Fig 1.
Summary of maize stamen development.
Major cellular events of stamen anther development are shown; left column, cartoon of locule; middle column, anther cross section with colors overlaid to indicate cell types (same colors used in cartoons and cross sections); right column, description of cell types present and defining characteristics for each stage. Stages based on Sanders et al., 1999.
Fig 2.
Male reproductive defects in fzt.
A normal spikelet (A) contains two florets; each floret is composed of a palea (pa), two lodicules (not visible) and three stamens (arrowheads). Two glumes (gl) subtend the two florets. A fzt spikelet (B) contains extra florets (arrows) and lacks glumes; fzt florets often contain abnormal floral organs, including abnormal stamens, and do not make the normal complement of floral organs. (C) Stamens from normal spikelet shown in (A). All stamens (three stamens per floret) in a normal spikelet are ~6mm at maturity, yellow in color, and have four plump locular lobes. (D) Stamens from fzt spikelet shown in (B). fzt spikelets produce more that six stamens; number of stamens per floret is variable. At maturity, fzt stamens are smaller than normal and variable in size; fzt stamens are often twisted or shrivelled and appear yellow to brown in color. Scale bars = 2mm.
Table 1.
Length of mature anthers from normal and fzt mutant plants.
Fig 3.
fzt anthers arrest at late stages of stamen maturation and do not dehisce.
(A) Stage of anther development is indicated, as well as the cell types and physiological events that occur at each stage. (B) Normal anthers fully mature and produce mature pollen; the septum degrades immediately prior to dehiscence. (C) fzt anthers often progress to stage 9, however never progress past stage 9 and do not dehisce. Scale bars = 20μm.
Table 2.
Frequency of locule phenotypes in mature fzt anthers.
Fig 4.
Pollen in fzt anthers has reduced viability.
Modified Alexander stain to assess pollen viability; viable pollen stains pink (black arrowheads), nonviable pollen stains blue (white arrowheads). Top box depicts whole anther, bottom box depicts close-up of pollen grains. (A) Almost all pollen from normal anthers is viable; pollen are round and plump in shape and stain pink. (B) fzt anthers (D-0.5) are heterogeneous. Class 1 anthers contain almost entirely viable pollen, similar to normal anthers. Class 2 anthers contain a mixture of viable and non-viable pollen grains. Nonviable pollen stains blue and is shrivelled. Class 3 anthers contain almost entirely nonviable pollen. C) fzt anthers (D+0.5) are all Class 2 or Class 3. Scale bars: top row = 500 μm; bottom row = 50 μm.
Table 3.
Germination frequencies of pollen from normal and fzt anthers.
Table 4.
fzt pollen arrests at the unicellular and bicellular stage.
Fig 5.
Pollen in fzt anthers does not accumulate starch.
(A) Pollen from normal anthers (D-0.5) stain black with iodine indicating high starch accumulation. (B) Pollen from fzt anthers (D-0.5) do not stain (low starch) or stain light brown (high starch) indicating minimal starch accumulation. (C, D) Pollen from fzt anthers one week (C) and two weeks (D) after normal siblings dehisced still had minimal starch accumulation. “Low starch” and “high starch” anthers show the range of phenotypes observed. Scale bars = 500μm.