Record ID No. |
85 |
Author(s) |
Sieberer BJ, Chabaud M, Fournier J, Timmers AC, Barker DG. , 2012 |
Affiliation |
Laboratory of Plant-Microbe Interactions, Institut National de Recherche Agronomique (UMR 441), Centre Nationale de Recherche Scientifique (UMR 2594), Castanet-Tolosan, France. e-mail:(Barker DG) David.Barker@toulouse.inra.fr |
Title |
A switch in Ca2+ spiking signature is concomitant with endosymbiotic microbe entry into cortical root cells of Medicago truncatula |
Source. Vol.(no):Page |
Plant Journal, 69 (5): 822-830p. |
Categories |
Arbuscular Mycorrhiza |
Subjects |
Biochemistry |
Host |
Medicago truncatula |
Organism |
Rhizobia |
Country |
France, Europe |
Abstracts |
Ca(2+) spiking is a central component of a common signaling pathway that is activated in the host epidermis during initial recognition of endosymbiotic microbes. However, it is not known to what extent Ca(2+) signaling also plays a role during subsequent root colonization involving apoplastic transcellular infection. Live-tissue imaging using calcium cameleon reporters expressed in Medicago truncatula roots has revealed that distinct Ca(2+) oscillatory profiles correlate with specific stages of transcellular cortical infection by both rhizobia and arbuscular mycorrhizal fungi. Outer cortical cells exhibit low-frequency Ca(2+) spiking during the extensive intracellular remodeling that precedes infection. This appears to be a prerequisite for the formation of either pre-infection threads or the pre-penetration apparatus, both of which are fully reversible processes. A transition from low- to high-frequency spiking is concomitant with the initial stages of apoplastic cell entry by both microbes. This high-frequency spiking is of limited duration in the case of rhizobial infection and is completely switched off by the time transcellular infection by both microsymbionts is completed. The Ca(2+) spiking profiles associated with both rhizobial and arbuscular mycorrhizal cell entry are remarkably similar in terms of periodicity, suggesting that microbe specificity is unlikely to be encoded by the Ca(2+) signature during this particular stage of host infection in the outer cortex. Together, these findings lead to the proposal that tightly regulated Ca(2+) -mediated signal transduction is a key player in reprogramming root cell development at the critical stage of commitment to endosymbiotic infection.
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