The plants are almost too quick and small for summer fields. They can be grown indoors in small pots at high density with relatively little supplemental lighting. The plants usually produce tillers that can be cut back to assist shoot capping on the main stalk. Tom Thumb offers a number of advantages as an experimental or educational line of maize. For instance, a seed mutagenesis experiment can produce dominant mutations (plant or seed) during a single academic quarter or semester. Also, Tom Thumb might be good for production of transgenic maize using genotype-independent protocols.
We are currently breeding meiotic mutations into the Tom Thumb background for use in our work on meiotic telomere functions. We have examined the pollen mother cells and found them to be suitable for FISH and immunocytochemical analysis of meiotic prophase. Figure 2 shows that telomeres and several knobs can be detected by 3D FISH carried out as previously described (Bass et al., J. Cell Biol., 137:5-18).
We are collecting size-staged anthers
of green-house grown Tom Thumb plants. The size classes are "A" < 0.5
mm; "B" 0.5-1.5 mm; "C" 1.5-2.5 mm; and "D" 2.5-3.5 mm. Figure
3 shows DAPI images of representative meiotic nuclei from A, B, and
C size classes which contain anthers from premeiotic interphase plus early
leptotene, leptotene plus zygotene, and zygotene plus pachytene, respectively.
These anthers will provide mRNA preparations for microarray analysis of
meiotic gene expression. Anthers from the larger floret are dissected in
the greenhouse, measured on a ruler under a dissecting microscope, and
frozen. Anthers are collected for four months at a time, then a new set
of collections is started. Those shown in Figure 3 are from the first trimester
of 2000 (Jan-April).
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