PMC

(A) Tetrad of wild type pollen with two blue fluorescent and two red fluorescent pollen grains, indicative of an absence of recombination between the markers. A crossover between the centromere and the upper marker may or may not have occurred. (B) Tetrad of wild-type pollen with one blue fluorescent, one red fluorescent pollen, one blue and red fluorescent and one non-fluorescent pollen grain, indicative of a crossover between the two markers. (C, D) Dyads of pollen from the osd1-1 and tam-2 mutants, respectively, each with one blue fluorescent and one red fluorescent pollen grain. (E, F) Dyads from osd1-1 and tam-2 mutants, respectively, each with one blue and red fluorescent pollen grain and one blue fluorescent pollen grains. (G, H) Dyads from osd1-1 and tam-2 mutants, respectively, each with two blue and red fluorescent pollen grain. (I, J) Dyad in osd1-1 and tam-2, respectively, with one blue and red fluorescent pollen grain and one red fluorescent pollen grain. (K, L) Dyads from MiMe-1 and MiMe-2 plants, respectively, each with two blue and red fluorescent pollen grains. Interpretations of chromosome segregation and crossover position, are shown on the left. (wild type n = 266, osd1 n = 263, tam n = 369). Rare cases indicative of multiple crossovers are not shown. Scale bar = 20 µm.

High temperature-induced pollen and untreated control pollen. (A) Pollen collected from untreated buds; (B) High temperature-induced pollen, showing large pollen grains (arrows) and aborted pollen grains (arrow heads); (C) Tetrad shaped aborted grains failed in cytokinesis (arrows); (D) Conjoined grains failed in microspore segregation (arrow); (E) Control pollen with DAPI staining; (F) High temperature-induced pollen with DAPI staining, showing a large grain with large gametophytic nuclei. Bars = 50 μm.

Segregation distortion is almost absent if measured in pollen but abundant in DH plants. Allele frequencies for “Morex” (black) and “Barke” (gray) measured in pollen (dashed line) and DH plants (straight line) are shown as 10 Mbp moving averages for (A) chromosome 2H and (B) chromosome 3H of barley. Dashed red lines represent the significance threshold of distorted segregation ratios (χ²-test, P < 0.05). Pollen or DH allele frequencies above the significance threshold mark genomic regions of distorted segregation ratios.

A tetrad of wild-type (qrt1-2 background) pollen (A) from a plant that was hemizygous for a transgene encoding a cyan fluorescent protein has two fluorescent and two non-fluorescent pollen grains. Dyads of pollen (B and C) from the osd1-1 and tam-2 mutants, respectively, having one fluorescent and one non-fluorescent pollen grain in each case. Dyads (D and E) from the osd1-1 and tam-2 mutants, respectively, each showing two fluorescent pollen grains (osd1 n = 173, tam n = 214). Interpretations, of chromosome segregation and crossover position, are shown on the left. Scale bar = 20 µm.