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Effects of ovular secretions on pollen in Pseudotsuga menziesii (Pinaceae)
Author(s) -
Takaso Tokushiro,
Owens John N.
Publication year - 1994
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.1537-2197.1994.tb15475.x
Subject(s) - ovule , pollen , pollen tube , biology , botany , elongation , ultrastructure , biophysics , pollination , materials science , metallurgy , ultimate tensile strength
Effects of ovular secretions on pollen grains were examined in Pseudotsuga menziesii. The exine is cast off in the micropylar canal. A membranelike structure covers parts of pollen grains and appears to protect them. The outer intine consists of fibrous materials, but it also shows a thicker filamentous appearance in some ovules during pollen elongation. The inner intine is electron‐dense. Its fibrous nature is occasionally visible. Dissolution of the outer intine varies in amount and manner in ovules from different trees. The plasma membrane near the pollen wall alternatively appears normal and distorted. These different morphologies of the outer intine and of the plasma membrane are considered to result from secretions from the ovule. The outer intine may contain electron‐dense globules that are formed in the tube cell and traverse the inner intine. Pollen tube formation appears to be triggered by a secretion from the ovule. Cross‐pollinated grains are less distorted compared with self‐pollinated grains.