility is rated as good.