Poster: Plant-pathogen interactions

Abs # 519: Citrus blight induces transcriptional responses on affected trees

Presenter:	Carlos, E.F. , efcarlos@ufl.edu
Authors	Carlos, E.F.  (A)   Beretta, M.J.G  (B)   Barthe, G.  (B)   Denslow, N.  (C)   Larkin, P.  (C)   Derrick, K.S.  (B)   Moore, G.A.  (A)
Affiliations:	(A): Plant Molecular and Cellular Biology Program, University of Florida, Gainesville, USA (B): Citrus Research and Education Center, Lake Alfred, USA (C): Interdisciplinary Center for Biotechnology Research-Protein Core, University of Florida, Gainesville, USA

Citrus is not only a nutritional and enjoyable food source but it is also an important industry in many places world wide, such as in Florida, the USA, and in São Paulo, Brazil. There are important production constraints according to location and citrus blight is one of them. It was first seen 120 years ago in Florida and only reported during the 1970s in São Paulo. Affected plants display Zinc deficiency in the leaves, blockage of xylem tissues, twig die back and overall tree decline rendering in economical failure of entire blocks of trees. The problem is dependent of the rootstock choice and can be root grafting transmitted, but in spite of that, its etiology remains unconfirmed. Therefore, we proposed to study how the plants respond to the process looking for variation on transcriptional patterns of selected genes. We built subtracted cDNA libraries from root samples of blighted and healthy rough lemon (Citrus jambhiri Lush) trees and selected clones randomly for sequencing and further analyzes. Non-redundant clones and tentative controls were PCR amplified and arrayed onto nylon membranes in duplicate spots for all the 188 entries. Feeder root samples collected in central Florida area from independent affected and healthy trees were labeled with P33 and hybridized against the membranes under stringent conditions. Some clones displayed significant differences between healthy and blighted samples and they were selected for confirmation using quantitative real time PCR. One clone has been confirmed having higher transcriptional level in blighted trees compared to healthy ones and it has sequence homology with a citrus EST generated by cold exposure experiments. This effort may open perspectives for gene characterizations and for citrus blight control.