Molecular cloning of the apoptosis-related calcium-binding protein AsALG-2 in Avena sativa.
Victorin, the host-selective toxin produced by the fungus Cochliobolus victoriae, induces programmed cell death (PCD) in victorin-sensitive oat lines with characteristic features of animal apoptosis, such as mitochondrial permeability transition, chromatin condensation, nuclear DNA laddering and rRNA/mRNA degradation. In this study, we characterized a calcium-binding protein, namely AsALG-2, which might have a role in the victorin-induced PCD. AsALG-2 is homologous to the Apoptosis-Linked Gene ALG-2 identified in mammalian cells. Northern blot analysis revealed that the accumulation of AsALG-2 transcripts increased during victorin-induced PCD, but not during necrotic cell death. Salicylic acid, chitosan and chitin strongly activated the expression of general defence response genes, such as PR-10; however, neither induced cell death nor the accumulation of AsALG-2 mRNA. Pharmacological studies indicated that victorin-induced DNA laddering and AsALG-2 expression were regulated through similar pathways. The calcium channel blocker, nifedipine, moderately inhibited the accumulation of AsALG-2 mRNA during cell death. Trifluoperazine (calmodulin antagonist) and K252a (serine-threonine kinase inhibitor) reduced the victorin-induced phytoalexin accumulation, but did not prevent the victorin-induced DNA laddering or accumulation of AsALG-2 mRNA. Taken together, our investigations suggest that there is a calcium-mediated signalling pathway in animal and plant PCD in common.
Laboratory of Plant Pathology, Graduate School of Science and Technology, Kobe University, Rokkodai, Nada-ku, Kobe, Japan. trinhxuanhoat@yahoo.com
Trinh Xuan
TX
Hoat
Hitoshi
H
Nakayashiki
Qian
Q
Yang
Yukio
Y
Tosa
Shigeyuki
S
Mayama
D017209:Apoptosis / Q000235:genetics / Q000502:physiology*; D018554:Avena / Q000235:genetics / Q000378:metabolism*; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*
D002135:Calcium-Binding Proteins; D010940:Plant Proteins