美国佛罗里达大学植物病理学方向博后职位招聘

Postdocs in plant pathology (effector biology, CRISPR, microbiome, or epidemiology) : Lake Alfred, United States

There are four positions available in the Wang lab at University of Florida.
Position 1
This postdoc position is for four years, funded by the Plant Biotic Interactions (a NSF-NIFA joint program).
Project description:
Citrus canker caused by Xanthomonas citri ssp. citri (Xcc) is one of the most devastating diseases of citrus varieties worldwide. Citrus is, perhaps, the single most valuable fruit tree species, and is amenable to gene transfer and genome editing techniques.
We have previously identified that CsLOB1 (Citrus sinensis Lateral Organ Boundaries) is a critical citrus susceptibility gene to citrus canker pathogen Xcc (Hu et al. 2014). CsLOB1 is a member of the Lateral Organ Boundaries (LOB) gene family of transcription factors. All strains of Xcc encode a transcription activator-like (TAL) effector PthA that recognizes an effector binding element (EBE) in the promoter of CsLOB1 and induces gene expression. Furthermore, the EBEs of individual critical TAL effectors in various canker causing pathotypes overlap with each other. Thus, the EBE region of CsLOB1 presents an attractive target for genomic engineering of broad resistance to citrus canker. We have been mutating the CsLOB1 the EBE region via CRISPR/Cas9/sgRNA technology, and the genome-edited varieties will then be examined for resistance to citrus canker and possible unintended physiological effects of the editing. We will also measure the stability of the canker resistant citrus varieties and assess the potential for the bacteria to overcome recessive resistance through targeting of additional EBEs and related LOB gene promoters. We will study the potential of evolution of Xcc to overcome the resistance due to modification of the coding region and the EBEPhtA4 in the promoter region of CsLOB1. Understanding the mechanism of Xcc evolution will help us to prolong the resistance.
In our previous study, we have generated canker resistant citrus varieties via stable transformation of CRISPR/Cas9 (Jia et al. 2016 a, b). The responsibility of the position is to generate non-transgenic plant lines with EBE modifications in the promoter region of CsLOB1 in Valencia sweet orange through protoplast transformation using purified recombinant Cas9 protein and sgRNA, or Cas9/sgRNA DNA and test the modified varieties against a worldwide Xcc strain collection. The postdoc will also measure the effects of the mutations on CsLOB1 expression, citrus development, and other horticultural traits.