Research Programs |
Citrus Canker Resistance
Worldwide the two most significant disease of citrus production are citrus canker and citrus greening. Canker's impact has been in the decreased marketability of fruit, losses in fruit production and tree vigor, the need for extra control measures, and the substantial cost incurred by eradication efforts. The economic impact of canker in the U.S. alone is on the order of over $300 million annually, in addition to the more than $1 billion spent to eradicate the pathogen without success.
Citrus canker is caused by the bacterial pathogen Xanthomonas citri subsp. citri (Xc). Like other bacterial pathogens, all citrus canker strains produce protein effectors that are injected into their plant hosts to subvert cell function for the establishment of infection.
2Blades is developing effective citrus canker resistance based on a specific class of effectors known as Transcription Activator Like (TAL) effectors. Some plants, including pepper and rice, have evolved resistance genes which are activated by TAL effectors via specific promoter sequences. Our citrus canker project uses this mechanism, dubbed 'Pathogen Inducible Promoters', to engineer new disease resistance genes in citrus that can be induced by multiple TAL effectors present in Xc strains.
The Pathogen Inducible Promoter strategy can be applied to other significant diseases caused by Xanthomonas, and a number of laboratories are now applying this approach to other crops, including the important staple crops, cassava and rice.
TAL effectors have several significant uses in plants and biotechnology (see TAL effector code) and are being developed into wide use (see News).
