Calcium changes during megasporogenesis and megaspore degeneration in lettuce (<Emphasis Type="Italic">Lactuca sativa</Emphasis> L.) |
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Authors: | Yi Lan Qiu Ru Shi Liu Chao Tian Xie Scott D Russell Hui Qiao Tian |
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Institution: | (1) School of Life Sciences, Xiamen University, 361005 Xiamen, China;(2) School of Life Sciences, Hunan Normal University, 410081 Changsha, China;(3) Department of Botany and Microbiology, University of Oklahoma, Norman, OK 73019, USA |
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Abstract: | Potassium pyroantimonate was used to localize loosely-bound calcium in young ovules of lettuce (Lactuca sativa L.) during megasporogenesis to investigate the relationship between ionically available calcium and megaspore degeneration.
At the megasporocyte (megaspore mother cell) stage, few calcium precipitates were located in the ovule. Following meiosis
in the megasporocyte, a linear tetrad of four megaspores is formed, with three of the four megaspores degenerating from the
micropylar end inward. Only the chalazal-most megaspore continues to develop, becoming the functional megaspore. A decrease
in amount of calcium precipitates in the megaspore, particularly in the nucleus, precedes the breakdown of the micropylar
megaspores, which subsequently undergo structural disintegration and loss of recognizable cellular features. A partial recovery
of calcium precipitates occurs during later degeneration. The functional megaspore retains a consistently higher concentration
of calcium precipitates during development, which is retained in the developing embryo sac. This, to our knowledge, is the
first report related to calcium dynamics during megaspore degeneration, and may facilitate future research aimed at elucidating
the mechanisms of megasporogenesis. |
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Keywords: | Calcium Embryo sac development Lettuce (Lactuca sativa L ) Megaspore Megasporogenesis |
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