Effects of quorum sensing inhibitor expression by Arabidopsis Thaliana on food crop associated

fungal and bacterial pathogenesis: a model for food crop QSI GMOs

A Grant Proposal by

Beau Smith & Jacob Harris

Background - Quorum Sensing● Bacteria used to be thought of as individualistic organisms

- They are not

● Use of autoinducers to “talk” to each other & coordinate cellular activities

● Quorum sensing (QS) - epigenetic pathway which modifies the expression of

genes based on the presence of conspecific and interspecific molecules and their

concentrations

● Many different types of QS molecules used for different activities

● Often used for activation of population virulence (Kalia 2013)

Background - QSI and Agriculture● Many organisms naturally produce quorum sensing

inhibitors (QSIs) that cripple communications

between QS organisms (Kalia 2013)

● Agricultural crops have to deal with pests that use QS

- Many don’t naturally produce QSIs to fight

them

● 20 - 40% loss in worldwide agricultural production

due to diseases (Savary et al. 2012)

- Pesticide resistance increasing

● Genetic engineering may allow these crops to

produce QSIs

P. syringae

Puccinia triticina

Background - Arabidopsis thaliana● One of the most well-studied model plant organisms

(Bortesi & Fischer 2015)

○ Seed is transparent, allowing developmental studies

○ Self polinates

● Used in CRISPR/Cas9 genetic engineering

● Test the efficacy of QSI expression in plants

Research Design and PlanHypothesis: Arabidopsis thaliana transformed to express and co-express farnesol and

QsdH will be more resistant to Pseudomonas syringae and Puccinia triticina than

wild-type A. thaliana.

Specific Aims:

● CRISPR/Cas9 and Plaques

● Surface Promoter + Variable CMV35s: Single, Double, Triple = 9 Cohorts

● QsdH and Farnesol cDNA

● Exposed to pathogen from leaf of infected A. Thaliana (Why do we do this?)

● Scored for phenotypic markers of stress vs untransformed control

Cohort Construct:

Scoring for Phenotypic Markers:

P. syringae Puccinia triticina

Perspectives● Expected results

- Decreased virulence & biofilm development

- Increased plant resistance, even when exposed to pathogens

● Test QSIs on murine gut microbiota health

● QSI production may produce undesirable crop traits due to resource shifts

● Applications in agriculture - P. syringae affects wheat and fruit trees (Moore

1988)

● Research can be used as stepping stone for future QS research

Significance● Quickly increasing world population = need for more agricultural production

- Est. 8.5 billion people by 2030 (United Nations 2015)

● Still high usage of pesticides even with increasing pesticide resistance

- US: 1 billion lbs per year (Alavanja 2009)

● Less food waste, fewer chemicals, more bountiful harvest

● QS is still a relatively new biological discovery

● Applicable future QS clinical studies

- P. aeruginosa: respiratory infections, developed drug resistance (Smith &

Iglewski 2003)

- Candida albicans: farnesol to prevent hyphal development, 1st QS eukaryote

(Shareck & Belhumeur 2011)

- Both affect immunocompromised persons, i.e. HIV infected

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