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A NOMARSKI INTERFERENCE STUDY OF MEGASPOROGENESIS AND MEGAGAMETOGENESIS IN SMELOWSKIA CALYCINA (CRUCIFERAE)
Author(s) -
Greene Craig W.
Publication year - 1978
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/j.1537-2197.1978.tb06078.x
Subject(s) - megaspore , ovule , biology , botany , egg cell , population , apomixis , pollen , ploidy , genetics , demography , sociology , gene , sperm
Ovule development, megasporogenesis and megagametogenesis in an aneuploid population of the arctic‐alpine crucifer, Smelowskia calycina , were examined to test for the possibility of apomictic seed production. Whole mounts of ovules cleared in Herr's “4½” clearing fluid were examined using Nomarski differential interference microscopy. The campylotropous ovule was bitegmic, with a micropyle formed by both integuments. The single archesporial cell of a crassinucellar nucellus functioned directly as a megasporocyte, dividing to form a linear tetrad of megaspores. The chalazal megaspore divided to form an 8‐nucleate, 7‐celled gametophyte of the Polygonum type, having hooked synergids with a well‐developed filiform apparatus and polar nuclei that fused prior to fertilization. In the absence of any anomalous development indicative of agamospermy, seed production was assumed to be sexual.