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NONESSENTIALITY OF CONCURRENT CELL DIVISIONS FOR DEGREE OF POLARIZATION OF LEAF GROWTH. I. STUDIES WITH RADIATION‐INDUCED MITOTIC INHIBITION
Author(s) -
Haber Alan H.
Publication year - 1962
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.1537-2197.1962.tb14985.x
Subject(s) - biology , elongation , cell division , mitosis , botany , horticulture , cell , microbiology and biotechnology , genetics , materials science , metallurgy , ultimate tensile strength
Haber, Alan H. (Oak Ridge Natl. Lab., Oak Ridge, Tenn.) Nonessentiality of concurrent cell divisions for degree of polarization of leaf growth. I. Studies with radiation‐induced mitotic inhibition. Amer. Jour. Bot. 49(6): 583–589. Illus. 1962.—During germination and seedling growth, the first foliage leaf of wheat shows polarized growth with striking changes in shape. During this polarized growth, most of the new cell plates are formed perpendicular to the axis of greatest elongation (longitudinal axis). The relation between leaf length and leaf width is the same in leaves normally growing with cell division as in leaves growing with negligible cell division after gamma‐irradiation (800 kr) of the unsown grain. Although cell division is necessary for continued growth and normal development, concurrent cell divisions play no role in determining the degree of polarization, i.e., the ratio of the rates of linear extension in length per mm length to linear extension in width per mm width. The majority of the new cell plates formed before the growth period studied were parallel to the axis of greatest absolute and relative elongation during the growth period studied. Irradiated and unirradiated wheat having the same leaf size, and thus the same leaf shape, have quite different cell sizes, shapes, and numbers in both the leaf epidermis and the chlorenchymatous mesophyll. It is concluded that: (1) the orientations of cell divisions, whether concurrent with or prior to the growth period studied, play no role in the basic mechanism which determines the manner in which leaves change shape; and (2) genetic information specifies leaf form independently of genetic influences on sizes and shapes of cells and on the extents and orientations of cell divisions.