‘Recovery’ from apple proliferation disease: an integrated approach.
Author(s)
Date Issued
2009
Type
Conference Proceedings
Abstract
Recovery is the spontaneous remission, sometimes permanent, from disease
symptoms. Phytoplasmas surviving in the roots are not able to recolonise the plant
crown. The causes that induce recovery remain still unknown and its physiological
bases are poorly understood. In this research the modifications in the phloem
tissue related to recovery-induced resistance in apple have been investigated
through ultrastructural, chemical, cytochemical and gene expression analyses of
leaf tissues from recovered, healthy and apple proliferation-diseased plants.
Ultrastructural observations detected abnormal callose and P-protein
accumulations in the phloem of recovered apple plants. Callose synthesis and Pprotein
plugging, which are Ca2+-dependent, would form physical barriers
preventing the in planta movement. The cytochemical localization by potassium
pyroantimonate detected the presence of Ca2+ ions in the phloem in all the three
groups of plants; however the Ca2+ concentration was remarkably higher in the
cytosol of the recovered apple plants. This observation would support the
hypothesis that resistance mechanisms would be related to an increased Ca2+-
dependent signaling activities. Apple genes coding for callose synthases and
phloem proteins were identified by an in silico approach. The expression patterns
of five genes encoding callose synthases (MDCALS1/5) and of four genes
encoding phloem proteins (MDPP2-1/3 and MDERG1) were analysed by
quantitative real time RT-PCR. Four of the nine analysed genes were up-regulated
in recovered plants in comparison to healthy and diseased ones, supporting the
hypothesis that recovered apple plants were able to develop resistance
mechanisms dependent from Ca2+ signal activities.
Citation
Musetti, R. et al. 2009. ‘Recovery’ from apple proliferation disease: an integrated approach. In: Bertaccini A., Amparo L., Torres E. (eds). COST Action FA0807. Integrated Management of Phytoplasma Epidemics in Different Crop Systems.
Current status and perspectives of phytoplasma disease research and management. Abstract book of the combined meeting of Work Groups. (Sitges, Spain February 1st and 2nd 2010) (1-4):89
Current status and perspectives of phytoplasma disease research and management. Abstract book of the combined meeting of Work Groups. (Sitges, Spain February 1st and 2nd 2010) (1-4):89
Subjects
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