Calcium-mediated signaling during sandalwood somatic embryogenesis. role for exogenous calcium as second messenger

Anil, Veena S. ; Sankara Rao, K. (2000) Calcium-mediated signaling during sandalwood somatic embryogenesis. role for exogenous calcium as second messenger Plant Physiology, 123 (4). pp. 1301-1312. ISSN 0032-0889

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Official URL: http://www.plantphysiol.org/content/123/4/1301.sho...

Related URL: http://dx.doi.org/10.1104/pp.123.4.1301

Abstract

The possible involvement of Ca2+-mediated signaling in the induction/regulation of somatic embryogenesis from pro-embryogenic cells of sandalwood (Santalum album) has been investigated. 45Ca2+-uptake studies and fura-2 fluorescence ratio photometry were used to measure changes in [Ca2+]cyt of pro-embryogenic cells in response to culture conditions conducive for embryo development. Sandalwood pro-embryogenic cell masses (PEMs) are obtained in the callus proliferation medium that contains the auxin 2,4-dichlorophenoxyacetic acid. Subculture of PEMs into the embryo differentiation medium, which lacks 2,4-dichlorophenoxyacetic acid and has higher osmoticum, results in a 4-fold higher45Ca2+ incorporation into the symplast. Fura-2 ratiometric analysis corroboratively shows a 10- to 16-fold increase in the [Ca2+]cyt of PEMs, increasing from a resting concentration of 30 to 50 nm to 650 to 800 nm. Chelation of exogenous Ca2+with ethyleneglycol-bis(aminoethyl ether)-N,N'-tetraacetic acid arrests such an elevation in [Ca2+]cyt. Exogenous Ca2+ when chelated or deprived also arrests embryo development and inhibits the accumulation of a sandalwood Ca2+-dependent protein kinase. However, such culture conditions do not cause cell death as the PEMs continue to proliferate to form larger cell clumps. Culture treatment withN-(6-aminohexyl)-5-chloro-1-naphthalene sulfonamide reduced embryogenic frequency by 85%, indicating that blockage of Ca2+-mediated signaling pathway(s) involving sandalwood Ca2+-dependent protein kinase and/or calmodulin causes the inhibition of embryogenesis. The observations presented are evidence to suggest a second messenger role for exogenous Ca2+ during sandalwood somatic embryogenesis.

Item Type:Article
Source:Copyright of this article belongs to American Society of Plant Biologists.
ID Code:54024
Deposited On:11 Aug 2011 12:07
Last Modified:11 Aug 2011 12:07

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