Quantification of Cauline Leaf Abscission in Response to Plant Pathogens

Abscission is a process that allows plants to shed unwanted organs. Plants can use abscission as a defense mechanism to shed leaves that are heavily infected with pathogenic bacteria. By shedding infected leaves, plants completely eliminate the bacteria from the plant body, thus preventing further spreading of the disease. A lot is known about how plants limit the growth of pathogenic bacteria in vegetative leaf tissues. Much less is known about how plants defend themselves in non-vegetative developmental stages and how they use organ level responses such as leaf abscission for defense. Organ level defense responses can be effectively studied in the Pseudomonas syringae-triggered leaf abscission system in Arabidopsis. This method article describes detailed procedures for quantitative analysis of cauline leaf abscission including dissecting abscission zones for extraction of RNA and proteins for quantitative gene or protein expression analysis. The method described for molecular analysis of abscission zones could also be used in other cases where tissue is extremely limiting.