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Role of Calcium in the Callose Response of Self-Pollinated Brassica Stigmas
Anuradha Singh and Dominick J. Paolillo, Jr.
American Journal of Botany
Vol. 77, No. 1 (Jan., 1990), pp. 128-133
Published by: Botanical Society of America, Inc.
Stable URL: http://www.jstor.org/stable/2444801
Page Count: 6
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In Brassica oleracea, sporophytic self-incompatibility prevents germination of self pollen, or normal growth of self pollen tubes. After self-pollination, the papillae of stigmas synthesize callose. The role of Ca++ in the formation of stigmatic callose was tested by adding compounds that interact with Ca++ to suspensions of pollen that were known to induce callose formation in self stigmas. The calcium channel antagonist, lanthanum, and the calcium chelating agent, EGTA, reduced or abolished the callose response to self-pollen suspensions. In the presence of Ca++, the calcium ionophore, A23187, induced callose in stigmatic papillae when added to pollen suspensions, or alone. Therefore, callose deposition in response to incompatible pollinations appears to be a calcium-dependent process. Pretreatment of pistils with 100 μM 2-deoxy-D-glucose abolished the callose response to self-pollination, while self pollen remained inhibited and cross pollen grew normally in treated pistils. Thus, callose formation in the stigma is not an essential part of the self-incompatibility mechanism preventing the growth of self pollen in Brassica.
American Journal of Botany © 1990 Botanical Society of America, Inc.